Updated on 2024/04/18

写真a

 
HOMMA, Takayuki
 
Affiliation
Faculty of Science and Engineering, School of Advanced Science and Engineering
Job title
Professor
Degree
博士(工学) ( 早稲田大学 )
Ph. D

Education Background

  •  
    -
    1992

    Waseda University   Graduate School, Division of Science and Engineering  

Committee Memberships

  • 2011
    -
     

    国際電気化学会  第5部門部門長

  • 2011
    -
     

    表面技術協会  常任理事

  • 2011
    -
     

    International Society of Electrochemistry  Chair, Division 5

  • 2011
    -
     

    Surface Finishing Society of Japan  Exective Board Member

  • 2009
    -
    2011

    エレクトロニクス実装学会  理事

  • 2009
    -
    2011

    電気化学会  常任理事

  • 2009
    -
    2011

    Japan Institute of Electronics Packaging  Exective Board Member

  • 2009
    -
    2011

    The Electrochemical Society of Japan  Exective Board Member

  • 2004
    -
    2007

    日本化学会  化学教育協議会 副議長

  • 2004
    -
    2007

    Chemical Socoety of Japan  Vice Chair, Council of Chemical Education

  • 2003
    -
     

    米国電気化学会  会誌"The Journal of the Electrochemical Society" 編集委員

  • 2003
    -
     

    The Electrochemical Society  Editorial Board Member, The Journal of The Electrochemical Society

▼display all

Professional Memberships

  •  
     
     

    International Society of Electrochemistry

  •  
     
     

    The Electrochemical Society

  •  
     
     

    日本磁気学会

  •  
     
     

    電気学会

  •  
     
     

    応用物理学会

  •  
     
     

    Japan Institute of Electronics Packaging

  •  
     
     

    Surface Finishing Society of Japan

  •  
     
     

    The Electrochemical Society of Japan

  •  
     
     

    Chemical Socoety of Japan

▼display all

Research Areas

  • Electron device and electronic equipment / Functional solid state chemistry / Nano/micro-systems

Research Interests

  • Electrochemistry, Nano fabrication process, MEMS, Surface chemistry, Data storage devices

Awards

  • 電気化学会 学術賞

    2015.03  

  • 電気化学会 論文賞

    2012.03  

  • Research Award(Electrodeposition Division), The Electrochemical Society

    2010.10  

  • Best Paper Presentation Award, Interfinish

    2000.09  

  • 電気化学会 佐野賞・進歩賞

    1999.04  

  • 表面技術協会 進歩賞

    1999.03  

  • 表面技術協会 柴田記念賞

    1991.03  

▼display all

 

Papers

  • Transmission-type plasmonic sensor for surface-enhanced Raman spectroscopy

    Masahiro Yanagisawa, Mikiko Saito, Masahiro Kunimoto, Takayuki Homma

    APPLIED PHYSICS EXPRESS   9 ( 12 )  2023.12  [Refereed]

     View Summary

    We present a novel optical device for the analysis of chemical surface properties utilizing surface-enhanced Raman scattering. The device, a transmission-type plasmonic sensor (TPS), offers the advantages of high sensitivity, nondestructive sample characterization, simple setup, and low-cost fabrication. The TPS is composed of Ag nanoparticles (NPs) deposited on a convex quartz glass substrate. The enhanced Raman spectrum is acquired by focusing a laser beam perpendicular to the sample surface through the substrate. The laser beam generates plasmon polarization in droplet-shaped Ag NPs at the sensor/sample interface. Our results indicate the potential of the device as a versatile surface-analytical tool. (C) 2016 The Japan Society of Applied Physics

    DOI

    Scopus

    8
    Citation
    (Scopus)
  • Surface enhanced Raman spectroscopy measurement of surface pH at the electrode during Ni electrodeposition reaction

    Homma, Takayuki, Homma, Takayuki, Kunimoto, Masahiro, Sasaki, Moe, Hanai, Tomoya, Yanagisawa, Masahiro

    Journal of Applied Electrochemistry   533 ( 6 ) 1 - 7  2023.12

     View Summary

    © 2017 Springer Science+Business Media B.V., part of Springer Nature Abstract: In this work, we developed a precise approach to analyze local proton concentration at the solid/liquid interface of electrodes, i.e. “surface pH”, during electrochemical reactions. For this, surface enhanced Raman spectroscopy (SERS) was applied to analyze pH-dependent structural changes of the –COOH group of p-mercaptobenzoic acid (p-MBA) modified onto Au nanoparticles (NPs) on the substrate close to a working electrode. Measurements using this system identified deprotonation of –COOH of p-MBA. Since preliminary experiments and density functional theory calculations suggest that the pKa of p-MBA attached to Au NPs is close to that in bulk solution, the SERS results indicate pH increase due to proton consumption by the cathodic overpotential of the working electrode. As an example, we applied this system to surface pH monitoring in electrodeposition process of Ni in an acidic bath, which indicated the validity of our method for precise detection of pH changes at electrode interfaces in situ. Graphical Abstract: [Figure not available: see fulltext.]

    DOI

    Scopus

    9
    Citation
    (Scopus)
  • Effect of indium and tin additives on the surface morphology of zinc negative electrodes for Zn-Ni flow-assisted batteries

    T.Otani, T.Okuma, T.Homma

    J. Electroanal. Chem.   878 ( 1 ) 341 - 348  2023.12  [Refereed]

     View Summary

    The effect of adding Si powder/granules on the electrochemical reduction rate of SiO2 granules in molten CaCl2 was investigated. Various starting materials were prepared by mixing different amounts (up to 80 mass pct) of Si powder/granules (four different sizes: &lt
     5, 20 to 100, 100 to 250 µm, 0.5 to 1.0 mm) with SiO2 granules, with these materials then being electrochemically reduced for 20 minutes in molten CaCl2 at 0.6 V vs Ca2+/Ca and a temperature of 1123 K (850 °C). The effects of the size and amount of Si added on the reaction rates were then studied. When the size of the Si powder added is less than 5 µm, the reaction rate decreases as more Si is added. When Si with a size of 20 to 100 or 100 to 250 µm is used, the reaction rate does not change substantially with the amount added. When 0.5 to 1.0 mm Si is used, the reduction rate is the largest when 40 mass pct Si is added. The reduction rate is influenced by the reaction surface and the diffusion of O2− ions in the mixture.

    DOI

  • Effect of Li+ Addition during Initial Stage of Electrodeposition Process on Nucleation and Growth of Zn

    Y.Onabuta, M.Kunimoto, S.Wang, Y.Fukunaka, H.Nakai, T.Homma

    J. Elecrochem. Soc.   169 ( 12 )  2023.09  [Refereed]

     View Summary

    We present a novel optical device for the analysis of chemical surface properties utilizing surface-enhanced Raman scattering. The device, a transmission-type plasmonic sensor (TPS), offers the advantages of high sensitivity, nondestructive sample characterization, simple setup, and low-cost fabrication. The TPS is composed of Ag nanoparticles (NPs) deposited on a convex quartz glass substrate. The enhanced Raman spectrum is acquired by focusing a laser beam perpendicular to the sample surface through the substrate. The laser beam generates plasmon polarization in droplet-shaped Ag NPs at the sensor/sample interface. Our results indicate the potential of the device as a versatile surface-analytical tool. (C) 2016 The Japan Society of Applied Physics

    DOI

    Scopus

    2
    Citation
    (Scopus)
  • Depth profiling of APTES self-assembled monolayers using surface-enhanced confocal Raman microspectroscopy

    Yingying Sun, Masahiro Yanagisawa, Masahiro Kunimoto, Masatoshi Nakamura, Takayuki Homma

    SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY   184 ( 1 ) 1 - 6  2023.09  [Refereed]

     View Summary

    The internal structure of self -assembled monolayers (SAMs) such as 3-aminopropyltriethoxysilane (APTES) fabricated on a glass substrate is difficult to characterize and analyze at nanometer level. In this study, we employed surface -enhanced Raman spectroscopy (SERS) to study the internal molecular structure of APTES SAMs. The sample APTES SAMs were deposited with Ag nanoparticles to enhance the Raman signal and to obtain subtler structure information, which were supported by density functional theory calculations. In addition, in order to carry out high -resolution analysis, especially for vertical direction, a fine piezo electric positioner was used to control the depth scanning with a step of 0.1 nm. We measured and distinguished the vertical Raman intensity variations of specific groups in APTES, such as Ag/NH2, CH2, and Si-O, with high resolution. The interfacial bond at the two interfaces of Ag-APTES and APTES-SiO2 was identified. Moreover, APTES molecule orientation was demonstrated to be inhomogeneous from frequency shift. (C) 2017 Elsevier B.V. All rights reserved.

    DOI

    Scopus

    21
    Citation
    (Scopus)
  • Roles of Water Molecules in Electroless Deposition Processes

    M.Kunimoto, T.Homma

    ELECTROCHIMICA ACTA   73 ( 10 ) 471 - 475  2023.08

     View Summary

    The morphological evolution of zinc during electrodeposition from an alkaline zincate solution, i.e., corresponding to charging operation in secondary zinc batteries, was investigated. The initiation and propagation of mossy structures were particularly focused; mossy structures represent one of the undesired, irregular morphologies at low cathodic overpotential. Scanning electron microscopy observations showed that mossy structures formed transiently from layer-like morphology followed by the formation of protrusions with a size of submicrometers. These protrusions still exhibited layer-like features in the initial stage. In addition to this transition behavior, the propagation of mossy structures was monitored in situ by optical microscopy. At -5.0 mA cm(-2), mossy structures formed successively and propagated, while there was no clear change in layer-like morphology during deposition outside these characteristic structures. At -20 mA cm(-2), the layer-like growth proceeded for longer duration and the population of the mossy structures apparently decreased. However, they continuously increased in size followed by successive formation of mossy structures once initiated. From these results, growth mode of zinc at low cathodic overpotential transiently changed from layer-like growth to mossy structure evolution accompanied with dynamic variations in local current density. (c) 2016 Elsevier Ltd. All rights reserved.

    DOI

    Scopus

    50
    Citation
    (Scopus)
  • Fabrication of a plasmonic sensor for surface-enhanced Raman spectroscopy using electroless deposition of Ag with hypophosphite

    Zhengke Tu, Masahiro Kunimoto, Masahiro Yanagisawa, Takayuki Homma

    Electrochemistry Communications   152   107513 - 107513  2023.07  [Refereed]

    DOI

    Scopus

    1
    Citation
    (Scopus)
  • Morphological evolution of mossy structures during the electrodeposition of zinc from an alkaline zincate solution

    Tomohiro Otani, Masato Nagata, Yasuhiro Fukunaka, Takayuki Homma

    ELECTROCHIMICA ACTA   206 ( 206 ) 366 - 373  2023.07  [Refereed]

     View Summary

    The morphological evolution of zinc during electrodeposition from an alkaline zincate solution, i.e., corresponding to charging operation in secondary zinc batteries, was investigated. The initiation and propagation of mossy structures were particularly focused; mossy structures represent one of the undesired, irregular morphologies at low cathodic overpotential. Scanning electron microscopy observations showed that mossy structures formed transiently from layer-like morphology followed by the formation of protrusions with a size of submicrometers. These protrusions still exhibited layer-like features in the initial stage. In addition to this transition behavior, the propagation of mossy structures was monitored in situ by optical microscopy. At -5.0 mA cm(-2), mossy structures formed successively and propagated, while there was no clear change in layer-like morphology during deposition outside these characteristic structures. At -20 mA cm(-2), the layer-like growth proceeded for longer duration and the population of the mossy structures apparently decreased. However, they continuously increased in size followed by successive formation of mossy structures once initiated. From these results, growth mode of zinc at low cathodic overpotential transiently changed from layer-like growth to mossy structure evolution accompanied with dynamic variations in local current density. (c) 2016 Elsevier Ltd. All rights reserved.

    DOI

    Scopus

    50
    Citation
    (Scopus)
  • Study of Multilayer X-ray Absorbers to Improve Detection Efficiency of TES X-ray Microcalorimeter Arrays

    T. Hayashi, K. Nagayoshi, H. Muramatsu, N. Y. Yamasaki, K. Mitsuda, M. Saito, T. Homma, T. Hara, H. Noda

    JOURNAL OF LOW TEMPERATURE PHYSICS   184 ( 1月2日 ) 257 - 262  2023.07  [Refereed]

     View Summary

    We report the fabrication and evaluation of the Cu/Bi bilayer absorber with electrodeposition. We designed the Cu/Bi absorber to satisfy the requirements for scanning transmission electron microscope (STEM). The residual resistivity ratios of films of Cu and Bi with electrodeposition was and , respectively; these values are sufficient for the requirements of STEM. We found that the Cu/Bi bilayer absorber TES microcalorimeter experienced a pulse-shape variation and we considered that these variations were caused by the quality of the contact surface between the absorber and TES. In addition, we examined the structure of the absorber using focus ion beam analysis and STEM. The results suggest that an oxidation between the Cu and seed layer, in which the layer is an electrode for electrodeposition, yielded variations. Moreover, thermal simulation suggests that the thermal conduction between the absorber and TES caused variations. The results of this study will improve the process of Bi electrodeposition.

    DOI

    Scopus

    3
    Citation
    (Scopus)
  • Zn dissolution−passivation behavior with ZnO formation via in-situ characterizations

    T.Wang, M.Kunimoto, M.Yanagisawa, M.Morita, T.Abe, T.Homma

    Energy & Environ. Mater.   9 ( 12 )  2023.07  [Refereed]

     View Summary

    We present a novel optical device for the analysis of chemical surface properties utilizing surface-enhanced Raman scattering. The device, a transmission-type plasmonic sensor (TPS), offers the advantages of high sensitivity, nondestructive sample characterization, simple setup, and low-cost fabrication. The TPS is composed of Ag nanoparticles (NPs) deposited on a convex quartz glass substrate. The enhanced Raman spectrum is acquired by focusing a laser beam perpendicular to the sample surface through the substrate. The laser beam generates plasmon polarization in droplet-shaped Ag NPs at the sensor/sample interface. Our results indicate the potential of the device as a versatile surface-analytical tool.

    DOI CiNii

    Scopus

  • Effect of lead and tin additives on surface morphology evolution of electrodeposited zinc

    Tomohiro Otani, Yasuhiro Fukunaka, Takayuki Homma

    ELECTROCHIMICA ACTA   242 ( 6 ) 364 - 372  2023.07  [Refereed]

     View Summary

    Effects of Pb and Sn additives on electrodeposition of Zn were investigated for the applications in Zn secondary battery, focused on their roles on morphological evolution. Similarly to well-known effect of Pb addition to smoothly electrodeposit Zn film surface, Sn also exhibited to suppress the formation of mossy structures, which were highly filamentous Zn electrodeposits to cause frequently battery failure. Pb significantly shifted deposition potential of Zn to negative value at concentration less than 1.0 mmol dm(-3), while Sn showed no substantial effect even at 50 mmol dm(-3). The morphological evolution analysis demonstrated that the addition of 1.0 mmol dm(-3) Pb significantly altered nucleation behavior of Zn at initial stages of deposition; stacking of layer-like structures (microsteps) were altered to discrete and uniform nuclei of Zn preferentially oriented to (002) direction. In contrast, with Sn additive, morphological features at the initial stage of deposition were similar to that without additive. However, microsteps evolution was gradually suppressed and relatively strong (002) texture of electrodeposited Zn was mitigated by Sn addition. These results suggested that the beneficial roles of Pb and Sn addition on Zn morphological evolution were ascribed to different reasons; Pb diminished the active growth sites of Zn surface by suppressing the deposition reaction of Zn, while Sn suppressed microsteps evolution by different texture evolution of Zn. (C) 2017 Elsevier Ltd. All rights reserved.

    DOI

    Scopus

    74
    Citation
    (Scopus)
  • Potentiostatic Li Electrodeposition in LiTFSI-PC Electrolyte

    Tetsuo Nishida, Yasuhiro Fukunaka, Takayuki Homma, Toshiyuki Nohira

    The Journal of Physical Chemistry C   127 ( 26 ) 12454 - 12465  2023.06  [Refereed]

    DOI

    Scopus

  • Potentiostatic Li Electrodeposition in LiTFSI-PC Electrolyte

    T.Nishida, lY.Fukunaka, T.Homma.T.Nohira

    J. Phys Chem C   127 ( 26 ) 12454 - 12465  2023.06  [Refereed]

     View Summary

    A structure's temperature can be determined from the Raman spectrum using the frequency and the ratio of the intensities of the anti-Stokes and Stokes signals (the I-as/I-s ratio). In this study, we apply this approach and an equation relating the temperature, Raman frequency, and I-as/I-s ratio to in-situ estimation of the phase change point of a (3-aminopropyl)triethoxysilane self-assembled monolayer (APTES SAM). Ag nanoparticles were deposited on APTES to enhance the Raman signals. A time-resolved measurement mode was used to monitor the variation in the Raman spectra in situ. Moreover, the structural change in APTES SAM (from ordered to disordered structure) under heating was discussed in detail, and the phase change point (around 118 degrees C) was calculated. (C) 2015 Elsevier B.V. All rights reserved.

    DOI

    Scopus

  • Fabrication of plasmonic sensors by electroless deposition of Ag nanoparticles with hypophosphite

    M.Kunimoto, M.Yanagisawa, T.Homma

    Electrochem. Commun.   152   107513 - 107513  2023.06  [Refereed]

     View Summary

    We have fabricated Co-Pt nanodot arrays by combining electrodeposition with electron beam lithography (EBL) for applications in ultra-high density magnetic recording media, such as bit-patterned media (BPM). In this work, we analyzed the initial nucleation and growth of Co-Pt inside nanopores to achieve nanodot arrays with high deposition uniformity, as well as magnetic properties. At -900 mV (vs. Ag/AgCl), multiple nuclei of 2.0-3.0 nm in size were randomly distributed, even in nanopores with a 10 nm diameter, which could result in a lack of uniformity in the magnetic properties. The number of nuclei was then reduced by applying a less negative potential (>-700 mV vs. Ag/AgCl) to deposit a single nucleus inside each nanopore. As a result, a single grain of 5.0-10 nm in size was successfully deposited inside the nanopore, which could induce uniform magnetic properties in each nanodot. In addition, at less negative potentials, the coercivity of the Co-Pt films increased, which was induced by the epitaxial-like growth of Co-Pt from the Ru substrate. Cross-sectional TEM analysis suggested that Co-Pt deposited with a less negative potential was single crystalline with uniform hcp lattice fringes in the direction perpendicular to the Ru interface, indicating the formation of highly uniform nanodot arrays with high perpendicular magnetic anisotropy. (C) 2015 Elsevier Ltd. All rights reserved.

    DOI

    Scopus

    1
    Citation
    (Scopus)
  • 計算化学と分光分析を組み合わせた電解めっき・無電解めっきの解析手法

    M.Masahiro, M.Kunimoto

    ECS Trans.   80 ( 88 ) 151 - 161  2023.06

     View Summary

    As one of the most cost-effective methods to produce solar-grade silicon (SOG-Si), purification of silica solution by extracting its impurities through wet chemical processes has been proposed. This paper reports on the design of channel type reactor for liquid-liquid extraction to purify silica solution, focusing particularly on the extraction of B (boric acid) in aqueous phase with 2,2,4-trimethyl-1,3-pentanediol (TMPD) in organic phase. The reactor fabricated by 3D printing technology was designed to have two characteristic structures: (i) a throat structure that shows gradually diverging part after converging near Y shaped inlets and (ii) obstacles structure on downstream. Two solutions were made to contact with each other by turbulent mixing around the throat structure, causing small droplets formation that was dispersed and retained efficiently even on downstream by obstacles structure. This droplet dispersion shortens diffusion distance of boric acid to meet TMPD at the liquid-liquid interface, providing efficient mass transfer. At higher flow rate i.e., 380 ml/min, the extraction efficiency was 97.43% after the multi stage process. The results suggest that the channel type reactor designed here is profitable for elimination of impurities, such as B or P, in silica solution to produce SOG-Si.

    DOI

  • Thickness control of 3-dimensional mesoporous silica ultrathin films by wet-etching

    Maho Kobayashi, Kyoka Susuki, Tomohiro Otani, Shinpei Enomoto, Haruo Otsuji, Yoshiyuki Kuroda, Hiroaki Wada, Atsushi Shimojima, Takayuki Homma, Kazuyuki Kuroda

    NANOSCALE   9 ( 24 ) 8321 - 8329  2023.06  [Refereed]

     View Summary

    The thickness of 3-dimensional (3D) mesoporous silica ultrathin films was controlled at a single-nano-meter scale by wet-etching. A drop casting method with an aqueous etchant of ammonium fluoride was effective in etching the surfaces of films in the direction perpendicular to their substrates. The decrease in the film thickness depends on the interface tension of etching solutions. The wettability of thin films also influences the etching. CoPt nanodots were electrodeposited within ultrathin silica films on Ru substrates to form CoPt nanodot patterns.

    DOI

    Scopus

    11
    Citation
    (Scopus)
  • Key Ionic Electrolytes for Highly Self‐Stable Light‐Emitting Electrochemical Cells Based on Ir(III) Complexes

    E. Fresta, M.A Monclus, M. Bertz, C. Ezquerro, J. M. Molina-Aldareguia, J. R. Berenguer, M. Kunimoto, T. Homma, R. D. Costa

    Adv. Opt. Mater.   8 ( 12 ) 1 - 14  2023.06  [Refereed]

     View Summary

    FeCuPt nanodot arrays were fabricated by electrodeposition onto a nanopore patterned substrate fabricated by electron beam lithography (EBL), for the purpose to manufacture and characterize model bit-patterned media. Addition of Cu to FePt was carried out to accelerate the phase transformation of FePt into the L10 -ordered phase in order to fabricate nanodot arrays with hard and uniform magnetic properties. Composition of the FeCuPt ternary alloy films was optimized by varying applied potential and CuSO4 concentration to form single L10 phase (40-50 at% Pt and 25 at% Cu). Annealing at 450 °C resulted in the phase transformation from fcc to L10 in FeCuPt ternary alloy films, whereas FePt binary alloy films did not show a phase transformation. Perpendicular coercivities of FeCuPt and FePt were 6 and 1 kOe, respectively, annealing at 450 °C, indicating the formation of the L10 phase with lower annealing temperature by Cu incorporation. FeCuPt nanodot arrays with 20 nm in diameter and 35 nm in pitch were successfully fabricated with the nanopore patterned substrate fabricated by EBL. In addition, cross-sectional transmission electron microscope analysis of FeCuPt nanodot arrays showed clear stacking of the L10 (111) lattice in a perpendicular direction through the growth direction having a single crystal nature, whereas phase transformation was insufficient with FePt nanodot arrays. The collective results have successfully demonstrated the electrochemical fabrication of ultra-fine FePt nanodot arrays with L10 structure by promoting L10 ordering with Cu additions.

    DOI

    Scopus

    15
    Citation
    (Scopus)
  • Experimental Measurement of Overpotential Sources during Anodic Gas Evolution in Aqueous and Molten Salt Systems

    B. Chmielowiec, T. Fujimura, T. Otani, K. Aoyama, T. Nohira, T. Homma, Y. Fukunaka, A. Allanore

    J. Electrochem. Soc.   166 ( 10 ) E323 - E329  2023.06  [Refereed]

     View Summary

    Current interrupt and galvanostatic EIS techniques were utilized in a complementary fashion to characterize the different sources of overpotential during anodic gas evolution. Room temperature anodic evolution of oxygen at a nickel working electrode in aqueous potassium hydroxide and the high temperature (348°C) anodic evolution of chlorine at a glassy carbon working electrode in molten (LiCl) -(KCl)13.3-(CsCl) where investigatd. Combining of the two techniques enables to separate the total measured overpotential into its ohmic, charge transfer, and mass transfer components. Potential decay curves indicated that natural convection (due to both bubble evolution and density driven flow) was a major driving force in reestablishing equilibrium conditions at the working electrode surface. During oxygen evolution, charge transfer resistance dominated the total overpotential at low current densities, but as the current density approached ∼100mA/cm , mass transfer overpotentials and ohmic overpotential became non-negligible. The mass transfer overpotential during chlorine evolution was found to be half that found during oxygen evolution. 57.5 29.2 2

    DOI

    Scopus

    6
    Citation
    (Scopus)
  • Mechanism of Electrolytic Reduction of SiO2 at Liquid Zn Cathode in Molten CaCl2

    Y. Ma, A. Ido, K. Yasuda, R. Hagiwara, T. Homma, T. Nohira

    J. Electochem. Soc.   166 ( 6 ) D162 - D167  2023.06  [Refereed]

    DOI

    Scopus

    14
    Citation
    (Scopus)
  • In Situ Measurement for Diffusion-Adsorption Process of Cl− and SPS in Through-Silicon Via Using SERS Effect Produced by Cu Nanodot Arrays

    M. Kunimoto, F. Yamaguchi, M. Yanagisawa, T. Homma

    J. Electrochem. Soc.   166 ( 6 ) D212 - D217  2023.06  [Refereed]

  • SERS Analysis of Buried Interface Using Plasmon Sensor

    T.Homma, M.Kunimoto, M.Beltz, M.Yanagisawa

    JOURNAL OF LOW TEMPERATURE PHYSICS   86 ( 8 ) 372 - 375  2023.05

     View Summary

    We report the fabrication and evaluation of the Cu/Bi bilayer absorber with electrodeposition. We designed the Cu/Bi absorber to satisfy the requirements for scanning transmission electron microscope (STEM). The residual resistivity ratios of films of Cu and Bi with electrodeposition was and , respectively; these values are sufficient for the requirements of STEM. We found that the Cu/Bi bilayer absorber TES microcalorimeter experienced a pulse-shape variation and we considered that these variations were caused by the quality of the contact surface between the absorber and TES. In addition, we examined the structure of the absorber using focus ion beam analysis and STEM. The results suggest that an oxidation between the Cu and seed layer, in which the layer is an electrode for electrodeposition, yielded variations. Moreover, thermal simulation suggests that the thermal conduction between the absorber and TES caused variations. The results of this study will improve the process of Bi electrodeposition.

    DOI

    Scopus

    3
    Citation
    (Scopus)
  • Analysis of the behavior of Zn atoms with a Pb additive on the surface during Zn electrodeposition

    Y.Onabuta, M.Kunimoto, S.Wang, Y.Fukunaga, H.Nakai, G.Zangari, T.Homma

    Electrochem. Commun.   138   195 - 198  2023.05  [Refereed]

     View Summary

    The thermal stability of graphene has a close relationship with defect generation, thermal oxidation, which in turn have a significant bearing on its properties and applications. This report discusses the effect of confocal laser heating on the structure of single-layer graphene (SLG) on the basal plane and the edge. The thermal stability of SLG basal plane and edge was demonstrated to be different by using in situ anti-Stokes and Stokes Raman spectroscopy. The basal plane was found to be unstable above 500 degrees C, while the edge could not endure even 220 degrees C. The variation in the intensity of D, G, and 2D peaks and the intensity ratios of I(D)/I(G) and I(2D)/I(G) indicated that the thermal instability started with defect generation at the basal plane. The initial point defects at edge were partially eliminated at low temperature and generated again at temperatures above 220 degrees C. (C) The Electrochemical Society of Japan, All rights reserved.

    DOI CiNii

    Scopus

    2
    Citation
    (Scopus)
  • Electrolytic Production of Silicon Using Liquid Zinc Alloy in Molten CaCl2

    K. Yasuda, T. Shimano, R. Hagiwara, T. Homma, T. Nohira

    J. Electrochem. Soc.   86 ( 164 ) H5049 - H5056  2023.05  [Refereed]

     View Summary

    A new electrolytic production process for solar-grade Si has been proposed utilizing liquid Si-Zn alloy cathode in molten CaCl2. To establish this process, the behavior of liquid Zn metal in molten CaCl2 at 1123 K was investigated. Evaporation of Zn metal was largely suppressed by immersion in the molten salt, which enabled the use of a Zn electrode despite its high vapor pressure. Cyclic voltammetry results suggested that the reduction of SiO2 on a Zn cathode proceeded at a more negative than 1.45 V vs. Ca2+/Ca. After potentiostatic electrolysis at 0.9 V, Si particles with sizes of 2-30 mu m were precipitated in the solidified Zn matrix by a slow cooling process. The rate-determining step for electrochemical reduction of SiO2 on the Zn cathode was discussed on the basis of a measurement of the alloying rate between solid Si and liquid Zn. (C) The Author(s) 2017. Published by ECS. This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 License (CC BY, http://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse of the work in any medium, provided the original work is properly cited. All rights reserved.

    DOI

    Scopus

    21
    Citation
    (Scopus)
  • Structural control of ultra-fine CoPt nanodot arrays via electrodeposition process

    Siggi Wodarz, Takashi Hasegawa, Shunji Ishio, Takayuki Homma

    JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS   430 ( 14 ) 52 - 58  2023.05  [Refereed]

     View Summary

    CoPt nanodot arrays were fabricated by combining electrodeposition and electron beam lithography (EBL) for the use of bit-patterned media (BPM). To achieve precise control of deposition uniformity and coercivity of the CoPt nanodot arrays, their crystal structure and magnetic properties were controlled by controlling the diffusion state of metal ions from the initial deposition stage with the application of bath agitation. Following bath agitation, the composition gradient of the CoPt alloy with thickness was mitigated to have a near-ideal alloy composition of Co:Pt =80:20, which induces epitaxial-like growth from Ru substrate, thus resulting in the improvement of the crystal orientation of the hcp (002) structure from its initial deposition stages. Furthermore, the cross-sectional transmission electron microscope (TEM) analysis of the nanodots deposited with bath agitation showed CoPt growth along its c-axis oriented in the perpendicular direction, having uniform lattice fringes on the hcp (002) plane from the Ru underlayer interface, which is a significant factor to induce perpendicular magnetic anisotropy. Magnetic characterization of the CoPt nanodot arrays showed increase in the perpendicular coercivity and squareness of the hysteresis loops from 2.0 kOe and 0.64 (without agitation) to 4.0 kOe and 0.87 with bath agitation. Based on the detailed characterization of nanodot arrays, the precise crystal structure control of the nanodot arrays with ultra-high recording density by electrochemical process was successfully demonstrated.

    DOI

    Scopus

    7
    Citation
    (Scopus)
  • Development of TES Microcalorimeters with Solar-Axion Converter

    R. Konno, K. Maehisa, K. Mitsuda, N.Y Yamasaki, R. Yamamoto, T. Hayashi, H. MuramatsuY. Nakashima, K. Maehata, T. Homma, M. Saito, M. Sugie, R. D. Costa

    J. Low Temp. Pys.   199   654 - 662  2023.05  [Refereed]

     View Summary

    In this work, the behavior of an additive designed to aid electrodeposition in through-silicon via (TSV) structures is monitored directly using surface enhanced Raman spectroscopy (SERS). A horizontal via structure with a transparent ceiling (corresponding to the side wall of the TSV) was prepared, which allowed the probe laser to reach the bottom of the structure (corresponding to the opposite side of the TSV wall). Au nanoparticles of size ~5 nm deposited on the bottom of the structure produced a SERS effect and enhanced the Raman signals of chemical species migrating nearby. The diffusion behavior of the additive inside the via structure could be monitored with high sensitivity by detecting these enhanced signals. As a case study, this direct measurement method was successfully used to follow the diffusion of a small amount of Janus Green B, a common additive for Cu electrodeposition. The diffusion coefficient of the additive determined by these measurements turned out to be different to that estimated electrochemically on flat electrodes. One of the advantages of our direct measurement setup is the ability to exclude the undesirable environmental changes that often occur in electrochemical measurements.

    DOI

    Scopus

    2
    Citation
    (Scopus)
  • Analysis and Control of the Initial Electrodeposition Stages of Co-Pt Nanodot Arrays

    Siggi Wodarz, Junya Abe, Takayuki Homma

    ELECTROCHIMICA ACTA   197 ( 197 ) 330 - 335  2023.04  [Refereed]

     View Summary

    We have fabricated Co-Pt nanodot arrays by combining electrodeposition with electron beam lithography (EBL) for applications in ultra-high density magnetic recording media, such as bit-patterned media (BPM). In this work, we analyzed the initial nucleation and growth of Co-Pt inside nanopores to achieve nanodot arrays with high deposition uniformity, as well as magnetic properties. At -900 mV (vs. Ag/AgCl), multiple nuclei of 2.0-3.0 nm in size were randomly distributed, even in nanopores with a 10 nm diameter, which could result in a lack of uniformity in the magnetic properties. The number of nuclei was then reduced by applying a less negative potential (>-700 mV vs. Ag/AgCl) to deposit a single nucleus inside each nanopore. As a result, a single grain of 5.0-10 nm in size was successfully deposited inside the nanopore, which could induce uniform magnetic properties in each nanodot. In addition, at less negative potentials, the coercivity of the Co-Pt films increased, which was induced by the epitaxial-like growth of Co-Pt from the Ru substrate. Cross-sectional TEM analysis suggested that Co-Pt deposited with a less negative potential was single crystalline with uniform hcp lattice fringes in the direction perpendicular to the Ru interface, indicating the formation of highly uniform nanodot arrays with high perpendicular magnetic anisotropy. (C) 2015 Elsevier Ltd. All rights reserved.

    DOI

    Scopus

    3
    Citation
    (Scopus)
  • Fabrication of a 64-Pixel TES Microcalorimeter Array With Iron Absorbers Uniquely Designed for 14.5-keV Solar Axion Search

    Y.Yagi, T.Hayashi, K.Tanaka, R.Miyagawa, R.Ota, N.Y.Yamasaki, K.Mitsuda, N.Yoshida, M.Saito, T.Homma

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   33 ( 5 ) 2100805 - 2100805  2023.04  [Refereed]

     View Summary

    As a fundamental study to develop a new process for producing solar-grade silicon, the effect of granule size on the kinetics of the electrochemical reduction of SiO2 granules in molten CaCl2 was investigated. SiO2 granules with different size ranges were electrolyzed in molten CaCl2 at 1123 K (850 A degrees C). The reduction kinetics was evaluated on the basis of the growth rate of the reduced Si layer and the behavior of the current during electrolysis. The results indicated that finer SiO2 granules are more favorable for a high reduction rate because the contact resistance between the bottom Si plate and the reduced Si particles is small and the diffusion of O2- ions in CaCl2 inside the porous Si shell is easy. Electrolysis using SiO2 granules less than 0.1 mm in size maintained a current density of no less than 0.4 A cm(-2) within 20 minutes, indicating that the electrochemical reduction of fine SiO2 granules in molten CaCl2 has the potential of becoming a high-yield production process for solar-grade silicon.

    DOI

  • Effect of Channel Type Reactor for Efficient Extraction of B for Production of High Purity Silica

    Y.V.Akash, M.Kunimoto, M.Mimura, Y.Fukunaka, T.Homma

    J. Surf. Finish. Soc. Jpn.   73 ( 6 ) 312 - 318  2023.04  [Refereed]

     View Summary

    Total reflection X-ray fluorescence (TXRF) analysis is extensively used by the semiconductor industry for measuring trace metal contamination on silicon surfaces. In addition to determining the quantity of impurities on a surface, TXRF can reveal information about the vertical distribution of contaminants by measuring the fluorescence signal as a function of the angle of incidence. In this study, two samples were intentionally contaminated with copper in non-deoxygenated and deoxygenated ultrapure water (UPW) resulting in impurity profiles that were either atomically dispersed in a thin film or particle-like, respectively. The concentration profile of the samples immersed into deoxygenated UPW was calculated using a theoretical concentration profile representative of particles, yielding a mean particle height of 16.1 nm. However, the resulting theoretical profile suggested that a distribution of particle heights exists on the surface. The fit of the angular distribution data was further refined by minimizing the residual error of a least-squares fit employing a model with a Gaussian distribution of particle heights about the mean height. The presence of a height distribution was also confirmed with atomic force microscopy measurements.

    DOI

    Scopus

    6
    Citation
    (Scopus)
  • Surface-enhanced Raman spectroscopy for versatile in situ measurements of local pH near electrode surface

    K.Ide, M.Kunimoto, T.Mori, M.Yanagisawa, T.Homma

    Electroanal.   34 ( 1 ) 1682 - 1689  2023.04  [Refereed]

     View Summary

    CoPt nanodot arrays were fabricated by combining electrodeposition and electron beam lithography (EBL) for the use of bit-patterned media (BPM). To achieve precise control of deposition uniformity and coercivity of the CoPt nanodot arrays, their crystal structure and magnetic properties were controlled by controlling the diffusion state of metal ions from the initial deposition stage with the application of bath agitation. Following bath agitation, the composition gradient of the CoPt alloy with thickness was mitigated to have a near-ideal alloy composition of Co:Pt =80:20, which induces epitaxial-like growth from Ru substrate, thus resulting in the improvement of the crystal orientation of the hcp (002) structure from its initial deposition stages. Furthermore, the cross-sectional transmission electron microscope (TEM) analysis of the nanodots deposited with bath agitation showed CoPt growth along its c-axis oriented in the perpendicular direction, having uniform lattice fringes on the hcp (002) plane from the Ru underlayer interface, which is a significant factor to induce perpendicular magnetic anisotropy. Magnetic characterization of the CoPt nanodot arrays showed increase in the perpendicular coercivity and squareness of the hysteresis loops from 2.0 kOe and 0.64 (without agitation) to 4.0 kOe and 0.87 with bath agitation. Based on the detailed characterization of nanodot arrays, the precise crystal structure control of the nanodot arrays with ultra-high recording density by electrochemical process was successfully demonstrated.

    DOI

    Scopus

    3
    Citation
    (Scopus)
  • Morphology Control of Cu Added Electrodeposited Bi-Sb-Te Thick Films For Micro-Thermoelectric Devices

    C.Chen, M.Saito, T.Homma

    ECS Trans.   97 ( 7 ) 877 - 883  2023.04  [Refereed]

     View Summary

    Elementary steps in the electrochemical reduction process of SiCl4 in trimethyl-n-hexylammonium bis(trifluoromethylsulfonyl) imide (TMHATFSI) was investigated, focusing on molecular level behavior of the reactants at solid-liquid interface. Electrochemical measurements using an electrochemical quartz crystal microbalance (EQCM) identified a reduction peak corresponding to Si electrodeposition and several elementary steps with stable intermediates forming prior to the deposition. For detailed analysis, X-ray reflectivity (XRR) measurements with synchrotron radiation were applied in situ. The change in reflectivity of the electrode surface during the deposition was found to be due to the formation of a polymer-like Si such as Si2Cl6, which is an intermediate layer during the deposition process. These results were theoretically supported by density functional theory (DFT) calculations: after an electron transfers from the electrode, the Si in SiCl4 forms the bond with another SiCl4, rather than the Si of the substrate, resulting in the formation of the intermediate structure. These data suggest an elementary step in the SiCl4 reduction process which can be described as follows
    when SiCl4 is reduced, a polymer-like Si form such as Si2Cl6 is generated. This intermediate species further reacts with other Si reactants after receiving additional electrons, which then finally deposits as Si on the substrate.

    DOI

    Scopus

  • Depth profiling of APTES self-assembled monolayers using surface-enhanced confocal Raman microspectroscopy

    Y. Sun, M. Yanagisawa, M. Kunimoto, M. Nakamura, T. Homma

    Spectrochim. Acta   73 ( Part A ) 43106 - 475  2023.04  [Refereed]

     View Summary

    The internal structure of self -assembled monolayers (SAMs) such as 3-aminopropyltriethoxysilane (APTES) fabricated on a glass substrate is difficult to characterize and analyze at nanometer level. In this study, we employed surface -enhanced Raman spectroscopy (SERS) to study the internal molecular structure of APTES SAMs. The sample APTES SAMs were deposited with Ag nanoparticles to enhance the Raman signal and to obtain subtler structure information, which were supported by density functional theory calculations. In addition, in order to carry out high -resolution analysis, especially for vertical direction, a fine piezo electric positioner was used to control the depth scanning with a step of 0.1 nm. We measured and distinguished the vertical Raman intensity variations of specific groups in APTES, such as Ag/NH2, CH2, and Si-O, with high resolution. The interfacial bond at the two interfaces of Ag-APTES and APTES-SiO2 was identified. Moreover, APTES molecule orientation was demonstrated to be inhomogeneous from frequency shift. (C) 2017 Elsevier B.V. All rights reserved.

    DOI

    Scopus

    21
    Citation
    (Scopus)
  • Thermal Stability of Single-layer Graphene Subjected to Confocal Laser Heating Investigated by Using in situ Anti-Stokes and Stokes Raman Spectroscopy

    Yingying Sun, Masahiro Yanagisawa, Takayuki Homma

    ELECTROCHEMISTRY   85 ( 4 ) 195 - 198  2023.04  [Refereed]

     View Summary

    The thermal stability of graphene has a close relationship with defect generation, thermal oxidation, which in turn have a significant bearing on its properties and applications. This report discusses the effect of confocal laser heating on the structure of single-layer graphene (SLG) on the basal plane and the edge. The thermal stability of SLG basal plane and edge was demonstrated to be different by using in situ anti-Stokes and Stokes Raman spectroscopy. The basal plane was found to be unstable above 500 degrees C, while the edge could not endure even 220 degrees C. The variation in the intensity of D, G, and 2D peaks and the intensity ratios of I(D)/I(G) and I(2D)/I(G) indicated that the thermal instability started with defect generation at the basal plane. The initial point defects at edge were partially eliminated at low temperature and generated again at temperatures above 220 degrees C. (C) The Electrochemical Society of Japan, All rights reserved.

    DOI

    Scopus

    6
    Citation
    (Scopus)
  • Formation of Si thin films by electrodeposition in ionic liquids for solar cell applications

    Y. Tsuyuki, H. Takai, Y. Fukunaka, T. Homma

    Jpn. J. Appl. Phys.   97 ( 57 ) 08RB11 - 883  2023.04  [Refereed]

    DOI

    Scopus

  • Effect of Li+ addition on growth behavior of ZnO during anodic dissolution of Zn negative electrode

    T. Otani, T. Yasuda, M. Kunimoto, M. Yanagisawa, Y. Fukunaka, T. Homma

    Electrochim. Acta   305   90 - 100  2023.04  [Refereed]

  • Analysis of the effect of surface wettability on hydrogen evolution reaction in water electrolysis using micro-patterned electrodes

    T. Fujimura, W. Hikima, Y. Fukunaka, T. Homma

    Electrochem. Commun.   101   43 - 46  2023.04  [Refereed]

     View Summary

    The hydrogen evolution reaction (HER) was investigated using Ni catalytic electrodes with micro-patterned surfaces. The present aim was to correlate HER efficiency with the surface wettability of Ni cathodes produced with different micropatterns. Regular Ni microdot arrays, 5–10 μm in diameter, 5–10 μm in pitch were fabricated on a 7 mm diameter Cu substrate and tested in alkaline water electrolysis (AWE) experiments. Using electrodes of this design, it may be possible to relate the electrochemical reaction kinetics to the electrolyte wettability localized to the microdot surface area. The surface microstructures of the electrode considerably influenced the reaction efficiency of the HER during alkaline water electrolysis at −20 mA cm . Furthermore, in situ video observations of the electrode surface during the HER revealed that the bubble size increased when the surface wettability of the electrodes was decreased. That is, the surface texture (micro-patterns) affected the HER efficiency by influencing bubble evolution and aggregation behavior. This observation may aid in the design of highly efficient HER catalytic electrodes. −2

    DOI

    Scopus

    36
    Citation
    (Scopus)
  • Carbonate formation on carbon electrode in rechargeable zinc-air battery revealed by in-situ Raman measurements

    T.Wang, M.Kunimoto, T.Mori, M.Yanagisawa, J.Niikura, I.Takahashi, M.Morita, T.Abe, T.Homma

    J. Power Sources   533 ( 85 ) 195 - 198  2023.03  [Refereed]

     View Summary

    The thermal stability of graphene has a close relationship with defect generation, thermal oxidation, which in turn have a significant bearing on its properties and applications. This report discusses the effect of confocal laser heating on the structure of single-layer graphene (SLG) on the basal plane and the edge. The thermal stability of SLG basal plane and edge was demonstrated to be different by using in situ anti-Stokes and Stokes Raman spectroscopy. The basal plane was found to be unstable above 500 degrees C, while the edge could not endure even 220 degrees C. The variation in the intensity of D, G, and 2D peaks and the intensity ratios of I(D)/I(G) and I(2D)/I(G) indicated that the thermal instability started with defect generation at the basal plane. The initial point defects at edge were partially eliminated at low temperature and generated again at temperatures above 220 degrees C. (C) The Electrochemical Society of Japan, All rights reserved.

    DOI

    Scopus

    14
    Citation
    (Scopus)
  • Multiscale Simulation of Irregular Shape Evolution during the Initial Stage of Zn Electrodeposition on a Negative Electrode Surface

    Y.Onabuta, M.Kunimoto, S.Wang, Y.Fukunaka, H.Nakai, T.Homma

    J. Phys Chem C   126 ( 11 ) 5224 - 5232  2023.03  [Refereed]

     View Summary

    Effects of Pb and Sn additives on electrodeposition of Zn were investigated for the applications in Zn secondary battery, focused on their roles on morphological evolution. Similarly to well-known effect of Pb addition to smoothly electrodeposit Zn film surface, Sn also exhibited to suppress the formation of mossy structures, which were highly filamentous Zn electrodeposits to cause frequently battery failure. Pb significantly shifted deposition potential of Zn to negative value at concentration less than 1.0 mmol dm(-3), while Sn showed no substantial effect even at 50 mmol dm(-3). The morphological evolution analysis demonstrated that the addition of 1.0 mmol dm(-3) Pb significantly altered nucleation behavior of Zn at initial stages of deposition; stacking of layer-like structures (microsteps) were altered to discrete and uniform nuclei of Zn preferentially oriented to (002) direction. In contrast, with Sn additive, morphological features at the initial stage of deposition were similar to that without additive. However, microsteps evolution was gradually suppressed and relatively strong (002) texture of electrodeposited Zn was mitigated by Sn addition. These results suggested that the beneficial roles of Pb and Sn addition on Zn morphological evolution were ascribed to different reasons; Pb diminished the active growth sites of Zn surface by suppressing the deposition reaction of Zn, while Sn suppressed microsteps evolution by different texture evolution of Zn. (C) 2017 Elsevier Ltd. All rights reserved.

    DOI

    Scopus

    2
    Citation
    (Scopus)
  • First-principle study of the oxidation mechanism of formaldehyde and hypophosphite for copper and nickel electroless deposition process

    Y. Onabuta, M. Kunimoto, H. Nakai, T. Homma

    Electrochim. Acta   307   536 - 542  2023.03  [Refereed]

  • Surface pH Effects on Catalytic Behavior of Pyridinic Nitrogen on Nitrogen-doped Carbon Nanotube in CO<sub>2</sub> Electrochemical Reduction

    Kohei IDE, Masahiro KUNIMOTO, Kota MIYOSHI, Kaori TAKANO, Koji MATSUOKA, Takayuki HOMMA

    Electrochemistry   91 ( 2 ) 027003 - 027003  2023.02  [Refereed]

    DOI

  • Performance of TES X-Ray Microcalorimeters Designed for 14.5-keV Solar Axion Search

    Y.Yagi, R.Konno, T.Hayashi, K.Tanaka, N.Y.Yamasaki, K.Mitsuda, R.Sato, M.Saito, T.Homma, Y.Nishida, S.Mori, N.Iyomoto, T.Hara

    Journal of Low Temperature Physics   211 ( 3 ) 255 - 264  2023.02  [Refereed]

     View Summary

    To establish a new Si-electrodeposition process, the optimum conditions for obtaining adherent, compact, and smooth Si films using molten KF-KCl-K2SiF6 were investigated at 923 K. Galvanostatic electrolysis was conducted on a Ag substrate in eutectic KF-KCl (45:55 mol%) with various current densities (10-500 mA cm(-2)) and K2SiF6 concentrations (0.5-5.0 mol%). Cross-sectional scanning electron microscopy (SEM) of the deposits revealed that compact and smooth Si films form at intermediate K2SiF6 concentrations and current densities. The relationship between the deposition conditions and Si morphology is discussed in terms of the electrodeposition mechanism. (C) 2015 The Electrochemical Society. All rights reserved.

    DOI

  • Surface pH Effects on Catalytic Behavior of Pyridinic Nitrogen on Nitrogen-doped Carbon Nanotube in CO2 Electrochemical Reduction

    K.Ide, M.Kunimoto, K.Miyoshi, K.Takano, K.Matsuoka, T.Homma

    Electrochem.   91 ( 2 ) 27003 - 27003  2023.02  [Refereed]

     View Summary

    Theoretical analyses of L-alanine (L-Ala)- and L-homocysteine (L-Hcy)-Cu(II) complexes in basic, neutral, and acidic solutions were carried out using density functional theory to investigate the pH dependence of the formation mechanism of amino acid-Cu(II) complexes. The calculated complex formation energies indicate that the amino acid-Cu(II) complexes were expected to form in basic and neutral solutions but not in acidic solutions. The factors that determine the stability of these complexes are the coordination ability of each amino acid and the significance of intramolecular interactions among ligands within the complexes. As predicted from the molecular structure, in neutral solutions, the coordination ability of amino acid becomes lower than that in basic solutions because of the inert structure of the protonated amino group, -NH3+; however, the coordination ability originating from the -COO- group is estimated to be sufficient for stabilizing the entire complex system. Moreover, two H2O molecules coordinate with the central Cu2+ ion from the equatorial direction and interact with the coordinating amino acids, providing additional stability within the complex. In contrast, in acidic solutions, the complex does not have either sufficient coordination ability of amino acids or effective intramolecular interactions within the complex.

    DOI

  • Purification of Diatomaceous Earth using Acid Leaching Process to Produce High Purity Silica for Solar-Grade Silicon

    Y.V.Akash, M.Kunimoto.S.Horie, Y.Fukunaka, T.Homma

    Separ. Sci. Technol   57 ( 14 ) 2261 - 2268  2023.02  [Refereed]

    DOI CiNii

    Scopus

    1
    Citation
    (Scopus)
  • Analysis of the hydrogen evolution reaction at Ni micro-patterned electrodes

    T.Fujimura, M.Kunimoto, Y.Fukunaka, T.Homma

    Electrochim. Acta   368 ( 1 ) 43105  2023.02  [Refereed]

    DOI

    Scopus

    25
    Citation
    (Scopus)
  • Electrodeposition of Fe-Ni-Pt alloy films for heat-assisted magnetic recording media: Synthesis, structure and magnetic properties

    S. Ge, Q. Lin, S. Wodarz, M. Kambe, T. Homma, G. Zangari

    Electrochim. Acta   302   92 - 101  2023.02  [Refereed]

  • Electrodeposited CoPt multilayered-nanowire for 3D memory device

    Md Mahmudul Hasan, Tongshuang Huang, Mikiko Saito, Yota Takamura, Daiki Oshima, Takeshi Kato, Takayuki Homma

    2023 IEEE International Magnetic Conference - Short Papers, INTERMAG Short Papers 2023 - Proceedings    2023

     View Summary

    In this study, we construct composite structures of CoPt multilayer alloy nanowires by electrodeposition using a polycarbonate template membrane (PT). The holes in PT are subsequently filled with CoPt multilayer alloy films to form nanowires. The composition of the films can be controlled by modifying the potential to produce high anisotropy CoPt alloy multilayer nanowires. The CoPt multilayer nanowires have a periodic structure like bamboo with a chemical composition of (Co80Pt20/Co30Pt70)n. Polycrystalline and ferromagnetic characteristics were visible in a single layer of Co80Pt20 nanowire. A vertical 3D magnetic domain wall memory has a ferromagnetic bit layer and a domain wall layer. Thus (Co80Pt20/Co30Pt70)n multilayer nanowires can be used in domain wall controlled 3D memory devices like racetrack memory.

    DOI

    Scopus

  • Direct Formation of Metal Layer on Anion Exchange Membrane Using Electroless Deposition Process

    T.Fujimura, M.Kunimoto, H.Ito, T.Homma

    Electrochem.   89 ( 2 ) 192 - 196  2023.01  [Refereed]

     View Summary

    The thickness of 3-dimensional (3D) mesoporous silica ultrathin films was controlled at a single-nano-meter scale by wet-etching. A drop casting method with an aqueous etchant of ammonium fluoride was effective in etching the surfaces of films in the direction perpendicular to their substrates. The decrease in the film thickness depends on the interface tension of etching solutions. The wettability of thin films also influences the etching. CoPt nanodots were electrodeposited within ultrathin silica films on Ru substrates to form CoPt nanodot patterns.

    DOI

    Scopus

    3
    Citation
    (Scopus)
  • Determination of copper nanoparticle size distributions with total reflection X-ray fluorescence spectroscopy

    Andy Singh, Katharina Luening, Sean Brennan, Takayuki Homma, Nobuhiro Kubo, Stanisław H. Nowak, Piero Pianetta

    Journal of Synchrotron Radiation   24 ( 1 ) 283 - 287  2023.01

     View Summary

    Total reflection X-ray fluorescence (TXRF) analysis is extensively used by the semiconductor industry for measuring trace metal contamination on silicon surfaces. In addition to determining the quantity of impurities on a surface, TXRF can reveal information about the vertical distribution of contaminants by measuring the fluorescence signal as a function of the angle of incidence. In this study, two samples were intentionally contaminated with copper in non-deoxygenated and deoxygenated ultrapure water (UPW) resulting in impurity profiles that were either atomically dispersed in a thin film or particle-like, respectively. The concentration profile of the samples immersed into deoxygenated UPW was calculated using a theoretical concentration profile representative of particles, yielding a mean particle height of 16.1 nm. However, the resulting theoretical profile suggested that a distribution of particle heights exists on the surface. The fit of the angular distribution data was further refined by minimizing the residual error of a least-squares fit employing a model with a Gaussian distribution of particle heights about the mean height. The presence of a height distribution was also confirmed with atomic force microscopy measurements.

    DOI

    Scopus

    6
    Citation
    (Scopus)
  • Raman Microscopy and Scanning Surface Potential Microscopy Analysis of Nanoscale Defects on Si Wafer Surfaces

    T. Homma, M. Kato, N. Kubo, K. Sakata, N. Kubo, M. Yanagisawa

    J. Electrochem. Soc.   156 ( 6 ) H475 - H478  2019.04

     View Summary

    Nanometer-scale defects on the surface of a Si wafer, fabricated by nanoindentation technique, were examined using Raman microscopy and scanning surface potential microscopy to determine the quantitative relation between surface potential shift and Raman shift. Formation of cracks has not observed at the defect sites, indicating that the plastic and elastic deformations were a major issue and that the residual stress from the plastic deformation was observed. The Raman peak of the array of defects formed by nanoindentation shifted to a lower wavenumber as the indentation force was increased. The results indicated that the amount of tensile strain increased with the indentation force, that is, tensile stress was dominant over the condition in the surrounded area, in the indentation-induced defects. Correspondingly, the surface potential of the defect arrays shifted to the negative direction with an increase in indentation force. These results suggest that the tensile stress at the defect site, indicated by the Raman shift, causes the negative shift in the surface potential, which is related to chemical reactivity. Furthermore, Raman shift of a single indent on a silicon-on-insulator (SOI) wafer was observed, which revealed an enhancement in the source-to-noise ratio of the Raman spectrum at the Si defect site, because the ratio of the volume of the defect site to that of the unstrained site increased due to the thin Si layer on the SOI wafer.

    DOI

    Scopus

    2
    Citation
    (Scopus)
  • Spectroscopic and Computational Analyses of Liquid-Liquid Interfacial Reaction Mechanism of Boric Acid Esterification with 2,2,4-Trimethyl-1,3-Pentanediol in Boron Extraction Processes

    M. Kunimoto, D. Bothe, R. Tamura, T. Oyanagi, Y. Fukunaka, H. Nakai, T. Homma

    J. Phys. Chem. C   368 ( 122 ) 10423 - 10429  2018.04  [Refereed]

    DOI

    Scopus

    25
    Citation
    (Scopus)
  • Surface enhanced Raman spectroscopy measurement of surface pH at the electrode during Ni electrodeposition reaction

    T. Homma, M. Kunimoto, M. Sasaki, T. Hanai, M. Yanagisawa

    J. Appl. Electrochem.   126 ( 48 ) 561 - 567  2017.12  [Refereed]

    DOI

    Scopus

    2
    Citation
    (Scopus)
  • Analysis of Cathodic Reaction Process of SiCl4 during Si Electrodeposition in Ionic Liquids

    Y. Tsuyuki, T. Fujimura, M. Kunimoto, Y. Fukunaka, P. Pianetta, T. Homma

    J. Electrochem. Soc.   164 ( 164(14) ) D994 - D998  2017.12  [Refereed]

     View Summary

    Elementary steps in the electrochemical reduction process of SiCl4 in trimethyl-n-hexylammonium bis(trifluoromethylsulfonyl) imide (TMHATFSI) was investigated, focusing on molecular level behavior of the reactants at solid-liquid interface. Electrochemical measurements using an electrochemical quartz crystal microbalance (EQCM) identified a reduction peak corresponding to Si electrodeposition and several elementary steps with stable intermediates forming prior to the deposition. For detailed analysis, X-ray reflectivity (XRR) measurements with synchrotron radiation were applied in situ. The change in reflectivity of the electrode surface during the deposition was found to be due to the formation of a polymer-like Si such as Si2Cl6, which is an intermediate layer during the deposition process. These results were theoretically supported by density functional theory (DFT) calculations: after an electron transfers from the electrode, the Si in SiCl4 forms the bond with another SiCl4, rather than the Si of the substrate, resulting in the formation of the intermediate structure. These data suggest an elementary step in the SiCl4 reduction process which can be described as follows
    when SiCl4 is reduced, a polymer-like Si form such as Si2Cl6 is generated. This intermediate species further reacts with other Si reactants after receiving additional electrons, which then finally deposits as Si on the substrate.

    DOI

    Scopus

    10
    Citation
    (Scopus)
  • Direct observation of the diffusion behavior of an electrodeposition additive in through-silicon via using in situ surface enhanced Raman spectroscopy

    T. Homma, A. Kato, M. Kunimoto, M. Yanagisawa

    Electrochem. Commun.   89 ( 88 ) 34 - 38  2017.10  [Refereed]

    DOI

    Scopus

    3
    Citation
    (Scopus)
  • Simultaneous measurement of kinetic mechanical properties and chemical structure: Tribology (1)

    Yanagisawa Masahiro, Saito Mikiko, Kunimoto Masahiro, Homma Takayuki

    Abstract of annual meeting of the Surface Science of Japan   36 ( 0 ) 79 - 79  2016.11

    DOI CiNii

  • Transmission-type plasmonic sensor for surface-enhanced Raman spectroscopy

    M. Yanagisawa, M. Saito, M. Kunimoto, T. Homma

    Appl. Phys. Express   ( 9 ) 122002  2016.11  [Refereed]

  • Chemical Analysis of Buried Interface Using SERS Sensors

    YANAGISAWA Masahiro, HOMMA Takayuki

    Hyomen Kagaku   37 ( 9 ) 435 - 440  2016.09

     View Summary

    <p>New technique for analyzing buried interface has developed based on surface-enhanced Raman scattering spectroscopy. It consists of plasmonic sensors and spectrometer equipped with high precision mechanisms. Performance of the system involves in-situ measurement of interfaces, i.e. liquid/solid or solid/solid, with high sensitivity and high depth resolution on a variety of samples. Additional functions are in-situ temperature measurement by anti-Stokes/Stokes ratio, simultaneous acquisition with laser heating, time-resolved measurement, and pulsed laser Raman spectroscopy. A depth profile of layered ultra-thin films, i.e. diamond-like carbon (DLC) or highly oriented pyrolytic graphite (HOPG), was analyzed in atomic scale resolution at solid/solid interface. Molecular configuration and bonding feature of liquid organic molecules, i.e. lubricants for magnetic disks or reducing agents for a plating, were analyzed at liquid/solid interface. Oxidation process or decomposition process of ultra-thin DLC films was analyzed for a variety of DLC films. Spectral change with irradiation time by pulsed laser heating exhibited a kinetic change of molecular structures in a chemical reaction with in-situ heating temperature measurement.</p>

    DOI CiNii

  • A new electrolytic production process of silicon using liquid Zn alloy cathode in molten salt

    T. Nohira, A. Ido, T. Shimano, X. Yang, K. Yasuda, R. Hagiwara, T. Homma

    ECS Trans.   75 ( 75 ) 17 - 33  2016.08  [Refereed]

     View Summary

    Electrolytic production process for solar-grade Si utilizing liquid Si-Zn alloy cathode in molten CaCl2 has been proposed. Toward the establishment of the process, the behavior of liquid Zn metal was investigated in molten CaCl2 at 1123 K. The evaporation of Zn metal was largely suppressed by an immersion into molten salt, which enables the use of Zn electrode in spite of the high vapor pressure of Zn. The cyclic voltammetry suggested the reduction of SiO2 at 1.45 V vs. Ca2+/Ca on a Zn cathode. After the potentiostatic electrolysis at 0.9 V, Si particles with diameters of 2-30 mu m were precipitated in the solidified Zn matrix by the slow cooling process of the produced liquid Si-Zn alloy. The alloying rate between solid Si and liquid Zn was measured as 4.56 mu m s(-1), and it linearly decreased with the Si content in liquid Zn phase.

    DOI

    Scopus

    7
    Citation
    (Scopus)
  • Electrodeposition of Si film from water-soluble KF-KCl molten salt and feasibility of SiCl4 as a Si source

    K. Yasuda, K. Saeki, K. Maeda, T. Nohira, R. Hagiwara, T. Homma

    ECS Trans.   75 ( 75 ) 593 - 601  2016.08  [Refereed]

     View Summary

    Toward an establishment of a new production method of solar cell substrates, electrodeposition of Si was investigated in molten KF-KCl (eutectic composition, 45:55 mol%) after the introduction of SiCl4. Gaseous SiCl4 was directly introduced into the molten salt at 1023 K by a vapor transport method using Ar carrier gas. The dissolution ratio of SiCl4 exceeded 80% even with the use of a simple tube for the bubbling. Galvanostatic electrolysis was conducted at 923 K on a Ag substrate at 155 mA cm(-2) for 20 min in molten KF-KCl after the dissolution of 2.30 mol% SiCl4. Although compact Si layer was formed, the smoothness was lower compared to that obtained from the melt after the addition of K2SiF6. The anionic molar fraction is probably one of the factors affecting the morphology of deposit.

    DOI

    Scopus

    3
    Citation
    (Scopus)
  • Electrodeposition of Si Film from Water-Soluble KF-KCl Molten Salt and Feasibility of SiCl4 as a Si Source

    Kouji Yasuda, Kazumi Saeki, Kazuma Maeda, Toshiyuki Nohira, Rika Hagiwara, Takayuki Homma

    MOLTEN SALTS AND IONIC LIQUIDS 20   75 ( 15 ) 593 - 601  2016.08  [Refereed]

     View Summary

    Toward an establishment of a new production method of solar cell substrates, electrodeposition of Si was investigated in molten KF-KCl (eutectic composition, 45:55 mol%) after the introduction of SiCl4. Gaseous SiCl4 was directly introduced into the molten salt at 1023 K by a vapor transport method using Ar carrier gas. The dissolution ratio of SiCl4 exceeded 80% even with the use of a simple tube for the bubbling. Galvanostatic electrolysis was conducted at 923 K on a Ag substrate at 155 mA cm(-2) for 20 min in molten KF-KCl after the dissolution of 2.30 mol% SiCl4. Although compact Si layer was formed, the smoothness was lower compared to that obtained from the melt after the addition of K2SiF6. The anionic molar fraction is probably one of the factors affecting the morphology of deposit.

    DOI

    Scopus

    3
    Citation
    (Scopus)
  • A New Electrolytic Production Process of Silicon Using Liquid Zn Alloy Cathode in Molten Salt

    Toshiyuki Nohira, Akifumi Ido, Takeyuki Shimao, Xiao Yang, Kouji Yasuda, Rika Hagiwara, Takayuki Homma

    MOLTEN SALTS AND IONIC LIQUIDS 20   75 ( 15 ) 17 - 33  2016.08  [Refereed]

     View Summary

    Electrolytic production process for solar-grade Si utilizing liquid Si-Zn alloy cathode in molten CaCl2 has been proposed. Toward the establishment of the process, the behavior of liquid Zn metal was investigated in molten CaCl2 at 1123 K. The evaporation of Zn metal was largely suppressed by an immersion into molten salt, which enables the use of Zn electrode in spite of the high vapor pressure of Zn. The cyclic voltammetry suggested the reduction of SiO2 at 1.45 V vs. Ca2+/Ca on a Zn cathode. After the potentiostatic electrolysis at 0.9 V, Si particles with diameters of 2-30 mu m were precipitated in the solidified Zn matrix by the slow cooling process of the produced liquid Si-Zn alloy. The alloying rate between solid Si and liquid Zn was measured as 4.56 mu m s(-1), and it linearly decreased with the Si content in liquid Zn phase.

    DOI

    Scopus

    7
    Citation
    (Scopus)
  • Theoretical study on the formation mechanism of amino acid-Cu(II) complexes on an enantio-sensing device interface

    M. Kunimoto, Y. Sadaoka, T. Nakanishi, T. Osaka, T. Homma

    J. Phys. Chem. C   120 ( 120 ) 15722 - 15728  2016.07  [Refereed]

     View Summary

    Theoretical analyses of L-alanine (L-Ala)- and L-homocysteine (L-Hcy)-Cu(II) complexes in basic, neutral, and acidic solutions were carried out using density functional theory to investigate the pH dependence of the formation mechanism of amino acid-Cu(II) complexes. The calculated complex formation energies indicate that the amino acid-Cu(II) complexes were expected to form in basic and neutral solutions but not in acidic solutions. The factors that determine the stability of these complexes are the coordination ability of each amino acid and the significance of intramolecular interactions among ligands within the complexes. As predicted from the molecular structure, in neutral solutions, the coordination ability of amino acid becomes lower than that in basic solutions because of the inert structure of the protonated amino group, -NH3+; however, the coordination ability originating from the -COO- group is estimated to be sufficient for stabilizing the entire complex system. Moreover, two H2O molecules coordinate with the central Cu2+ ion from the equatorial direction and interact with the coordinating amino acids, providing additional stability within the complex. In contrast, in acidic solutions, the complex does not have either sufficient coordination ability of amino acids or effective intramolecular interactions within the complex.

    DOI

    Scopus

    3
    Citation
    (Scopus)
  • 電解析出法による多層構造を有したFePtナノドットアレイの低温L10規則化の検討

    斎藤学, 橋本尚吾, ヴォダルツジギー, G. Zangari, 本間敬之

    信学技報   ( 116 ) 43105  2016.07  [Refereed]

  • Life estimation of carbon overcoat on magnetic media for heatassisted magnetic recording using novel Raman spectroscopy

    M. Yanagisawa, M. Kunimoto, T. Homma

    ASME 2016 Conference on Information Storage and Processing Systems ISPS 2016    2016.06  [Refereed]

     View Summary

    A heat-assisted magnetic recording (HAMR) is expected for a future high density recording of a hard disk drive. However, a. carbon overcoat (COC) composed of diamond-like carbon (DLC) or a lubricant film is possibly damaged when a magnetic medium, i.e. CoPt alloy, is heated at around Curie temperature (Tc) of 600K by a near-field HAMR head. We carried out HAMR. simulation experiments by using newly developed Raman spectroscopic systems, composed of plasmonic sensors for surface-enhanced Raman scattering (SERS), a pulsed laser heating, and an in-situ temperature measurement with an intensity ratio of anti-Stokes/Stokes lines. It was found that the heated temperature of the COC is higher than that of the magnetic film, i.e., 580 degrees C and 366 degrees C, respectively. Intensity changes of G-band peak in Raman spectra for DLC films were observed during the pulsed laser heating. The Raman intensity was exponentially decreased by oxidation in air, where time constants were calculated as a parameter of a pulse width. Degradation life of the DLC film can be estimated from a critical pulse width, where the time constant is extrapolated to zero. The estimated pulse width for no degradation was 250 mu s at the heating temperature of 580 degrees C. The result shows no damage can be estimated in DLC films for HAMR. because the effective irradiation time is 5ns and the accumulated irradiation time is 0.5ms in HAMR operations.

  • Depth profile analysis of chemical structures around lubricant/overcoat interface using plasmonic sensor

    M. Yanagisawa, M. Kunimoto, T. Homma

    ASME 2016 Conference on Information Storage and Processing Systems ISPS 2016    2016.06  [Refereed]

     View Summary

    A chemical depth profile in lubricant films, carbon films, and their interfaces is an informative parameter for hard disk media because molecular features of lubricants bonded to a surface of carbon overcoats (COCs), which usually consist of a nitrogen doped layer, are important to achieve high tribological performance. However, it was difficult to analyze their interfaces with high depth resolution because thickness of lubricant films and COC films are so thin, i.e. 1.5nm and 2nm, respectively. We have developed new method using plasmonic sensors, which has measurement capability for chemical structures with depth resolution of 0.1nm by surface-enhanced Raman spectroscopy (SERS). We examined the lubricant film composed of perfluorinated polyether (PEPE) with phosphazene derivative (A2OH) on a diamond-like carbon (DLC) film. The result shows that the functional group is adsorbed on the DLC surface, where lower shift in the wave number of phenyl group is observed. The depth profile of the intensity ratio of D-peak to G-peak shows the maximum at around the surface of the DLC film. A variety of organic components in the DLC films, fabricated by a chemical vapor deposition (CVD), were observed in it. Besides, the depth profiles shows that organic materials, involving methyl, ethyl, or ethylene groups, Co(OH)x exist in the film

  • Life estimation of carbon overcoat on magnetic media for heatassisted magnetic recording using novel Raman spectroscopy

    M. Yanagisawa, M. Kunimoto, T. Homma

    ASME 2016 Conference on Information Storage and Processing Systems ISPS 2016    2016.06  [Refereed]

     View Summary

    © Copyright 2016 by ASME.A heat-assisted magnetic recording (HAMR) is expected for a future high density recording of a hard disk drive. However, a carbon overcoat (COC) composed of diamond-like carbon (DLC) or a lubricant film is possibly damaged when a magnetic medium, i.e. CoPt alloy, is heated at around Curie temperature (Tc) of 600K by a near-field HAMR head. We carried out HAMR simulation experiments by using newly developed Raman spectroscopic systems, composed of plasmonic sensors for surface-enhanced Raman scattering (SERS), a pulsed laser heating, and an in-situ temperature measurement with an intensity ratio of anti-Stokes/Stokes lines. It was found that the heated temperature of the COC is higher than that of the magnetic film, i.e., 580°C and 366°C, respectively. Intensity changes of G-band peak in Raman spectra for DLC films were observed during the pulsed laser heating. The Raman intensity was exponentially decreased by oxidation in air, where time constants were calculated as a parameter of a pulse width. Degradation life of the DLC film can be estimated from a critical pulse width, where the time constant is extrapolated to zero. The estimated pulse width for no degradation was 250μs at the heating temperature of 580°C. The result shows no damage can be estimated in DLC films for HAMR because the effective irradiation time is 5ns and the accumulated irradiation time is 0.5ms in HAMR operations.

    DOI

    Scopus

    2
    Citation
    (Scopus)
  • Estimated Phase Transition and Melting Temperature of APTES Self-Assembled Monolayer Using Surface-Enhanced Anti-Stokes and Stokes Raman Scattering

    Y. Sun, M. Yanagisawa, M. Kunimoto, M. Nakamura, T. Homma

    Appl. Surf. Sci.   ( 363 ) 572 - 577  2016.02  [Refereed]

  • Electrodeposition of ZnO from Acetate Bath for Thermoelectric Devices

    H. Matsuo, K. Yoshitoku, D. Furuyama, M. Saito, T. Homma

    ECS Trans.   75 ( 75 ) 143 - 148  2016.02  [Refereed]

     View Summary

    We attempted to form ZnO films with smooth surface for the application of thermoelectric micro-devices, using electrodeposition process. In order to reduce the defects of the films such as cracks and pits mainly caused by the gas evolution, the bath containing acetate in addition to nitrate ions was developed to reduce the gas evolution during the deposition. Using this bath, formation of ZnO. rather than Zn metallic films, was confirmed by Raman spectroscopy. The films had no cracks and the surface became smoother than those eiectrodeposited from the conventional nitrate-based bath. In order to fabricate the micro- devices, The ZnO was eiectrodeposited into the patterns with diameter of 200μm. As a result, ZnO successfully filled the pattern keeping the smooth surface conditions, which demonstrated the applicability of the ZnO films to micro-device fabrication.

    DOI

    Scopus

    4
    Citation
    (Scopus)
  • Depth profile analysis of chemical structures around lubricant/overcoat interface using plasmonic sensor

    Yanagisawa, M, Kunimoto, M, Homma, T

    ASME 2016 Conference on Information Storage and Processing Systems, ISPS 2016    2016.01  [Refereed]

     View Summary

    © Copyright 2016 by ASME.A chemical depth profile in lubricant films, carbon films, and their interfaces is an informative parameter for hard disk media because molecular features of lubricants bonded to a surface of carbon overcoats (COCs), which usually consist of a nitrogen doped layer, are important to achieve high tribological performance. However, it was difficult to analyze their interfaces with high depth resolution because thickness of lubricant films and COC films are so thin, i.e. 1.5nm and 2nm, respectively. We have developed new method using plasmonic sensors, which has measurement capability for chemical structures with depth resolution of 0.1nm by surface-enhanced Raman spectroscopy (SERS). We examined the lubricant film composed of perfluorinated polyether (PFPE) with phosphazene derivative (A2OH) on a diamond-like carbon (DLC) film. The result shows that the functional group is adsorbed on the DLC surface, where lower shift in the wave number of phenyl group is observed. The depth profile of the intensity ratio of D-peak to G-peak shows the maximum at around the surface of the DLC film. A variety of organic components in the DLC films, fabricated by a chemical vapor deposition (CVD), were observed in it. Besides, the depth profiles shows that organic materials, involving methyl, ethyl, or ethylene groups, Co(OH)x exist in the film.

    DOI

    Scopus

    2
    Citation
    (Scopus)
  • Theoretical Analysis of Catalytic Reaction Mechanism of BH4 on Cu and Pd Surface in Electroless Deposition Process

    KUNIMOTO Masahiro, NAKAI Hiromi, HOMMA Takayuki

    Journal of the Surface Finishing Society of Japan   66 ( 66 ) 666 - 669  2015.12  [Refereed]

     View Summary

    To elucidate the catalytic reaction mechanism of BH4 (a reducing agent) on metal surfaces during electroless deposition, its oxidation reaction was investigated theoretically using density functional theory (DFT) calculation. Particularly in this study, dehydrogenation reaction of BH4 was modeled and analyzed because it is the most important elementary step of overall oxidation for the catalytic behavior of metal surfaces. To ascertain the tendencies of catalytic activity of metal surfaces, the reaction on Cu(111) and that on Pd(111) were compared. Actually, Cu shows little catalytic activity toward BH4 oxidation, whereas Pd shows strong catalytic activity. Results of reaction energy calculations show that the BH4 dehydrogenation occurs with difficulty on Cu(111), but it occurs easily on Pd(111), which corresponds to experimental results. Detailed analyses of reaction system electronic structures show that the d-band states of each surface are important to assess the background of the difference. Because the Pd surface has a high-energy d-band, it can interact with high-energy unoccupied orbitals of BH4, leading to electron donation from the surface toward BH4. This electron donation effect from Pd provides dissociation activity of the B-H bond, which promotes dehydrogenation of BH4.

    DOI CiNii

  • Electrochemical quartz crystal microbalance, X-ray photoelectron spectroscopy, and Raman spectroscopy analysis of SiCl4 reduction in ionic liquids

    Yasuhiro Tsuyuki, Tram Anh Pham Huynh, Jason Komadina, Yasuhiro Fukunaka, Takayuki Homma

    ELECTROCHIMICA ACTA   183   49 - 55  2015.11

     View Summary

    The reaction mechanism of Si electrodeposition in the ionic liquid trimethyl-n-hexylammonium bis (trifluoromethylsulfonyl) imide (TMHATFSI) with SiCl4 was investigated using an electrochemical quartz crystal microbalance (EQCM) and X-ray photoelectron spectroscopy (XPS). The deposited films were further characterized by Raman spectroscopy. The EQCM method measured the frequency change in situ during electrodeposition, whereas XPS provided the Si mass concentration in the electrodeposited films. By combining these results, the mass change due to SiCl4 reduction was estimated. Then, the current efficiency for Si electrodeposition at various potentials was evaluated. The calculated current efficiency was almost 100% when it was assumed that SiCl4 reduction progressed by four-electron electroreduction. The XPS and Raman results showed that the deposited films were composed primarily of amorphous Si with Si-Si bonds. Crystalline Si thin films were obtained after annealing in an Ar gas stream. (C) 2015 Elsevier Ltd. All rights reserved.

    DOI

    Scopus

    8
    Citation
    (Scopus)
  • 3.めっきプロセスを用いたナノドット形成

    ヴォダルツ ジギー, 本間 敬之

    Electrochemistry   83 ( 11 ) 1012 - 1015  2015.11

    DOI CiNii

  • Electrochemical quartz crystal microbalance, X-ray photoelectron spectroscopy, and Raman spectroscopy analysis of SiCl4 reduction in ionic liquids

    Yasuhiro Tsuyuki, Tram Anh Pham Huynh, Jason Komadina, Yasuhiro Fukunaka, Takayuki Homma

    ELECTROCHIMICA ACTA   183 ( 183 ) 49 - 55  2015.11  [Refereed]

     View Summary

    The reaction mechanism of Si electrodeposition in the ionic liquid trimethyl-n-hexylammonium bis (trifluoromethylsulfonyl) imide (TMHATFSI) with SiCl4 was investigated using an electrochemical quartz crystal microbalance (EQCM) and X-ray photoelectron spectroscopy (XPS). The deposited films were further characterized by Raman spectroscopy. The EQCM method measured the frequency change in situ during electrodeposition, whereas XPS provided the Si mass concentration in the electrodeposited films. By combining these results, the mass change due to SiCl4 reduction was estimated. Then, the current efficiency for Si electrodeposition at various potentials was evaluated. The calculated current efficiency was almost 100% when it was assumed that SiCl4 reduction progressed by four-electron electroreduction. The XPS and Raman results showed that the deposited films were composed primarily of amorphous Si with Si-Si bonds. Crystalline Si thin films were obtained after annealing in an Ar gas stream. (C) 2015 Elsevier Ltd. All rights reserved.

    DOI

    Scopus

    8
    Citation
    (Scopus)
  • Electrochemical quartz crystal microbalance, X-ray photoelectron spectroscopy, and Raman spectroscopy analysis of SiCl4 reduction in ionic liquids

    Yasuhiro Tsuyuki, Tram Anh Pham Huynh, Jason Komadina, Yasuhiro Fukunaka, Takayuki Homma

    ELECTROCHIMICA ACTA   183   49 - 55  2015.11  [Refereed]

     View Summary

    The reaction mechanism of Si electrodeposition in the ionic liquid trimethyl-n-hexylammonium bis (trifluoromethylsulfonyl) imide (TMHATFSI) with SiCl4 was investigated using an electrochemical quartz crystal microbalance (EQCM) and X-ray photoelectron spectroscopy (XPS). The deposited films were further characterized by Raman spectroscopy. The EQCM method measured the frequency change in situ during electrodeposition, whereas XPS provided the Si mass concentration in the electrodeposited films. By combining these results, the mass change due to SiCl4 reduction was estimated. Then, the current efficiency for Si electrodeposition at various potentials was evaluated. The calculated current efficiency was almost 100% when it was assumed that SiCl4 reduction progressed by four-electron electroreduction. The XPS and Raman results showed that the deposited films were composed primarily of amorphous Si with Si-Si bonds. Crystalline Si thin films were obtained after annealing in an Ar gas stream. (C) 2015 Elsevier Ltd. All rights reserved.

    DOI

    Scopus

    8
    Citation
    (Scopus)
  • 無電解めっきプロセスにおける最近の研究動向

    國本雅宏, 本間敬之

    表面技術   ( 66 ) 438 - 442  2015.10  [Refereed]

  • High purity silicon materials prepared through wet-chemical and electrochemical approaches

    Takayuki Homma, Nobufumi Matsuo, Xiao Yang, Kouji Yasuda, Yasuhiro Fukunaka, Toshiyuki Nohira

    ELECTROCHIMICA ACTA   179   512 - 518  2015.10  [Refereed]

     View Summary

    A new approach to produce high purity solar grade silicon (SOG-Si) using wet-chemical and electrochemical processes was proposed. First, diatomaceous earth was used as a source of silica and wet-chemical purification by acid leaching and solvent extraction processes were applied for eliminating heavy metal and light element such as boron, respectively. In particular, the solvent extraction using channel flow reactor demonstrated extremely high efficiency for eliminating boron to 7N (99.99999%) level purity. Secondly, the high-purity silica was reduced to silicon by the direct electrolysis method using molten CaCl2 as an electrolyte and Si plate as cathode. We proposed the continuous electrolysis system by feeding silica granules to the Si cathode set at the bottom of the cell. It was confirmed that the reduction proceeded steadily to form crystalline Si with a sufficient reduction rate. We also attempted electrodeposition of Si films and have developed a process using KF-KCl + K2SiF6 molten salt, from which uniform layer of Si with a thickness larger than 100 mu m could be formed. (C) 2015 Elsevier Ltd. All rights reserved.

    DOI

    Scopus

    21
    Citation
    (Scopus)
  • Electrochemical Processes for the Fabrication of Functional Micro/nano Structures and Devices: Mechanistic Understanding and Process Development

    T. Homma

    Electrochemistry   83 ( 83 ) 680 - 687  2015.09  [Refereed]

     View Summary

    Electrochemical approaches for the fabrication of functional micro–nano structures and devices were comprehensively described primarily on the basis of the results obtained from previous studies conducted by the author's group with the aim of demonstrating the potential for achieving further precise controllability. First, a theoretical study was conducted for investigating the processes, mainly focusing upon electroless deposition to present an approach for analyzing its reaction mechanism from the molecular level. These approaches could be powerful tools for elucidating the overall process and could contribute toward achieving the precise design of processes. Second, some experimental approaches for achieving the precise control of micro–nano fabrication of functional structures, such as maskless and electroless fabrication of metal nano-patterns, lateral enhanced electrodeposition to form ultrathin layers, as well as the nanostructures for various devices by through-mask electrochemical deposition, were introduced to demonstrate high capability of the processes for nanoscale fabrication in various applications.

    CiNii

  • Electrochemical Processes for the Fabrication of Functional Micro/nano Structures and Devices: Mechanistic Understanding and Process Development

    T. Homma

    Electrochemistry   83 ( 83 ) 680 - 687  2015.09  [Refereed]

     View Summary

    Electrochemical approaches for the fabrication of functional micro-nano structures and devices were comprehensively described primarily on the basis of the results obtained from previous studies conducted by the author's group with the aim of demonstrating the potential for achieving further precise controllability. First, a theoretical study was conducted for investigating the processes, mainly focusing upon electroless deposition to present an approach for analyzing its reaction mechanism from the molecular level. These approaches could be powerful tools for elucidating the overall process and could contribute toward achieving the precise design of processes. Second, some experimental approaches for achieving the precise control of micro-nano fabrication of functional structures, such as maskless and electroless fabrication of metal nano-patterns, lateral enhanced electrodeposition to form ultrathin layers, as well as the nanostructures for various devices by through-mask electrochemical deposition, were introduced to demonstrate high capability of the processes for nanoscale fabrication in various applications. (C) The Electrochemical Society of Japan, All rights reserved.

    DOI

    Scopus

  • The Role of Granule Size on the Kinetics of Electrochemical Reduction of SiO2 Granules in Molten CaCl2

    X. Yang, K. Yasuda, T. Nohira, R. Hagiwara, T. Homma

    Metallurgical and Mat. Trans. B   ( 47 ) 788 - 797  2015.09  [Refereed]

  • Fabrication of FePt Nanodot Arrays with High Coercivity by Pulse Electrodeposition

      115 ( 115 ) 25 - 29  2015.07  [Refereed]

    CiNii

  • Silicon Electrodeposition in Water-Soluble KF-KCl Molten Salt: Investigations on the Reduction of Si(IV) Ions

    Kazuma Maeda, Kouji Yasuda, Toshiyuki Nohira, Rika Hagiwara, Takayuki Homma

    JOURNAL OF THE ELECTROCHEMICAL SOCIETY   162 ( 9 ) D444 - D448  2015.06  [Refereed]

     View Summary

    A new method for electroplating Si using a water-soluble KF-KCl molten salt electrolyte and high-purity gaseous SiCl4 has been proposed. To gain a fundamental understanding of the process, the electrodeposition of Si from Si(IV) complex ions on a Ag electrode in a molten KF-KCl-K2SiF6 system was investigated by cyclic voltammetry at 923 K. The reduction of Si(IV) ions to metallic Si was observed as a single 4-electron wave, which is explained by an EqEr (quasireversible-reversible electron transfer reactions) mechanism. The diffusion coefficient of the Si(IV) ions in the electrolyte was determined to be 3.2 x 10(-5) cm(2) s(-1) at 923 K by chronoamperometry. (C) 2015 The Electrochemical Society. All rights reserved.

    DOI

    Scopus

    58
    Citation
    (Scopus)
  • Silicon Electrodeposition in Water-Soluble KF-KCl Molten Salt: Investigations on the Reduction of Si(IV) Ions

    Kazuma Maeda, Kouji Yasuda, Toshiyuki Nohira, Rika Hagiwara, Takayuki Homma

    JOURNAL OF THE ELECTROCHEMICAL SOCIETY   162 ( 9 ) D444 - D448  2015.06  [Refereed]

     View Summary

    A new method for electroplating Si using a water-soluble KF-KCl molten salt electrolyte and high-purity gaseous SiCl4 has been proposed. To gain a fundamental understanding of the process, the electrodeposition of Si from Si(IV) complex ions on a Ag electrode in a molten KF-KCl-K2SiF6 system was investigated by cyclic voltammetry at 923 K. The reduction of Si(IV) ions to metallic Si was observed as a single 4-electron wave, which is explained by an EqEr (quasireversible-reversible electron transfer reactions) mechanism. The diffusion coefficient of the Si(IV) ions in the electrolyte was determined to be 3.2 x 10(-5) cm(2) s(-1) at 923 K by chronoamperometry. (C) 2015 The Electrochemical Society. All rights reserved.

    DOI

    Scopus

    58
    Citation
    (Scopus)
  • Silicon Electrodeposition in Water-Soluble KF?KCl Molten Salt: Optimization of Electrolysis Conditions at 923 K

    K. Yasuda, K. Saeki, K. Maeda, T. Nohira, R. Hagiwara, T. Homma

    J. Electrochem. Soc.   163 ( 163 ) D95 - D99  2015.06  [Refereed]

     View Summary

    To establish a new Si-electrodeposition process, the optimum conditions for obtaining adherent, compact, and smooth Si films using molten KF-KCl-K2SiF6 were investigated at 923 K. Galvanostatic electrolysis was conducted on a Ag substrate in eutectic KF-KCl (45:55 mol%) with various current densities (10-500 mA cm(-2)) and K2SiF6 concentrations (0.5-5.0 mol%). Cross-sectional scanning electron microscopy (SEM) of the deposits revealed that compact and smooth Si films form at intermediate K2SiF6 concentrations and current densities. The relationship between the deposition conditions and Si morphology is discussed in terms of the electrodeposition mechanism. (C) 2015 The Electrochemical Society. All rights reserved.

    DOI

    Scopus

    35
    Citation
    (Scopus)
  • Elimination of Boron from Soluble Silica Via Solvent Extraction with 2,2,4-Trimethyl-1,3-Pentanediol Using a Multistage Flow-Type Reactor

    N. Matsuo, T. Ishihara, T. Oyanagi, K. Nakajima, M. Kunimoto, Y. Fukunaka, T. Homma

    ECS Trans.   64 ( 64 ) 91 - 97  2015.04  [Refereed]

     View Summary

    Elimination of boron species via solvent extraction with 2,2,4-trimethyl-1,3-pentandiaol was engaged in a flow-type device into which the aqueous solution dissolving diatomaceous earth, a -candidate of the resource for high-purity silicon material. The flow-type device has a 2-stage channel with 1.0 mm width, 0.10 mm depth, and 25 mm length each, and the specific interfacial area is comparable to a typical microchannel device. Residual boron content in the aqueous solution decreased to less than 0.1 ppm after the solvent extraction under the restriction of short contact duration shorter than 100 ms. In addition, the analysis with density functional theory indicated that the number of neighbor carbon on the central carbon is one of the keys for improvement of reactivity of extractant. Hence, it is suggested that the flow-type microchannel device with solvent extraction with alkyldiol extractant can be utilized as an attractive approach toward the production of high-purity silica as a source for solar-grade silicon.

    DOI

    Scopus

    2
    Citation
    (Scopus)
  • Characterization of Electrodeposited Co-Pt Nanodot Array at Initial Deposition Stage

    S. Wodarz, T. Otani, H. Hagiwara, T. Homma

    ECS Trans.   64 ( 64 ) 99 - 105  2015.04  [Refereed]

     View Summary

    We have fabricated Co-Pt nanodot arrays by electrochemical process for the application of bit patterned media (BPM), which is proposed as a key technology for future recording media. Since formation of uniform nanodot arrays is required for BPM, controlling the initial stages of electrodeposition is significant. In this work, we analyzed the effects of applied potential and size of nano-patterns on initial stages of Co-Pt electrodeposition. As a result, number of Co-Pt nuclei decreased in smaller nano-pore. In particular, formation of Co-Pt single grains, which exhibit high and uniform coercivity, was expected with low overpotential in nanopore with 10 nm diameter. Furthermore, coercivities of Co-Pt films at the initial stage increased with lower overpotential, since Co-Pt nucleated and grew along with Ru underlayer with high orientation. These results indicate that magnetic properties of Co-Pt nanodot arrays can be optimized by controlling the nucleation and growth behavior of Co-Pt.

    DOI

    Scopus

    2
    Citation
    (Scopus)
  • Fabrication of FePt and CoPt Magnetic Nanodot Arrays by Electrodeposition Process

    T. Homma, S. Wodarz, D. Nishiie, T. Otani, S. Ge, G. Zangari

    ECS Trans.   ( 64 ) 43109  2015.03  [Refereed]

  • Fabrication of Pi-structured Bi-Te thermoelectric micro-device by electrodeposition

    Kazuho Uda, Yuta Seki, Mikiko Saito, Yoshiaki Sonobe, Yu-Chin Hsieh, Hidefumi Takahashi, Ichiro Terasaki, Takayuki Homma

    ELECTROCHIMICA ACTA   153   515 - 522  2015.01  [Refereed]

     View Summary

    A Pi-structured Bi-Te micro-thermoelectric device with a large upper electrode, i.e., an umbrella-type device, was fabricated via electrodeposition, and the effect of the size of the electrode was evaluated. The Bi-Te thermoelectric materials were electrodeposited from HNO3-based aqueous electrolyte. The device consisted of eight arrays, each consisting of 110 thermoelectric units, each of which was electrodeposited onto the patterned substrate with an array of 50 x 50 mu m(2) holes that were 20 mu m deep. The deposition conditions for the n-type and p-type Bi-Te films were optimized to enable patterned electrodeposition of the materials to yield dense and uniform deposits. Accordingly, the materials were selectively deposited in a pattern to fabricate the thermoelectric micro-device. The resultant umbrella-type device, whose electrode is 1.65 times larger than smaller electrode, generated 4.57 times more power than the device with a smaller electrode. Therefore, we confirmed the improvement power by using an umbrella-type device. (C) 2014 Elsevier Ltd. All rights reserved.

    DOI

    Scopus

    28
    Citation
    (Scopus)
  • Trap-state passivation of titania nanotubes by electrochemical doping for enhanced photoelectrochemical performance

    Lok-kun Tsui, Mikiko Saito, Takayuki Homma, Giovanni Zangari

    JOURNAL OF MATERIALS CHEMISTRY A   3 ( 1 ) 360 - 367  2014.11  [Refereed]

     View Summary

    TiO2 nanotubes are widely investigated materials for photoelectrochemical water splitting, but the presence of trap states limits their performance by facilitating the recombination of electron/hole pairs. In this investigation we unequivocally demonstrate that the photocurrent improvement observed in TiO2 nanotubes after performing electrochemical doping with hydrogen or lithium ions is due to trap state passivation. Specifically, electrochemical impedance spectroscopy evidences that trap state defects disappear upon electrochemical doping, concurrent with an increase in the electron lifetime and faster photocurrent transients. This results in a two-fold enhancement in the photocurrent under simulated sunlight at 1.0 V vs. SCE. Li intercalation was confirmed and the structure as well as the composition of the modified nanotubes was elucidated by GDOES, XPS, and TEM.

    DOI

    Scopus

    42
    Citation
    (Scopus)
  • Trap-state passivation of titania nanotubes by electrochemical doping for enhanced photoelectrochemical performance

    L. Tsui, M. Saito, T. Homma, G. Zangari

    J. Mat. Chem. A   3 ( 3 ) 360 - 367  2014.11  [Refereed]

     View Summary

    TiO2 nanotubes are widely investigated materials for photoelectrochemical water splitting, but the presence of trap states limits their performance by facilitating the recombination of electron/hole pairs. In this investigation we unequivocally demonstrate that the photocurrent improvement observed in TiO2 nanotubes after performing electrochemical doping with hydrogen or lithium ions is due to trap state passivation. Specifically, electrochemical impedance spectroscopy evidences that trap state defects disappear upon electrochemical doping, concurrent with an increase in the electron lifetime and faster photocurrent transients. This results in a two-fold enhancement in the photocurrent under simulated sunlight at 1.0 V vs. SCE. Li intercalation was confirmed and the structure as well as the composition of the modified nanotubes was elucidated by GDOES, XPS, and TEM.

    DOI

    Scopus

    42
    Citation
    (Scopus)
  • Reaction Behavior of Stratified SiO2 Granules during Electrochemical Reduction in Molten CaCl2

    Xiao Yang, Kouji Yasuda, Toshiyuki Nohira, Rika Hagiwara, Takayuki Homma

    METALLURGICAL AND MATERIALS TRANSACTIONS B-PROCESS METALLURGY AND MATERIALS PROCESSING SCIENCE   45 ( 4 ) 1337 - 1344  2014.08  [Refereed]

     View Summary

    The electrochemical reduction behavior of stratified SiO2 granules in molten CaCl2 at 1123 K (850 A degrees C) was investigated to develop a new process for producing solar-grade silicon. The cross sections of the electrolyzed electrode prepared from a graphite crucible filled with SiO2 granules were observed and analyzed. The visual and SEM observations indicate that the overall reduction proceeds via two different routes. In one route, the reduction proceeds along the granule surfaces from the SiO2 near the conductor to the distant SiO2. In the other route, the reduction proceeds from the granule surface to the core of each granule. The reduction along the granule surfaces is faster than that from the surface to the core. Fine SiO2 granules are expected to be favorable for a high reduction rate. (C) The Minerals, Metals & Materials Society and ASM International 2014

    DOI

    Scopus

    21
    Citation
    (Scopus)
  • Kinetic Characteristics of Electrochemical Reduction of SiO2 Granules in Molten CaCl2

    Xiao Yang, Kouji Yasuda, Toshiyuki Nohira, Rika Hagiwara, Takayuki Homma

    JOURNAL OF THE ELECTROCHEMICAL SOCIETY   161 ( 7 ) D3116 - D3119  2014.05  [Refereed]

     View Summary

    The kinetic characteristics of electrochemical reduction of SiO2 granules in molten CaCl2 were investigated to develop a new process for producing solar-grade silicon. The reduction rate was-evaluated based-on-the time dependence of the reduction fractions measured from the growth of the reduced Si layer and the weight change of the samples during electrolysis. The samples were prepared by potentiostatic electrolysis of SiO2 granules in molten CaCl2 at 1123 K. The results indicated that the reduction was fast at the initial stage of electrolysis, and gradually slowed as the reaction progressed. The apparent current density reached 0.7 A cm(-2) at the initial stage, which was comparable to the commercial Hall-Heroult process for aluminum production. (C) 2014 The Electrochemical Society. All rights reserved.

    DOI

    Scopus

    20
    Citation
    (Scopus)
  • Kinetic Characteristics of Electrochemical Reduction of SiO2 Granules in Molten CaCl2

    X. Yang, K. Yasuda, T. Nohira, R. Hagiwara, T. Homma

    J. Electrochem. Soc.   16 ( 161 (7) ) D3116 - D3119  2014.05  [Refereed]

    CiNii

  • Kinetic Characteristics of Electrochemical Reduction of SiO2 Granules in Molten CaCl2

    X. Yang, K.Yasuda, T. Nohira, R. Hagiwara, T. Homma

    J. Electrochem. Soc.   ( 161 ) D3116 - D3119  2014.05  [Refereed]

  • Boron Extraction with 2-Ethyl-1,3-hexanediol Using a Microchannel Device for High-Purity Source of Solar-Grade Silicon

    Nobufumi Matsuo, Yuki Matsui, Yasuhiro Fukunaka, Takayuki Homma

    JOURNAL OF THE ELECTROCHEMICAL SOCIETY   161 ( 5 ) E93 - E96  2014.04  [Refereed]

     View Summary

    A novel approach toward the purification of silica and removal of boron impurities via solvent extraction with 2-ethyl-1,3-hexanediol using a microchannel device is presented. The microchannel, fabricated on Si substrates using lithographic techniques, had 100 mu m width, 100 mu m depth, and 10 mm length. Amorphous silica spiked with a trace amount of boric acid and refined diatomaceous earth used as silica feedstock were purified. Residual boron content was determined by inductively coupled argon plasma atomic emission spectrometry. Following extraction using a microchannel device, the residual boron content was less than 1.0 ppm for the former silica feedstock and than 2.5 ppm for the latter one, and the contact reaction period was 0.03 seconds for both type of silica feedstock. These are lower and significantly shorter due to much shorter diffusion distance and much larger specific interfacial area as compared to those observed when using a conventional separatory funnel, for both types of silica feedstock. Hence, it is suggested that microchannel devices can be utilized as an attractive approach toward the production of high-purity silica as a source for solar-grade silicon. (C) 2014 The Electrochemical Society. All rights reserved.

    DOI

    Scopus

    6
    Citation
    (Scopus)
  • Boron Extraction with 2-Ethyl-1,3-hexanediol Using a Microchannel Device for High-Purity Source of Solar-Grade Silicon

    Nobufumi Matsuo, Yuki Matsui, Yasuhiro Fukunaka, Takayuki Homma

    JOURNAL OF THE ELECTROCHEMICAL SOCIETY   161 ( 5 ) E93 - E96  2014.04  [Refereed]

     View Summary

    A novel approach toward the purification of silica and removal of boron impurities via solvent extraction with 2-ethyl-1,3-hexanediol using a microchannel device is presented. The microchannel, fabricated on Si substrates using lithographic techniques, had 100 mu m width, 100 mu m depth, and 10 mm length. Amorphous silica spiked with a trace amount of boric acid and refined diatomaceous earth used as silica feedstock were purified. Residual boron content was determined by inductively coupled argon plasma atomic emission spectrometry. Following extraction using a microchannel device, the residual boron content was less than 1.0 ppm for the former silica feedstock and than 2.5 ppm for the latter one, and the contact reaction period was 0.03 seconds for both type of silica feedstock. These are lower and significantly shorter due to much shorter diffusion distance and much larger specific interfacial area as compared to those observed when using a conventional separatory funnel, for both types of silica feedstock. Hence, it is suggested that microchannel devices can be utilized as an attractive approach toward the production of high-purity silica as a source for solar-grade silicon. (C) 2014 The Electrochemical Society. All rights reserved.

    DOI

    Scopus

    6
    Citation
    (Scopus)
  • Reaction Behavior of Stratified SiO2 Granules during Electrochemical Reduction in Molten CaCl2

    X. Yang, K.Yasuda, T. Nohira, R. Hagiwara, T. Homma

    Metallurgical and Mat. Trans. B   ( 45 ) 1337 - 1344  2014.03  [Refereed]

  • Special Section: ELECTROCHEMICAL MICRO & NANO-SYSTEMS TECHNOLOGY Selection of papers from the 9th International Symposium (EMNT 2012) 15-17 August 2012, Linz, Austria Foreword

    Achim Walter Hassel, Takayuki Homma

    ELECTROCHIMICA ACTA   113   719 - 719  2013.12  [Refereed]

    DOI

    Scopus

  • Foreword

    Walter Hassel, Achim, Homma, Takayuki

    Electrochimica Acta   113   9 - 10  2013.12  [Refereed]

    DOI

    Scopus

  • Nanoindentation analysis for mechanical properties of electroless NiP imprinting mold replicated from self-assembled-monolayer modified master mold

    Cheng Ping Lin, Mikiko Saito, Takayuki Homma

    Japanese Journal of Applied Physics   52 ( 11 )  2013.11

     View Summary

    A NiP imprinting mold with patterns, whose size is from nanometer to submicrometer (170, 500, and 1000nm diameter), was fabricated by electroless deposition of NiP on a 3-aminopropyltriethoxysilane (APTES) modified master mold. The NiP deposit as a replicate mold was then detached from the master mold. The initial NiP deposition in patterns of the master mold was investigated
    moreover, nanoindentation was successfully performed on a single NiP pattern for investigating the hardness. The NiP had a similar grain size in different sizes of patterns of the master mold during the initial deposition, as well as the same hardness of the NiP patterns (approximately 12 GPa) was observed. These results indicated that the initial NiP deposition and hardness of NiP were not size dependent above 170 nm. The surface morphology of the NiP detached from the master mold and NiP pattern of different sizes were investigated as well. © 2013 The Japan Society of Applied Physics.

    DOI

    Scopus

    1
    Citation
    (Scopus)
  • Nanoindentation analysis for mechanical properties of electroless NiP imprinting mold replicated from self-assembled-monolayer modified master mold

    Cheng Ping Lin, Mikiko Saito, Takayuki Homma

    Japanese Journal of Applied Physics   52 ( 11 )  2013.11

     View Summary

    A NiP imprinting mold with patterns, whose size is from nanometer to submicrometer (170, 500, and 1000nm diameter), was fabricated by electroless deposition of NiP on a 3-aminopropyltriethoxysilane (APTES) modified master mold. The NiP deposit as a replicate mold was then detached from the master mold. The initial NiP deposition in patterns of the master mold was investigated
    moreover, nanoindentation was successfully performed on a single NiP pattern for investigating the hardness. The NiP had a similar grain size in different sizes of patterns of the master mold during the initial deposition, as well as the same hardness of the NiP patterns (approximately 12 GPa) was observed. These results indicated that the initial NiP deposition and hardness of NiP were not size dependent above 170 nm. The surface morphology of the NiP detached from the master mold and NiP pattern of different sizes were investigated as well. © 2013 The Japan Society of Applied Physics.

    DOI

    Scopus

    1
    Citation
    (Scopus)
  • Characterization and analysis of deposition behavior of ultra-high density ferromagnetic nanodot arrays fabricated by electrochemical processes

    WODARZ Siggi, MANIWA Yuta, HAGIWARA Hiroki, OTANI Tomohiro, NISHIIE Daiki, ZANGARI Giovanni, HOMMA Takayuki

    IEICE technical report. Magnetic recording   113 ( 297 ) 7 - 10  2013.11

     View Summary

    We fabricated hcp-Co_<80>Pt_<20> and L1_0-FePt thin films and nanodot arrays onto hcp-Ru (002) / Si substrate by electrodeposition and lithography processes. The effect of applied potential and diameter of the nanodot on deposition behavior of Co-Pt was analyzed in order to control the deposition of Co-Pt. By using electron beam lithography, nanodot patterns with 10 nm diameter and 18 nm pitch were uniformly fabricated. It was suggested that the particle size of Co-Pt could be controlled by the applied potential, and in the case of relatively positive applied potential of -400 mV and -500 mV vs Ag / AgCl, progressive nucleation preferentially occurred to increase the size of each Co-Pt particle. The phase transformation from fcc-Fe-Pt to L1_0 Fe-Pt was observed by annealing at 650℃, and Fe-Pt films with perpendicular coercivity of 9.0 kOe and 9.8 kOe with a thickness of 10 nm and 25 nm were obtained. In addition, Fe-Pt nanodot arrays having a pitch and a diameter of 100 nm and 35 nm were successfully fabricated by UV-nanoimprint lithography.

    CiNii

  • Fabrication of electroless NiP nanoimprinting mold by replication of uv-treated and self-assembled-monolayer-modified cyclo-olefin polymer nanopatterns

    Cheng Ping Lin, Mikiko Saito, Takayuki Homma

    Electrochemistry   81 ( 9 ) 678 - 681  2013.09

     View Summary

    An electroless NiP imprinting mold was fabricated through replication of a cyclo-olefin polymer (COP) master mold. The NiP was electrolessly deposited on a nanopatterned COP master mold, pretreated by ultraviolet (UV) irradiation prior to modification with 3-aminopropyltriethoxysilane (APTES). The NiP deposit as a "replicate" was then detached from the COP master mold. Additionally, by optimizing the UV irradiation period, APTES could be formed on the COP master mold for electroless deposition without disturbing the nanopattern geometry of the COP master mold. The water contact angle and surface morphology of the COP surface, and the adhesion strength between deposited NiP and the COP surface were investigated. © 2013 The Electrochemical Society of Japan, All rights reserved.

    DOI

    Scopus

    2
    Citation
    (Scopus)
  • Raman and DFT Study of the Reaction of Hydrazine and Hypophosphite on a Cu Surface in the Electroless Deposition Process

    Bin Jiang, Siggi Wodarz, Masahiro Kunimoto, Masahiro Yanagisawa, Takayuki Homma

    ELECTROCHEMISTRY   81 ( 9 ) 674 - 677  2013.09  [Refereed]

     View Summary

    Oxidation of the reductants is a dominant factor in the electroless deposition process. In order to obtain fundamental knowledge about the reaction mechanism of reductant oxidation for more precise control of the solid-liquid interface in this process, we have attempted to characterize the behavior of reductants adsorbed on Cu surface by using plasmon antenna enhanced Raman scattering. The concentric-patterned antenna coated with Cu, which consisted of a dimple array with single hole or a single hole with coaxial dimples, was designed by Finite Difference Time Domain (FDTD) calculation to enhance the electric field by focusing surface plasmons. By using this antenna and comparing the spectra to the results of Density Functional Theory (DFT) calculations, Raman peaks of adsorbed reductants on Cu were identified. Furthermore, we examined the conformation of adsorbed reductants by DFT calculation of the adsorption model of reductants on fcc-Cu(111) surface. As a result, the nature of reductant adsorption on Cu surface has been investigated from a computational point of view and an experimental point of view, and such in-situ characterization will be useful for analysis of a variety of systems at solid-liquid interface. (c) The Electrochemical Society of Japan, All rights reserved.

    DOI

    Scopus

    8
    Citation
    (Scopus)
  • Raman and DFT Study of the Reaction of Hydrazine and Hypophosphite on a Cu Surface in the Electroless Deposition Process

    Bin Jiang, Siggi Wodarz, Masahiro Kunimoto, Masahiro Yanagisawa, Takayuki Homma

    ELECTROCHEMISTRY   81 ( 9 ) 674 - 677  2013.09  [Refereed]

     View Summary

    Oxidation of the reductants is a dominant factor in the electroless deposition process. In order to obtain fundamental knowledge about the reaction mechanism of reductant oxidation for more precise control of the solid-liquid interface in this process, we have attempted to characterize the behavior of reductants adsorbed on Cu surface by using plasmon antenna enhanced Raman scattering. The concentric-patterned antenna coated with Cu, which consisted of a dimple array with single hole or a single hole with coaxial dimples, was designed by Finite Difference Time Domain (FDTD) calculation to enhance the electric field by focusing surface plasmons. By using this antenna and comparing the spectra to the results of Density Functional Theory (DFT) calculations, Raman peaks of adsorbed reductants on Cu were identified. Furthermore, we examined the conformation of adsorbed reductants by DFT calculation of the adsorption model of reductants on fcc-Cu(111) surface. As a result, the nature of reductant adsorption on Cu surface has been investigated from a computational point of view and an experimental point of view, and such in-situ characterization will be useful for analysis of a variety of systems at solid-liquid interface. (c) The Electrochemical Society of Japan, All rights reserved.

    DOI

    Scopus

    8
    Citation
    (Scopus)
  • Fabrication of electroless NiP nanoimprinting mold by replication of uv-treated and self-assembled-monolayer-modified cyclo-olefin polymer nanopatterns

    Cheng Ping Lin, Mikiko Saito, Takayuki Homma

    Electrochemistry   81 ( 9 ) 678 - 681  2013.09

     View Summary

    An electroless NiP imprinting mold was fabricated through replication of a cyclo-olefin polymer (COP) master mold. The NiP was electrolessly deposited on a nanopatterned COP master mold, pretreated by ultraviolet (UV) irradiation prior to modification with 3-aminopropyltriethoxysilane (APTES). The NiP deposit as a "replicate" was then detached from the COP master mold. Additionally, by optimizing the UV irradiation period, APTES could be formed on the COP master mold for electroless deposition without disturbing the nanopattern geometry of the COP master mold. The water contact angle and surface morphology of the COP surface, and the adhesion strength between deposited NiP and the COP surface were investigated. © 2013 The Electrochemical Society of Japan, All rights reserved.

    DOI

    Scopus

    2
    Citation
    (Scopus)
  • Electrolytic reduction of SiO2 granules in molten CaCl 2

    Tetsuya Toba, Kouji Yasuda, Toshiyuki Nohira, Xiao Yang, Rika Hagiwara, Koki Ichitsubo, Kenta Masuda, Takayuki Homma

    Electrochemistry   81 ( 7 ) 559 - 565  2013.07

     View Summary

    Direct electrolytic reduction of SiO2 was investigated in molten CaCl2 at 1123K as a fundamental study to develop a continuous process for solar-grade Si production. Several different types of SiO 2 granules, as well as SiO2 pellets, were successfully reduced to Si on the bottom cathode of a Si plate. Three parameters were varied in the reduction of SiO2 granules: electrode potential, layer thickness of the SiO2 granules, and SiO2 particle size. The reduction rate was evaluated by the magnitude of the reduction current. The main factor determining the reduction rate was the diffusion of O2- ions inside the reduced porous Si layer filled with the electrolyte. Another factor which influenced the reduction rate was the contact resistance between Si granules. © The Electrochemical Society of Japan 2013.

    DOI

    Scopus

    31
    Citation
    (Scopus)
  • Characterization and analysis of deposition process of ultra-high density magnetic nanodot arrays fabricated by electrochemical processes

    Wodarz Siggi, Maniwa Yuta, Hagiwara Hiroki, Homma Takayuki

    IEICE technical report. Magnetic recording   113 ( 127 ) 13 - 17  2013.07

     View Summary

    We have been fabricating ferromagnetic nanodot arrays for bit patterned media (BPM) by using lithography techniques and electrochemical processes. In this research, we attemped to fabricate hcp-Co-Pt(002) and L10-Fe-Pt thin films and nanodot arrays with high coercivity. Nano-patterns were formed by electron beam lithography (EBL) and Co-Pt and Fe-Pt were electrodeposited into the nano-patterns. For obtaining Co-Pt thin films and nanodot arrays with high perpendicular coercivities, we applied hcp-Ru(002) intermediate layer on Si substrate. As a result, the magnetic properties and the crystallinities of Co-Pt thin films and nanodot arrays were improved by using Ru(002) layer, and Co-Pt nanodot arrays with 10 nm diameters and 18 nm pitches were observed. Investigation of initial deposition suggested that the particle size of Co-Pt can be controlled by changing the applied potential. The phase transformation from fcc-Fe-Pt to L1_0-Fe-Pt was verified by annealing, and the coercivities of Fe-Pt were improved.

    CiNii

  • Analysis of hydrazine on a Cu surface with nanoscale resolution using surface enhanced Raman spectroscopy

    Bin Jiang, Takanari Ouchi, Naofumi Shimano, Akira Otomo, Masahiro Kunimoto, Masahiro Yanagisawa, Takayuki Homma

    ELECTROCHIMICA ACTA   100   317 - 320  2013.06  [Refereed]

     View Summary

    This paper described characterization of hydrazine adsorption on Cu surface with high-selectivity of component at right angle down to single molecular level using a plasmonic antenna enhancing Raman scattering. The antenna deposited by Cu with concentric pattern was designed by Finite Difference Time Domain (FDTD) calculation to enhance the electric field by focusing surface plasmon. By using this antenna, Raman peaks of adsorbed hydrazine on Cu was provided at 385 cm(-1). Furthermore, these peaks were only observed at 1-2 nm from the antenna surface which meant that this approach had a potential to define the structure of adsorbed hydrazine just only on the plasmon antenna. The structure of adsorbed hydrazine was gauche-conformation. This data corresponded to the Density Functional Theory (DFT) of adsorption model of hydrazine on fcc-Cu (1 1 1) surface. These results suggest that this method creates a wide range of spin-off effects to the characterization of solid-liquid interface. (c) 2012 Elsevier Ltd. All rights reserved.

    DOI

    Scopus

    15
    Citation
    (Scopus)
  • Special Section: RENEWABLE ENERGY AND MATERIALS TAILORING Foreword

    Thomas P. Moffat, Rika Hagiwara, Takayuki Homma, Yasuhiro Fukunaka

    ELECTROCHIMICA ACTA   100   212 - 213  2013.06  [Refereed]

    DOI

    Scopus

  • Electrochemical quartz crystal microbalance study of Si electrodeposition in ionic liquid

    J. Komadina, T. Akiyoshi, Y. Ishibashi, Y. Fukunaka, T. Homma

    ELECTROCHIMICA ACTA   100 ( 100 ) 236 - 241  2013.06  [Refereed]

     View Summary

    The electrodeposition of silicon from silicon tetrachloride in the hydrophobic room temperature ionic liquid trimethyl-n-hexyl ammonium bis-(trifluoromethylsulfonyl) imide was investigated by cyclic voltammetry and chronoamperometry. In situ electrochemical quartz crystal microbalance (EQCM) impedance spectroscopy was used to estimate the mass of films during deposition. The charge efficiency estimated from EQCM measurements is similar to 190-250% for four-electron silicon reduction. However, compositional analysis by XPS shows that the EQCM current efficiency estimates are artificially high due to ionic liquid inclusion in the films. Taking the mass concentration of impurities into account, the bestcase estimate of current efficiency is found to be approximately 130% for constant potential deposition, suggesting silicon may not have been completely reduced at the potentials investigated, or a chemical reaction step occurs. We also consider that the EQCM analysis may include too many deviations from assumptions for accurate estimation of mass with the conditions studied. (C) 2012 Elsevier Ltd. All rights reserved.

    DOI

    Scopus

    34
    Citation
    (Scopus)
  • Electrochemical quartz crystal microbalance study of Si electrodeposition in ionic liquid

    J. Komadina, T. Akiyoshi, Y. Ishibashi, Y. Fukunaka, T. Homma

    ELECTROCHIMICA ACTA   100   236 - 241  2013.06  [Refereed]

     View Summary

    The electrodeposition of silicon from silicon tetrachloride in the hydrophobic room temperature ionic liquid trimethyl-n-hexyl ammonium bis-(trifluoromethylsulfonyl) imide was investigated by cyclic voltammetry and chronoamperometry. In situ electrochemical quartz crystal microbalance (EQCM) impedance spectroscopy was used to estimate the mass of films during deposition. The charge efficiency estimated from EQCM measurements is similar to 190-250% for four-electron silicon reduction. However, compositional analysis by XPS shows that the EQCM current efficiency estimates are artificially high due to ionic liquid inclusion in the films. Taking the mass concentration of impurities into account, the bestcase estimate of current efficiency is found to be approximately 130% for constant potential deposition, suggesting silicon may not have been completely reduced at the potentials investigated, or a chemical reaction step occurs. We also consider that the EQCM analysis may include too many deviations from assumptions for accurate estimation of mass with the conditions studied. (C) 2012 Elsevier Ltd. All rights reserved.

    DOI

    Scopus

    34
    Citation
    (Scopus)
  • Foreword

    Moffat, Thomas P, Hagiwara, Rika, Homma, Takayuki, Fukunaka, Yasuhiro

    Electrochimica Acta   100   212 - 213  2013.06  [Refereed]

    DOI

    Scopus

  • Analysis of hydrazine on a Cu surface with nanoscale resolution using surface enhanced Raman spectroscopy

    Bin Jiang, Takanari Ouchi, Naofumi Shimano, Akira Otomo, Masahiro Kunimoto, Masahiro Yanagisawa, Takayuki Homma

    ELECTROCHIMICA ACTA   100   317 - 320  2013.06  [Refereed]

     View Summary

    This paper described characterization of hydrazine adsorption on Cu surface with high-selectivity of component at right angle down to single molecular level using a plasmonic antenna enhancing Raman scattering. The antenna deposited by Cu with concentric pattern was designed by Finite Difference Time Domain (FDTD) calculation to enhance the electric field by focusing surface plasmon. By using this antenna, Raman peaks of adsorbed hydrazine on Cu was provided at 385 cm(-1). Furthermore, these peaks were only observed at 1-2 nm from the antenna surface which meant that this approach had a potential to define the structure of adsorbed hydrazine just only on the plasmon antenna. The structure of adsorbed hydrazine was gauche-conformation. This data corresponded to the Density Functional Theory (DFT) of adsorption model of hydrazine on fcc-Cu (1 1 1) surface. These results suggest that this method creates a wide range of spin-off effects to the characterization of solid-liquid interface. (c) 2012 Elsevier Ltd. All rights reserved.

    DOI

    Scopus

    15
    Citation
    (Scopus)
  • Photocurrent Conversion in Anodized TiO2 Nanotube Arrays: Effect of the Water Content in Anodizing Solutions

    Lok-kun Tsui, Takayuki Homma, Giovanni Zangari

    JOURNAL OF PHYSICAL CHEMISTRY C   117 ( 14 ) 6979 - 6989  2013.04  [Refereed]

     View Summary

    The TiO2 nanotube system exhibits properties of interest in photoelectrochemical water splitting for hydrogen production, including high surface area and vectorial charge transport along the nanotube length. Changes in the anodizing electrolyte chemistry provide the means to control nanotube morphology as well as their length and width. Despite the large amount of work available on nanotube synthesis, however, a thorough assessment of the effect of anodization conditions on the photoelectrochemical performance is still unavailable. In this paper, we characterize TiO2 nanotubes produced by varying the water content of the organic anodization electrolyte and investigate the influence of the electrolyte on their photoelectrochemical performance. We find that the photocurrent efficiency of the nanotubes is optimized by using an 11 vol % water:ethylene glycol ratio. We also demonstrate that a double-anodization technique produces a cleaner surface, resulting in higher photon-to-current conversion efficiencies of up to 30% at 350 nm. Raman spectroscopy, X-ray diffraction, and electrochemical impedance studies support the notion that the variation in crystallinity as a function of water content is the main factor in determining the photocurrent efficiency of the nanotube system.

    DOI

    Scopus

    76
    Citation
    (Scopus)
  • Fabrication of Nanogap Electrodes by Enhancing Lateral Growth of Au Electrodeposition for Electrical Property Measurement of Organic Nanowires

    Chiaki Kobayashi, Yutaka Wakayama, Yasuhiro Shirai, Takayuki Homma

    ELECTROCHEMISTRY   81 ( 4 ) 236 - 238  2013.04  [Refereed]

     View Summary

    We demonstrated fabrication of nanogap electrodes with flat and thin Au films by using laterally enhanced growth of Au electrodeposition and applied the electrodes for electrical measurement of poly(3-methylthiophene) (P3MT) nanowires. The Au electrodeposition was performed on nnicrogap electrodes following an organic modification process on an insulator surface of the microgap electrodes. Then, P3MT nanowires were aligned between the nanogap electrodes for transistor property measurement. The result suggested that the fabricated nanogap electrodes were suitable to apply for electrical properties measurement of such organic nanowires because of small difference in height between top of the electrodes and the insulator surface. (C) The Electrochemical Society of Japan, All rights reserved.

    DOI

    Scopus

    2
    Citation
    (Scopus)
  • Fabrication of Nanogap Electrodes by Enhancing Lateral Growth of Au Electrodeposition for Electrical Property Measurement of Organic Nanowires

    Chiaki Kobayashi, Yutaka Wakayama, Yasuhiro Shirai, Takayuki Homma

    ELECTROCHEMISTRY   81 ( 4 ) 236 - 238  2013.04  [Refereed]

     View Summary

    We demonstrated fabrication of nanogap electrodes with flat and thin Au films by using laterally enhanced growth of Au electrodeposition and applied the electrodes for electrical measurement of poly(3-methylthiophene) (P3MT) nanowires. The Au electrodeposition was performed on nnicrogap electrodes following an organic modification process on an insulator surface of the microgap electrodes. Then, P3MT nanowires were aligned between the nanogap electrodes for transistor property measurement. The result suggested that the fabricated nanogap electrodes were suitable to apply for electrical properties measurement of such organic nanowires because of small difference in height between top of the electrodes and the insulator surface. (C) The Electrochemical Society of Japan, All rights reserved.

    DOI

    Scopus

    2
    Citation
    (Scopus)
  • Electrochemical potential measurement and finite element structure analysis of Si wafer surface under mechanical stress

    Kaoruho Sakata, Takayuki Homma

    ELECTROCHEMISTRY COMMUNICATIONS   25 ( 1 ) 144 - 146  2012.11  [Refereed]

     View Summary

    Mechanical stress was applied to a Si single crystal wafer to evaluate the changes in its surface properties arising from the lattice strain induced by mechanical stress. The stress was applied quantitatively to the wafer in order to investigate the correlation between the degree of strain and the electrochemical properties of its surface. Finite element method (FEM) structural analysis was used to estimate the degree of strain on the surface, and the open circuit potential was measured in order to investigate the surface electrochemical properties. The analysis suggested that the surface of the wafer was under tensile strain, and the open circuit potential shifted toward the negative direction with the strain. This indicates that mechanical stress applied to a Si surface can change its electronic properties by changing the surface crystal structure. (C) 2012 Elsevier B.V. All rights reserved.

    DOI

    Scopus

    1
    Citation
    (Scopus)
  • Initial catalyzation analysis of electroless NiP nanoimprinting mold replicated from self-assembled monolayer modified nanopatterns

    Cheng Ping Lin, Mikiko Saito, Takayuki Homma

    ELECTROCHIMICA ACTA   82   75 - 81  2012.11  [Refereed]

     View Summary

    A nanoimprint lithography mold was fabricated through electroless deposition combined with self-assembled monolayer (SAM) modification. To copy nanopatterns as "replicates", NiP was electrolessly deposited on a nanopatterned master mold (made of SiO2/Si), whose surface was modified with 3-[2-(2-aminoethylamino)ethylamino]propyltrimethoxysilane (TAS). NiP deposits were then manually detached from the mold. SAM improves Pd catalyst coverage for electroless deposition, further improving the morphology of the electroless deposition of NiP on the nanopatterned master mold and controlling the adhesion strength between electroless deposited NiP and the nanopatterned master mold to a level appropriate for smooth detachment. The initial catalyzation process and mechanical properties (such as, the hardness and adhesion strength of the SiO2 substrate) of electroless deposited NiP were also systematically investigated. (c) 2012 Elsevier Ltd. All rights reserved.

    DOI

    Scopus

    7
    Citation
    (Scopus)
  • Electrochemical potential measurement and finite element structure analysis of Si wafer surface under mechanical stress

    Kaoruho Sakata, Takayuki Homma

    ELECTROCHEMISTRY COMMUNICATIONS   25 ( 1 ) 144 - 146  2012.11

     View Summary

    Mechanical stress was applied to a Si single crystal wafer to evaluate the changes in its surface properties arising from the lattice strain induced by mechanical stress. The stress was applied quantitatively to the wafer in order to investigate the correlation between the degree of strain and the electrochemical properties of its surface. Finite element method (FEM) structural analysis was used to estimate the degree of strain on the surface, and the open circuit potential was measured in order to investigate the surface electrochemical properties. The analysis suggested that the surface of the wafer was under tensile strain, and the open circuit potential shifted toward the negative direction with the strain. This indicates that mechanical stress applied to a Si surface can change its electronic properties by changing the surface crystal structure. (C) 2012 Elsevier B.V. All rights reserved.

    DOI

    Scopus

    1
    Citation
    (Scopus)
  • Initial catalyzation analysis of electroless NiP nanoimprinting mold replicated from self-assembled monolayer modified nanopatterns

    Cheng Ping Lin, Mikiko Saito, Takayuki Homma

    ELECTROCHIMICA ACTA   82   75 - 81  2012.11

     View Summary

    A nanoimprint lithography mold was fabricated through electroless deposition combined with self-assembled monolayer (SAM) modification. To copy nanopatterns as "replicates", NiP was electrolessly deposited on a nanopatterned master mold (made of SiO2/Si), whose surface was modified with 3-[2-(2-aminoethylamino)ethylamino]propyltrimethoxysilane (TAS). NiP deposits were then manually detached from the mold. SAM improves Pd catalyst coverage for electroless deposition, further improving the morphology of the electroless deposition of NiP on the nanopatterned master mold and controlling the adhesion strength between electroless deposited NiP and the nanopatterned master mold to a level appropriate for smooth detachment. The initial catalyzation process and mechanical properties (such as, the hardness and adhesion strength of the SiO2 substrate) of electroless deposited NiP were also systematically investigated. (c) 2012 Elsevier Ltd. All rights reserved.

    DOI

    Scopus

    7
    Citation
    (Scopus)
  • Measurement Technology for Hard Disk Interface : Application of Plasmonic Sensor-A Challenge to Sub-nanometer Scale-

    YANAGISAWA Masahiro, SAITO Mikiko, HOMMA Takayuki

    IEICE technical report. Magnetic recording   112 ( 294 ) 1 - 4  2012.11

     View Summary

    Chemical structure of ultra-thin lubricant film/DLC overcoat for 4Tbpsi and more was measured with plasmonic sensor and surface-enhanced Raman scattering spectroscopy. Depth profile of the chemical structure for the film system was also measured with a depth resolution of 0.1nm.

    CiNii

  • Measurement Technology for Hard Disk Interface:Application of Plasmonic Sensor : A Challenge to Sub-nanometer Scale

    YANAGISAWA Masahiro, SAITO Mikiko, HOMMA Takayuki

      112 ( 294 ) 1 - 4  2012.11

    CiNii

  • Laterally enhanced growth of electrodeposited Au to form ultrathin films on nonconductive surfaces

    Chiaki Kobayashi, Mikiko Saito, Takayuki Homma

    ELECTROCHIMICA ACTA   74   235 - 243  2012.07  [Refereed]

     View Summary

    We investigated the laterally enhanced growth of electrodeposited Au for fabricating nanogap electrodes. To enhance the lateral growth, we carried out electrodeposition over patterned electrodes onto a SiO2 surface modified with self-assembled monolayers (SAMs) or dendrimers with amine groups. The morphology and thickness of the Au films were controlled by adjusting deposition conditions such as duration, applied potential, and Au ion concentration in the bath. To investigate the mechanism of the laterally enhanced growth, the surface states of SAM- or dendrimer-modified SiO2 were analyzed by X-ray photoelectron spectroscopy (XPS). The XPS results indicate the existence of organic molecules and Au ions on the SiO2 surface, which suggests that laterally enhanced growth is induced by the Au ions coordinated on the amine groups of the organic molecules. To further analyze the mechanism of the laterally enhanced growth, we investigated the relationship between the morphology of the laterally enhanced growth of Au and the amount of Au ions on organic molecules. The laterally enhanced growth of Au is expected to be useful for fabricating thin film nanogap electrodes. (C) 2012 Elsevier Ltd. All rights reserved.

    DOI

    Scopus

    8
    Citation
    (Scopus)
  • Laterally enhanced growth of electrodeposited Au to form ultrathin films on nonconductive surfaces

    Chiaki Kobayashi, Mikiko Saito, Takayuki Homma

    ELECTROCHIMICA ACTA   74   235 - 243  2012.07  [Refereed]

     View Summary

    We investigated the laterally enhanced growth of electrodeposited Au for fabricating nanogap electrodes. To enhance the lateral growth, we carried out electrodeposition over patterned electrodes onto a SiO2 surface modified with self-assembled monolayers (SAMs) or dendrimers with amine groups. The morphology and thickness of the Au films were controlled by adjusting deposition conditions such as duration, applied potential, and Au ion concentration in the bath. To investigate the mechanism of the laterally enhanced growth, the surface states of SAM- or dendrimer-modified SiO2 were analyzed by X-ray photoelectron spectroscopy (XPS). The XPS results indicate the existence of organic molecules and Au ions on the SiO2 surface, which suggests that laterally enhanced growth is induced by the Au ions coordinated on the amine groups of the organic molecules. To further analyze the mechanism of the laterally enhanced growth, we investigated the relationship between the morphology of the laterally enhanced growth of Au and the amount of Au ions on organic molecules. The laterally enhanced growth of Au is expected to be useful for fabricating thin film nanogap electrodes. (C) 2012 Elsevier Ltd. All rights reserved.

    DOI

    Scopus

    8
    Citation
    (Scopus)
  • Steps Going Forward

    HOMMA Takayuki

      63 ( 5 ) 285 - 285  2012.05

    CiNii

  • Theoretical Analysis of Adsorption Structure of Hydrated Hypophosphite Ion on Pd (111) Surface

    Masahiro Kunimoto, Kenji Seki, Hiromi Nakai, Takayuki Homma

    ELECTROCHEMISTRY   80 ( 4 ) 222 - 225  2012.04  [Refereed]

     View Summary

    The influence of water molecules on the reaction behavior of hypophosphite ion, which acts as a reducing agent for electroless deposition, on metal surfaces was elucidated by calculating the adsorption structure of hydrated hypophosphite ion on a Pd surface using Monte-Carlo simulation and density functional theory calculations. Through geometrical optimization, the most favorable structure of the hydrated hypophosphite ion was obtained, in which six water molecules interact with the oxygen of hypophosphite ion and no water interacts with the hydrogen of hypophosphite ion. Further calculations indicated that the hydrated hypophosphite ion adsorbed on the Pd surface via hydrogen. (C) The Electrochemical Society of Japan, All rights reserved.

    DOI

    Scopus

    6
    Citation
    (Scopus)
  • Theoretical Analysis of Adsorption Structure of Hydrated Hypophosphite Ion on Pd (111) Surface

    Masahiro Kunimoto, Kenji Seki, Hiromi Nakai, Takayuki Homma

    ELECTROCHEMISTRY   80 ( 4 ) 222 - 225  2012.04  [Refereed]

     View Summary

    The influence of water molecules on the reaction behavior of hypophosphite ion, which acts as a reducing agent for electroless deposition, on metal surfaces was elucidated by calculating the adsorption structure of hydrated hypophosphite ion on a Pd surface using Monte-Carlo simulation and density functional theory calculations. Through geometrical optimization, the most favorable structure of the hydrated hypophosphite ion was obtained, in which six water molecules interact with the oxygen of hypophosphite ion and no water interacts with the hydrogen of hypophosphite ion. Further calculations indicated that the hydrated hypophosphite ion adsorbed on the Pd surface via hydrogen. (C) The Electrochemical Society of Japan, All rights reserved.

    DOI

    Scopus

    6
    Citation
    (Scopus)
  • Theoretical Analysis of Catalytic Activity of Metal Surfaces on Reaction of Hypophosphite Ion

    Masahiro Kunimoto, Hiromi Nakai, Takayuki Homma

    ELECTROCHEMISTRY   80 ( 3 ) 126 - 131  2012.03  [Refereed]

     View Summary

    To elucidate the mechanism of catalytic activity of metal surfaces on the reaction of hypophosphite ions, which act as a reducing agent for electroless deposition, molecular orbital interactions between hypophosphite ions and metal surfaces were analyzed using density functional theory. Pd (111) and Cu (111) were chosen as the surfaces with high and low catalytic activity, respectively. The electronic states of adsorption systems were analyzed using the Mulliken population analysis. The position of the d-band plays a key role in determining the catalytic activity on P-H bond cleavage of hypophosphite. The Pd surface has a d-band near the Fermi level and contains a vacancy; this enables the donation and back-donation effect to occur on the adsorbed hypophosphite and promotes P-H bond cleavage. On the other hand, the Cu surface has a d-band in the deep energy area and contains no vacancy; the donation and back-donation effect is not induced and P-H bond cleavage is not promoted. This difference in the degree of promotion of P-H cleavage is responsible for the difference in the catalytic activity on P-H cleavage and dehydrogenation of hypophosphite ions, which in turn explains the difference in the catalytic activity during the entire hypophosphite oxidation process. (C) The Electrochemical Society of Japan, All rights reserved.

    DOI

    Scopus

    7
    Citation
    (Scopus)
  • Theoretical Analysis of Catalytic Activity of Metal Surfaces on Reaction of Hypophosphite Ion

    Masahiro Kunimoto, Hiromi Nakai, Takayuki Homma

    ELECTROCHEMISTRY   80 ( 3 ) 126 - 131  2012.03  [Refereed]

     View Summary

    To elucidate the mechanism of catalytic activity of metal surfaces on the reaction of hypophosphite ions, which act as a reducing agent for electroless deposition, molecular orbital interactions between hypophosphite ions and metal surfaces were analyzed using density functional theory. Pd (111) and Cu (111) were chosen as the surfaces with high and low catalytic activity, respectively. The electronic states of adsorption systems were analyzed using the Mulliken population analysis. The position of the d-band plays a key role in determining the catalytic activity on P-H bond cleavage of hypophosphite. The Pd surface has a d-band near the Fermi level and contains a vacancy; this enables the donation and back-donation effect to occur on the adsorbed hypophosphite and promotes P-H bond cleavage. On the other hand, the Cu surface has a d-band in the deep energy area and contains no vacancy; the donation and back-donation effect is not induced and P-H bond cleavage is not promoted. This difference in the degree of promotion of P-H cleavage is responsible for the difference in the catalytic activity on P-H cleavage and dehydrogenation of hypophosphite ions, which in turn explains the difference in the catalytic activity during the entire hypophosphite oxidation process. (C) The Electrochemical Society of Japan, All rights reserved.

    DOI

    Scopus

    7
    Citation
    (Scopus)
  • Quantum Chemical Analysis of Electroless Deposition Processes

    KUNIMOTO Masahiro, HOMMA Takayuki

    Jitsumu Hyomen Gijutsu   62 ( 12 ) 657 - 662  2011.12

    DOI CiNii

  • CoNiP electroless deposition process for fabricating ferromagnetic nanodot arrays

    Takanari Ouchi, Naofumi Shimano, Takayuki Homma

    ELECTROCHIMICA ACTA   56 ( 26 ) 9575 - 9580  2011.11  [Refereed]

     View Summary

    An electroless deposition process for fabricating CoNiP nanodot arrays (less than 50 nm in height) with high magnetic coercivities was investigated. To fabricate such nanostructures, we improved the crystallinity of the CoNiP deposits in the initial deposition stage by applying an fcc-Cu(1 1 1) underlayer with low lattice mismatch to hcp-Co(0 0 0 2), and an autocatalytic electroless deposition process at the Cu surface was carried out by using dual reducing agents, H(2)PO(2)(-) and N(2)H(4). CoNiP films demonstrated high perpendicular magnetic coercivities in the initial deposition stage since the highly crystalline hcp(0 0 0 2) CoNiP layers were grown parallel to the Cu underlayers. Nanopatterned substrates were formed by UV-nanoimprint lithography. CoNiP was electroless deposited on the nanopatterned substrates. As a result. CoNiP was deposited selectively from the bottom of the nanopores with few defects in a large area. Perpendicular coercivities higher than 3000 Oe were obtained for nanodots even with heights of 50 nm. Thus, an electroless deposition process that can be used to form nanostructures with high crystallinities in the initial stage without any anomalous deposition was demonstrated. (C) 2011 Elsevier Ltd. All rights reserved.

    DOI

    Scopus

    12
    Citation
    (Scopus)
  • CoNiP electroless deposition process for fabricating ferromagnetic nanodot arrays

    Takanari Ouchi, Naofumi Shimano, Takayuki Homma

    ELECTROCHIMICA ACTA   56 ( 26 ) 9575 - 9580  2011.11  [Refereed]

     View Summary

    An electroless deposition process for fabricating CoNiP nanodot arrays (less than 50 nm in height) with high magnetic coercivities was investigated. To fabricate such nanostructures, we improved the crystallinity of the CoNiP deposits in the initial deposition stage by applying an fcc-Cu(1 1 1) underlayer with low lattice mismatch to hcp-Co(0 0 0 2), and an autocatalytic electroless deposition process at the Cu surface was carried out by using dual reducing agents, H(2)PO(2)(-) and N(2)H(4). CoNiP films demonstrated high perpendicular magnetic coercivities in the initial deposition stage since the highly crystalline hcp(0 0 0 2) CoNiP layers were grown parallel to the Cu underlayers. Nanopatterned substrates were formed by UV-nanoimprint lithography. CoNiP was electroless deposited on the nanopatterned substrates. As a result. CoNiP was deposited selectively from the bottom of the nanopores with few defects in a large area. Perpendicular coercivities higher than 3000 Oe were obtained for nanodots even with heights of 50 nm. Thus, an electroless deposition process that can be used to form nanostructures with high crystallinities in the initial stage without any anomalous deposition was demonstrated. (C) 2011 Elsevier Ltd. All rights reserved.

    DOI

    Scopus

    12
    Citation
    (Scopus)
  • S165011 Molecular structure analysis on magnetic disk surface with plasmonic sensor

    YANAGISAWA Masahiro, SAITO Mikiko, HOMMA Takayuki

    Mechanical Engineering Congress, Japan   2011   "S165011 - 1"-"S165011-5"  2011.09

     View Summary

    Ultra-thin DLC films and lubricant films are requested for high density magnetic recording. It was difficult for Raman spectroscopy to measure their molecular structures because of its low sensitivity. Newly-developed plasmonic sensor successfully acquired Raman spectrum of DLC films or lubricant/DLC interfaces with sub-nanometer thickness. Crystal structure of ultra-thin DLC films were slightly changed compared with that of thick films. Specifically, a graphite-like structure increases with decreasing thickness. It was found that organic and inorganic contaminations exist on a magnetic layer or a magnetic layer/DLC interface. According to the Raman spectrum analysis, a feature of adsorbed lubricant molecules of lubricant on the DLC film was confirmed.

    CiNii

  • Fabrication of magnetic nanodot array using electrochemical deposition processes

    Takanari Ouchi, Yuki Arikawa, Yohei Konishi, Takayuki Homma

    ELECTROCHIMICA ACTA   55 ( 27 ) 8081 - 8086  2010.11  [Refereed]

     View Summary

    We investigated fabrication processes of magnetic nanodot arrays for the ultra-high density magnetic recording media by using an electrodeposition A CoZrNb underlayer was sputter-deposited on a glass disk substrate as a soft magnetic underlayer (SUL) Nano-patterns were formed on the substrate by UV-nanoimprint lithography (UV-NIL) and CoPt was electrodeposited into the nano-patterns For obtaining uniform CoPt nanodot arrays with high perpendicular coercivities we applied thin Cu intermediate layer on CoZrNb SUL and minimized its thickness As a result we obtained CoPt nanodot arrays with 150-nm diameter 300-nm pitches and 20-nm heights which have uniform structures on the substrates with the construction of Cu (1-2 nm)/CoZrNb (100 nm)/Cr (5 nm)/glass disk The perpendicular coercivity of the CoPt nanodot arrays was as high as 5 4 kOe From these results we showed that the Cu intermediate layer with even 1-2 nm thick considerably improved the deposition condition on the substrates with CoZrNb SUL to successfully fabricate CoPt nanodot arrays with the diameter and pitches of 80 nm and 160 nm with sufficient uniformity (C) 2010 Elsevier Ltd All rights reserved

    DOI

    Scopus

    18
    Citation
    (Scopus)
  • Fabrication of magnetic nanodot array using electrochemical deposition processes

    Takanari Ouchi, Yuki Arikawa, Yohei Konishi, Takayuki Homma

    ELECTROCHIMICA ACTA   55 ( 27 ) 8081 - 8086  2010.11

     View Summary

    We investigated fabrication processes of magnetic nanodot arrays for the ultra-high density magnetic recording media by using an electrodeposition A CoZrNb underlayer was sputter-deposited on a glass disk substrate as a soft magnetic underlayer (SUL) Nano-patterns were formed on the substrate by UV-nanoimprint lithography (UV-NIL) and CoPt was electrodeposited into the nano-patterns For obtaining uniform CoPt nanodot arrays with high perpendicular coercivities we applied thin Cu intermediate layer on CoZrNb SUL and minimized its thickness As a result we obtained CoPt nanodot arrays with 150-nm diameter 300-nm pitches and 20-nm heights which have uniform structures on the substrates with the construction of Cu (1-2 nm)/CoZrNb (100 nm)/Cr (5 nm)/glass disk The perpendicular coercivity of the CoPt nanodot arrays was as high as 5 4 kOe From these results we showed that the Cu intermediate layer with even 1-2 nm thick considerably improved the deposition condition on the substrates with CoZrNb SUL to successfully fabricate CoPt nanodot arrays with the diameter and pitches of 80 nm and 160 nm with sufficient uniformity (C) 2010 Elsevier Ltd All rights reserved

    DOI

    Scopus

    18
    Citation
    (Scopus)
  • Electrochemistry 誌をご活用下さい!

    本間 敬之

    電気化学および工業物理化学 : denki kagaku   78 ( 9 ) 747 - 747  2010.09

    DOI CiNii

    Scopus

  • Electrochemical etching process to tune the diameter of arrayed deep pores by controlling carrier collection at a semiconductor-electrolyte interface

    Hirotaka Sato, Takuya Yamaguchi, Tetsuhiko Isobe, Shuichi Shoji, Takayuki Homma

    ELECTROCHEMISTRY COMMUNICATIONS   12 ( 6 ) 765 - 768  2010.06  [Refereed]

     View Summary

    An approach to control the diameter of high-aspect-ratio pores formed into a silicon wafer by an electrochemical etching process is reported. Hole (h(+)) was involved in the etching reaction and the collection of the h(+) was the key factor. Artificial micro-cavities were fabricated on the silicon surface prior to the etching. The depth of the space charge region (SCR), Schottky barrier on the silicon-electrolyte interface, was adjusted regarding the depth of the micro-cavities by applied overpotential and specific resistance of the silicon wafer. The collection of h at the tip of the cavity site was widely controlled by the adjusted SCR. Consequently the electrochemically etched domain at the cavity site was actively tuned, and then high-aspect-ratio pore with the controlled diameter was formed. The diameter was tuned by the SCR depth which was controlled by the overpotential and the specific resistance. The diameter tuning mechanism worked under the mask-free condition. (C) 2010 Elsevier B.V. All rights reserved.

    DOI

    Scopus

    7
    Citation
    (Scopus)
  • Electrochemical Fabrication and Characterization of CoPt Bit Patterned Media: Towards a Wetchemical, Large-Scale Fabrication

    Takanari Ouchi, Yuki Arikawa, Taisuke Kuno, Jun Mizuno, Shuichi Shoji, Takayuki Homma

    IEEE TRANSACTIONS ON MAGNETICS   46 ( 6 ) 2224 - 2227  2010.06  [Refereed]

     View Summary

    This paper describes the fabrication process of CoPt nandot arrays on a glass disk substrate with a CoZrNb underlayer as a soft magnetic underlayer (SUL) by using an electrochemical process, and also the analysis on the magnetic properties of these fabricated CoPt nanodot arrays. We formed nano-patterned substrates by UV-nanoimprint lithography (UV-NIL) on the glass disk substrate. CoPt was electrodeposited into the nano-patterned substrates optimizing the electrodeposition condition and bath composition as well as a Cu intermediate layer. The construction of the nanodot arrays were CoPt nanodot arrays (20 nm)/Cu (5 nm)/CoZrNb (100 nm)/Cr (5 nm)/Glass disk. Magnetic signals were clearly observed on the dc magnetized state and multi domain were observed in each nanodot on the ac magnetized state by magnetic force microscopy (MFM). The perpendicular coercivity of the CoPt nanodot arrays was 430 kA/m. These results showed electrochemical process can be used for the manufacture of magnetic recording media.

    DOI

    Scopus

    11
    Citation
    (Scopus)
  • Magnetization Reversal Process of Hard/Soft Nano-Composite Structures Formed by Ion Irradiation

    M. Aniya, A. Shimada, Y. Sonobe, K. Sato, T. Shima, K. Takanashi, Simon J. Greaves, T. Ouchi, T. Homma

    IEEE TRANSACTIONS ON MAGNETICS   46 ( 6 ) 2132 - 2135  2010.06  [Refereed]

     View Summary

    Discrete track media (DTM) and bit-patterned media (BPM) are being extensively studied as routes to achieve higher density hard disk drives. In the DTM and BPM, it is essential to isolate the data tracks or bits with non-magnetic materials to reduce the magnetic noise from adjacent tracks or bits. In contrast to the conventional procedure of physically etching the media, we attempted to isolate the tracks or bits with soft regions using an area-selective ion irradiation method. We prepared hard and soft nano-composite structures by nanoimprinting, followed by ion irradiation. In this study, we confirmed the magnetic reversal process of the hard and soft regions of the nano-composite structure using magnetic force microscopy (MFM) with various external applied magnetic fields. The analysis of the magnetization reversal process of patterned Coupled Granular Continuous (CGC) films with weak exchange coupling confirmed the validity of this novel approach for the fabrication of DTM and BPM.

    DOI

    Scopus

    6
    Citation
    (Scopus)
  • Synchrotron radiation-induced total reflection X-ray fluorescence analysis

    F. Meirer, A. Singh, G. Pepponi, C. Streli, T. Homma, P. Pianetta

    TRAC-TRENDS IN ANALYTICAL CHEMISTRY   29 ( 6 ) 479 - 496  2010.06  [Refereed]

     View Summary

    Synchrotron radiation-induced total reflection X-ray fluorescence (SR-TXRF) analysis is a high sensitive analytical technique that offers limits of detection in the femtogram range for most elements. Besides the analytical aspect, SR-TXRF is mainly used in combination with angle-dependent measurements and/or X-ray absorption near-edge structure (XANES) spectroscopy to gain additional information about the investigated sample. In this article, we briefly discuss the fundamentals of SR-TXRF and follow with several examples of recent research applying the above-mentioned combination of techniques to analytical problems arising from industrial applications and environmental research. (C) 2010 Elsevier Ltd. All rights reserved.

    DOI

    Scopus

    45
    Citation
    (Scopus)
  • Electrochemical etching process to tune the diameter of arrayed deep pores by controlling carrier collection at a semiconductor-electrolyte interface

    Hirotaka Sato, Takuya Yamaguchi, Tetsuhiko Isobe, Shuichi Shoji, Takayuki Homma

    ELECTROCHEMISTRY COMMUNICATIONS   12 ( 6 ) 765 - 768  2010.06

     View Summary

    An approach to control the diameter of high-aspect-ratio pores formed into a silicon wafer by an electrochemical etching process is reported. Hole (h(+)) was involved in the etching reaction and the collection of the h(+) was the key factor. Artificial micro-cavities were fabricated on the silicon surface prior to the etching. The depth of the space charge region (SCR), Schottky barrier on the silicon-electrolyte interface, was adjusted regarding the depth of the micro-cavities by applied overpotential and specific resistance of the silicon wafer. The collection of h at the tip of the cavity site was widely controlled by the adjusted SCR. Consequently the electrochemically etched domain at the cavity site was actively tuned, and then high-aspect-ratio pore with the controlled diameter was formed. The diameter was tuned by the SCR depth which was controlled by the overpotential and the specific resistance. The diameter tuning mechanism worked under the mask-free condition. (C) 2010 Elsevier B.V. All rights reserved.

    DOI

    Scopus

    7
    Citation
    (Scopus)
  • Electrochemical Fabrication and Characterization of CoPt Bit Patterned Media: Towards a Wetchemical, Large-Scale Fabrication

    Takanari Ouchi, Yuki Arikawa, Taisuke Kuno, Jun Mizuno, Shuichi Shoji, Takayuki Homma

    IEEE TRANSACTIONS ON MAGNETICS   46 ( 6 ) 2224 - 2227  2010.06  [Refereed]

     View Summary

    This paper describes the fabrication process of CoPt nandot arrays on a glass disk substrate with a CoZrNb underlayer as a soft magnetic underlayer (SUL) by using an electrochemical process, and also the analysis on the magnetic properties of these fabricated CoPt nanodot arrays. We formed nano-patterned substrates by UV-nanoimprint lithography (UV-NIL) on the glass disk substrate. CoPt was electrodeposited into the nano-patterned substrates optimizing the electrodeposition condition and bath composition as well as a Cu intermediate layer. The construction of the nanodot arrays were CoPt nanodot arrays (20 nm)/Cu (5 nm)/CoZrNb (100 nm)/Cr (5 nm)/Glass disk. Magnetic signals were clearly observed on the dc magnetized state and multi domain were observed in each nanodot on the ac magnetized state by magnetic force microscopy (MFM). The perpendicular coercivity of the CoPt nanodot arrays was 430 kA/m. These results showed electrochemical process can be used for the manufacture of magnetic recording media.

    DOI

    Scopus

    11
    Citation
    (Scopus)
  • Influence of Specific Si Resistance on the Morphology of Zn Films Formed by Reacting Al-Si Alloy with Zincate Solution

    SAITO Mikiko, MAEGAWA Takeyuki, HOMMA Takayuki

    Jitsumu Hyomen Gijutsu   61 ( 6 ) 447 - 451  2010.06

     View Summary

    The electrochemical behavior of Al-Si alloy films in zincate solution was investigated to elucidate the effects of zincate pretreatment on the Zn morphology and subsequent electroless NiP deposition, which is used for under bump metallization (UBM) in integrated circuit (IC) chip packaging. To investigate the electrochemical behavior of the Al-Si films during the zincate pretreatment, the immersion potential and the surface morphology during Zn and NiP deposition were evaluated using Al-Si electrodes that had been fabricated onto two types of Si substrates with different specific resistances. A heterogeneous point was observed for samples fabricated onto Si substrates with high specific resistance (45-95 Ωm), but no such point was observed on samples fabricated onto Si substrates with low specific resistance (0.00001-0.00002 Ωm). This result suggests that the morphology of the deposits was affected considerably by the specific resistance of the Si substrate.

    DOI CiNii

  • Transient mass transfer rate of Cu2+ ion caused by copper electrodeposition with alternating electrolytic current

    S. Kawai, M. Ogawa, K. Ishibashi, Y. Kondo, T. Matsuoka, T. Homma, Y. Fukunaka, S. Kida

    ELECTROCHIMICA ACTA   55 ( 12 ) 3987 - 3994  2010.04  [Refereed]

     View Summary

    Copper electrolysis is carried out in a stagnant 0.05 M CuSO4 aqueous electrolyte under alternating current (AC) condition. Transient mass transfer rate of Cu2+ ion caused by copper electrodeposition with AC is studied theoretically and experimentally with the holographic interferometer. The effect of buoyancy convection developing along the vertical plane electrodes on the transient concentration boundary layer (CBL) structure accompanying with AC is focused on. Two different electrode configurations, the horizontal cathode over anode and the vertical electrode settings, are employed for this purpose. The CBL thickness tends to increase over long duration time in the former configuration, while it converges to a steady-state value in the latter. Both calculated and measured concentration profiles in the vertical electrode configuration exhibit the characteristic transient behaviors composed of the pulsating CBL (PCBL) in the vicinity of the cathode surface and the stationary CBL (SCBL) outside the PCBL The appearance of the SCBL is ascribed to mass transfer by advection, and the overall CBL thickness depends on the hydrodynamic conditions such as the magnitude of buoyancy convection. (C) 2010 Elsevier Ltd. All rights reserved.

    DOI

    Scopus

    9
    Citation
    (Scopus)
  • Magnetic Properties of Patterned CGC Perpendicular Films With Soft Magnetic Fillings

    M. Aniya, A. Mitra, A. Shimada, Y. Sonobe, T. Ouchi, Simon J. Greaves, T. Homma

    IEEE TRANSACTIONS ON MAGNETICS   45 ( 10 ) 3539 - 3542  2009.10  [Refereed]

     View Summary

    To increase the areal density of hard disk drives (HDDs), discrete track media (DTM) and bit-patterned media (BPM) are being extensively studied. In the DTM and BPM, it is essential to isolate data tracks or bits. Unlike isolating the data tracks or bits using the conventional procedure involving physical etching, we attempted to isolate the tracks or bits with a soft guard band using an area-selective ion irradiation method. We prepared hard and soft (H/S) patterned films by nanoimprinting followed by ion irradiation. We confirmed the magnetic isolation of tracks and bits using magnetic force microscopy (MFM) images and magnetooptical Kerr effect (MOKE) signals. The results of an analysis of the magnetic properties of patterned coupled granular continuous (CGC) films with weak exchange coupling confirmed the validity of this novel approach for the fabrication of DTM and BPM.

    DOI

    Scopus

    5
    Citation
    (Scopus)
  • Fabrication of CoPt magnetic nanodot arrays by electrodeposition process

    Takanari Ouchi, Yuki Arikawa, Takayuki Homma

    JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS   320 ( 22 ) 3104 - 3107  2008.11  [Refereed]

     View Summary

    We attempted to fabricate patterned media using the electrochemical deposition process along with nanopatterned substrates prepared by the electron beam lithography (EBL), UV nanoimprint lithography (UV-NIL), and spin-on-glass nanoimprint lithography (SOG-NIL) approaches. CoPt was electrodeposited into the nanopatterned substrates and chemical mechanical polishing was carried out to planarize the surface. It was clarified that CoPt nanodot arrays were successfully deposited into the patterned nanopores fabricated by UV-NIL and SOG-NIL as well as by EBL with high area selectivity and uniformity. The density of the CoPt nanodot arrays deposited into the nanopores fabricated by EBL was equal up to an areal recording density of 250 Gbit/in(2). (C) 2008 Elsevier B. V. All rights reserved.

    DOI

    Scopus

    33
    Citation
    (Scopus)
  • Fabrication of catalyst-functionalized three-dimensional micromesh structures

    Satoshi Keino, Hironobu Sato, Takayuki Homma, Shuichi Shoji

    JAPANESE JOURNAL OF APPLIED PHYSICS   47 ( 6 ) 5204 - 5207  2008.06  [Refereed]

     View Summary

    We present fabrication methods of functional three-dimensional (3-D) micromesh structures coated with titanium dioxide (TiO(2)) microparticles and biocatalysts. The 3-D micromesh structures are useful for fabricating highly efficient microreactors because of their large surface area. In this study, TiO(2)-embedded SU-8 micromesh structures were formed by coating a TiO(2)/SU-8 mixture onto the surface of SU-8 micromesh structures. Biocatalyst-immobilized micromesh structures were also formed by coating a biocatalyst/photopolymer mixture onto SU-8 micromesh structures.

    DOI

    Scopus

    1
    Citation
    (Scopus)
  • Characterization of the Surface Layer on Strained Si Wafer by Electrochemical Methods

    K. Sakata, M. Kato, N. Kubo, T. Senda, K. Izunome, T. Homma

    J. Phys. Chem. C   112   3785 - 3788  2008.03

  • Estimation of Redox Potential of Strained Si by Density Functional Theory Calculation

    K. Sakata, S. Ishizaki, H. Nakai, T. Homma

    J. Phys. Chem. C   112 ( 10 ) 3104 - 3107  2008.03

    DOI

    Scopus

    3
    Citation
    (Scopus)
  • Self-aligned formation of nano-holes to arrayed micro glass tubes

    Hirotaka Sato, Takuya Yamaguchi, Tetsuhiko Isobe, Takayuki Homma, Shuichi Shoji

    ELECTROCHIMICA ACTA   53 ( 1 ) 200 - 204  2007.11  [Refereed]

     View Summary

    Microreactors and micro-fluidic devices require micro-tube structures to reserve and manipulate extremely small volume of liquid specimen, and nano-hole on the micro-tube is useful for its injection, aspiration and filtration, etc. In the present study, we attempted to develop a precise etching process to form nano-hole to the edge part of the micro glass tube by controlling SiO2 etching conditions with diluted aqueous HF solution. The arrayed micro-glass-tubes were fabricated by electrochemical etching of Si wafer followed by wet-thermal oxidation. The bottoms of arrayed micro-glass-tubes were exposed from Si wafer, which possessed pyramid-shape edges. The etching with optimized concentration of HF formed uniform nano-holes only at every bottom edge, indicating self-alignment of the etching process. The diameter of the nano-holes was controllable in the range of ca. 100-500 nm by adjusting the immersion duration and thickness of the glass tube. Nonlinear diffusion of fluoride species to the bottom edges could be the origin of the self-aligned formation of nano-holes at the bottom edges. (C) 2007 Elsevier Ltd. All rights reserved.

    DOI

    Scopus

    1
    Citation
    (Scopus)
  • Fabrication of metallic nanopatterns using the vacuum type UV-NIL equipment

    Makoto Fukuhara, Jun Mizuno, Mikiko Saito, Takayuki Homma, Shuichi Shoji

    IEEJ TRANSACTIONS ON ELECTRICAL AND ELECTRONIC ENGINEERING   2 ( 3 ) 307 - 312  2007.05  [Refereed]

     View Summary

    Nanoscale dot patterns of cobalt alloy were formed on a silicon substrate using the ultra-violet nanoimprint lithography (UV-NIL) technology in combination with an electrodeposition process. We developed an improved UV-NIL equipment that can evacuate the chamber during imprinting. Using this equipment, we successfully imprinted 240-nm dot patterns with 500 nm pitch on a photocurable resin with high dimensional accuracy. Thickness control of the resin and imprinting under vacuum are important issues to obtain fine nanopatterns. Using these resin patterns as a mask layer, 300-nm cobalt alloy patterns are successfully formed by the electrodeposition process. (c) 2007 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

    DOI

    Scopus

    15
    Citation
    (Scopus)
  • Molecular orbital study on the oxidation mechanism of hydrazine and hydroxylamine as reducing agents for electroless deposition process

    Takuya Shimada, Amiko Tamaki, Hiromi Nakai, Takayuki Homma

    ELECTROCHEMISTRY   75 ( 1 ) 45 - 49  2007.01  [Refereed]

     View Summary

    The oxidation mechanism of hydrazine and hydroxylamine were investigated using molecular orbital (MO) calculation. Two pathways for their reactions were verified. One is initiated by hydrogen elimination from the reducing agent, followed by coordination of hydroxyl group to center nitrogen atom accompanied with electron emission. Another is initiated by coordination of hydroxyl group to hydrogen atom to form H2O, which is eliminated later, followed by electron emission. The calculated results indicated that the oxidation reactions of hydrazine preferentially proceeded via the second pathway. It was also indicated that only the first electron emission steps of the hydrazine oxidation took place on Cu surface, while the following reactions proceeded at near the solid/liquid interface. The oxidation of hydroxylamine also proceeded via the elimination reaction of H2O. After the oxidation, calculated heats of reactions suggested that OH radical, generated from N2O as a product, decomposed hydroxylamine.

  • Adsorption of organic molecules by photochemical reaction on Cl : Si(111) and H : Si(111) evaluated by HREELS

    Katsuhiko Nishiyama, Yosuke Tanaka, Hiroshi Harada, Taro Yamada, Daisuke Niwa, Tomoyuki Inoue, Takayuki Homma, Tetsuya Osaka, Isao Taniguchi

    SURFACE SCIENCE   600 ( 10 ) 1965 - 1972  2006.05  [Refereed]

     View Summary

    The covalent attachment of alkyl groups to silicon surfaces, via carbon-silicon bond formation, has been attempted using gas-surface reactions starting from Cl-terminated Si(111) or H:Si(111) under ultraviolet light irradiation. The formation of Cl-terminated Si(111) and its resulting stability were examined prior to deposition of organic molecules. High-resolution electron energy loss spectroscopy (HREELS) was utilized for detecting surface-bound adsorbates. The detection of photo-deposited organic species on CI:Si(111) from gas-phase CH4 or CH2=CH2 was not significant. On H:Si(111), it was evident that after the photoreaction with gas-phase C2H5Cl, C2H5 groups were chemically bonded to the surface Si atoms through single covalent bonds. The C2H5 groups were thermally stable at temperatures below 600 K. Alkyl monolayers prepared on silicon surfaces by dry process will lead to a new prospective technology of nanoscale fabrication and biochemical applications. (c) 2006 Elsevier B.V. All rights reserved.

    DOI

    Scopus

    11
    Citation
    (Scopus)
  • Evaluation of 256-pixel TES microcalorimeter arrays with electrodeposited Bi absorbers

    U Morita, Y Yamakawa, T Fujimori, Y Ishisaki, T Ohashi, Y Takei, K Yoshida, T Yoshino, K Mitsuda, NY Yamasaki, R Fujimoto, H Sato, Y Minoura, N Takahashi, T Homma, S Shoji, Y Kuroda, M Onishi

    NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT   559 ( 2 ) 539 - 541  2006.04  [Refereed]

     View Summary

    We succeeded in fabricating 256-pixel arrays of Ti/Au transition edge sensor (TES) microcalorimeters with electrodeposited microabsorbers made of Bi, and report on their test results. We confirmed till pixels tested so far were alive, however most of the microabsorbers were stripped off during cooling cycles. We investigated some pixels by irradiating with 5.9 keV X-rays, and confirmed that they actually worked as microcalorimeters. The X-ray pulses are represented by a sum of two components with different decay times. The ratio of the two components fluctuates from pulse to pulse, which limits the energy resolution to similar to 200 eV. We discuss the pulse shape of two decay-time components considering thermal conductivities, i.e., inside microabsorbers, between microabsorbers and TES. (c) 2005 Elsevier B.V. All rights reserved.

    DOI

    Scopus

    8
    Citation
    (Scopus)
  • Density functional theory study on the oxidation mechanisms of aldehydes as reductants for electroless Cu deposition process

    T Shimada, K Sakata, T Homma, H Nakai, T Osaka

    ELECTROCHIMICA ACTA   51 ( 5 ) 906 - 915  2005.11  [Refereed]

     View Summary

    The oxidation mechanism of aldehydes, which are commonly used as reductants for an electroless deposition process, was studied by using Density Functional Theory (DFT) calculations. The reaction pathway of the three aldehydes, i.e., formaldehyde, acetaldehyde and glyoxylic acid, with different functional groups, were examined by calculating energy profiles of all intermediate species. It was indicated that the pathway in an isolated system proceeds via dianion-free intermediate species. Taking the solvation effect into consideration, it was indicated that the oxidation reactions of the three aldehydes preferably proceed at the solid/liquid interface. In combination with a Cu metal cluster as a model of metal surface, it was also indicated that the oxidation reactions proceed preferentially at the Cu surface. It was expected that the adsorption/desorption energy at the Cu surface of glyoxylic acid, which has an electron-accepting carboxyl group, was smaller and substituent effect lead to its high reducibility. (C) 2005 Elsevier Ltd. All rights reserved.

    DOI

    Scopus

    20
    Citation
    (Scopus)
  • Fabrication of patterned nanostructures with various metal species on Si wafer surfaces by maskless and electroless process

    N Kubo, T Homma, Y Hondo, T Osaka

    ELECTROCHIMICA ACTA   51 ( 5 ) 834 - 837  2005.11  [Refereed]

     View Summary

    Maskless and electroless fabrication was demonstrated to form patterned nanostructures of various metal species, based upon the process previously developed by the authors. In this process, the metallic nanostructures were formed on the surface of clean, hydrogen terminated p-(1 0 0) Si wafer with pre-patterned nanoscopic defects, which were confirmed to possess higher activity for the reductive deposition reaction of the metal ion species. The deposition was achieved spontaneously and selectively at the defect sites on the wafer surface by immersing into dilute aqueous fluoride solution containing trace amount of metal ion species. By optimizing the formation condition of the patterned defects and composition of the solution, fabrication of patterned nanostructures of various metallic species such as Au, Ag, and Co, was achieved. Formation of the patterned nanostructures to 10 mu m(2) in extent, as well as control of the feature size of the deposits by adjusting the formation condition of the pattemed defects were also attempted. (C) 2005 Elsevier Ltd. All rights reserved.

    DOI

    Scopus

    28
    Citation
    (Scopus)
  • Electrochemical analysis of zincate treatments for Al and Al alloy films

    M Saito, T Maegawa, T Homma

    ELECTROCHIMICA ACTA   51 ( 5 ) 1017 - 1020  2005.11  [Refereed]

     View Summary

    Electrochemical behavior of At and At alloy films in zincate solution was investigated to elucidate the effect of the zincate pretreatment for electroless NiP deposition, which is used for under bump metallization for LSI interconnects. The immersion potential for AlCu and AlSiCu, immediately reached to constant, which was almost equal potential to zinc reference electrode. The corrosion current for the AlCu and AlSiCu films was larger than that of the At and AlSi films in the zincate solution. It was also confirmed that the deposited Zn at the surface of AlCu and AlSiCu films possessed smaller grain size and larger amount of nucleation, resulted in the formation of flat NiP films. (C) 2005 Elsevier Ltd. All rights reserved.

    DOI

    Scopus

    22
    Citation
    (Scopus)
  • Picoliter volume glass tube array fabricated by Si electrochemical etching process

    H Sato, T Homma, K Mori, T Osaka, S Shoji

    ELECTROCHIMICA ACTA   51 ( 5 ) 844 - 848  2005.11  [Refereed]

     View Summary

    Fabrication process for picoliter volume SiO2 glass tube array partially embedded in Si wafer was developed. As a template for the glass tubes, macropore array was formed at the surface of n-Si(1 0 0) wafer by photo-assisted electrochemical etching process. The area-selective formation of the array was achieved by applying Au/Cr micropatterns formed at the back-side surface of the substrate as the shade mask, which controls the illumination condition to optimize the etching reaction conditions. Subsequently, surface of the macropores was wet-thermally oxidized to form glass layer, and the bulk Si region was removed by alkaline etching, remaining the "glass tubes". As a result of complete removal of the bulk Si, released glass tubes were obtained. By partial removal of the bulk Si part, the glass tubes were exposed, fixed in the remaining Si substrate in the form of well-ordered array. It was confirmed that the depth, the exposed region and the wall thickness of each glass tube were controllable by adjusting the parameters such as the duration of the Si electrochemical etching, the alkaline etching and the wet-thermal oxidation, respectively. In order to demonstrate microreaction in the glass tube, aqueous rhodamine B solution was injected into the tubes and excitation light was irradiated to them. As a result, the fluorescence of rhodamine B was clearly detected, confirming the applicability of the glass tubes for various kinds of devices and systems such as microreactors. (C) 2005 Elsevier Ltd. All rights reserved.

    DOI

    Scopus

    5
    Citation
    (Scopus)
  • High efficiency electrochemical immuno sensors using 3D comb electrodes

    N Honda, M Inaba, T Katagiri, S Shoji, H Sato, T Homma, T Osaka, M Saito, J Mizuno, Y Wada

    BIOSENSORS & BIOELECTRONICS   20 ( 11 ) 2306 - 2309  2005.05  [Refereed]

     View Summary

    To realize highly sensitive electrochemical immunoassays, a micro-fabricated three-dimensional (313) electrode was fabricated and applied to enzyme immuno assay based on production of a redox species. The dimensions of the electrodes are 10 mu m in width and 30 mu m in height, with 20 mu m spacing in between, and the 30 pairs of anode and cathode electrodes made up a single sensor. This structure lead to enhancement of the electrochemical reaction, nearly 100% of trap ratio of redox species. It can be applied to highly sensitive enzyme immuno sensing based on p-aminophenylphosphate (PAPP). Applicability of this technique to the immuno assay for one of the clinical diagnostic marker proteins (alpha-fetoprotein; AFP) from 6 to 500 ng/mL was demonstrated. (c) 2004 Elsevier B.V. All rights reserved.

    DOI

    Scopus

    44
    Citation
    (Scopus)
  • High efficiency electrochemical immuno sensors using 3D comb electrodes

    N Honda, M Inaba, T Katagiri, S Shoji, H Sato, T Homma, T Osaka, M Saito, J Mizuno, Y Wada

    BIOSENSORS & BIOELECTRONICS   20 ( 11 ) 2306 - 2309  2005.05

     View Summary

    To realize highly sensitive electrochemical immunoassays, a micro-fabricated three-dimensional (313) electrode was fabricated and applied to enzyme immuno assay based on production of a redox species. The dimensions of the electrodes are 10 mu m in width and 30 mu m in height, with 20 mu m spacing in between, and the 30 pairs of anode and cathode electrodes made up a single sensor. This structure lead to enhancement of the electrochemical reaction, nearly 100% of trap ratio of redox species. It can be applied to highly sensitive enzyme immuno sensing based on p-aminophenylphosphate (PAPP). Applicability of this technique to the immuno assay for one of the clinical diagnostic marker proteins (alpha-fetoprotein; AFP) from 6 to 500 ng/mL was demonstrated. (c) 2004 Elsevier B.V. All rights reserved.

    DOI

    Scopus

    44
    Citation
    (Scopus)
  • Electrochemical formation process of Si macropore and metal filling for high aspect ratio metal microstructure using single electrolyte system

    H Sato, T Homma, K Mori, T Osaka, S Shoji

    ELECTROCHEMISTRY   73 ( 4 ) 275 - 278  2005.04

     View Summary

    Array of macropores filled with electrodeposited Ni was formed on Si substrate applying the novel process, which consists of Si electrochemical etching and Ni electrodeposition using single electrolyte. This electrolyte contained HF as Si dissolution agent and Ni(OSO2NH2)(2) 4H(2)O as Ni2+ source for Ni electrodeposition. First, array of macropores was formed on Si (100) substrate by applying anodic current. The formation was carried out area-selectively by applying Au/Cr micropatterns formed at the back side surface of the substrate as the shade mask, which enables to control the illumination condition for hole generation condition. Subsequently, the applied bias was switched to cathodic current, and Ni was filled into c.a. 200 mu m depth Si macropores without void-like defects. Array of Ni needles with smooth surface was formed area-selectively by removal of the Si region of the Ni filled specimen with 25 wt% tetramethylammonium hydroxide (TMAH) aqueous solution at 90 degrees C.

  • Electrochemical formation process of Si macropore and metal filling for high aspect ratio metal microstructure using single electrolyte system

    H Sato, T Homma, K Mori, T Osaka, S Shoji

    ELECTROCHEMISTRY   73 ( 4 ) 275 - 278  2005.04  [Refereed]

     View Summary

    Array of macropores filled with electrodeposited Ni was formed on Si substrate applying the novel process, which consists of Si electrochemical etching and Ni electrodeposition using single electrolyte. This electrolyte contained HF as Si dissolution agent and Ni(OSO2NH2)(2) 4H(2)O as Ni2+ source for Ni electrodeposition. First, array of macropores was formed on Si (100) substrate by applying anodic current. The formation was carried out area-selectively by applying Au/Cr micropatterns formed at the back side surface of the substrate as the shade mask, which enables to control the illumination condition for hole generation condition. Subsequently, the applied bias was switched to cathodic current, and Ni was filled into c.a. 200 mu m depth Si macropores without void-like defects. Array of Ni needles with smooth surface was formed area-selectively by removal of the Si region of the Ni filled specimen with 25 wt% tetramethylammonium hydroxide (TMAH) aqueous solution at 90 degrees C.

  • Microstructure of a Co/Pd multilayered perpendicular recording medium with Pd seeds prepared by electrochemical process

    M Tanaka, J Kawaji, K Kimura, T Asahi, T Homma, S Matsunuma, T Osaka

    JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS   287   188 - 192  2005.02  [Refereed]

     View Summary

    Effects of the Pd seeds formed by an electrochemical process on the microstructures of Co/Pd multilayered perpendicular recording media were investigated. By immersing a CoZrNb soft magnetic underlayer (SUL) into PdCl2 aqueous solution, island-like Pd clusters were deposited on the SUL, resulting from the electrochemical substitution reaction. Transmission electron microscopic observations revealed that the columnar Co/Pd multilayered grains with clear boundaries grew on the SUL with the Pd clusters. The clear grain boundaries, where the densities of Co and Pd elements were low, were thought to cause the magnetic exchange decoupling between the Co/Pd grains, leading to an increase of perpendicular coercivity and a decrease of magnetic cluster size of Co/Pd multilayered film. Consequently, lower medium noise was obtained for the Co/Pd multilayered medium with the Pd clusters than for that with a sputter-deposited Pd seedlayer. From these investigations, it was clarified that the SUL surface with Pd clusters provided the effective nucleation sites for a well-defined Co/Pd multilayered grain growth. (C) 2004 Elsevier B.V. All rights reserved.

    DOI

    Scopus

    7
    Citation
    (Scopus)
  • Area selective formation of magnetic nanodot arrays on Si wafer by electroless deposition

    J Kawaji, F Kitaizumi, H Oikawa, D Niwa, T Homma, T Osaka

    JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS   287   245 - 249  2005.02  [Refereed]

     View Summary

    Electroless deposition process for fabricating magnetic dot arrays was studied. A patterned Si substrate with a SiO2 resist was produced by processes combined with electron-beam lithography and reactive ion etching. By immersing the patterned Si substrate into a CoNiP electroless deposition bath, CoNiP was deposited only into the patterned pores, demonstrating a satisfactory area selectivity of the deposition. Excellent uniformity on the CoNiP deposition into the patterned pores with diameter less than 100 nm and high aspect ratio (&gt; 5) was achieved by applying chemical activation processes using a Pd solution prior to the deposition. The CoNiP dot arrays exhibited higher perpendicular squareness ratio than that of CoNiP continuous film and showed a clear magnetization state at DC-magnetized state, which originated from the shape anisotropy caused by high aspect ratio of the dot patterns. (C) 2004 Elsevier B.V. All rights reserved.

    DOI

    Scopus

    9
    Citation
    (Scopus)
  • Microstructure of a Co/Pd multilayered perpendicular recording medium with Pd seeds prepared by electrochemical process

    M Tanaka, J Kawaji, K Kimura, T Asahi, T Homma, S Matsunuma, T Osaka

    JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS   287   188 - 192  2005.02

     View Summary

    Effects of the Pd seeds formed by an electrochemical process on the microstructures of Co/Pd multilayered perpendicular recording media were investigated. By immersing a CoZrNb soft magnetic underlayer (SUL) into PdCl2 aqueous solution, island-like Pd clusters were deposited on the SUL, resulting from the electrochemical substitution reaction. Transmission electron microscopic observations revealed that the columnar Co/Pd multilayered grains with clear boundaries grew on the SUL with the Pd clusters. The clear grain boundaries, where the densities of Co and Pd elements were low, were thought to cause the magnetic exchange decoupling between the Co/Pd grains, leading to an increase of perpendicular coercivity and a decrease of magnetic cluster size of Co/Pd multilayered film. Consequently, lower medium noise was obtained for the Co/Pd multilayered medium with the Pd clusters than for that with a sputter-deposited Pd seedlayer. From these investigations, it was clarified that the SUL surface with Pd clusters provided the effective nucleation sites for a well-defined Co/Pd multilayered grain growth. (C) 2004 Elsevier B.V. All rights reserved.

    DOI

    Scopus

    7
    Citation
    (Scopus)
  • Area selective formation of magnetic nanodot arrays on Si wafer by electroless deposition

    J Kawaji, F Kitaizumi, H Oikawa, D Niwa, T Homma, T Osaka

    JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS   287   245 - 249  2005.02  [Refereed]

     View Summary

    Electroless deposition process for fabricating magnetic dot arrays was studied. A patterned Si substrate with a SiO2 resist was produced by processes combined with electron-beam lithography and reactive ion etching. By immersing the patterned Si substrate into a CoNiP electroless deposition bath, CoNiP was deposited only into the patterned pores, demonstrating a satisfactory area selectivity of the deposition. Excellent uniformity on the CoNiP deposition into the patterned pores with diameter less than 100 nm and high aspect ratio (&gt; 5) was achieved by applying chemical activation processes using a Pd solution prior to the deposition. The CoNiP dot arrays exhibited higher perpendicular squareness ratio than that of CoNiP continuous film and showed a clear magnetization state at DC-magnetized state, which originated from the shape anisotropy caused by high aspect ratio of the dot patterns. (C) 2004 Elsevier B.V. All rights reserved.

    DOI

    Scopus

    9
    Citation
    (Scopus)
  • 微小流路を用いた無電解析出プロセスによる複合金属ナノ粒子の作製

    佐藤裕崇, 大日向陽, 本間敬之, 逢坂哲彌

    表面技術   55 ( 12 ) 966 - 967  2004.12

    J-GLOBAL

  • Formation of Pd nanocluster seeds by electrochemical process for control of magnetic properties in Co/Pd multilayered film

    J Kawaji, M Tanaka, K Kimura, T Asahi, T Homma, T Osaka

    IEEE TRANSACTIONS ON MAGNETICS   40 ( 4 ) 2473 - 2475  2004.07

     View Summary

    Pd cluster seeds for a double-layered perpendicular magnetic recording medium composed of a Co/Pd multilayered film and a CoZrNb soft magnetic underlayer (SUL) were fabricated with an electrochemical treatment. By immersing the SUL into an aqueous PdCl2 solution, the substitution of Pd for Co at the surface of the SUL took place, which was caused by the difference in electrochemical redox potential between Pd and Co. Uniformly distributed Pd clusters with 8 nm in diameter were successfully formed with the treatment for the optimized duration. Use of the Pd clusters as the seeds for deposition of the Co/Pd multilayered film increased the perpendicular coercivity and reduced the size of magnetic cluster of the film. These results suggested that the Pd cluster seeds led to the formation of magnetically isolated Co/Pd multilayered grains, improving the magnetic properties of Co/Pd multilayered film.

    DOI

  • Formation of Pd nanocluster seeds by electrochemical process for control of magnetic properties in Co/Pd multilayered film

    J Kawaji, M Tanaka, K Kimura, T Asahi, T Homma, T Osaka

    IEEE TRANSACTIONS ON MAGNETICS   40 ( 4 ) 2473 - 2475  2004.07

     View Summary

    Pd cluster seeds for a double-layered perpendicular magnetic recording medium composed of a Co/Pd multilayered film and a CoZrNb soft magnetic underlayer (SUL) were fabricated with an electrochemical treatment. By immersing the SUL into an aqueous PdCl2 solution, the substitution of Pd for Co at the surface of the SUL took place, which was caused by the difference in electrochemical redox potential between Pd and Co. Uniformly distributed Pd clusters with 8 nm in diameter were successfully formed with the treatment for the optimized duration. Use of the Pd clusters as the seeds for deposition of the Co/Pd multilayered film increased the perpendicular coercivity and reduced the size of magnetic cluster of the film. These results suggested that the Pd cluster seeds led to the formation of magnetically isolated Co/Pd multilayered grains, improving the magnetic properties of Co/Pd multilayered film.

    DOI

  • Ab initio molecular orbital study of the electron emission mechanism of TiCl3 as a reductant for an electroless deposition process

    T Shimada, Komatsu, I, T Homma, H Nakai, T Osaka

    ELECTROCHEMISTRY   72 ( 6 ) 462 - 465  2004.06  [Refereed]

     View Summary

    The oxidation mechanism of TiCl3 as a reductant for an electroless deposition process was studied by ab initio molecular orbital method. The reaction process of TiCl3 proceeds with the substitution of Cl- to OH-. Net charge and spin density of the reactant, product, and intermediates were evaluated. It was suggested that the electron emission of TiCl3, which is originated by the oxidation of Ti(III) to Ti(IV), took place when Cl is replaced by OH- to form Ti(OH)(4). The catalytic activity of the metal surface, which is one of the most important factors for the electroless deposition process, was studied using a Pd-4 Cluster as a model surface. It was suggested that the Pd-4 cluster enhanced the reaction of TiCl3 to emit the electron. The effect of solvation is also taken into account in terms of the dielectric field constant. It was indicated that the heat of oxidation reaction shifted to an exothermic reaction with decreasing dielectric constant, indicating that the reaction preferentially proceeds in the vicinity of solid/liquid interface. However, it was indicated that the reaction could proceed in the bulk solution, suggesting that appropriate stabilization such as formation of complex is required for the application of the TiCl3 to the electroless deposition process.

  • Development of Bi electrodeposition process for fabricating microabsorber array for high sensitive X-ray imaging sensor

    H Sato, H Kobayashi, H Kudo, T Izumi, T Homma, T Osaka, S Shoji, Y Ishisaki, R Fujimoto, K Mitsuda

    ELECTROCHEMISTRY   72 ( 6 ) 424 - 426  2004.06  [Refereed]

     View Summary

    Microscale Bi electrodeposition process was developed to fabricate the array of mushroom-shaped absorbers for the high sensitive X-ray imaging sensor, so called X-ray microcalorimeter array. The bath composition and operating conditions for Bi electrodeposition was optimized, and sufficient bath stability and surface smoothness of the deposits were achieved by applying the additives such as diethylenetriamine pentaacetic acid and sodium n-dodecyl sulfate with appropriate concentration. By applying the two-step exposure steps for the "stem" part and the "roof" part, the mold to deposit the mushroom-shaped microstructure was formed from single-layered photoresist coating. The absorber array was successfully fabricated by the sequential processes of Bi electrodeposition into the mold, precise polishing, and mold removal.

  • Ab initio molecular orbital study of the electron emission mechanism of TiCl3 as a reductant for an electroless deposition process

    T Shimada, Komatsu, I, T Homma, H Nakai, T Osaka

    ELECTROCHEMISTRY   72 ( 6 ) 462 - 465  2004.06  [Refereed]

     View Summary

    The oxidation mechanism of TiCl3 as a reductant for an electroless deposition process was studied by ab initio molecular orbital method. The reaction process of TiCl3 proceeds with the substitution of Cl- to OH-. Net charge and spin density of the reactant, product, and intermediates were evaluated. It was suggested that the electron emission of TiCl3, which is originated by the oxidation of Ti(III) to Ti(IV), took place when Cl is replaced by OH- to form Ti(OH)(4). The catalytic activity of the metal surface, which is one of the most important factors for the electroless deposition process, was studied using a Pd-4 Cluster as a model surface. It was suggested that the Pd-4 cluster enhanced the reaction of TiCl3 to emit the electron. The effect of solvation is also taken into account in terms of the dielectric field constant. It was indicated that the heat of oxidation reaction shifted to an exothermic reaction with decreasing dielectric constant, indicating that the reaction preferentially proceeds in the vicinity of solid/liquid interface. However, it was indicated that the reaction could proceed in the bulk solution, suggesting that appropriate stabilization such as formation of complex is required for the application of the TiCl3 to the electroless deposition process.

  • Development of Bi electrodeposition process for fabricating microabsorber array for high sensitive X-ray imaging sensor

    H Sato, H Kobayashi, H Kudo, T Izumi, T Homma, T Osaka, S Shoji, Y Ishisaki, R Fujimoto, K Mitsuda

    ELECTROCHEMISTRY   72 ( 6 ) 424 - 426  2004.06

     View Summary

    Microscale Bi electrodeposition process was developed to fabricate the array of mushroom-shaped absorbers for the high sensitive X-ray imaging sensor, so called X-ray microcalorimeter array. The bath composition and operating conditions for Bi electrodeposition was optimized, and sufficient bath stability and surface smoothness of the deposits were achieved by applying the additives such as diethylenetriamine pentaacetic acid and sodium n-dodecyl sulfate with appropriate concentration. By applying the two-step exposure steps for the "stem" part and the "roof" part, the mold to deposit the mushroom-shaped microstructure was formed from single-layered photoresist coating. The absorber array was successfully fabricated by the sequential processes of Bi electrodeposition into the mold, precise polishing, and mold removal.

  • Performance analyse's of TES microcalorimeters with mushroom shaped X-ray absorbers made of Sn or Bi

    Y Ishisaki, U Morita, T Koga, K Shinozaki, K Sato, N Takai, T Ohashi, T Arakawa, H Kudo, H Sato, H Kobayashi, T Izumi, S Ohtsuka, K Mori, S Shoji, T Osaka, T Homma, K Mitsuda, NY Yamasaki, R Fujimoto, N Iyomoto, T Oshima, K Futamoto, Y Takei, T Ichitsubo, T Fujimori, K Yoshida, Y Kuroda, M Onishi, M Goto, F Beppu

    NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT   520 ( 1月3日 ) 452 - 455  2004.03

     View Summary

    Performance of microcalorimeters with a Ti/Au transition-edge sensor (TES) and an electrodeposited absorber has been investigated. The absorbers are in a mushroom-shape made of Sn or Bi. With an Sn absorber we observed a long time scale component of 1.8 ms for X-ray pulses, which is due presumably to recombination of quasiparticles into phonons. As a result, the energy resolution is not good with the Sn absorber. Better energy resolution of 28 +/- 1 eV was obtained with an incomplete-shaped Bi absorber, although the long component was also seen with smaller level. A calorimeter with only a neck of the An seed layer for the electrodeposition had the best energy resolution of 6.3 +/- 0.4 eV in spite of saturated pulses and relatively high transition temperature of 210 mK. (C) 2003 Elsevier B.V. All rights reserved.

    DOI

    Scopus

    3
    Citation
    (Scopus)
  • Fabrication of multi-pixel TES microcalorimeters with an electrodeposited Sn absorber and Bi absorber

    T Arakawa, H Kudo, H Sato, H Kobayashi, T Izumi, S Ohtsuka, K Mori, S Shoji, T Osaka, T Homma, K Mitsuda, N Yamasaki, R Fujimoto, N Iyomoto, Y Ishisaki, U Morita, T Koga, K Shinozaki, K Sato, N Takai, T Ohashi, Y Kuroda, M Onishi, M Goto, F Beppu

    NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT   520 ( 1月3日 ) 456 - 459  2004.03

     View Summary

    We have developed multi-pixel TES microcalorimeters in order to realize high-energy resolution and X-ray imaging. A Sn absorber and a Bi absorber were formed on Si3N4 and SiO2 membrane using two-step exposure photolithography and electrodeposition. A FEM analysis was carried out to investigate the performance of the X-ray microabsorbers. In addition, a superconducting through-wafer interconnection was demonstrated considering the future X-ray imager using microcalorimeters. Detail of the fabrication techniques, characteristics and simulation results of two types of the microabsorbers, as well as those of the calorimeters are described. (C) 2003 Elsevier B.V. All rights reserved.

    DOI

    Scopus

    3
    Citation
    (Scopus)
  • TES microcalorimeter development for future Japanese X-ray astronomy missions

    R Fujimoto, K Mitsuda, NY Yamasaki, N Iyomoto, T Oshima, Y Takei, K Futamoto, T Ichitsubo, T Fujimori, K Yoshida, Y Ishisaki, U Morita, T Koga, K Shinozaki, K Sato, N Takai, T Ohashi, H Kudo, H Sato, T Arakawa, H Kobayashi, T Izumi, S Ohtsuka, K Mori, S Shoji, T Osaka, T Homma, Y Kuroda, M Onishi, M Goto, F Beppu, T Tanaka, T Morooka, S Nakayama, K Chinone

    NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT   520 ( 1月3日 ) 431 - 434  2004.03

     View Summary

    We are developing a Ti/Au TES microcalorimeter array for future Japanese X-ray astronomy missions. The goal is an energy resolution of 2-5 eV at 6 keV, and an array of 100-1000 pixels to achieve a geometrical area of &gt;1 cm(2) and a moderate spatial resolution simultaneously. The energy resolution was improved to similar to6 eV at 6 keV with a very fast time constant (&lt;100 mus). To achieve a high coverage fraction, it is necessary to fabricate mushroom-shaped X-ray microabsorbers. We are developing an electrodeposition fabrication technique that is suitable for our process. Sn was used as absorber material, but the energy resolution was not good due to the existence of long-lived quasiparticles. Bi is also used, and the process is under optimization now. The readout strategy is to multiplex signals in the frequency domain, using a bridge circuit. So far, we succeeded in multiplexing two pixels modulated with 50 and 20 kHz at 440 mK. The energy resolution obtained at 110 mK was 33 eV (25 kHz). (C) 2003 Elsevier B.V. All rights reserved.

    DOI

    Scopus

    3
    Citation
    (Scopus)
  • Electrochemical behavior of methyl- and butyl-terminated Si(111) in aqueous solution

    D Niwa, T Inoue, H Fukunaga, T Akasaka, T Yamada, T Homma, T Osaka

    CHEMISTRY LETTERS   33 ( 3 ) 284 - 285  2004.03  [Refereed]

     View Summary

    Formation of the methyl- and n-butyl monolayer on (Cl)Si(I 11) surfaces by using the Grignard reaction and their electro-chemical behavior was investigated. The modified Si(I 11) surfaces were indicated to be closely packed with a single moiety species. The methyl-modified Si(I 11) surface was composed of (I x 1) adlattice structure. The methyl-modified surface was stable in aqueous solution, and showed essentially good electrical conductive property with p-n junction like behavior.

    DOI

    Scopus

    21
    Citation
    (Scopus)
  • Performance analyse's of TES microcalorimeters with mushroom shaped X-ray absorbers made of Sn or Bi

    Y Ishisaki, U Morita, T Koga, K Shinozaki, K Sato, N Takai, T Ohashi, T Arakawa, H Kudo, H Sato, H Kobayashi, T Izumi, S Ohtsuka, K Mori, S Shoji, T Osaka, T Homma, K Mitsuda, NY Yamasaki, R Fujimoto, N Iyomoto, T Oshima, K Futamoto, Y Takei, T Ichitsubo, T Fujimori, K Yoshida, Y Kuroda, M Onishi, M Goto, F Beppu

    NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT   520 ( 1月3日 ) 452 - 455  2004.03  [Refereed]

     View Summary

    Performance of microcalorimeters with a Ti/Au transition-edge sensor (TES) and an electrodeposited absorber has been investigated. The absorbers are in a mushroom-shape made of Sn or Bi. With an Sn absorber we observed a long time scale component of 1.8 ms for X-ray pulses, which is due presumably to recombination of quasiparticles into phonons. As a result, the energy resolution is not good with the Sn absorber. Better energy resolution of 28 +/- 1 eV was obtained with an incomplete-shaped Bi absorber, although the long component was also seen with smaller level. A calorimeter with only a neck of the An seed layer for the electrodeposition had the best energy resolution of 6.3 +/- 0.4 eV in spite of saturated pulses and relatively high transition temperature of 210 mK. (C) 2003 Elsevier B.V. All rights reserved.

    DOI

    Scopus

    3
    Citation
    (Scopus)
  • Fabrication of multi-pixel TES microcalorimeters with an electrodeposited Sn absorber and Bi absorber

    T Arakawa, H Kudo, H Sato, H Kobayashi, T Izumi, S Ohtsuka, K Mori, S Shoji, T Osaka, T Homma, K Mitsuda, N Yamasaki, R Fujimoto, N Iyomoto, Y Ishisaki, U Morita, T Koga, K Shinozaki, K Sato, N Takai, T Ohashi, Y Kuroda, M Onishi, M Goto, F Beppu

    NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT   520 ( 1月3日 ) 456 - 459  2004.03  [Refereed]

     View Summary

    We have developed multi-pixel TES microcalorimeters in order to realize high-energy resolution and X-ray imaging. A Sn absorber and a Bi absorber were formed on Si3N4 and SiO2 membrane using two-step exposure photolithography and electrodeposition. A FEM analysis was carried out to investigate the performance of the X-ray microabsorbers. In addition, a superconducting through-wafer interconnection was demonstrated considering the future X-ray imager using microcalorimeters. Detail of the fabrication techniques, characteristics and simulation results of two types of the microabsorbers, as well as those of the calorimeters are described. (C) 2003 Elsevier B.V. All rights reserved.

    DOI

    Scopus

    3
    Citation
    (Scopus)
  • TES microcalorimeter development for future Japanese X-ray astronomy missions

    R Fujimoto, K Mitsuda, NY Yamasaki, N Iyomoto, T Oshima, Y Takei, K Futamoto, T Ichitsubo, T Fujimori, K Yoshida, Y Ishisaki, U Morita, T Koga, K Shinozaki, K Sato, N Takai, T Ohashi, H Kudo, H Sato, T Arakawa, H Kobayashi, T Izumi, S Ohtsuka, K Mori, S Shoji, T Osaka, T Homma, Y Kuroda, M Onishi, M Goto, F Beppu, T Tanaka, T Morooka, S Nakayama, K Chinone

    NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT   520 ( 1月3日 ) 431 - 434  2004.03  [Refereed]

     View Summary

    We are developing a Ti/Au TES microcalorimeter array for future Japanese X-ray astronomy missions. The goal is an energy resolution of 2-5 eV at 6 keV, and an array of 100-1000 pixels to achieve a geometrical area of &gt;1 cm(2) and a moderate spatial resolution simultaneously. The energy resolution was improved to similar to6 eV at 6 keV with a very fast time constant (&lt;100 mus). To achieve a high coverage fraction, it is necessary to fabricate mushroom-shaped X-ray microabsorbers. We are developing an electrodeposition fabrication technique that is suitable for our process. Sn was used as absorber material, but the energy resolution was not good due to the existence of long-lived quasiparticles. Bi is also used, and the process is under optimization now. The readout strategy is to multiplex signals in the frequency domain, using a bridge circuit. So far, we succeeded in multiplexing two pixels modulated with 50 and 20 kHz at 440 mK. The energy resolution obtained at 110 mK was 33 eV (25 kHz). (C) 2003 Elsevier B.V. All rights reserved.

    DOI

    Scopus

    3
    Citation
    (Scopus)
  • Electrochemical behavior of methyl- and butyl-terminated Si(111) in aqueous solution

    D Niwa, T Inoue, H Fukunaga, T Akasaka, T Yamada, T Homma, T Osaka

    CHEMISTRY LETTERS   33 ( 3 ) 284 - 285  2004.03

     View Summary

    Formation of the methyl- and n-butyl monolayer on (Cl)Si(I 11) surfaces by using the Grignard reaction and their electro-chemical behavior was investigated. The modified Si(I 11) surfaces were indicated to be closely packed with a single moiety species. The methyl-modified Si(I 11) surface was composed of (I x 1) adlattice structure. The methyl-modified surface was stable in aqueous solution, and showed essentially good electrical conductive property with p-n junction like behavior.

    DOI

    Scopus

    21
    Citation
    (Scopus)
  • Formation of micro and nanoscale patterns of monolayer templates for position selective immobilization of oligonucleotide using ultraviolet and electron beam lithography

    D Niwa, K Omichi, N Motohashi, T Homma, T Osaka

    CHEMISTRY LETTERS   33 ( 2 ) 176 - 177  2004.02  [Refereed]

     View Summary

    Formation of organosilane monolayer templates using ultraviolet and electron-beam (EB) lithography was investigated. The oligonucleotides were covalently immobilized with high selectivity only to the amino-monolayer modified regions locally formed on the template surfaces at micro and nanometer scale. By using EB lithography, patterned immobilization in nanometer scale, as small as 20nm, was achieved.

    DOI

    Scopus

    13
    Citation
    (Scopus)
  • Formation of micro and nanoscale patterns of monolayer templates for position selective immobilization of oligonucleotide using ultraviolet and electron beam lithography

    D Niwa, K Omichi, N Motohashi, T Homma, T Osaka

    CHEMISTRY LETTERS   33 ( 2 ) 176 - 177  2004.02

     View Summary

    Formation of organosilane monolayer templates using ultraviolet and electron-beam (EB) lithography was investigated. The oligonucleotides were covalently immobilized with high selectivity only to the amino-monolayer modified regions locally formed on the template surfaces at micro and nanometer scale. By using EB lithography, patterned immobilization in nanometer scale, as small as 20nm, was achieved.

    DOI

    Scopus

    13
    Citation
    (Scopus)
  • Sn electrodeposition process for fabricating microabsorber arrays for an X-ray microcalorimeter

    T Homma, H Sato, H Kobayashi, T Arakawa, H Kudo, T Osaka, S Shoji, Y Ishisaki, T Oshima, N Iyomoto, R Fujimoto, K Mitsuda

    JOURNAL OF ELECTROANALYTICAL CHEMISTRY   559 ( 1 ) 143 - 148  2003.11

     View Summary

    Sn electrodeposition was employed for fabricating an array of microabsorbers with a 'mushroom-shaped' microstructure for a precision X-ray microdetector, the so called X-ray microcalorimeter. A deposition process for flat and smooth Sn films, which was suitable for the use of the absorber material, was developed by optimizing the conditions of additives such as o-cresol-4-sulfonic acid and polyethyleneglycol (PEG) to the Sn bath. The Sn films exhibited suitable properties, i.e. a higher superconducting transition temperature than the operating temperature of the X-ray microcalorimeter. The mushroom-shaped absorber array was successfully fabricated by Sn electrodeposition in combination with a photolithographic technique. (C) 2002 Elsevier Science B.V. All rights reserved.

    DOI

    Scopus

    11
    Citation
    (Scopus)
  • Survey of the metal nucleation processes on silicon surfaces in fluoride solutions: from dilute HF to concentrated NH4F solutions

    M Chemla, T Homma, Bertagna, V, R Erre, N Kubo, T Osaka

    JOURNAL OF ELECTROANALYTICAL CHEMISTRY   559 ( 1 ) 111 - 123  2003.11

     View Summary

    As is well known, contamination of the silicon surface by trace metal impurities is responsible for detrimental effects in the production of ULSI circuits. An extensive experimental study of the factors influencing the spontaneous metal nucleation from fluoride solutions on Si substrates was undertaken. In acidic media (dilute HF solution) only noble metals can be deposited. The mechanism for the formation of Cu element nuclei was chosen as a model example. The first stage was the appearance of Cu crystals of a nanoscopic scale, observed by AFM microscopy. These nuclei soon induce corrosion pits due to the formation of a short-circuited electrochemical cell. In concentrated NH4F solutions, the open circuit potential (ocp) of Si samples is highly negative and provides an efficient driving force for nucleation even for common metals like Fe. Our results show that the deposition of Fe is hardly observable when Fe only is present, but in the presence of Cu, a catalytic effect is observed leading to the co-deposition of Fe + Cu nuclei. In all cases surface defects on the Si substrate are generated by the corrosion pits. (C) 2002 Elsevier Science B.V. All rights reserved.

    DOI

    Scopus

    47
    Citation
    (Scopus)
  • Sn electrodeposition process for fabricating microabsorber arrays for an X-ray microcalorimeter

    T Homma, H Sato, H Kobayashi, T Arakawa, H Kudo, T Osaka, S Shoji, Y Ishisaki, T Oshima, N Iyomoto, R Fujimoto, K Mitsuda

    JOURNAL OF ELECTROANALYTICAL CHEMISTRY   559 ( 1 ) 143 - 148  2003.11

     View Summary

    Sn electrodeposition was employed for fabricating an array of microabsorbers with a 'mushroom-shaped' microstructure for a precision X-ray microdetector, the so called X-ray microcalorimeter. A deposition process for flat and smooth Sn films, which was suitable for the use of the absorber material, was developed by optimizing the conditions of additives such as o-cresol-4-sulfonic acid and polyethyleneglycol (PEG) to the Sn bath. The Sn films exhibited suitable properties, i.e. a higher superconducting transition temperature than the operating temperature of the X-ray microcalorimeter. The mushroom-shaped absorber array was successfully fabricated by Sn electrodeposition in combination with a photolithographic technique. (C) 2002 Elsevier Science B.V. All rights reserved.

    DOI

    Scopus

    11
    Citation
    (Scopus)
  • Molecular orbital study on the reaction process of dimethylamine borane as a reductant for electroless deposition

    Takayuki Homma, Amiko Tamaki, Hiromi Nakai, Tetsuya Osaka

    Journal of Electroanalytical Chemistry   559 ( 1 ) 131 - 136  2003.11

     View Summary

    The oxidation mechanism of dimethylamine borane (DMAB), which acts as a reductant in the electroless deposition process, was studied using ab initio molecular orbital approaches such as Hartree-Fock (HF) and second order Møller-Plesset (MP2) calculations. The overall oxidation process of the DMAB was divided into each elementary reaction in which OH- substitutes H one by one and eventually forms B(OH)4-. The oxidation mechanism of DMAB in the isolated state, which was previously proposed by us, was refined using more accurate basis sets, and the effects of solvation and interaction with metal surface sites on the oxidation mechanism were also studied. Taking the solvation effect into consideration using the self-consistent reaction field method with an isodensity polarized continuum model (SCRF-IPCM), the heat of oxidation was transferred to an exothermic reaction with decreasing dielectric constant. This indicated that the reaction preferably proceeds at the solid|liquid interface. Combined with Cu(111) and Pd(111) neutral cluster models as metal surface sites, it was found that the oxidation reaction proceeds preferentially at the metal surface sites. It was also suggested that the catalytic activity of the deposited metal is caused by its electron acceptivity. © 2003 Elsevier Science B.V. All rights reserved.

    DOI

    Scopus

    71
    Citation
    (Scopus)
  • Survey of the metal nucleation processes on silicon surfaces in fluoride solutions: from dilute HF to concentrated NH4F solutions

    M Chemla, T Homma, Bertagna, V, R Erre, N Kubo, T Osaka

    JOURNAL OF ELECTROANALYTICAL CHEMISTRY   559 ( 1 ) 111 - 123  2003.11

     View Summary

    As is well known, contamination of the silicon surface by trace metal impurities is responsible for detrimental effects in the production of ULSI circuits. An extensive experimental study of the factors influencing the spontaneous metal nucleation from fluoride solutions on Si substrates was undertaken. In acidic media (dilute HF solution) only noble metals can be deposited. The mechanism for the formation of Cu element nuclei was chosen as a model example. The first stage was the appearance of Cu crystals of a nanoscopic scale, observed by AFM microscopy. These nuclei soon induce corrosion pits due to the formation of a short-circuited electrochemical cell. In concentrated NH4F solutions, the open circuit potential (ocp) of Si samples is highly negative and provides an efficient driving force for nucleation even for common metals like Fe. Our results show that the deposition of Fe is hardly observable when Fe only is present, but in the presence of Cu, a catalytic effect is observed leading to the co-deposition of Fe + Cu nuclei. In all cases surface defects on the Si substrate are generated by the corrosion pits. (C) 2002 Elsevier Science B.V. All rights reserved.

    DOI

    Scopus

    47
    Citation
    (Scopus)
  • Maskless and electroless fabrication of patterned metal nanostructures on silicon wafers by controlling local surface activities

    T Homma, N Kubo, T Osaka

    ELECTROCHIMICA ACTA   48 ( 20-22 ) 3115 - 3122  2003.09  [Refereed]

     View Summary

    Attempt was made to develop novel maskless and electroless fabrication process of metal nanostructures by controlling local surface activity for the deposition reaction at silicon wafer surfaces. P-Si(100) wafers were cleaned to obtain hydrogen-terminated surface and nanoscopic patterns were formed on the surface by nanoindentation technique using a scanning probe microscope (SPM) with a diamond probe. By controlling the parameters such as the indentation force (within the order of 1 - 10 muN), nanoscopic patterns with different degrees of defects were formed. The scanning surface potential microscopy (SPoM) analysis clarified that these sites locally possessed negative shift in potential, i.e., higher activity for the reductive deposition of metal ions, which increased with an increase in the degree of defect. In order to achieve spontaneous (electroless) and selective deposition at those patterns, conditions of the solution were optimized and the formation of metal nanostructures, such as Cu nanodot arrays and wires, has been achieved. Capability of the present process to form nanostructures whose feature size is as small as 50 nm was demonstrated. (C) 2003 Elsevier Ltd. All rights reserved.

    DOI

    Scopus

    38
    Citation
    (Scopus)
  • Improvement of signal to noise ratio for Co/Pd multilayer perpendicular magnetic recording media by the addition of an underlayer

    T Onoue, T Asahi, K Kuramochi, J Kawaji, T Homma, T Osaka

    JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS   235 ( 1月3日 ) 40 - 44  2001.10

     View Summary

    Signal and noise characteristics of Co/Pd multilayer perpendicular magnetic recording media are discussed based upon MFM analysis. The noise of the Co/Pd multilayer media is originated mainly from irregularities in the magnetic transition regions, and can be drastically suppressed by increasing the thickness of the carbon underlayer although a large number of reversed magnetic domains between the magnetic transitions still exist. The fine magnetic clusters formed in the medium with a thick carbon underlayer result in clear magnetic transition boundaries of recorded bits in the high recording density region. By examining the profile of the M-H loops. the decrement in the x value, which is defined as the slope of M-H loop at the value of coercivity, improves the signal to noise (S/N) ratio for the Co/Pd multilayer media. (C) 2001 Elsevier Science B.V. All rights reserved.

  • Improvement of signal to noise ratio for Co/Pd multilayer perpendicular magnetic recording media by the addition of an underlayer

    T Onoue, T Asahi, K Kuramochi, J Kawaji, T Homma, T Osaka

    JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS   235 ( 1月3日 ) 40 - 44  2001.10

     View Summary

    Signal and noise characteristics of Co/Pd multilayer perpendicular magnetic recording media are discussed based upon MFM analysis. The noise of the Co/Pd multilayer media is originated mainly from irregularities in the magnetic transition regions, and can be drastically suppressed by increasing the thickness of the carbon underlayer although a large number of reversed magnetic domains between the magnetic transitions still exist. The fine magnetic clusters formed in the medium with a thick carbon underlayer result in clear magnetic transition boundaries of recorded bits in the high recording density region. By examining the profile of the M-H loops. the decrement in the x value, which is defined as the slope of M-H loop at the value of coercivity, improves the signal to noise (S/N) ratio for the Co/Pd multilayer media. (C) 2001 Elsevier Science B.V. All rights reserved.

  • Molecular orbital study on the reaction mechanisms of electroless deposition processes

    T Homma, Komatsu, I, A Tamaki, H Nakai, T Osaka

    ELECTROCHIMICA ACTA   47 ( 1月2日 ) 47 - 53  2001.09

     View Summary

    Molecular orbital study was applied to investigate electroless deposition processes, focusing upon reducibility of reductants as well as the effect of catalytic activity of the metal surfaces. Elementary reaction pathways of the reductants such as dimethylamine borane, hypophosphite ion, formaldehyde, and titanium trichloride were quantitatively examined in terms of the heat of reaction. It was indicated that the reaction via 5-coordinate intermediates was favorable for these species and that the value could be used for quantitative evaluation of the reducibility of the reductant species. The analysis of solvation effect on the reactions suggested that the reactions preferably proceed at the interfacial region, i.e. the surface of the metal, rather than in the 'bulk' solution region. The effect of catalytic activity of metal surfaces was investigated using a cluster-model surface. It was suggested that the elementary reactions were stabilized on the metal surfaces to enhance the electron emission from the reductants. On the other hand, difference in the stabilization effects for the reaction of hypophosphite ion was obtained due to the variation in the metal species, it was expected that the copper surface is not catalytically active for the reaction, which corresponds to the experimentally known results. (C) 2001 Elsevier Science Ltd. All rights reserved.

  • CoCrPtTa and Co/Pd perpendicular magnetic recording media with amorphous underlayers

    T Onoue, T Asahi, K Kuramochi, J Kawaji, T Homma, T Osaka

    IEEE TRANSACTIONS ON MAGNETICS   37 ( 4 ) 1592 - 1594  2001.07

     View Summary

    The effect of amorphous carbon underlayers on magnetic properties and read-write characteristics of Co73Cr18Pt6Ta3 single layer and Co/Pd multilayer perpendicular magnetic recording media were investigated. The increase in H-c and decrease in alpha, defined as 4 pi (dM/dH)(H=Hc), were observed by increasing the underlayer thickness for both Co-73 Cr18Pt6Ta3 and Co/Pd media. The media with a low alpha value, suggesting a decrease in the exchange coupling, exhibited the higher coercivity and the improvement of S/N ratio. In read-write experiments, the improvement of S/N ratio for the Co/Pd media was achieved up to 400 kFRPI or even higher in the recording density by increasing carbon underlayer thickness, while that for the Co73Cr18Pt6Ta3 media was obtained up to ca. 250 kFRPI.

  • CoCrPtTa and Co/Pd perpendicular magnetic recording media with amorphous underlayers

    T Onoue, T Asahi, K Kuramochi, J Kawaji, T Homma, T Osaka

    IEEE TRANSACTIONS ON MAGNETICS   37 ( 4 ) 1592 - 1594  2001.07

     View Summary

    The effect of amorphous carbon underlayers on magnetic properties and read-write characteristics of Co73Cr18Pt6Ta3 single layer and Co/Pd multilayer perpendicular magnetic recording media were investigated. The increase in H-c and decrease in alpha, defined as 4 pi (dM/dH)(H=Hc), were observed by increasing the underlayer thickness for both Co-73 Cr18Pt6Ta3 and Co/Pd media. The media with a low alpha value, suggesting a decrease in the exchange coupling, exhibited the higher coercivity and the improvement of S/N ratio. In read-write experiments, the improvement of S/N ratio for the Co/Pd media was achieved up to 400 kFRPI or even higher in the recording density by increasing carbon underlayer thickness, while that for the Co73Cr18Pt6Ta3 media was obtained up to ca. 250 kFRPI.

  • Electrochemical studies on the deposition process of electroless CoNiP films with graded magnetic properties

    T Homma, Y Kita, T Osaka

    JOURNAL OF THE ELECTROCHEMICAL SOCIETY   147 ( 11 ) 4138 - 4141  2000.11  [Refereed]

     View Summary

    In order to clarify the origin of the graded magnetic properties by the substrate rotational speed for electroless CoNiP films, electrochemical characteristics such as mixed potential and polarization behaviors were investigated. The results of mixed potential analysis revealed that the cathodic and anodic partial reactions in this system were diffusion- and reaction-controlled stale, respectively. It was shown that the mixed potential of the CoNiP deposition with the substrate rotational speed was dominated mainly by the deposition reaction of Co. The results of the polarization curves for each metal ion clarified that the Co deposition is in the diffusion-controlled state, whereas such a tendency did not appear for the deposition of Ni. This suggests that such a difference in deposition behaviors between Co and Ni with respect to the rotational speed of the substrate results in the formation of graded film properties. (C) 2000 The Electrochemical Society. S0013-4651(00)02-081-4. All rights reserved.

  • Electrochemical studies on the deposition process of electroless CoNiP films with graded magnetic properties

    T Homma, Y Kita, T Osaka

    JOURNAL OF THE ELECTROCHEMICAL SOCIETY   147 ( 11 ) 4138 - 4141  2000.11  [Refereed]

     View Summary

    In order to clarify the origin of the graded magnetic properties by the substrate rotational speed for electroless CoNiP films, electrochemical characteristics such as mixed potential and polarization behaviors were investigated. The results of mixed potential analysis revealed that the cathodic and anodic partial reactions in this system were diffusion- and reaction-controlled stale, respectively. It was shown that the mixed potential of the CoNiP deposition with the substrate rotational speed was dominated mainly by the deposition reaction of Co. The results of the polarization curves for each metal ion clarified that the Co deposition is in the diffusion-controlled state, whereas such a tendency did not appear for the deposition of Ni. This suggests that such a difference in deposition behaviors between Co and Ni with respect to the rotational speed of the substrate results in the formation of graded film properties. (C) 2000 The Electrochemical Society. S0013-4651(00)02-081-4. All rights reserved.

  • Evaluation of substrate (Ni)-catalyzed electroless gold plating process

    T Osaka, T Misato, J Sato, H Akiya, T Homma, M Kato, Y Okinaka, O Yoshioka

    JOURNAL OF THE ELECTROCHEMICAL SOCIETY   147 ( 3 ) 1059 - 1064  2000.03

     View Summary

    The substrate (Ni)-catalyzed electroless gold plating process invented by Iacovangelo and Zarnoch has been investigated for plating gold on electroless nickel substrates for application to bonding of electronic devices. The process was found to yield uniform and adherent gold films on Ni-B substrates, whereas on Ni-P substrates acceptable gold films were obtained only when the P content was low and a pretreatment procedure was introduced to prevent the formation of surface oxide or to remove it completely. Unlike the conventional galvanic displacement process, the substrate-catalyzed process does not attack the nickel substrates and yields gold films with a very low porosity. Compared with autocatalytic electroless gold plating baths, the substrate-catalyzed bath is inherently more stable, although the maximum gold thickness obtainable is naturally limited. Results of these evaluations are presented in detail. (C) 2000 The Electrochemical Society. S0013-4651(99)106-062-0. All rights reserved.

  • Evaluation of substrate (Ni)-catalyzed electroless gold plating process

    T Osaka, T Misato, J Sato, H Akiya, T Homma, M Kato, Y Okinaka, O Yoshioka

    JOURNAL OF THE ELECTROCHEMICAL SOCIETY   147 ( 3 ) 1059 - 1064  2000.03

     View Summary

    The substrate (Ni)-catalyzed electroless gold plating process invented by Iacovangelo and Zarnoch has been investigated for plating gold on electroless nickel substrates for application to bonding of electronic devices. The process was found to yield uniform and adherent gold films on Ni-B substrates, whereas on Ni-P substrates acceptable gold films were obtained only when the P content was low and a pretreatment procedure was introduced to prevent the formation of surface oxide or to remove it completely. Unlike the conventional galvanic displacement process, the substrate-catalyzed process does not attack the nickel substrates and yields gold films with a very low porosity. Compared with autocatalytic electroless gold plating baths, the substrate-catalyzed bath is inherently more stable, although the maximum gold thickness obtainable is naturally limited. Results of these evaluations are presented in detail. (C) 2000 The Electrochemical Society. S0013-4651(99)106-062-0. All rights reserved.

  • Microstructural study on the functionally graded magnetic thin films prepared by electroless deposition

    Takayuki Homma, Yosuke Kita, Tetsuya Osaka

    Journal of the Electrochemical Society   147 ( 1 ) 160 - 163  2000.01

     View Summary

    Gradient control of magnetic properties in electroless-deposited CoNiP films was attempted and microstructural origin of the graded properties was investigated. Control of the single and dual gradient in magnetic properties, such as coercivity, Hc, in the direction of the film thickness was achieved by controlling the rotational speed of substrates during the deposition. The results of cross-sectional scanning electron microscopy and transmission electron microscopy investigations clarified that the size of the crystallites changed according to the speed of the rotation, forming the `graded' microstructure in the film thickness direction, which resulted in the graded properties.

    DOI

    Scopus

    26
    Citation
    (Scopus)
  • Microstructural study on the functionally graded magnetic thin films prepared by electroless deposition

    T Homma, Y Kita, T Osaka

    JOURNAL OF THE ELECTROCHEMICAL SOCIETY   147 ( 1 ) 160 - 163  2000.01

     View Summary

    Gradient control of magnetic properties in electroless-deposited CoNiP films was attempted and microstructural origin of the graded properties ties was investigated. Control of the single and dual gradient in magnetic properties, such as coercivity, Hc, in the direction of the film thickness was achieved by controlling the rotational speed or substrates during the deposition. The results of cross-sectional scanning electron microscopy and transmission electron microscopy investigations clarified that the size of the crystalites changed according to the speed of the rotation, forming the "graded" microstructure in the film thickness direction, which resulted in the graded properties. (C) 2000 The Electrochemical Society. All rights reserved.

  • Pd/Sn混合触媒を用いた銅ダイレクトプレーティングにおける導体化過程の解析

    飯塚 淳, 中本剛輔, 内藤和久, 奥野和義, 本間敬之, 逢坂哲彌

    表面技術   50 ( 10 ) 915 - 922  1999.10

     View Summary

    The mechanism of direct copper plating on nonconductive resin substrates was studied using high-resolution TEM, SEM and XPS. Substrates were catalyzed by Pd/Sn catalyst and subsequently immersed in alkaline solution containing either copper ions or sulfide ions before electroplating. After conversion in the alkaline solution containing copper ions, catalyst colloid particles formed clusters and crystallinity improved. Sulfide compounds, however, formed by conversion in alkaline solution containing sulfide ions. Both conversion techniques markedly promoted propagation in electroplating. The effect is explained by propagation in which improved palladium colloid crystallinity and palladium sulfide formed in conversion play a critical role in determining the propagation rate.

    DOI CiNii

  • めっき析出過程の基礎解析

    本間敬之

    表面技術   50 ( 5 ) 395 - 399  1999.05

    CiNii

  • スパッタ法により作製した垂直面内複合型媒体のノイズ特性

    尾上貴弘, 滝澤敦尚, 平山貴邦, 池田 真, 本間敬之, 法橋滋郎, 逢坂哲彌, 酒井浩志, 吉川利彦

    日本応用磁気学会誌   23 ( 4 ) 977 - 980  1999.04

     View Summary

    The read-write characteristics of a perpendicular/longitudinal composite medium prepared by sputtering were investigated. The composite medium exhibited a higher voltage than a perpendicular single-layered medium, although the noise of these media was almost the same. The noise of the composite medium increased slightly with the recording density, suggesting that it was affected by the longitudinal underlayer. However, the noise reduction effect of the composite medium was observed by comparing with the simple superposition of the noise of each single layered medium. As a result, it was found that the perpendicular/longitudinal composite medium exhibited a higher S/N value than the perpendicular single-layered medium.

    DOI CiNii

  • 無電解CoNiP傾斜機能磁性薄膜の断面構造解析

    喜多洋介, 本間敬之, 逢坂哲彌

    表面技術   49 ( 12 ) 1358 - 1359  1998.12

    DOI CiNii

  • 電気化学的手法による磁気的機能傾斜薄膜の作製

    本間敬之, 喜多洋介, 逢坂哲彌

    日本金属学会誌   62 ( 11 ) 1025 - 1030  1998.11

  • Nucleation of Trace Copper on the H-Si(111) Surface in Aqueous Fluoride Solutions

    T. Homma, C.P.Wade, C.E.D.Chidsey

    J. Phys.Chem. B   102 ( 41 ) 7919 - 7922  1998.10

     View Summary

    The initial nucleation process of trace amounts of copper metal on the H-Si(111)(1 x 1) surface in aqueous fluoride solution was investigated by ex-situ scanning tunneling microscopy. We observed that copper nucleates preferentially along step edges and appears to inhibit the step-flow etching of silicon. The presence of copper species in the fluoride solution also appears to inhibit the formation of terrace etch pits, which are known to be initiated by dissolved oxygen. It is suggested that silicon-dihydroxyl-cuprous ion complexes are formed at dihydroxyl kink sites, resulting in the preferential nucleation of Cu metal at step edges and the inhibition of step-flow etching. Copper ions in solution may act as catalysts for the disproportionation and electrocatalytic reduction of superoxide anion radical formed by the electrochemical reduction of dissolved oxygen at the silicon surface. Such reactions would reduce the rate of etch-pit initiation and may also decrease the rate of deposition of metallic copper on the silicon surface.

  • Nucleation of Trace Copper on the H-Si(111) Surface in Aqueous Fluoride Solutions

    T. Homma, C.P.Wade, C.E.D.Chidsey

    J. Phys.Chem. B   102 ( 41 ) 7919 - 7922  1998.10  [Refereed]

     View Summary

    The initial nucleation process of trace amounts of copper metal on the H-Si(111)(1 x 1) surface in aqueous fluoride solution was investigated by ex-situ scanning tunneling microscopy. We observed that copper nucleates preferentially along step edges and appears to inhibit the step-flow etching of silicon. The presence of copper species in the fluoride solution also appears to inhibit the formation of terrace etch pits, which are known to be initiated by dissolved oxygen. It is suggested that silicon-dihydroxyl-cuprous ion complexes are formed at dihydroxyl kink sites, resulting in the preferential nucleation of Cu metal at step edges and the inhibition of step-flow etching. Copper ions in solution may act as catalysts for the disproportionation and electrocatalytic reduction of superoxide anion radical formed by the electrochemical reduction of dissolved oxygen at the silicon surface. Such reactions would reduce the rate of etch-pit initiation and may also decrease the rate of deposition of metallic copper on the silicon surface.

  • 表面技術便覧

    本間敬之

    日刊工業新聞     1613 - 1622  1998.02

  • Gradient Control of Magnetic Properties in Electroless Deposited CoNiP Films

    T. Homma, M.Suzuki, T.Osaka

    J.Electrochem.Soc.   145 ( 1 ) 134 - 138  1998.01

     View Summary

    In order to establish the methodology for the preparation of the magnetic recording medium whose properties graded along the head field distribution, an intentional gradient control of coercivity, He, in electroless-deposited CoNiP thin films was attempted. Microstructure and He of the films changed significantly with the rotational speed of the substrate during deposition. Based upon these results, the gradient control of He was achieved by employing a programmed variation of the rotational speed of the substrate during the deposition. It was confirmed that not only "single-gradient" but also "dual-gradient" control of He in the direction of film thickness can be realized. This method is expected to be a useful technique for preparing a recording medium with magnetic properties most suitable for recording system parameters such as head properties.

  • Gradient Control of Magnetic Properties in Electroless Deposited CoNiP Films

    T. Homma, M.Suzuki, T.Osaka

    J.Electrochem.Soc.   145 ( 1 ) 134 - 138  1998.01

     View Summary

    In order to establish the methodology for the preparation of the magnetic recording medium whose properties graded along the head field distribution, an intentional gradient control of coercivity, He, in electroless-deposited CoNiP thin films was attempted. Microstructure and He of the films changed significantly with the rotational speed of the substrate during deposition. Based upon these results, the gradient control of He was achieved by employing a programmed variation of the rotational speed of the substrate during the deposition. It was confirmed that not only "single-gradient" but also "dual-gradient" control of He in the direction of film thickness can be realized. This method is expected to be a useful technique for preparing a recording medium with magnetic properties most suitable for recording system parameters such as head properties.

  • Tapping Mode Atomic Force Microscopy Analysis of the Growth Process of Electroless Nickel-Phosphorus Films on Nonconducting Surfaces

    T. Homma, M. Tanabe, K. Itakura, T. Osaka

    J.Electrochem.Soc.   144 ( 12 ) 4123 - 4127  1997.12

     View Summary

    The growth process of electroless nickel-phosphorous (NiP) films on nonconducting substrate was investigated quantitatively using tapping mode atomic force microscopy (TMAFM) with focus upon the nucleation density on the substrate surface. Three kinds of catalyzing processes were used for polyimide substrates to obtain nucleation densities of 900, 750, and 550 nuclei/mu m(2). The TMAFM observation showed that the film growth proceeds mainly through successive nucleation of fine ''particles'' with several nanometers in diameter and their three-dimensional growth, and that the nucleation density influences the state of aggregation of the particles and hence the resulting surface topography The lower nucleation density developed the rougher surface with larger ''grains'' with a diameter of ca. 80 nm. However, the effect of nucleation density decayed with film growth and eventually vanished at a thickness of ca. 2000 nm due to successive nucleation. For comparison, the growth process of NiP on NiP coated Al substrate, which is used for rigid magnetic disk applications and has a higher nucleation density of 3000 nuclei/mu m(2), was also examined. This process resulted in a smooth surface without the formation of ''aggregates.'' Bated upon these results, the root-mean-square roughness and scaling analyses were performed to evaluate quantitatively the differences in growth process.

  • Electrodeposition of soft gold from a thiosulfate-sulfite bath for electronics applications

    T Osaka, A Kodera, T Misato, T Homma, Y Okinaka, O Yoshioka

    JOURNAL OF THE ELECTROCHEMICAL SOCIETY   144 ( 10 ) 3462 - 3469  1997.10

     View Summary

    The possibility of electrodeposition of soft gold from a thiosulfate-sulfite bath was explored for electronics applications. The bath does not contain cyanide, and it is operated at a near neutral pH and a mildly elevated temperature. The bath is stable, does not undergo spontaneous decomposition without the addition of any stabilizer, and yields gold deposits with a hardness sufficiently low for use as gold bumps on semiconductor devices. Factors affecting the hardness were investigated in detail. It is shown that the use of high concentrations of the complexing agents and/or the addition of thallium(I) ions decreases both hardness and sulfur content of the deposit. The lowest Vickers hardness values achieved were approximately 80 kg mm(-2) in the as-deposited state and 50 kg mm(-2) after annealing at 350 degrees C for 30 min in air. The relationship between hardness and microstructure of the deposit was also examined.

  • Compositional Inhomogeneity in Electroless- Deposited CoNiP Films studied By Spin-Echo 59 Co Nuclear Magnetic Resonance

    T. Homma, Y. Sezai, T. Osaka, Y. Maeda, D. M. Donnet

    J.Magn.Magn.Mater   177 ( 6 ) 314 - 320  1997.10  [Refereed]

     View Summary

    A compositionally inhomogeneous state in electroless-deposited CoNiP films with perpendicular magnetic anisotropy is investigated using spin-echo 59Co nuclear magnetic resonance (NMR), focusing on its correlation with magnetic properties. By adjusting pH of the electroless-deposition bath, films were prepared which possess almost the same average composition (Co42Ni50P8) and crystal orientation, but the differing values of coercivity (Hc). By analyzing the shift in peak resonance frequency of NMR spectra of the CoNiP films with respect to that of bulk CoNi alloys, we observed the formation of a compositionally inhomogeneous state in the film which possesses high Hc of 2600 Oe, whereas formation of inhomogeneities was not observed for the low-Hc films. By assuming that a Co-enriched ferromagnetic component detected by NMR was separated from a non-magnetic amorphous Ni-P component, we found that the high-Hc film consists of Co42Ni26 and Ni24P8. Moreover, the results of high spatial resolution X-ray microanalysis on the high-Hc film showed a tendency that the Co-enriched ferromagnetic component segregates to the center of grains and the Ni-P non-magnetic component segregates to grain boundaries. Such evidence indicates that compositional inhomogeneities could be one of the origins of high-Hc in CoNiP films.

    DOI

    Scopus

    23
    Citation
    (Scopus)
  • Electrodeposition of soft gold from a thiosulfate-sulfite bath for electronics applications

    T Osaka, A Kodera, T Misato, T Homma, Y Okinaka, O Yoshioka

    JOURNAL OF THE ELECTROCHEMICAL SOCIETY   144 ( 10 ) 3462 - 3469  1997.10

     View Summary

    The possibility of electrodeposition of soft gold from a thiosulfate-sulfite bath was explored for electronics applications. The bath does not contain cyanide, and it is operated at a near neutral pH and a mildly elevated temperature. The bath is stable, does not undergo spontaneous decomposition without the addition of any stabilizer, and yields gold deposits with a hardness sufficiently low for use as gold bumps on semiconductor devices. Factors affecting the hardness were investigated in detail. It is shown that the use of high concentrations of the complexing agents and/or the addition of thallium(I) ions decreases both hardness and sulfur content of the deposit. The lowest Vickers hardness values achieved were approximately 80 kg mm(-2) in the as-deposited state and 50 kg mm(-2) after annealing at 350 degrees C for 30 min in air. The relationship between hardness and microstructure of the deposit was also examined.

  • Compositional Inhomogeneity in Electroless- Deposited CoNiP Films studied By Spin-Echo 59 Co Nuclear Magnetic Resonance

    T. Homma, Y. Sezai, T. Osaka, Y. Maeda, D. M. Donnet

    J.Magn.Magn.Mater   177 ( 6 ) 314 - 320  1997.10

     View Summary

    A compositionally inhomogeneous state in electroless-deposited CoNiP films with perpendicular magnetic anisotropy is investigated using spin-echo 59Co nuclear magnetic resonance (NMR), focusing on its correlation with magnetic properties. By adjusting pH of the electroless-deposition bath, films were prepared which possess almost the same average composition (Co42Ni50P8) and crystal orientation, but the differing values of coercivity (Hc). By analyzing the shift in peak resonance frequency of NMR spectra of the CoNiP films with respect to that of bulk CoNi alloys, we observed the formation of a compositionally inhomogeneous state in the film which possesses high Hc of 2600 Oe, whereas formation of inhomogeneities was not observed for the low-Hc films. By assuming that a Co-enriched ferromagnetic component detected by NMR was separated from a non-magnetic amorphous Ni-P component, we found that the high-Hc film consists of Co42Ni26 and Ni24P8. Moreover, the results of high spatial resolution X-ray microanalysis on the high-Hc film showed a tendency that the Co-enriched ferromagnetic component segregates to the center of grains and the Ni-P non-magnetic component segregates to grain boundaries. Such evidence indicates that compositional inhomogeneities could be one of the origins of high-Hc in CoNiP films.

    DOI

    Scopus

    23
    Citation
    (Scopus)
  • Noise Properties of an Electroless-deposited CoNiReP Perpendicular Magnetic Prcording Medium and a Perpendicular / Longitudinal Composite Medium

    J. Hokkyo, T. Osaka, T. Homma, T. Onoue, N. Miyamoto

    J.Magn.Soc.Jpn.   21 ( S2 ) 525 - 528  1997.09

  • Noise Properties of an Electroless-deposited CoNiReP Perpendicular Magnetic Prcording Medium and a Perpendicular / Longitudinal Composite Medium

    J. Hokkyo, T. Osaka, T. Homma, T. Onoue, N. Miyamoto

    J.Magn.Soc.Jpn.   21 ( S2 ) 525 - 528  1997.09

  • 垂直面内複合型媒体の記録再生特性

    黒川義昭, 本間敬之, 逢坂哲彌

    日本応用磁気学会誌   21 ( 6 ) 977 - 982  1997.06

     View Summary

    The recording characteristics of a composite medium with a longitudinal magnetization recording layer as a underlayer of a perpendicular magnetization recording layer were evaluated by using ring-type heads. The results suggest that the residual magnetization mode of the medium is a phase synchronization mode, which forms a horseshoe-shaped magnetization region composed of the strong perpendicular magnetization region of the perpendicular layer and the longitudinal magnetization region of the underlayer. The reproduced voltage of the medium is higher than that obtained by simple superposition of the outputs of the perpendicular top layer and the longitudinal under-layer, and the waveform of the medium shows an almost single-peaked pulse. The recording density response and peak shift characteristics are not restricted by the characteristics of the underlayer. The magnetization state of the medium can be controlled by the medium and head parameters, indicating the importance of optimizing these parameters.

    CiNii

  • リングヘッド-垂直面内複合型媒体系におけるスペーシングの影響

    黒川義昭, 長崎 顕, 本間敬之, 逢坂哲彌

    日本応用磁気学会誌   21 ( S1 ) 163 - 168  1997.04

  • CoCrTa/Cr磁性薄膜におけるSi基板前処理効果の検討

    逢坂哲彌, 本間敬之, 黒川義昭, 田口智一, 瀧澤敦尚

    日本応用磁気学会誌   21 ( 4 ) 213 - 216  1997.04

  • Effect of Perpendicular Layer Thickness on Read/Write Characteristics of Perpendicular/Longitudinal Composite Media Using Ring-Type Head

    Y. Kurokawa, A. Nagasaki, T. Homma, T. Osaka

    IEEE Trans.Magn   32 ( 6 ) 3810 - 3812  1996.11

     View Summary

    The effects of perpendicular layer thickness on rémanent magnetization states and recording characteristics of perpendicular-longitudinal composite media were investigated. The contribution of perpendicular magnetic reversal is varied due to a change in the thickness of perpendicular layer
    the transition length of the thinner perpendicular layer medium was broader than that of thicker perpendicular medium. The medium with thicker perpendicular layer shown better performance not only in recording density response but also peak shift characteristics. In order to realize excellent read/write characteristics, optimization of the thickness of perpendicular layer becomes one of the important factors, in addition to the optimization of the underlayer parameters. © 1996 IEEE.

    DOI

    Scopus

    5
    Citation
    (Scopus)
  • Effect of Perpendicular Layer Thickness on Read/Write Characteristics of Perpendicular/Longitudinal Composite Media Using Ring-Type Head

    Y. Kurokawa, A. Nagasaki, T. Homma, T. Osaka

    IEEE Trans.Magn   32 ( 6 ) 3810 - 3812  1996.11

  • CoCrTa/Cr磁性薄膜のSi(100)基板上への成膜における基板前処理効果

    逢坂哲彌, 本間敬之, 黒川義昭, 田口智一

    電気化学および工業物理化学   64 ( 7 ) 850 - 851  1996.07  [Refereed]

  • 高速銅電析によるプリント配線板用銅箔のモルフォロジーに及ぼす塩素イオンとにかわの相乗作用

    逢坂哲彌, 榊原彰良, 田村圭有, 本間敬之, 沖中 裕

    回路実装学会誌   11 ( 7 ) 494 - 499  1996.07

     View Summary

    Effects of additives of Cl- and glue in the high speed copper electrodeposition on the surface morphology of copper foil to form pyramidal shape were investigated by means of SEM and TEM observation. The surface pyramidal deposition at the copper foil deposited from the standard conditions of 50ppm Cl- and 2ppm glue is controlled by formation of perpendicular columnar microstructure. The structure became clearer, at the surface region. The additives of Cl- and glue promoted and suppressed the formation of columnar structure, respectively, the columnar structure formation corresponded well to the &lsaquo;110&rsaquo; direction growth of copper crystals. The complex effect of 50ppmCl- and 2ppm glue determined the uniformity of surface pyramidal deposition and the shape of pyramid form became shaper with the additive of glue.

    DOI CiNii

  • Magnetic Force Microscopy Analysis of Micromagnetization Mode of Double-Layered Perpendicular Magnetic Recording Media

    T.Homma, Y.Kurokawa, T.Nakamura, T.Osaka, I.Otsuka

    J.Vac.Sci.Technol B   14 ( 2 ) 1184 - 1187  1996.04

  • リングヘッド/垂直面内複合型媒体系のピークシフト特性

    黒川義昭, 長崎 顕, 本間敬之, 逢坂哲彌

    日本応用磁気学会誌   20 ( 2 ) 141 - 144  1996.04

     View Summary

    The peak shift characteristics of perpendicular-longitudinal composite media in combination with a ring-typehead were investigated. It was found that the composite media had excellent peak shift characteristics in the region where the underlayer-medium showed worse characteristics. In the case of the composite media, strong perpendicular magnetization of the perpendicular recording layer suppressed the unfavorable effect of the underlayer. The underlayer's magnetization had great influence on the peak shift characteristics of the composite media, especially in the higher recording region. It is suggested that the peak shift characteristics are mainly subject to the condition of perpendicular magnetic reversal formed in the composite media.

    DOI CiNii

  • Magnetic Force Microscopy Analysis of Micromagnetization Mode of Double-Layered Perpendicular Magnetic Recording Media

    T.Homma, Y.Kurokawa, T.Nakamura, T.Osaka, I.Otsuka

    J.Vac.Sci.Technol B   14 ( 2 ) 1184 - 1187  1996.04

  • EFFECTS OF HEAD PARAMETERS ON READ WRITE CHARACTERISTICS OF PERPENDICULAR LONGITUDINAL COMPOSITE MEDIA

    Y KUROKAWA, A NAGASAKI, T HOMMA, T OSAKA

    IEEE TRANSACTIONS ON MAGNETICS   31 ( 6 ) 3102 - 3104  1995.11

     View Summary

    Effects of saturation flux density (Bs) of read/write head on the recording characteristics of perpendicular/longitudinal composite medium were investigated. It was found that the recording sensitivity was improved by applying the higher Bs head. In higher density region, the reproduced-voltage-enhancement was enlarged with high Bs head, however, at the higher MMF region, the read/write characteristics was worse because the head field penetration becomes broad. Therefore, it was necessary to optimize the medium parameters in account to the head parameter.

  • Correlation between Magnetic Properties and Phase-Separated Microstructure of Electroless CoNiP Perpendicular Magnetic Recording Media

    T. Homma, T. Osaka, Y. Yamazaki, T. Namikawa

    Scripta Metallurgica et Materialia   33 ( 10 ) 1569 - 1573  1995.11

  • Correlation between Magnetic Properties and Phase-Separated Microstructure of Electroless CoNiP Perpendicular Magnetic Recording Media

    T. Homma, T. Osaka, Y. Yamazaki, T. Namikawa

    Scripta Metallurgica et Materialia   33 ( 10 ) 1569 - 1573  1995.11

  • 走査トンネル顕微鏡による銀電析過程の観察

    中村高士, 本間敬之, 逢坂哲彌

    表面技術   46 ( 10 ) 956 - 959  1995.10

     View Summary

    The growth morphologies of electrodeposited silver under potential control on an Au (111) surface from the solutions of 5mM AgNO3/0.5M HNO3 and 5mM KAg (CN)2/0.5M KCN were investigated using Scanning Tunneling Microscopy (STM) in air. The silver films were deposited between 20mV and 100mV overpotential. From 5mM AgNO3/0.5M HNO3, silver was deposited like a single crystal along the gold substrate at 20mV overpotential. At 50mV overpotential large grains (300-500nm) were formed. Finally, at 100mV overpotential rough films were formed. From 5mM KAg (CN)2/0.5M KCN, silver was deposited like a single crystal at 20mV overpotential, and between 50mV and 100mV, smaller grain deposition with 50-100nm particles were clearly deposited compared to the deposit from 5mM AgNO3/0.5M HNO3.

    DOI CiNii

  • Electrochemically Deposited Thin Films for Magnetic Recording Devices

    T. Osaka, T. Homma

    Interface   4 ( 2 ) 42  1995.04

  • 機能性薄膜材料の評価(1)磁性薄膜材料

    本間敬之

    電気化学および工業物理化学/電気化学協会   63 ( 4 ) 281 - 285  1995.04

    CiNii

  • Electrochemically Deposited Thin Films for Magnetic Recording Devices

    T. Osaka, T. Homma

    Interface   4 ( 2 ) 42  1995.04

  • Effects of head parameters on read/write characteristics of perpendicular/longitudinal composite media

    Y. Kurokawa, A. Nagasaki, T. Homma, T. Osaka

    IEEE Transactions on Magnetics   31 ( 6 ) 3102 - 3104  1995.04

     View Summary

    Effects of saturation flux density (Bs) of read/write head on the recording characteristics of perpendicular/longitudinal composite medium were investigated. It was found that the recording sensitivity was improved by applying the higher Bs head. In higher density region, the reproduced-voltage-enhancement was enlarged with high Bs head, however, at the higher MMF region, the read/write characteristics was worse because the head field penetration becomes broad. Therefore, it was necessary to optimize the medium parameters in account to the head parameter. © 1995 IEEE

    DOI

    Scopus

    6
    Citation
    (Scopus)
  • Electrochemical Fabrication of CoPt Nanodot Arrays on Glass Disks by UV Nanoimprint Lithography

    T. Ouchi, Y. Arikawa, J. Mizuno, S. Shoji, T. Homma

    Electrochem. Soc. Trans.   16 ( 45 ) 79 - 84  1905.07

  • Electrochemical Evaluation and Finite Element Structural Analysis of Si Wafer Surface under Mechanical Stress

    K. Sakata, T. Homma

    Electrochem. Soc. Trans.   16 ( 40 ) 79 - 84  1905.07

     View Summary

    The effect of mechanical strain on the surface properties of Si wafer was investigated as a model experiment to evaluate the correlation between the degree of the strain and the electrochemical properties of the Si wafer surface. Finite element structure analysis was applied to estimate the degree of strain, and the open circuit potential measurement was carried out to investigate the surface electrochemical property. The results of these experiments suggested that the mechanical stress induces strain to the Si crystal structure to change the surface reactivity. ©The Electrochemical Society.

    DOI

    Scopus

  • Preparation of Electrodeposited Pt Nano Patterned Electrode using UV-Nano Imprinting Lithography

    M. Saito, J. Mizuno, H. Nishikubo, H. Fujiwara, T. Homma

    Electrochem. Soc. Trans.   16 ( 25 ) 131 - 136  1905.07

     View Summary

    We attempt to prepare the patterned electrode for the formation of nano particles using electrochemical deposition with the cathode whose surface has nano dot patterns. In particular, we applied electrodeposition of Pt and UV nano imprinting lithography (UV-NIL) to prepare the nano patterned electrode. In order to achieve higher activity, the deposition condition of Pt was optimized using additives such as polyethylene glycol (PEG). The surface activity of the Pt films was affected by molecular weight of PEG. It was revealed that the surface activity of the films deposited with the order of thousands of molecular weight of PEG indicated the highest effective current density among the examined films. The Pt films, which exhibited the highest current density, were adapted to fabricate nano-patterned electrode with 400 nm pith periodic structure using UV-NIL. ©The Electrochemical Society.

    DOI

    Scopus

    2
    Citation
    (Scopus)
  • Effect of Cu Seed Layers on the Properties of Electroplated Sn-Cu Films

    M. Saito, H. Sasaki, K. Katou, T. Toba, T. Homma

    J. Electrochem. Soc.   156 ( 5 ) E86 - E90  1905.07  [Refereed]

     View Summary

    Sn-Cu films were electroplated on Cu seed layers of various thicknesses. The velocity of the diffusion of Cu atoms from a seed layer into the electroplated Sn-Cu film was investigated, focusing on the effect of microstructural properties of the film. It was found that the diffusion velocity of Cu from a Cu seed layer into the electroplated Sn-Cu film increased with a decrease in the thickness of the Cu seed layer. Moreover, the film microstructure was influenced by the thickness of the Cu seed layer. When the crystalline quality of the Cu seed layer was inferior, a large lattice mismatch developed at the interface between the electroplated Sn-Cu film and the Cu seed layer. As a result of this lattice mismatch, many lattice defects and stress may exist at the interface between the electroplated Sn-Cu films and the Cu seed layers. Therefore, the lattice mismatch was considered to be related to the high-diffusion velocity of Cu from the Cu seed layer. Furthermore, the high-diffusion velocity of Cu was found to cause whisker formation. (C) 2009 The Electrochemical Society. [DOI: 10.1149/1.3090179] All rights reserved.

    DOI

    Scopus

    5
    Citation
    (Scopus)
  • In Situ Observation of Dendrite Growth of Electrodeposited Li Metal

    Kei Nishikawa, Takeshi Mori, Tetsuo Nishida, Yasuhiro Fukunaka, Michel Rosso, Takayuki Homma

    JOURNAL OF THE ELECTROCHEMICAL SOCIETY   157 ( 11 ) A1212 - A1217  1905.07  [Refereed]

     View Summary

    The dendrite growth behavior of Li metal galvanostatically electrodeposited on Ni substrate in a LiClO(4)-propylene carbonate electrolyte solution was in situ observed by a laser scanning confocal microscope with a metallographic microscope. A Li dendrite precursor is stochastically evolved on Ni substrate probably through a solid electrolyte interphase layer produced by the surface chemical reaction between a reduced Li metal and an organic electrolyte. The measured length of randomly growing Li dendrite arms was statistically analyzed. The initiation period of the dendrite precursor becomes shorter with increasing current density and decreasing LiClO(4) concentration. Once it has been initiated, the ionic mass transfer rate starts to govern the growth process of the dendrite arm length, exceeding over the surface chemistry controlling step. The dendrite arm length averaged over the substrate surface grows linearly proportional to the square root of time. The lower the concentration of LiClO(4), the steeper the inclination of the line at 5 mA cm(-2), whereas the concentration dependence of inclination is not evident at 0.5 mA cm(-2). (C) 2010 The Electrochemical Society. [DOI: 10.1149/1.3486468] All rights reserved.

    DOI

    Scopus

    126
    Citation
    (Scopus)
  • Effect of Tl-codeposition on Au Electrodeposition from Non-Cyanide Bath

    M. Saito, K. Inoue, K. Shiokawa, T. Homma

    Electrochem. Soc. Trans.   25 ( 34 ) 87 - 92  1905.07  [Refereed]

     View Summary

    Effect of Tl on the electrodeposition behavior of Au was investigated by electrochemical analysis, total-reflection X-ray fluorescene analysis, XRD, glow discharge optical emission spectrometer (GD-OES) and hardness measurement. The deposition rate increased with an increase in the amount of Tl addition to the bath. Tl was co-deposited at the interface between the seed layer and the Au films, as well as in the films. In as-deposited condition, the Tl contained films exhibited higher hardness compared with the Tl-free films, while both of them showed almost the same hardness after annealing. It was suggested that the hardness is correlated with the crystal orientation of the grains.

    DOI

    Scopus

    8
    Citation
    (Scopus)
  • High Perpendicular Coercivity Electroless Cobalt Alloy Films with 25 nm Thicknesses

    T. Ouchi, Y. Arikawa, T. Kuno, T. Homma

    Electrochem. Soc. Trans.   25 ( 41 ) 125 - 134  1905.07  [Refereed]

     View Summary

    This paper describes the development of Co alloy films thinner than 50 nm with high perpendicular magnetic coercivity using an electroless deposition process. In order to obtain these films, we used a Cu underlayer for a heteroepitaxial growth of the Co alloys and an optimized bath composition which included sodium hypophosphite and hydrazine as reductants. As a results, the perpendicular coercivity of the films turned to be higher 3000 Oe at the initial deposition stage with the thickness lower than 80 nm. In particular, the high perpendicular magnetic coercivity of the film as thin as 25 nm thick was obtained. These results indicate that electroless deposition is applicable for formation of the films with high perpendicular magnetic coercivity by optimizing the deposition conditions.

    DOI

    Scopus

  • Fabrication of Nanogap Electrodes using Electrodeposition Process

    C. Kobayashi, S. Yoshida, M. Saito, Y. Wakayama, T. Homma

    Electrochem. Soc. Trans.   25 ( 41 ) 29 - 40  1905.07  [Refereed]

     View Summary

    Laterally-enhanced growth of Au using electrochemical deposition from an electrode onto SiO2 surface modified with organic molecules for fabrication of nanogap electrodes was investigated. After modifying the SiO2 surface with self-assembled monolayers (SAMs) or dendrimer, electrodeposition was carried out and the enhanced lateral deposition was observed from the edge of Au electrode onto the SiO2 surface. In order to analyze the surface states modified with SAMs or dendrimer, X-ray photoelectron spectroscopy (XPS) were conducted and the existence of the organic molecules and Au ions on the SiO2 surface was confirmed. It was suggested that the enhanced lateral deposition was induced by the adsorbed Au ions. Furthermore, we tried to measure the electrical property of phthalocyanine molecular wire using the gap electrodes. In order to improve the contact state between the wire and the electrodes, electrodeposition was applied. As a result, improvement of contact state was observed from Current-Voltage characterization.

    DOI

    Scopus

    2
    Citation
    (Scopus)
  • Electrochemical Fabrication and Characterization of CoPt Bit Patterned Media: towards a Wet Chemical, Large-Scale Fabrication

    T. Ouchi, Y. Arikawa, T. Kuno, J. Mizuno, S. Shoji, T. Homma

    IEEE Trans. Magn.   46   2224 - 2227  1905.07

  • Fabrication of Magnetic Nanodot Array using Electrochemical Deposition Processes

    T. Ouchi, Y. Arikawa, Y. Konishi, T. Homma

    Electrochim. Acta   55   8081 - 8086  1905.07

  • Microstructure Formation within Films of Silicon using Electrochemical Anodization

    J. B. Ratchford, M. Saito, T. Homma

    Trans, Mat. Res. Soc.   35 ( 1 ) 69 - 72  1905.07

     View Summary

    The electrochemical anodization of silicon films in aqueous solutions containing hydrofluoric acid was investigated. The films were deposited onto fused quartz chips from poly-crystalline, phosphorous doped silicon using magnetron physical vapor deposition in argon plasma. X-ray diffraction from these films showed that the atomic structure of silicon was amorphous. Current-potential profiles of the films in hydrofluoric acid solutions showed a linear increase in current with increasing anodic potential, unlike the diffusion limited profiles obtained from arsenic-doped silicon (100) crystals. In order to form microstructures within selected regions of the silicon, an epoxy resin was lithographically patterned onto the surface of the silicon prior to anodization. Three-dimensional profiles of the film's surface after removal of the resin revealed that the regions of silicon protected by the resin had formed microstructures.

    DOI CiNii

  • Electrochemical Etching Process to Tune the Diameter of Arrayed Deep Pores by Controlling Carrier Collection at a Semiconductor-Electrolyte Interface

    H. Sato, T. Yamaguchi, T. Isobe, S. Shoji, T. Homma

    Electrochem. Comm.   12   765 - 768  1905.07

  • Al-Si合金膜表面のジンケート処理に対する下地Si基板の影響

    齋藤美紀子, 前川武之, 本間敬之

    表面技術   61 ( 6 ) 447 - 451  1905.07

  • In Situ Observation of Dendrite Growth of Electrodeposited Li Metal

    K. Nishikawa, T. Mori, T. Nishid, Y. Fukunaka, M. Rosso, T. Homma

    J. Electrochem. Soc.   157 ( 11 ) A1212 - A1217  1905.07  [Refereed]

     View Summary

    The dendrite growth behavior of Li metal galvanostatically electrodeposited on Ni substrate in a LiClO(4)-propylene carbonate electrolyte solution was in situ observed by a laser scanning confocal microscope with a metallographic microscope. A Li dendrite precursor is stochastically evolved on Ni substrate probably through a solid electrolyte interphase layer produced by the surface chemical reaction between a reduced Li metal and an organic electrolyte. The measured length of randomly growing Li dendrite arms was statistically analyzed. The initiation period of the dendrite precursor becomes shorter with increasing current density and decreasing LiClO(4) concentration. Once it has been initiated, the ionic mass transfer rate starts to govern the growth process of the dendrite arm length, exceeding over the surface chemistry controlling step. The dendrite arm length averaged over the substrate surface grows linearly proportional to the square root of time. The lower the concentration of LiClO(4), the steeper the inclination of the line at 5 mA cm(-2), whereas the concentration dependence of inclination is not evident at 0.5 mA cm(-2). (C) 2010 The Electrochemical Society. [DOI: 10.1149/1.3486468] All rights reserved.

    DOI

    Scopus

    126
    Citation
    (Scopus)
  • Density Functional Theory Analysis for Orbital Interaction between Hypophosphite Ions and Metal Surfaces

    Masahiro Kunimoto, Hiromi Nakai, Takayuki Homma

    JOURNAL OF THE ELECTROCHEMICAL SOCIETY   158 ( 10 ) D626 - D633  1905.07  [Refereed]

     View Summary

    In order to elucidate the reactivity difference of hypophosphite ions used as reducing agents for electroless deposition on different metal surfaces, such as Pd and Cu, electronic structures of the activation states of hypophosphite ion oxidation on these surfaces were intensively analyzed by using Density Functional Theory (DFT). In the calculation, we focused on the dehydrogenation reaction which should be a rate-determining step in the elementary reaction steps. From the calculation results, a particular orbital interaction between the hypophosphite ion and the metal surface was observed. On Pd (111), the s-orbital of H in the hypophosphite ion interacts singly with the d- or p-orbital of Pd (111). This interaction induces an anti-bonding interaction between H and P in the hypophosphite ion, which is responsible for P-H cleavage. On the other hand, on Cu (111), the s-orbital of H and the s-orbital of P in a hypophosphite ion interact simultaneously with the p-orbital of Cu (111). This interaction barely induces an anti-bonding interaction between H and P in the hypophosphite ion. Such a difference in orbital interaction structures should be related to P-H cleavage activity and the reactivity difference of hypophosphite ion on each metal surface. (C) 2011 The Electrochemical Society. [DOI: 10.1149/1.3623782] All rights reserved.

    DOI

    Scopus

    23
    Citation
    (Scopus)
  • Density Functional Theory Analysis of Reaction Mechanism of Hypophosphite Ions on Metal Surfaces

    Masahiro Kunimoto, Takuya Shimada, Shuichi Odagiri, Hiromi Nakai, Takayuki Homma

    JOURNAL OF THE ELECTROCHEMICAL SOCIETY   158 ( 9 ) D585 - D589  1905.07  [Refereed]

     View Summary

    The elementary steps of the reactions of hypophosphite ions with Cu, Ni, and Pd were calculated theoretically using Density Functional Theory (DFT) to demonstrate the reaction mechanism and gain insight at the molecular level. The elementary steps of these reactions are adsorption, dehydrogenation, and oxidation (hydroxyl base attack). In the adsorption step, hypophosphite ions adsorb onto each surface spontaneously with stabilities in the order of Ni (111) &gt; Pd (111) &gt; Cu (111). In the dehydrogenation step, hypophosphite ions dehydrogenate on Ni (111) and Pd (111) with small reaction barriers, whereas they react on Cu (111) with a large reaction barrier. The large reaction barrier on Cu (111) is not compensated for by the adsorption energy on the surface. In the oxidation step, dehydrogenated anions on each metal surface react spontaneously with the hydroxyl base. The reaction barriers on each metal surface in this step are not so significant compared to the adsorption energies on each surface, suggesting that a reaction barrier of hypophosphite ion oxidation should exist in the dehydrogenation step and only be observed for Cu (111). This proposition elucidates the experimental catalytic behaviors of metal surfaces in the electroless deposition process using hypophosphite ions. (C) 2011 The Electrochemical Society. [DOI: 10.1149/1.3609000] All rights reserved.

    DOI

    Scopus

    29
    Citation
    (Scopus)
  • CoNiP electroless deposition process for fabricating ferromagnetic nanodot arrays

    T. Ouchi, T. Homma

    Electrochim. Acta   ( 56 ) 9575 - 9580  1905.07  [Refereed]

  • Potential-Dependent Surface Morphology and Microtexture Evolution of Electrodeposited Copper Films

    M. C. Lafouresse, Y. Fukunaka, T. Homma, S. Honjo, S. Kikuchi, W. Schwarzacher

    Electrochem. Solid-State Lett.   14 ( 14(7) ) D77 - D79  1905.07  [Refereed]

     View Summary

    Two distinct morphologies were observed for copper films electrodeposited from an organic additive-free acid sulphate electrolyte near the limiting current density, namely facetted columns and spheroidal nodules. Facetted columns form for overpotentials eta = 200-280 mV while nodules form for eta &gt; 240 mV. Electron Back Scattering Diffraction (EBSD) was applied to cross-sections of the columnar films to determine the crystallographic orientation of individual grains. Over the first few microns, the substrate has a strong influence, but for greater thicknesses, the columnar film develops a strong &lt; 110 &gt; and weak &lt; 112 &gt; fibre texture. (C) 2011 The Electrochemical Society. [DOI: 10.1149/1.3578016] All rights reserved.

    DOI

    Scopus

    6
    Citation
    (Scopus)
  • Density Functional Theory Analysis of Reaction Mechanism of Hypophosphite Ions on Metal Surface

    M. Kunimoto, T. Shimada, S. Odagiri, H. Nakai, T. Homma

    J. Electrochem. Soc.   158 ( 158(9) ) D585 - D589  1905.07  [Refereed]

    DOI

    Scopus

    29
    Citation
    (Scopus)
  • Density Functional Theory Analysis for Orbital Interaction between Hypophosphite Ions and Metal Surfaces

    M. Kunimoto, H. Nakai, T. Homma

    J. Electrochem. Soc.   ( 158(10) ) D626 - D633  1905.07  [Refereed]

  • Theoretical Analysis of Catalytic Activity of Metal Surfaces on Reaction of Hypophosphite Ion

    M. Kunimoto, H. Nakai, T. Homma

    Electrochemistry   ( 80(3) ) 126 - 131  1905.07  [Refereed]

  • Density Functional Theory Analysis for Orbital Interaction between Hypophosphite Ions and Metal Surfaces

    Masahiro Kunimoto, Hiromi Nakai, Takayuki Homma

    JOURNAL OF THE ELECTROCHEMICAL SOCIETY   158 ( 10 ) D626 - D633  1905.07

     View Summary

    In order to elucidate the reactivity difference of hypophosphite ions used as reducing agents for electroless deposition on different metal surfaces, such as Pd and Cu, electronic structures of the activation states of hypophosphite ion oxidation on these surfaces were intensively analyzed by using Density Functional Theory (DFT). In the calculation, we focused on the dehydrogenation reaction which should be a rate-determining step in the elementary reaction steps. From the calculation results, a particular orbital interaction between the hypophosphite ion and the metal surface was observed. On Pd (111), the s-orbital of H in the hypophosphite ion interacts singly with the d- or p-orbital of Pd (111). This interaction induces an anti-bonding interaction between H and P in the hypophosphite ion, which is responsible for P-H cleavage. On the other hand, on Cu (111), the s-orbital of H and the s-orbital of P in a hypophosphite ion interact simultaneously with the p-orbital of Cu (111). This interaction barely induces an anti-bonding interaction between H and P in the hypophosphite ion. Such a difference in orbital interaction structures should be related to P-H cleavage activity and the reactivity difference of hypophosphite ion on each metal surface. (C) 2011 The Electrochemical Society. [DOI: 10.1149/1.3623782] All rights reserved.

    DOI

    Scopus

    23
    Citation
    (Scopus)
  • Density Functional Theory Analysis of Reaction Mechanism of Hypophosphite Ions on Metal Surfaces

    Masahiro Kunimoto, Takuya Shimada, Shuichi Odagiri, Hiromi Nakai, Takayuki Homma

    JOURNAL OF THE ELECTROCHEMICAL SOCIETY   158 ( 9 ) D585 - D589  1905.07  [Refereed]

     View Summary

    The elementary steps of the reactions of hypophosphite ions with Cu, Ni, and Pd were calculated theoretically using Density Functional Theory (DFT) to demonstrate the reaction mechanism and gain insight at the molecular level. The elementary steps of these reactions are adsorption, dehydrogenation, and oxidation (hydroxyl base attack). In the adsorption step, hypophosphite ions adsorb onto each surface spontaneously with stabilities in the order of Ni (111) &gt; Pd (111) &gt; Cu (111). In the dehydrogenation step, hypophosphite ions dehydrogenate on Ni (111) and Pd (111) with small reaction barriers, whereas they react on Cu (111) with a large reaction barrier. The large reaction barrier on Cu (111) is not compensated for by the adsorption energy on the surface. In the oxidation step, dehydrogenated anions on each metal surface react spontaneously with the hydroxyl base. The reaction barriers on each metal surface in this step are not so significant compared to the adsorption energies on each surface, suggesting that a reaction barrier of hypophosphite ion oxidation should exist in the dehydrogenation step and only be observed for Cu (111). This proposition elucidates the experimental catalytic behaviors of metal surfaces in the electroless deposition process using hypophosphite ions. (C) 2011 The Electrochemical Society. [DOI: 10.1149/1.3609000] All rights reserved.

    DOI

    Scopus

    29
    Citation
    (Scopus)
  • State-of-the-art Plating Technologies : Processes and Perspective

    HOMMA Takayuki

    Journal of the Japan Society of Precision Engineering   78 ( 12 ) 1021 - 1024  1905.07

    DOI CiNii

    Scopus

  • Theoretical Analysis of Adsorption Structure of Hydrated Hypophosphite Ion on Pd (111) Surface

    M. Kunimoto, K. Seki, H. Nakai, T. Homma

    Electrochemistry   80 ( 80(4) ) 222 - 225  1905.07  [Refereed]

    DOI

    Scopus

    6
    Citation
    (Scopus)
  • Laterally enhanced growth of electrodeposited Au to form ultrathin films on nonconductive surfaces

    C. Kobayashi, M. Saito, T. Homma

    Electrochim. Acta   ( 74 ) 235 - 243  1905.07  [Refereed]

  • Initial catalyzation analysis of electroless NiP nanoimprinting mold replicated from self-assembled monolayer modified nanopatterns

    C-P. Lin, M. Saito, T. Homma

    Electrochim. Acta   ( 82 ) 75 - 81  1905.07  [Refereed]

  • Electrochemical potential measurement and finite element structure analysis of Si wafer surface under mechanical stress

    K. Sakata, T. Homma

    Electrochem. Commun.   ( 25 ) 144 - 146  1905.07  [Refereed]

  • Theoretical analysis of the influence of surface defects on the reactivity of hypophosphite ions

    Kunimoto, Masahiro, Otomo, Akira, Takahashi, Nana, Nakai, Hiromi, Homma, Takayuki

    Electrochimica Acta   113   785 - 791  1905.07  [Refereed]

     View Summary

    To elucidate the influence of surface defects, such as steps, on the oxidation of a reducing agent that is used in the electroless deposition process, we theoretically analyzed the reaction behavior of hypophosphite ion around the defect using density functional theory calculations. The reason why we chose the hypophosphite ion is that it is a typical reducing agent and reacts through a universal reaction mechanism. In this analysis, we focused on the dehydrogenation reaction, which is the rate-determining step in the oxidation pathway. Pd and Cu surfaces were chosen as the metal surfaces, because they exhibit completely different catalytic activity from each other, both experimentally and theoretically. Our calculations showed that the surface defect stabilized the final state of dehydrogenation on both Pd and Cu surfaces, which indicates that the defect accelerates the oxidation of the hypophosphite ion. In the final state of dehydrogenation, dissociated hydrogen adsorbs on the hollow site, which appears on the slope of the defect. More detailed analyses of the final state indicate that the stabilization effect by the surface defect originates from the highly efficient interactions between the dissociated hydrogen and the slope. The molecular orbital structure on this slope is distorted, which leads to high electron density around the slope that enables the highly efficient interactions between the hydrogen and the slope. © 2013 Elsevier Ltd.

    DOI

    Scopus

    8
    Citation
    (Scopus)
  • Effect of Thiourea on Oxidation of Hypophosphite Ions on Ni Surface Investigated by Raman Spectroscopy and DFT Calculation

    Bin Jiang, Masahiro Kunimoto, Masahiro Yanagisawa, Takayuki Homma

    JOURNAL OF THE ELECTROCHEMICAL SOCIETY   160 ( 9 ) D366 - D371  1905.07  [Refereed]

     View Summary

    Thiourea is well known and widely used additive for controlling the rate of electroless Ni deposition, and it is known to show complicated behavior in acidic/alkaline electroless deposition baths. To understand this, several experiments and theoretical calculations were performed. In the experiments, the adsorption of thiourea and the reducing agent (i.e., hypophosphite ions) on a Ni surface was characterized with a high-selectivity component at a right angle down to the sub-monolayer level using surface-enhanced Raman spectroscopy. By comparing the results with those obtained from the theoretical calculation, co-adsorption of thiourea and hypophosphite ions on the Ni surface was confirmed. Moreover, the acceleration or suppression effects of thiourea on the oxidation of hypophosphite ions on a Ni surface in acidic/alkaline bath were analyzed from the experimental and computational perspectives. Accordingly, an explanation that unifies both the acceleration and suppression mechanisms of thiourea in terms of its own fundamental characteristics is proposed; this will be one of the most important processes for industrial applications of electroless Ni deposition. (C) 2013 The Electrochemical Society. All rights reserved.

    DOI

    Scopus

    6
    Citation
    (Scopus)
  • Acceleration effect of thiourea on the oxidation reaction of hypophosphite ion on Ni surface

    Kunimoto, Masahiro, Endo, Kazuaki, Nakai, Hiromi, Homma, Takayuki

    Electrochimica Acta   100   311 - 316  1905.07  [Refereed]

     View Summary

    The acceleration effect of thiourea on an electroless Ni deposition reaction was analyzed through experimental and theoretical approaches. In the experimental approach, the entire deposition process was physically separated into the anodic and the cathodic reactions by preparing two cells connected by a salt bridge. The cells contained either a bath without metal (Ni) ions or a bath without a reducing agent (hypophosphite ions). The current flowing between the two separated baths increased when thiourea was added only to the anodic reaction bath, which indicated that the acceleration effect of thiourea was mainly on the anodic reaction of the hypophosphite ions. Based on this experimental result, in the theoretical calculation approach, a co-adsorption system consisting of thiourea, hypophosphite, and a Ni metal surface was analyzed using density functional theory. Among all the elementary steps of a hypophosphite reaction, thiourea primarily should promote the adsorption step owing to the following two factors. One was the molecular interaction between thiourea and the hypophosphite ion. The other was the restructuring of the electronic states of the Ni surface owing to the adsorption of thiourea, which enhanced the interaction between hypophosphite and its adsorption site on the Ni surface. © 2012 Elsevier Ltd.

    DOI

    Scopus

    8
    Citation
    (Scopus)
  • Acceleration effect of thiourea on the oxidation reaction of hypophosphite ion on Ni surface

    M. Kunimoto, K. Endo, H. Nakai, T. Homma

    Electrochim. Acta   ( 100 ) 311 - 316  1905.07  [Refereed]

  • Photocurrent Conversion in Anodized TiO2 Nanotube Arrays: Effect of the Water Content in Anodizing Solution

    L-K. Tsui, T. Homma, G. Zangari

    J. Phys. Chem. C   117 ( 117 ) 6979 - 6989  1905.07  [Refereed]

     View Summary

    The TiO2 nanotube system exhibits properties of interest in photoelectrochemical water splitting for hydrogen production, including high surface area and vectorial charge transport along the nanotube length. Changes in the anodizing electrolyte chemistry provide the means to control nanotube morphology as well as their length and width. Despite the large amount of work available on nanotube synthesis, however, a thorough assessment of the effect of anodization conditions on the photoelectrochemical performance is still unavailable. In this paper, we characterize TiO2 nanotubes produced by varying the water content of the organic anodization electrolyte and investigate the influence of the electrolyte on their photoelectrochemical performance. We find that the photocurrent efficiency of the nanotubes is optimized by using an 11 vol % water:ethylene glycol ratio. We also demonstrate that a double-anodization technique produces a cleaner surface, resulting in higher photon-to-current conversion efficiencies of up to 30% at 350 nm. Raman spectroscopy, X-ray diffraction, and electrochemical impedance studies support the notion that the variation in crystallinity as a function of water content is the main factor in determining the photocurrent efficiency of the nanotube system.

    DOI

    Scopus

    76
    Citation
    (Scopus)
  • Effect of Thiourea on Oxidation of Hypophosphite Ions on Ni Surface Investigated by Raman Spectroscopy and DFT Calculation

    B. Jiang, M. Kunimoto, M. Yanagisawa, T. Homma

    J. Electrochem. Soc.   160 ( 160 (9) ) D366 - D371  1905.07  [Refereed]

     View Summary

    Thiourea is well known and widely used additive for controlling the rate of electroless Ni deposition, and it is known to show complicated behavior in acidic/alkaline electroless deposition baths. To understand this, several experiments and theoretical calculations were performed. In the experiments, the adsorption of thiourea and the reducing agent (i.e., hypophosphite ions) on a Ni surface was characterized with a high-selectivity component at a right angle down to the sub-monolayer level using surface-enhanced Raman spectroscopy. By comparing the results with those obtained from the theoretical calculation, co-adsorption of thiourea and hypophosphite ions on the Ni surface was confirmed. Moreover, the acceleration or suppression effects of thiourea on the oxidation of hypophosphite ions on a Ni surface in acidic/alkaline bath were analyzed from the experimental and computational perspectives. Accordingly, an explanation that unifies both the acceleration and suppression mechanisms of thiourea in terms of its own fundamental characteristics is proposed; this will be one of the most important processes for industrial applications of electroless Ni deposition. (C) 2013 The Electrochemical Society. All rights reserved.

    DOI

    Scopus

    6
    Citation
    (Scopus)
  • Theoretical analysis of the influence of surface defects on the reactivity of hypophosphite ions

    M. Kunimoto, A. Otomo, N. Takahashi, H. Nakai, T. Homma

    Electrochim. Acta   113 ( 113 ) 785 - 791  1905.07  [Refereed]

    DOI

    Scopus

    8
    Citation
    (Scopus)
  • Acceleration effect of thiourea on the oxidation reaction of hypophosphite ion on Ni surface

    Kunimoto, Masahiro, Endo, Kazuaki, Nakai, Hiromi, Homma, Takayuki

    Electrochimica Acta   100   311 - 316  1905.07  [Refereed]

     View Summary

    The acceleration effect of thiourea on an electroless Ni deposition reaction was analyzed through experimental and theoretical approaches. In the experimental approach, the entire deposition process was physically separated into the anodic and the cathodic reactions by preparing two cells connected by a salt bridge. The cells contained either a bath without metal (Ni) ions or a bath without a reducing agent (hypophosphite ions). The current flowing between the two separated baths increased when thiourea was added only to the anodic reaction bath, which indicated that the acceleration effect of thiourea was mainly on the anodic reaction of the hypophosphite ions. Based on this experimental result, in the theoretical calculation approach, a co-adsorption system consisting of thiourea, hypophosphite, and a Ni metal surface was analyzed using density functional theory. Among all the elementary steps of a hypophosphite reaction, thiourea primarily should promote the adsorption step owing to the following two factors. One was the molecular interaction between thiourea and the hypophosphite ion. The other was the restructuring of the electronic states of the Ni surface owing to the adsorp

    DOI

    Scopus

    8
    Citation
    (Scopus)
  • Effect of Thiourea on Oxidation of Hypophosphite Ions on Ni Surface Investigated by Raman Spectroscopy and DFT Calculation

    Bin Jiang, Masahiro Kunimoto, Masahiro Yanagisawa, Takayuki Homma

    JOURNAL OF THE ELECTROCHEMICAL SOCIETY   160 ( 9 ) D366 - D371  1905.07  [Refereed]

     View Summary

    Thiourea is well known and widely used additive for controlling the rate of electroless Ni deposition, and it is known to show complicated behavior in acidic/alkaline electroless deposition baths. To understand this, several experiments and theoretical calculations were performed. In the experiments, the adsorption of thiourea and the reducing agent (i.e., hypophosphite ions) on a Ni surface was characterized with a high-selectivity component at a right angle down to the sub-monolayer level using surface-enhanced Raman spectroscopy. By comparing the results with those obtained from the theoretical calculation, co-adsorption of thiourea and hypophosphite ions on the Ni surface was confirmed. Moreover, the acceleration or suppression effects of thiourea on the oxidation of hypophosphite ions on a Ni surface in acidic/alkaline bath were analyzed from the experimental and computational perspectives. Accordingly, an explanation that unifies both the acceleration and suppression mechanisms of thiourea in terms of its own fundamental characteristics is proposed; this will be one of the most important processes for industrial applications of electroless Ni deposition. (C) 2013 The Electrochemical Society. All rights reserved.

    DOI

    Scopus

    6
    Citation
    (Scopus)
  • Theoretical analysis of the influence of surface defects on the reactivity of hypophosphite ions

    Kunimoto, Masahiro, Otomo, Akira, Takahashi, Nana, Nakai, Hiromi, Homma, Takayuki

    Electrochimica Acta   113   785 - 791  1905.07

     View Summary

    To elucidate the influence of surface defects, such as steps, on the oxidation of a reducing agent that is used in the electroless deposition process, we theoretically analyzed the reaction behavior of hypophosphite ion around the defect using density functional theory calculations. The reason why we chose the hypophosphite ion is that it is a typical reducing agent and reacts through a universal reaction mechanism. In this analysis, we focused on the dehydrogenation reaction, which is the rate-determining step in the oxidation pathway. Pd and Cu surfaces were chosen as the metal surfaces, because they exhibit completely different catalytic activity from each other, both experimentally and theoretically. Our calculations showed that the surface defect stabilized the final state of dehydrogenation on both Pd and Cu surfaces, which indicates that the defect accelerates the oxidation of the hypophosphite ion. In the final state of dehydrogenation, dissociated hydrogen adsorbs on the hollow site, which appears on the slope of the defect. More detailed analyses of the final state indicate that the stabilization effect by the surface defect originates from the highly efficient interactio

    DOI

    Scopus

    8
    Citation
    (Scopus)
  • In Situ Observation of Lithium Deposition Processes in Solid Polymer and Gel Electrolytes

    T. Osaka, T. Homma, T. Momma, H. Yarimizu

    J. Electroanal. Chem.   421 ( 1 ) 153 - 158  1905.06  [Refereed]

     View Summary

    Deposition processes of lithium in solid polymer [poly(ethylene oxide) (PEG)8+LiClO4] and gel [PEO8+propylene carbonate(PC) +LiClO4] electrolytes, as well as in the liquid (PC+LiClO4) one, were observed in situ using an optical microscope and their difference is discussed. It was confirmed that the dendritic growth of lithium, which appeared in the liquid electrolyte, is suppressed in the solid polymer due to the immobility of the electrolyte molecules, although non-uniform coverage of the cathode was observed because of its low conductivity. In contrast, the gel electrolyte possessed advantages of both the liquid and solid electrolytes, resulting in a smooth and uniform deposition in the current density region up to 2.0 mA cm(-2).

  • In Situ Observation of Lithium Deposition Processes in Solid Polymer and Gel Electrolytes

    T. Osaka, T. Homma, T. Momma, H. Yarimizu

    J. Electroanal. Chem.   421 ( 1 ) 153 - 158  1905.06  [Refereed]

     View Summary

    Deposition processes of lithium in solid polymer [poly(ethylene oxide) (PEG)8+LiClO4] and gel [PEO8+propylene carbonate(PC) +LiClO4] electrolytes, as well as in the liquid (PC+LiClO4) one, were observed in situ using an optical microscope and their difference is discussed. It was confirmed that the dendritic growth of lithium, which appeared in the liquid electrolyte, is suppressed in the solid polymer due to the immobility of the electrolyte molecules, although non-uniform coverage of the cathode was observed because of its low conductivity. In contrast, the gel electrolyte possessed advantages of both the liquid and solid electrolytes, resulting in a smooth and uniform deposition in the current density region up to 2.0 mA cm(-2).

  • A study on growth processes of CoNiP perpendicular magnetic anisotropy films electroless-deposited at room temperature

    T Homma, Y Sezai, T Osaka

    ELECTROCHIMICA ACTA   42 ( 20-22 ) 3041 - 3047  1905.06

     View Summary

    In order to elucidate the origin of magnetic properties and microstructure of electroless-deposited CoNiP films with perpendicular magnetic anisotropy, their initial growth processes were investigated mainly focusing upon the effects of bath factors. It was clarified that coercivity and grain size of the films changed widely with an increase in the ammonia concentration in the bath without varying the average film composition and crystal orientation. Detailed analysis of the growth processes clarified that an increase in ammonia concentration in the bath inhibited the growth of each crystallite, resulting in small grain size and coercivity, whereas it hardly affected the deposition activity of the catalytically-treated substrate surface and average film composition. (C) 1997 Published by Elsevier Science Ltd.

  • A study on growth processes of CoNiP perpendicular magnetic anisotropy films electroless-deposited at room temperature

    T Homma, Y Sezai, T Osaka

    ELECTROCHIMICA ACTA   42 ( 20-22 ) 3041 - 3047  1905.06

     View Summary

    In order to elucidate the origin of magnetic properties and microstructure of electroless-deposited CoNiP films with perpendicular magnetic anisotropy, their initial growth processes were investigated mainly focusing upon the effects of bath factors. It was clarified that coercivity and grain size of the films changed widely with an increase in the ammonia concentration in the bath without varying the average film composition and crystal orientation. Detailed analysis of the growth processes clarified that an increase in ammonia concentration in the bath inhibited the growth of each crystallite, resulting in small grain size and coercivity, whereas it hardly affected the deposition activity of the catalytically-treated substrate surface and average film composition. (C) 1997 Published by Elsevier Science Ltd.

  • Tapping mode atomic force microscopy analysis of the growth process of electroless nickel-phosphorus films on nonconducting surfaces

    Takayuki Homma, Masayuki Tanabe, Kunimasa Itakura, Tetsuya Osaka

    Journal of the Electrochemical Society   144 ( 12 ) 4123 - 4127  1905.06

     View Summary

    The growth process of etectroless nickel-phosphorous (NiP) films on nonconducting substrate was investigated quantitatively using tapping mode atomic force microscopy (TMAFM) with focus upon the nucleation density on the substrate surface. Three kinds of catalyzing processes were used for polyimide substrates to obtain nucleation densities of 900, 750, and 550 nuclei/μm2. The TMAFM observation showed that the film growth proceeds mainly through successive nucleation of fine "particles" with several nanometers in diameter and their three-dimensional growth, and that the nucleation density influences the state of aggregation of the particles and hence the resulting surface topography. The lower nucleation density developed the rougher surface with larger "grains" with a diameter of ca. 80 nm. However, the effect of nucleation density decayed with film growth and eventually vanished at a thickness of ca. 2000 nm due to successive nucleated. For comparison, the growth process of NiP on NiP coated Al substrate, which is used for rigid magnetic disk applications and has a higher nucleation density of 3000 nuclei/μm2, was also examined. This process resulted in a smooth surface without the formation of "aggregates." Based upon these results, the root-mean-square roughness and scaling analyses were performed to evaluate quantitatively the differences in growth process.

    DOI

    Scopus

    33
    Citation
    (Scopus)
  • Ab Initio Molecular Orbital Study on the Oxidation Mechanism for Dimethylamine Borane as a Reductant for an Electroless Deposition Process

    T. Homma, H. Nakai, M. Onishi, T. Osaka

    J. Phys.Chem. B   103 ( 10 ) 1774 - 1778  1905.06  [Refereed]

     View Summary

    The oxidation mechanism of dimethylamine borane (DMAB) as a reductant fur an electroless deposition process was studied by an ab initio molecular orbital method. Two types of reaction pathways, via either three-coordinate borane molecules obtained by primary dehydrogenation reactions, or five-coordinate ones by primary additions of OH- for the oxidation of the DMAB, were examined. While the former pathway corresponds to the general oxidation mechanism of the reductant proposed by Meerakker, the present theoretical results support the latter one. Furthermore, it was clarified that an electron emission occurs when OH- adds to the four-coordinate compounds, which agrees with the Meerakker's mechanism. Results of the normal-mode analyses showed that the five-coordinate compounds are the transition states, The optimized geometries of monoanion five-coordinate molecules are nearly bipyramidal. The charge and spin-population analyses indicated that the axial bondings in the five-coordinate compounds are stabilized by the three-center three- or four-electron bondings. During the oxidation reaction of the DMAB, the change in the net charge of B is much smaller than that in the formal oxidation number, which is due to a great covalence. The existences of the five-coordinate borane molecules, which are first clarified by the present study, could be the key points of the catalytic activities of the deposited metals.

  • Ab Initio Molecular Orbital Study on the Oxidation Mechanism for Dimethylamine Borane as a Reductant for an Electroless Deposition Process

    T. Homma, H. Nakai, M. Onishi, T. Osaka

    J. Phys.Chem. B   103 ( 10 ) 1774 - 1778  1905.06

     View Summary

    The oxidation mechanism of dimethylamine borane (DMAB) as a reductant fur an electroless deposition process was studied by an ab initio molecular orbital method. Two types of reaction pathways, via either three-coordinate borane molecules obtained by primary dehydrogenation reactions, or five-coordinate ones by primary additions of OH- for the oxidation of the DMAB, were examined. While the former pathway corresponds to the general oxidation mechanism of the reductant proposed by Meerakker, the present theoretical results support the latter one. Furthermore, it was clarified that an electron emission occurs when OH- adds to the four-coordinate compounds, which agrees with the Meerakker's mechanism. Results of the normal-mode analyses showed that the five-coordinate compounds are the transition states, The optimized geometries of monoanion five-coordinate molecules are nearly bipyramidal. The charge and spin-population analyses indicated that the axial bondings in the five-coordinate compounds are stabilized by the three-center three- or four-electron bondings. During the oxidation reaction of the DMAB, the change in the net charge of B is much smaller than that in the formal oxidation number, which is due to a great covalence. The existences of the five-coordinate borane molecules, which are first clarified by the present study, could be the key points of the catalytic activities of the deposited metals.

  • Effect of deposition site condition on the initial growth process of electroless CoNiP films

    K Itakura, T Homma, T Osaka

    ELECTROCHIMICA ACTA   44 ( 21-22 ) 3707 - 3711  1905.06

     View Summary

    Effect of deposition site condition on the growth process of electroless CoNiP films was investigated by employing the intermediate 'treatment' step during the deposition. The effect of chemical species in the bath on the deposition sites, i.e., the film growth process, was examined using scanning electron microscopy (SEM) and atomic force microscopy (AFM). By changing the pH of the solutions for the 'treatment' step, it was found that the 'treatment' with higher pH solution resulted in the formation of smaller grains which possess lower perpendicular coercivity, Hc(perpendicular to). From these results, ammonia in the deposition bath results in the inhibition of the growth of crystallites, which leads lower Hc(perpendicular to). Based upon this, a model of the growth process of the CoNiP films was proposed. (C) 1999 Elsevier Science Ltd. All rights reserved.

  • Effect of deposition site condition on the initial growth process of electroless CoNiP films

    K Itakura, T Homma, T Osaka

    ELECTROCHIMICA ACTA   44 ( 21-22 ) 3707 - 3711  1905.06

     View Summary

    Effect of deposition site condition on the growth process of electroless CoNiP films was investigated by employing the intermediate 'treatment' step during the deposition. The effect of chemical species in the bath on the deposition sites, i.e., the film growth process, was examined using scanning electron microscopy (SEM) and atomic force microscopy (AFM). By changing the pH of the solutions for the 'treatment' step, it was found that the 'treatment' with higher pH solution resulted in the formation of smaller grains which possess lower perpendicular coercivity, Hc(perpendicular to). From these results, ammonia in the deposition bath results in the inhibition of the growth of crystallites, which leads lower Hc(perpendicular to). Based upon this, a model of the growth process of the CoNiP films was proposed. (C) 1999 Elsevier Science Ltd. All rights reserved.

  • リングヘッド/垂直単層磁気記録媒体系におけるトラック端部磁化状態の解析

    平山貴邦, 尾上貴弘, 朝日 透, 本間敬之, 法橋滋郎, 逢坂哲彌

    日本応用磁気学会誌   24 ( 4 ) 271 - 274  1905.06

  • Ge下地層を有する垂直単層磁気記録媒体の作製

    森田善幸, 倉持健太郎, 尾上貴弘, 朝日 透, 本間敬之, 逢坂哲彌

    日本応用磁気学会誌   24 ( 4 ) 223 - 226  1905.06

  • Mechanism of Sulfur Inclusion in Soft Gold Electrodeposited from the Thiosulfate-Sulfite Bath

    T. Osaka, M. Kato, J. Sato, K. Yoshizawa, T. Homma, Y. Okinaka, O. Yoshioka

    J. Electrochem. Soc   148 ( 10 ) C659 - C662  1905.06  [Refereed]

     View Summary

    The hardness of the soft gold electrodeposited from the thiosulfate-sulfite mixed ligand bath which we developed recently, has previously been found to increase with increasing sulfur content of the gold deposit. In the present study the mechanism of the sulfur inclusion was investigated by analyzing for sulfur gold deposits produced under various experimental conditions and also by observing weight gains resulting from the adsorption of sulfur-containing species on gold using the quartz crystal microbalance (QCM) technique. The results led us to conclude that the origin of the included sulfur is primarily the adsorbed Au(I)-thiosulfate species, (Au2S2O3)(ads), formed as an intermediate in the gold deposition reaction. (C) 2001 The Electrochemical Society.

  • Molecular Orbital Study on the Reaction Mechanisms of Electroless Deposition Processes

    T. Homma, I. Komatsu, A. Tamaki, H. Nakai, T. Osaka

    Electrochimica Acta   47 ( 1 ) 47 - 53  1905.06

    DOI

    Scopus

    52
    Citation
    (Scopus)
  • Ab initio molecular orbital study of the oxidation mechanism of hypophosphite ion as a reductant for an electroless deposition process

    H. Nakai, T. Homma, I. Komatsu, T. Osaka

    J. Phys. Chem. B   105 ( 9 ) 1701 - 1704  1905.06

    DOI

    Scopus

    35
    Citation
    (Scopus)
  • 無電解析出法による傾斜機能磁性薄膜の作製

    本間敬之, 逢坂哲彌, 佐藤裕崇

    表面科学   22 ( 6 ) 350 - 356  1905.06

    CiNii

  • アモルファスSi中間層を用いた垂直面内複合型媒体の作製

    森田善幸, 尾上貴弘, 朝日 透, 本間敬之, 逢坂哲彌

    日本応用磁気学会誌   25 ( 4 ) 619 - 622  1905.06

  • Mechanism of Sulfur Inclusion in Soft Gold Electrodeposited from the Thiosulfate-Sulfite Bath

    T. Osaka, M. Kato, J. Sato, K. Yoshizawa, T. Homma, Y. Okinaka, O. Yoshioka

    J. Electrochem. Soc   148 ( 10 ) C659 - C662  1905.06  [Refereed]

     View Summary

    The hardness of the soft gold electrodeposited from the thiosulfate-sulfite mixed ligand bath which we developed recently, has previously been found to increase with increasing sulfur content of the gold deposit. In the present study the mechanism of the sulfur inclusion was investigated by analyzing for sulfur gold deposits produced under various experimental conditions and also by observing weight gains resulting from the adsorption of sulfur-containing species on gold using the quartz crystal microbalance (QCM) technique. The results led us to conclude that the origin of the included sulfur is primarily the adsorbed Au(I)-thiosulfate species, (Au2S2O3)(ads), formed as an intermediate in the gold deposition reaction. (C) 2001 The Electrochemical Society.

  • Ab initio molecular orbital study of the oxidation mechanism of hypophosphite ion as a reductant for an electroless deposition process

    H. Nakai, T. Homma, I. Komatsu, T. Osaka

    J. Phys. Chem. B   105 ( 9 ) 1701 - 1704  1905.06

  • Substrate(Ni)-Catalyzed Electroless Gold Deposition from a Noncyanide Bath Containing Thiosulfate and Sulfite: Part I Reaction Mechanism

    M. Kato, J. Sato, H. Otani, T. Homma, Y. Okinaka, T. Osaka, O. Yoshioka

    J. Electrochem. Soc   149 ( 3 ) C164 - C167  1905.06

     View Summary

    Electroless gold deposition is known to take place on Ni-based substrates even when the conventional reducing agent is excluded from the autocatalytic bath containing thiosulfate and sulfite as ligands for gold ions. It is shown in this paper that the reaction of gold deposition from this bath on electroless Ni-B substrate is not autocatalytic but, instead, proceeds primarily by the mechanism of substrate catalysis with galvanic displacement playing a secondary role. It was established that sulfite serves as the reducing agent for the substrate-catalyzed gold deposition reaction. (C) 2002 The Electrochemical Society.

    DOI

    Scopus

    44
    Citation
    (Scopus)
  • Substrate(Ni)-Catalyzed Electroless Gold Deposition from a Noncyanide Bath Containing Thiosulfate and Sulfite: Part II Deposit Characteristics and Substrate Effects

    J. Sato, M. Kato, H. Otani, T. Homma, Y. Okinaka, T. Osaka, O. Yoshioka

    J. Electrochem. Soc   149 ( 3 ) C168 - C171  1905.06  [Refereed]

     View Summary

    Characteristics of the gold deposit produced by the substrate (Ni)-catalyzed process in the thiosulfate-sulfite bath described in Part I of this series of papers are profoundly affected by bath composition and the composition and pretreatment of the substrate. This paper, Part II of a series of two, describes effects of those variables on the appearance, uniformity, morphology, and porosity of the gold deposit. (C) 2002 The Electrochemical Society.

    DOI

    Scopus

    27
    Citation
    (Scopus)
  • Substrate(Ni)-Catalyzed Electroless Gold Deposition from a Noncyanide Bath Containing Thiosulfate and Sulfite: Part I Reaction Mechanism

    M. Kato, J. Sato, H. Otani, T. Homma, Y. Okinaka, T. Osaka, O. Yoshioka

    J. Electrochem. Soc   149 ( 3 ) C164 - C167  1905.06  [Refereed]

     View Summary

    Electroless gold deposition is known to take place on Ni-based substrates even when the conventional reducing agent is excluded from the autocatalytic bath containing thiosulfate and sulfite as ligands for gold ions. It is shown in this paper that the reaction of gold deposition from this bath on electroless Ni-B substrate is not autocatalytic but, instead, proceeds primarily by the mechanism of substrate catalysis with galvanic displacement playing a secondary role. It was established that sulfite serves as the reducing agent for the substrate-catalyzed gold deposition reaction. (C) 2002 The Electrochemical Society.

    DOI

    Scopus

    44
    Citation
    (Scopus)
  • Substrate(Ni)-Catalyzed Electroless Gold Deposition from a Noncyanide Bath Containing Thiosulfate and Sulfite: Part II Deposit Characteristics and Substrate Effects

    J. Sato, M. Kato, H. Otani, T. Homma, Y. Okinaka, T. Osaka, O. Yoshioka

    J. Electrochem. Soc   149 ( 3 ) C168 - C171  1905.06

     View Summary

    Characteristics of the gold deposit produced by the substrate (Ni)-catalyzed process in the thiosulfate-sulfite bath described in Part I of this series of papers are profoundly affected by bath composition and the composition and pretreatment of the substrate. This paper, Part II of a series of two, describes effects of those variables on the appearance, uniformity, morphology, and porosity of the gold deposit. (C) 2002 The Electrochemical Society.

    DOI

    Scopus

    27
    Citation
    (Scopus)
  • Maskless and Electroless Fabrication of Patterned Metal Nanostructures on Silicon Wafers by Controlling Local Surface Activities

    T. Homma, N. Kubo, T. Osaka

    Electrochim. Acta   48 ( 20 ) 3115 - 3122  1905.06

  • Molecular Orbital Study on the Reaction Process of Dimethylamine Borane as a Reductant for Electroless Deposition

    T. Homma, A. Tamaki, H. Nakai, T. Osaka

    J. Electroanal. Chem.   559 ( 1 ) 131 - 136  1905.06

    DOI

    Scopus

    71
    Citation
    (Scopus)
  • 電気化学的手法を用いた垂直二層膜媒体用下地層の作製

    川治 純, 北泉太士, 本間敬之, 逢坂哲彌

    信学技報   MR2003 ( 1 ) 1 - 5  1905.06

  • 無電解めっき法による磁性ナノドットアレイの作製

    川治 純, 朝日 透, 田中睦美, 木村公治, 本間敬之, 逢坂哲彌

    信学技報   MR2003 ( 28 ) 7 - 11  1905.06

  • High Sensitive X-ray Microcalorimeter Using Bi-Au Microabsorber for Imaging Applications

    H. Kudo, T. Arakawa, S. Ohtsuka, T. Izumi, S. Shoji, H. Sato, H. Kobayashi, K. Mori, T. Homma, T. Osaka, N. Iyomoto, R. Fujimoto, K. Mitsuda

    Jpn. J. Appl. Phys.   43 ( 3 ) 1190 - 1195  1905.06  [Refereed]

     View Summary

    An X-ray microcalorimeter is a cryogenic energy-dispersive spectrometer, which has an energy resolution almost comparable to that of conventional wavelength-dispersive spectrometers. Using a transition edge sensor (TES) as a temperature sensor, the energy resolution can be further improved. We have developed a new method of achieving an array of TES microcalorimeters for the purpose of X-ray imaging. To achieve this, mushroom-shaped X-ray microabsorbers formed using electrodeposition were applied. The temperature of the TES, which is easily degraded by thermal diffusion, was kept sufficiently low throughout the process to achieve practical use. On the bases of this new method, a 2 x 2 (x 4) array of TES microcalorimeters was fabricated and tested. A high energy resolution of 13.0 eV at 6 keV was achieved and the filling factor was improved to 83%. Although several issues still need to be investigated, we verified that our method is useful for fabricating a Ti-Au TES microcalorimeter array.

    DOI

    Scopus

    5
    Citation
    (Scopus)
  • Formation of Molecular Templates for Fabricating On-Chip Biosensing Devices

    D. Niwa, Y. Yamada, T. Homma, T. Osaka

    J. Phys. Chem. B   108 ( 10 ) 3240 - 3245  1905.06  [Refereed]

     View Summary

    Formation of organosilane monolayers having various functional groups on silicon oxide surfaces for fabricating on-chip biosensing devices was investigated. Alkyl and perfluoro-alkyl functionalized monolayers were prepared by a chemical vapor deposition, and amino functionalized monolayers were formed by a liquid phase reaction. Each monolayer was confirmed to be closely packed and composed of single moiety species. A molecular patterning process using these organic monolayers was performed. The monolayer patterns were uniformly formed on the substrate by using ultraviolet light patterning and oxygen plasma ashing processes. The pH responsibility at the liquid/modified electrode interface was examined by using capacitor profiles of the structure of monolayer/silicon oxide/silicon. The amino modified surface showed good pH sensitivity of -44 mV/pH. This value was similar to that of the silicon nitride surface. On the other hand, the potential was not changed in any pH solutions in the case of the alkyl and perfluoro-alkyl monolayer-modified surface. It was demonstrated that the pH response of these surfaces was greatly affected by the variation of the functional group. Furthermore, by using the patterned monolayers, fabrication of a multichannel electrode for multiple detection of pH response was achieved.

    DOI

    Scopus

    41
    Citation
    (Scopus)
  • Fabrication of Organic Monolayer Modified Ion-Sensitive Field Effect Transistors with High Chemical Durability

    D. Niwa, T. Homma, T. Osaka

    Jpn. J. Appl. Phys.   43 ( 1A/B ) L105 - L107  1905.06

  • Deposition Mechanism of Ni on Si(100) Surfaces in Aqueous Alkaline Solution

    D. Niwa, T. Homma, T. Osaka

    J. Phys. Chem. B   108 ( 28 ) 9900 - 9904  1905.06

  • High Sensitive X-ray Microcalorimeter Using Bi-Au Microabsorber for Imaging Applications

    H. Kudo, T. Arakawa, S. Ohtsuka, T. Izumi, S. Shoji, H. Sato, H. Kobayashi, K. Mori, T. Homma, T. Osaka, N. Iyomoto, R. Fujimoto, K. Mitsuda

    Jpn. J. Appl. Phys.   43 ( 3 ) 1190 - 1195  1905.06

     View Summary

    An X-ray microcalorimeter is a cryogenic energy-dispersive spectrometer, which has an energy resolution almost comparable to that of conventional wavelength-dispersive spectrometers. Using a transition edge sensor (TES) as a temperature sensor, the energy resolution can be further improved. We have developed a new method of achieving an array of TES microcalorimeters for the purpose of X-ray imaging. To achieve this, mushroom-shaped X-ray microabsorbers formed using electrodeposition were applied. The temperature of the TES, which is easily degraded by thermal diffusion, was kept sufficiently low throughout the process to achieve practical use. On the bases of this new method, a 2 x 2 (x 4) array of TES microcalorimeters was fabricated and tested. A high energy resolution of 13.0 eV at 6 keV was achieved and the filling factor was improved to 83%. Although several issues still need to be investigated, we verified that our method is useful for fabricating a Ti-Au TES microcalorimeter array.

    DOI

    Scopus

    5
    Citation
    (Scopus)
  • Formation of Molecular Templates for Fabricating On-Chip Biosensing Devices

    D. Niwa, Y. Yamada, T. Homma, T. Osaka

    J. Phys. Chem. B   108 ( 10 ) 3240 - 3245  1905.06

  • Fabrication of Organic Monolayer Modified Ion-Sensitive Field Effect Transistors with High Chemical Durability

    D. Niwa, T. Homma, T. Osaka

    Jpn. J. Appl. Phys.   43 ( 1A/B ) L105 - L107  1905.06

  • Deposition Mechanism of Ni on Si(100) Surfaces in Aqueous Alkaline Solution

    D. Niwa, T. Homma, T. Osaka

    J. Phys. Chem. B   108 ( 28 ) 9900 - 9904  1905.06

  • Area-selective formation of macropore array by anisotropic electrochemical etching on n-Si (100) surface in aqueous HF solution

    T. Homma, H. Sato, K. Mori, T. Osaka, S. Shoji

    J. Phys. Chem. B   109   5724  1905.06

  • Preparation and characterization of electroplated amorphous gold?nickel alloy film for electrical contact applications

    N. Togasaki, Y. Okinaka, T. Hommaa, T. Osaka

    Electrochim. Acta   51   882 - 887  1905.06

  • Characterization of strained Si wafer surface by density functional theory analysis

    K. Sakata, T. Homma, H. Nakai, T. Osaka

    Electrochim. Acta   51   1000 - 1003  1905.06

  • Deposition Behavior of Ni on Si(100) Surfaces in an Aqueous Alkaline Solution

    D. Niwa, T. Homma, T. Osaka

    J. Electrochem.Soc.   152 ( 2 ) C52 - C59  1905.06  [Refereed]

     View Summary

    The spontaneous deposition of Ni on Si(100) surface in aqueous alkaline solution was investigated under various conditions. In a 0.1 M NiSO4 solution containing 0.2-0.5 M (NH4)(2)SO4, the optimum pH for the homogeneous deposition at 60-80degreesC at each set of operating conditions shifted in the high-pH direction as both (NH4)2SO(4) concentration and the operating temperature were decreased. The potential at which the deposition terminates and the deposition duration were determined from electrochemical open-circuit potential profiles. The different behaviors, observed at different pH levels, are discussed in terms of these potential measurements. Ultraviolet-visible absorption spectra of various Ni solutions used indicated that the deposition behavior was strongly affected by the composition of the Ni complex and the reactivity of Si surface. The deposition reaction efficiently proceeded when the Ni complex was present in a specific composition. The anodic reaction rate of Si decreased steeply when the solution temperature was lowered. The optimum condition for the homogeneous deposition was greatly affected by the reactivity of the Si surface rather than the composition of the complex, the higher pH favoring the overall reaction. (C) 2004 The Electrochemical Society. All rights reserved.

  • Surface Conductivity in Methyl- Monolayer/Si Heterojunction Structure in the Presence of Water

    D. Niwa, K. Omichi, N. Motohashi, T. Homma, T. Osaka

    Chem.Lett.   34 ( 4 ) 520 - 521  1905.06

     View Summary

    The heterojunction between Si(111) semiconductor and the well-ordered methyl monolayer was formed to investigate the channel conduction at the surface in the heterojunction structure. With the presence of water, the methyl monolayer/Si heterojunction structure showed switching action with a high trance-conductance of 2.8 x 10(-3) A/V under the application of bias voltage, while without the presence of water, such a switching behavior was not observed. The methyl monolayer/Si heterojunction structure worked as a p-type mode with the presence of water at the modified surface.

  • Nucleation and growth of copper nanoparticles on silicon surfaces

    A. Singh, K. Luening, S. Brennan, T. Homma, N. Kubo, P. Pianetta

    PHYSICA SCRIPTA   T115   714 - 716  1905.06  [Refereed]

     View Summary

    The recent adoption of copper interconnect technology by the semiconductor industry, has led to great interest in understanding the mechanisms of copper metal deposition onto silicon wafer surfaces from ultra pure water (UPW) solutions. We have studied these processes by using total reflection X-ray fluorescence (TXRF) and X-ray absorption near edge spectroscopy (XANES) in a grazing incidence geometry to determine the surface concentration and chemical state of copper atoms on intentionally contaminated Si surfaces. These measurements established that in deoxygenated UPW, copper is deposited on the silicon surface in the form of metallic nanoparticles with sizes up to 16 nm. However, in non-deoxygenated UPW, the copper is incorporated uniformly into the silicon surface oxide as Cu oxide.

  • Density functional theory study on the oxidation mechanisms of aldehydes as reductants for electroless Cu deposition process

    T. Shimada, K. Sakata, T. Homma, H. Nakai, T. Osaka

    Electrochim. Acta   51 ( 5 ) 906 - 915  1905.06

    DOI

    Scopus

    20
    Citation
    (Scopus)
  • Area-selective formation of macropore array by anisotropic electrochemical etching on n-Si (100) surface in aqueous HF solution

    T. Homma, H. Sato, K. Mori, T. Osaka, S. Shoji

    J. Phys. Chem. B   109 ( 12 ) 5724 - 5727  1905.06  [Refereed]

     View Summary

    A photoassisted anodization process to fabricate arrays of uniform and straight macropores at selected areas of a Si wafer surface was developed. The front- and backside surfaces of n-type Si(100) wafers were coated with a thin Si3N4 layer, and the frontside layer was micro-patterned using photolithography and reactive ion etching to form an array of microscopic openings at selected areas. The inverted pyramid-shape micropits were formed at these openings by anisotropic etching using aqueous KOH solution; these pits act as the initiation sites for the anodization to form macropores. The electrochemical etching was carried out in aqueous HF solution under illumination from the backside of the wafer, on which Au/Cr electric contact was formed following removal of the Si3N4 layer. To improve the uniformity of the formation condition of the macropores at the selected area, holes were area-selectively generated by controlling the illumination condition during the anodization. For this, micropatterns were formed on the Au/Cr layer at the backside surface, which were aligned to those at the frontside surface. The parameters, such as HF concentration, current density, and wafer thickness, i.e., hole diffusion length, were optimized, and the arrays of uniform and high-aspect-ratio macropores were formed at the selected area of the domain at the silicon surface.

    DOI

    Scopus

    11
    Citation
    (Scopus)
  • Preparation and characterization of electroplated amorphous gold?nickel alloy film for electrical contact applications

    N. Togasaki, Y. Okinaka, T. Hommaa, T. Osaka

    Electrochim. Acta   51   882 - 887  1905.06

  • Fabrication of patterned nanostructures with various metal species on Si wafer surfaces by maskless and electroless process

    N. Kubo, T. Homma, Y. Hondo, T. Osaka

    Electrochim. Acta   51   834 - 837  1905.06

  • Electrochemical analysis of zincate treatments for Al and Al alloy films

    M. Saito, T. Maegawa, T. Homma

    Electrochim. Acta   51   1017 - 1020  1905.06

  • Characterization of strained Si wafer surface by density functional theory analysis

    K. Sakata, T. Homma, H. Nakai, T. Osaka

    Electrochim. Acta   51 ( 5 ) 1000 - 1003  1905.06  [Refereed]

    DOI

    Scopus

    4
    Citation
    (Scopus)
  • Picoliter volume glass tube array fabricated by Si electrochemical etching process

    H. Sato, T. Homma, K. Mori, T. Osaka, S. Shoji

    Electrochim. Acta   51   844 - 848  1905.06

  • Deposition Behavior of Ni on Si(100) Surfaces in an Aqueous Alkaline Solution

    D. Niwa, T. Homma, T. Osaka

    J. Electrochem.Soc.   152 ( 2 ) C52 - C59  1905.06  [Refereed]

     View Summary

    The spontaneous deposition of Ni on Si(100) surface in aqueous alkaline solution was investigated under various conditions. In a 0.1 M NiSO4 solution containing 0.2-0.5 M (NH4)(2)SO4, the optimum pH for the homogeneous deposition at 60-80degreesC at each set of operating conditions shifted in the high-pH direction as both (NH4)2SO(4) concentration and the operating temperature were decreased. The potential at which the deposition terminates and the deposition duration were determined from electrochemical open-circuit potential profiles. The different behaviors, observed at different pH levels, are discussed in terms of these potential measurements. Ultraviolet-visible absorption spectra of various Ni solutions used indicated that the deposition behavior was strongly affected by the composition of the Ni complex and the reactivity of Si surface. The deposition reaction efficiently proceeded when the Ni complex was present in a specific composition. The anodic reaction rate of Si decreased steeply when the solution temperature was lowered. The optimum condition for the homogeneous deposition was greatly affected by the reactivity of the Si surface rather than the composition of the complex, the higher pH favoring the overall reaction. (C) 2004 The Electrochemical Society. All rights reserved.

  • Surface Conductivity in Methyl- Monolayer/Si Heterojunction Structure in the Presence of Water

    D. Niwa, K. Omichi, N. Motohashi, T. Homma, T. Osaka

    Chem.Lett.   34 ( 4 ) 520 - 521  1905.06  [Refereed]

     View Summary

    The heterojunction between Si(111) semiconductor and the well-ordered methyl monolayer was formed to investigate the channel conduction at the surface in the heterojunction structure. With the presence of water, the methyl monolayer/Si heterojunction structure showed switching action with a high trance-conductance of 2.8 x 10(-3) A/V under the application of bias voltage, while without the presence of water, such a switching behavior was not observed. The methyl monolayer/Si heterojunction structure worked as a p-type mode with the presence of water at the modified surface.

  • Nucleation and growth of copper nanoparticles on silicon surfaces

    A. Singh, K. Luening, S. Brennan, T. Homma, N. Kubo, P. Pianetta

    PHYSICA SCRIPTA   T115   714 - 716  1905.06  [Refereed]

     View Summary

    The recent adoption of copper interconnect technology by the semiconductor industry, has led to great interest in understanding the mechanisms of copper metal deposition onto silicon wafer surfaces from ultra pure water (UPW) solutions. We have studied these processes by using total reflection X-ray fluorescence (TXRF) and X-ray absorption near edge spectroscopy (XANES) in a grazing incidence geometry to determine the surface concentration and chemical state of copper atoms on intentionally contaminated Si surfaces. These measurements established that in deoxygenated UPW, copper is deposited on the silicon surface in the form of metallic nanoparticles with sizes up to 16 nm. However, in non-deoxygenated UPW, the copper is incorporated uniformly into the silicon surface oxide as Cu oxide.

  • Fabrication of High-Aspect-Ratio Arrayed Structures Using Si Electrochemical Etching

    H. Sato, T. Homma

    Sci. Tech. of Adv. Mater.   7   468 - 474  1905.06

  • Electrochemical Formation of Intermediate Layer for Co/Pd Multilayered Media

    J. Kawaji, K. Kimura, T. Asahi, T. Homma, T. Osaka

    J. Mag. Mag. Mat.   303 ( 2 ) e128 - e132  1905.06  [Refereed]

     View Summary

    Pd nanocluster seeds were formed on a soft magnetic underlayer (SUL) using an electrochemical substitution reaction, and were utilized as an intermediate layer for a Co/Pd multilayered ([Co/Pd](n)) perpendicular magnetic recording medium. A CoNiFeB film prepared with electroless deposition was used as SUL, which was immersed into a PdCl2 solution for the formation of Pd seeds. The Pd seeds were found to effectively reduce the size of magnetic domains in the [Co/Pd](n) film deposited on them. The optimization of the concentration of the PdCl2 solution and the use of the pretreatment process with a SnCl2 solution were effective to obtain the smooth SUL surface with fine Pd seeds as small as 5 nm. The 20 nm-thick [Co/Pd] n film deposited on the optimized Pd seeds/CoNiFeB SUL exhibited a high coercivity of 7.8 kOe and a small magnetic domain size of 69 nm. These results indicated that the combination of the Pd seeds and the electroless-deposited SUL was desirable in terms of the improvement not only in the magnetic properties of [Co/Pd] n media but also in the mass productivity of the underlayer. (C) 2006 Elsevier B.V. All rights reserved.

    DOI

    Scopus

    4
    Citation
    (Scopus)
  • Fabrication of Magnetic Nanodot Arrays for Patterned Magnetic Recording Media

    H. Sato, T. Homma

    J. Nanosci. Nanotech   7 ( 1 ) 225 - 231  1905.06

    J-GLOBAL

  • Density Functional Theory Study on the Reaction Mechanism of Reductants for Electroless Ag Deposition Process

    T. Shimada, H. Nakai, T. Homma

    J. Electrochem. Soc.   154 ( 4 ) D273 - D276  1905.06  [Refereed]

     View Summary

    Oxidation reaction mechanisms of reductants for electroless Ag deposition process were investigated using density functional theory calculation, focusing upon behavior of the reaction intermediate species. It was indicated that the oxidation processes of reductants, such as dimethylamine borane, formaldehyde, and hypophosphite ion, on the Ag surface are initiated by addition of OH- and proceed via five-coordinate intermediate species. Catalytic activity of the Ag surface for the oxidation reaction of the reductants was investigated by using energy density analysis, focusing upon the local interaction of the species. The results indicated that the adsorption of the reductants onto the Ag surface is driven by destabilization of the reductant and stabilization of the Ag surface. It was also indicated that the destabilization of the five-coordinate intermediate species at the Ag surface is a key factor of the "catalytic activity" for the oxidation reaction. In the case of the reaction of formaldehyde, in which the Ag surface acts as catalyst, the intermediates were considerably activated at the Ag surface, whereas such an effect was not clearly seen with the hypophosphite ion, for which the Ag surface is not catalytic. It was also suggested that the activation of the intermediates is affected by coordination behavior of OH- species. (c) 2007 The Electrochemical Society.

    DOI

    Scopus

    10
    Citation
    (Scopus)
  • Nanoscopic and Electrochemical characterization of Defects and Strain at Si Wafer Surfaces

    T. Homma, K. Sakata, N. Kubo

    Proc. Adv. Sci. Tech. Si Mat.   5   32 - 36  1905.06

▼display all

Books and Other Publications

  • Electrocrystallizationin Nanotechnology

    G. Staikov, Ed

    Wiley-VCH  2007

  • 実験化学講座 24 表面・界面

    谷口 功, 山田太郎編

    丸善  2007.01

  • 実験化学講座 27 機能性材料

    逢坂哲彌, 本間敬之編

    丸善  2004.09

  • 表面処理工学—基礎と応用

    表面技術協会編

    日刊工業新聞社  2000.02

Presentations

  • Zn負極不働態化に対するケイ酸イオンの抑制作用機構の理論的解析

    横田喬一朗

    電気化学会第91回大会  (愛知) 

    Presentation date: 2024.03

  • アニオン交換膜水電解用NiFeP触媒電極の形成に向けた貴金属フリー無電解析出プロセスの開発

    伊藤陸

    電気化学会第91回大会  (愛知) 

    Presentation date: 2024.03

  • アニオン交換膜への酸素発生反応用NiFe触媒の直接形成に向けた無電解析出プロセスの開発

    杉﨑知樹

    電気化学会第91回大会  (愛知) 

    Presentation date: 2024.03

  • HFガスを用いたガラス表面への超撥水微細構造の構築と他部材への密着特性向上

    安田興平

    電気化学会第91回大会  (愛知) 

    Presentation date: 2024.03

  • CoPt電析薄膜の磁気特性に対するサッカリン添加効果の解析

    鈴木 律兵

    表面技術協会第149回講演大会  (東京) 

    Presentation date: 2024.03

  • Ni電解析出における浴中アニオン種挙動のin-situラマン分光法による解析

    小林秀生

    表面技術協会第149回講演大会  (東京) 

    Presentation date: 2024.03

  • HFガスを用いたガラス表面ねの超撥水微細構造の構築

    安田興平

    表面技術協会第149回講演大会  (東京) 

    Presentation date: 2024.03

  • 電気めっきと無電解めっきの基礎

    國本雅宏  [Invited]

    表面技術協会冬季セミナー 研究/技術者のための表面処理基礎講座  (オンライン) 

    Presentation date: 2023.12

  • Electroless Deposition Processes of NiFeP Thin Film on Anion Exchange Membranes as an HER Catalyst for Water Electrolysis

    Masahiro Kunimoto

    Advanced Materials Research Grand Meeting, MRM 2023/IUMRS-ICA223  (京都) 

    Presentation date: 2023.12

  • Electrochemical Deposition Of Compact Cu2Se Films For Thermoelectric Applications.

    Collen Takaza

    Advanced Materials Research Grand Meeting, MRM 2023/IUMRS-ICA223  (京都) 

    Presentation date: 2023.12

  • 潤滑油-鉄摩擦界面における添加剤ラウリン酸の作用機構のin-situ表面増強ラマン分光解析

    澤木昴

    第13回CSJ化学フェスタ  (東京) 

    Presentation date: 2023.10

  • Electrochemical Deposition Processes for Fabrication of Cathodes/Anodes of Alkaline Water Electrolysis Device

    Masahiro Kunimoto

    244th ECS Meeting  (Sweden) 

    Presentation date: 2023.10

  • Investigation of structural and magnetic properties of electrodeposited CoPt alloy nanowires for 3D magnetic memory application

    Md. Mahmudul Hasan,

    The 47th Annual Conference on Magnetics in Japan  (大阪) 

    Presentation date: 2023.09

  • 酸素発生反応用NiFe電極の触媒性能にパルス電析条件が及ぼす影響の解析

    石橋勇輝

    2023電気化学秋季大会  (福岡) 

    Presentation date: 2023.09

  • 低濃度浴系を用いたCoPt電析薄膜の作製

    荒木大輝

    2023電気化学秋季大会  (福岡) 

    Presentation date: 2023.09

  • 添加剤SnがZn電析時の異常析出の抑制に与える影響の解析

    原澤爽香

    表面技術協会第148回講演大会  (山形) 

    Presentation date: 2023.09

  • Approaches for Mechanistic Understanding of Electrodeposition Processes for Fabricating Micro/Nano Structures and Devices

    Takayuki Homma  [Invited]

    243rd ECS Meeting with SOFC-XVIII  (Boston) 

    Presentation date: 2023.05

  • 電気めっきと無電解めっきの基本 -いろはの『い』からめっきへ-

    國本雅宏  [Invited]

    2023年関東支部セミナー 1から学ぶ電気化学のいろは (原理からアプリケーションまで)  (オンライン) 

    Presentation date: 2023.05

  • Electrodeposited CoPt multilayer nanowires for 3D memory device

    Md. Mahmudul Hasan

    Intermag2023  (Sendai) 

    Presentation date: 2023.05

  • CO2電解還元用新規複合電極の試作および特性評価

    船岡聖矢

    電気化学会第90回大会  (宮城) 

    Presentation date: 2023.03

  • イオン液体を用いた電析Si薄膜形成におけるセル内加圧効果の検討

    吉原昌幸

    電気化学会第90回大会  (宮城) 

    Presentation date: 2023.03

  • 電解液へのLi添加がZn負極上ZnO膜の特性に及ぼす影響の検討

    小宮歩睦

    電気化学会第90回大会  (宮城) 

    Presentation date: 2023.03

  • Fabrication of plasmonic sensors by electroless deposition of Ag nanoparticles with hypophosphite

    Zhengke Tu

    一般社団法人表面技術協会 第147回講演大会  (千葉) 

    Presentation date: 2023.03

  • Preparation and evaluation of electrodeposited CoPt nanowires for 3D magnetic memory

    Md. Mahmudul Hasan

    一般社団法人表面技術協会 第147回講演大会  (千葉) 

    Presentation date: 2023.03

  • Zn負極における添加剤Snの吸着機構と電析反応に対する影響の理論的解析

    山野桃果

    一般社団法人表面技術協会 第147回講演大会  (千葉) 

    Presentation date: 2023.03

  • 酸化鉄溶液からの電析によるTES型マイクロカロリメータ用Fe吸収体作製の検討

    吉田奈央

    一般社団法人表面技術協会 第147回講演大会  (千葉) 

    Presentation date: 2023.03

  • イオン液体を用いた電析Si薄膜に対する低不純物化の検討

    吉原昌幸

    日本材料科学会 第27回 若手研究者討論会  (神奈川) 

    Presentation date: 2022.12

  • Versatile In Situ SERS Setup for Electrochemical Interface Analysis and Its Application to Zn Secondary Battery and Cu Electroplating

    Zhengke. Tu

    8th DGIST-WASEDA Workshop on Electrochemistry  (Busan(South Korea)) 

    Presentation date: 2022.11

  • Analysis of Action Mechanism of Additives in Zinc Anode Reaction by In Situ Shell-isolated Nanoparticle-Enhanced Raman Spectroscopy

    Ayumu. Komiya

    8th DGIST-WASEDA Workshop on Electrochemistry  (Busan(South Korea)) 

    Presentation date: 2022.11

  • ラマン散乱分光分析によるPPS樹脂を用いた射出成形における金型表面劣化機構の解析

    齊藤圭祐

    第12回CSJ化学フェスタ  (東京) 

    Presentation date: 2022.10

  • 計算化学概論

    國本雅宏  [Invited]

    第50回先端科学セミナー 電気化学のための計算化学入門  (千葉) 

    Presentation date: 2022.10

  • In situ surface-enhanced Raman spectroscopy analysis for estimation of the role of pyridinic nitrogen on nitrogen-doped carbon catalyst in CO2 electroreduction

    Kohei Ide

    242nd ECS meeting  (Atranta, US) 

    Presentation date: 2022.10

  • CO2電解還元用新規ナノ複合電極創製に向けた金属薄膜の特性把握

    越智洋次郎

    2022年 電気化学秋季大会  (神奈川) 

    Presentation date: 2022.09

  • Zn電析の表面形態にカチオン種が与える影響の電気化学測定による解析

    高橋士

    2022年 電気化学秋季大会  (神奈川) 

    Presentation date: 2022.09

  • PVA添加によるp型Bi-Sb-Te電析膜形態制御および熱電変換素子への応用

    小柳翔也

    表面技術協会 第146回講演大会  (埼玉) 

    Presentation date: 2022.09

  • In-situ Monitoring Systems of Electrolytic/electroless Deposition Processes using Surface Enhanced Raman Spectroscopy with Plasmon Sensors

    M. Kunimoto  [Invited]

    15th International Fischer Symposium  (Germany,Seeon-Seebruck) 

    Presentation date: 2022.06

  • Effect of Additive Species on the Nucleation and Growth Process on Zn Negative Electrode Surface

    Takayuki Homma  [Invited]

    241st ECS meeting  (Canada, Vancouver) 

    Presentation date: 2022.06

  • 表面増強ラマン分光法を用いた氷の摺動界面における摩擦と化学構造の解析

    吉田立樹

    トライボロジー会議2022 春 東京  (オンライン) 

    Presentation date: 2022.05

  • 電気めっきと無電解めっきの基本 -いろはの『い』からめっきへ-

    國本雅宏  [Invited]

    電気化学会関東支部 2022年関東支部セミナー 1から学ぶ電気化学のいろは(原理からアプリケーションまで)  (オンライン) 

    Presentation date: 2022.05

  • Cu電極におけるCO2ガス相を利用した電気化学的還元特性

    宮崎涼

    電気化学会第89回大会  (オンライン) 

    Presentation date: 2022.03

  • 電解・無電解法によるアニオン交換膜型水電解プロセス用触媒電極の形成

    藤村樹

    電気化学会第89回大会  (オンライン) 

    Presentation date: 2022.03

  • TiO2シェルを有する高耐液性プラズモンセンサの開発とめっき反応解析への応用

    涂政珂

    一般社団法人表面技術協会 第145回講演大会  (埼玉) 

    Presentation date: 2022.03

  • Zn電析過程におけるZn原子吸着挙動に対する重金属添加剤の影響の理論的解析

    小野文雅

    一般社団法人表面技術協会 第145回講演大会  (埼玉) 

    Presentation date: 2022.03

  • Theoretical and Spectroscopic Investigation of the Effect of Sulfur-containing Additives in Electrodeposition Processes

    M. Kunimoto  [Invited]

    International Workshop on Electrodeposited Nanostructures (EDNANO)  (online) 

    Presentation date: 2022.02

  • Operando Raman Microscopy - From Polymers to Microorganisms

    M. Bertz

    表面技術協会表協エレクトロニクス部会 電気化学会ナノ・マイクロファブリケーション研究会 合同研究会  (オンライン) 

    Presentation date: 2021.12

  • 無電解析出プロセスの界面反応機構における水の働き

    國本雅宏  [Invited]

    関東支部 第99回講演会および未来のくらしと水の科学研究会 第2回定例研究会 合同講演会  (長野(オンライン併用)) 

    Presentation date: 2021.11

  • 計算化学概論

    國本雅宏  [Invited]

    第49回先端科学セミナー 電気化学のための計算化学入門  (千葉(オンライン併用)) 

    Presentation date: 2021.11

  • 電解/無電解析出プロセスにおける表面反応機構の理論化学的及び分光学的解析

    國本雅宏  [Invited]

    シンポジウム 次世代自動車端子コネクタ用の超高導電性・耐摩耗性銀-グラフェン系複合めっきの創製とデバイスへの応用  (オンライン) 

    Presentation date: 2021.11

  • トライボロジーのオペランド観察(第8報)潤滑油のトライ ボ触媒反応

    柳沢雅広

    トライボロジー会議2021 秋  (オンライン) 

    Presentation date: 2021.10

  • ナノスケール接着界面の計測・解析

    柳沢雅広

    トライボロジー会議2021 秋  (オンライン) 

    Presentation date: 2021.10

  • ナノ隙間における固液界面分子構造の表面増強ラマ ン分光解析

    吉田立樹

    トライボロジー会議2021 秋  (オンライン) 

    Presentation date: 2021.10

  • Visualizing Stress Distributions Using Raman Imaging Combined with Machine Learning

    ベルツモルテン

    トライボロジー会議2021 秋  (オンライン) 

    Presentation date: 2021.10

  • エラストマー変形時における表面及び内部変化の計 測・解析

    山口健

    トライボロジー会議2021 秋  (オンライン) 

    Presentation date: 2021.10

  • p型Bi-Sb-Te系電析膜の熱電変換特性向上に向けた添加剤の効果の検討

    土屋進悟

    表面技術協会 第144回講演大会  (オンライン) 

    Presentation date: 2021.09

  • Zn電析過程における Zn原子の表面拡散挙動と電子状態の解析

    王松毅

    2021年 電気化学秋季大会  (オンライン) 

    Presentation date: 2021.09

  • Development and Application of SERS Sensor Elements for Reaction Analyses in Electrochemical Deposition Processes

    M. Kunimoto

    Interfinish2020  (オンライン) 

    Presentation date: 2021.09

  • Development of Direct Fabrication Process of Metal Layer on Anion Exchange Membrane Using Electroless Deposition Process

    T. Fujimura

    Interfinish2020  (オンライン) 

    Presentation date: 2021.09

  • A DFT and KMC study for the shape evolution at the initial stage of the Zn electrodeposition

    Y. Onabuta

    Interfinish2020  (オンライン) 

    Presentation date: 2021.09

  • In-situ SERS measurement of organic additive mechanism on Zn electrode surface under anodic conditions

    T. Zhengke

    Interfinish2020  (オンライン) 

    Presentation date: 2021.09

  • Si Thin Film Fabrication by Pulse Electrodeposition Technique from Acetonitrile as Organic Solvent

    K. Hirasawa

    Interfinish2020  (オンライン) 

    Presentation date: 2021.09

  • In-situ Spectroscopic Analyses of Electrolyte Decomposition Reaction in Li Ion Battery using Plasmonic Sensor Element

    M. Kunimoto

    72nd Annual Meeting of the International Society of Electrochemistry (ISE 2021)  (オンライン) 

    Presentation date: 2021.08

  • トライボロジ-界面計測の新技術コンセプ ト

    柳沢雅広

    トライボロジー会議2021 春  (オンライン) 

    Presentation date: 2021.05

  • トライボロジーのオペランド観察(第7報)- 潤滑油の化学反応-

    柳沢雅広

    トライボロジー会議2021 春  (オンライン) 

    Presentation date: 2021.05

  • Operando Observation of Wear during Sliding using Multipoint Raman Microscopy

    Bertz Morten

    トライボロジー会議2021 春  (オンライン) 

    Presentation date: 2021.05

  • 表面増強ラマン分光法による衛生設備機 器/水垢界面の分析

    古賀遼

    トライボロジー会議2021 春  (オンライン) 

    Presentation date: 2021.05

  • エラストマー変形時における内部構造変 化の計測・解析

    山口健

    トライボロジー会議2021 春  (オンライン) 

    Presentation date: 2021.05

  • 表面増強ラマン散乱を用いたセリア表面 の吸着ポリマの水中観察

    李相哲

    トライボロジー会議2021 春  (オンライン) 

    Presentation date: 2021.05

  • プラズモンセンサ実装の電気化学セルを用いた電解液分解反応のin-situ SERS測定

    國本雅宏  [Invited]

    電気化学会第88回大会  (オンライン) 

    Presentation date: 2021.03

  • 磁性体を吸収体とするTES型X線マイクロカロリメータの動作実証

    八木雄太

    第68回 応用物理学会春季学術講演会  (オンライン) 

    Presentation date: 2021.03

  • Cu電極上の表面修飾がCO2の電気化学的還元特性に与える影響

    宮崎涼

    電気化学会第88回大会  (オンライン) 

    Presentation date: 2021.03

  • 太陽Axion探査型TESマイクロカロリメータのノイズ特性

    田中圭太

    第68回 応用物理学会春季学術講演会  (オンライン) 

    Presentation date: 2021.03

  • イオン液体を用いたSi薄膜形成に対するパルス電析条件の影響の検討

    福住康太

    表面技術協会 第143回講演大会  (オンライン) 

    Presentation date: 2021.03

  • 量子科学計算とラマン分光計測を応用した電解/無電解めっき反応の解析

    國本雅宏

    表面技術協会 第143回講演大会  (オンライン) 

    Presentation date: 2021.03

  • リン酸系浴を用いたSUS304電解研磨における反応効率の解析

    趙康

    表面技術協会 第143回講演大会  (オンライン) 

    Presentation date: 2021.03

  • Zn負極の電析初期における析出形態形成過程のマルチスケールシミュレーションによる解析

    女部田勇介

    第2回非鉄精錬学Web討論会  (オンライン) 

    Presentation date: 2021.01

  • トライボロジーのオペランド観察(第6報)

    柳沢雅広

    トライボロジー会議2020秋 別府  (オンライン) 

    Presentation date: 2020.11

  • マルチメッセンジャープローブによるトライボロジー界面の解析

    柳沢雅広

    トライボロジー会議2020秋 別府  (オンライン) 

    Presentation date: 2020.11

  • STI-CMPスラリにおける添加剤ポリマの基板への吸着特性観察

    李相哲

    トライボロジー会議2020秋 別府  (オンライン) 

    Presentation date: 2020.11

  • 計算化学概論

    國本雅宏  [Invited]

    第48回先端科学セミナー 電気化学のための計算化学入門  (オンライン) 

    Presentation date: 2020.11

  • Initial Stage of Li Electrodeposition in PC Electrolyte

    T. Nishida

    Pacific Rim meeting on Electrochemical &Solid-State Science (PRiME2020)  (オンライン) 

    Presentation date: 2020.10

  • The Effect of Surface Nano and Microstructures on Hydrogen Gas Evolution Behavior on Ni Patterned Electrodes

    T. Fujimura

    Pacific Rim meeting on Electrochemical &Solid-State Science (PRiME2020)  (オンライン) 

    Presentation date: 2020.10

  • Multiscale Simulation for Effects of the Li+ Addition at the Initial Stage of Zn Electrodeposition Processes

    Y. Onabuta

    Pacific Rim meeting on Electrochemical &Solid-State Science (PRiME2020)  (オンライン) 

    Presentation date: 2020.10

  • Optical Trapping Raman Spectroscopy As a Sensor / Actuator / Treatment System

    M. Bertz

    Pacific Rim meeting on Electrochemical &Solid-State Science (PRiME2020)  (オンライン) 

    Presentation date: 2020.10

  • Zn負極における電析初期形成過程に対する金属添加剤の影響の解析

    工藤亮介

    表面技術協会 第142回公演大会  (オンライン) 

    Presentation date: 2020.09

  • In-Situ Raman and DFT Analyses of ZnO Formation Reaction at Zn Negative Electrodes during Discharge Process

    M. Kunimoto

    237th ECS Meeting with the 18th International Meeting on Chemical Sensors (IMCS 2020)  (オンライン) 

    Presentation date: 2020.05

  • Multiscale Simulation for Initial Stage of the Zn Electrodeposition with Kinetic Monte Carlo Based on First-Principle Calculation

    Y. Onabuta

    237th ECS Meeting with the 18th International Meeting on Chemical Sensors (IMCS 2020)  (オンライン) 

    Presentation date: 2020.05

  • Initial Stage of Si Electrodeposition Process in Ionic Liquids

    T. Homma

    237th ECS Meeting with the 18th International Meeting on Chemical Sensors (IMCS 2020)  (オンライン) 

    Presentation date: 2020.05

  • Morphology Control of Cu Added Electrodeposited Bi-Sb-Te Thick Films for Micro Thermoelectric Device

    C. Chen

    237th ECS Meeting with the 18th International Meeting on Chemical Sensors (IMCS 2020)  (オンライン) 

    Presentation date: 2020.05

  • Zn電析初期過程におけるZn原子表面拡散の第一原理計算及びkinetic Monte Carli法による解析

    女部田勇介

    電気化学会第87回大会  (愛知) 

    Presentation date: 2020.03

  • 電極表面構造が水素発生反応に与える影響の解析に向けたマイクロパターン電極の作製

    佐久間翔吾

    電気化学会第87回大会  (愛知) 

    Presentation date: 2020.03

  • 量子化学計算による界面反応解析とその実証計測技術開発

    國本雅宏

    表面技術協会第142回講演大会  (東京) 

    Presentation date: 2020.03

  • イオン液体を用いたパルス電析法による Si 薄膜形成に浴温度が与える影響の検討

    福住康太

    表面技術協会第142回講演大会  (東京) 

    Presentation date: 2020.03

  • Zn 電析過程における Zn 原子表面拡散挙動の第一原理計算解析

    王松毅

    表面技術協会第142回講演大会  (東京) 

    Presentation date: 2020.03

  • マイクロパターン電極を用いたアルカリ水電解プロセスにおける水素発生反応挙動の解析

    藤村樹

    第43回電解技術討論会  (京都) 

    Presentation date: 2019.11

  • Introduction of Power Energy Professionals

    T. Homma

    7th DGIST-Waseda Workshop on Electrochemistry 2019  (Tokyo) 

    Presentation date: 2019.11

  • Pulsed electrodeposition of Si under light illumination in ionic liquid

    S. Watanuki

    7th DGIST-Waseda Workshop on Electrochemistry 2019  (Tokyo) 

    Presentation date: 2019.11

  • Morphology control of electrodeposited Cu doped p-type Bi-Sb-Te thermoelectric film

    C. Chen

    7th DGIST-Waseda Workshop on Electrochemistry 2019  (Tokyo) 

    Presentation date: 2019.11

  • 顕微ラマン分光法を用いた細胞イメージング解析に向けた試み

    鈴木文菜

    日本化学秋季事業 第9回 CSJ化学フェスタ2019  (東京) 

    Presentation date: 2019.10

  • Electrochemical Interfacial Phenomena Under Microgravity

    Y. Fukunaka  [Invited]

    236th Meeting of the Electrochemical Society (236th ECS Meeting)  (Atlanta) 

    Presentation date: 2019.10

  • 有機溶媒からのパルス電析法によるp型及びn型Si薄膜の作製

    日高光士郎

    表面技術協会 第139回講演大会  (福岡) 

    Presentation date: 2019.09

  • Bi-Sb-Te thermoelectric film

    佐藤瑠美

    2019年 電気化学秋季大会  (甲府) 

    Presentation date: 2019.09

  • Morphology control of electrodeposited Cu doped p-type Bi-Sb-Te thermoelectric film

    C. Chen

    9th Jilin-Korea-Waseda Alliance Annual Symposium  (Jilin) 

    Presentation date: 2019.08

  • First-Principle Study of the Oxidation of Formaldehyde and Hypophosphite As Reducing Agents in Electroless Deposition

    Y. Onabuta

    9th Jilin-Korea-Waseda Alliance Annual Symposium  (Jilin) 

    Presentation date: 2019.08

  • Mechanistic Understanding of Liquid-liquid Interfacial Reactions and Reactor Design for Boron Extraction to Produce Highly Purified Silica

    M. Kunimoto

    9th Jilin-Korea-Waseda Alliance Annual Symposium  (Jilin) 

    Presentation date: 2019.08

  • Mass Transfer Rate along Gas Evolving Electrode

    Y. Fukunaka

    70th Annual Meeting of the International Society of Electrochemistry  (Durban) 

    Presentation date: 2019.08

  • Chemical Recognition Based on Deep Convolutional Neural Networks and Surface-enhanced Raman Spectroscory

    M. Bertz

    70th Annual Meeting of the International Society of Electrochemistry  (Durban) 

    Presentation date: 2019.08

  • 電解・無電解めっきの基礎

    本間敬之  [Invited]

    表面処理基礎講座(Ⅰ)  (東京) 

    Presentation date: 2019.06

  • Hydrogen Gas Bubble Behaviors on Ni Micro-Patterned Electrode during Alkaline Water Electrolysis

    T. Fujimura

    World Hydrogen Technologies Convention 2019 (WHTC2019)  (Tokyo) 

    Presentation date: 2019.06

  • Effect of Gravitational Level n the Initial Stage of Cu Electrodepposition

    Y. Fukunaka

    235th Meetnigs of the Electrochemical Society (235th ECS Meeting)  (Dallas) 

    Presentation date: 2019.05

  • Molecuar-Level Analysis of Electrodeposition Processes Using Theoretical Calculations and Surface Enhanced Raman Microscopy

    T. Homma

    235th Meetnigs of the Electrochemical Society (235th ECS Meeting)  (Dallas) 

    Presentation date: 2019.05

  • Pulsed Electrodeposition of Si Under Light Illumination in Ionic Liquid

    S. Watanuki

    235th Meetnigs of the Electrochemical Society (235th ECS Meeting)  (Dallas) 

    Presentation date: 2019.05

  • Zn電解析出における添加金属種の反応抑制効果に対する理論的解析

    大貫浩介

    電気化学会第86回大会  (京都) 

    Presentation date: 2019.03

  • ZnO形成過程に着目したZn負極表面形態の解析

    工藤亮介

    電気化学会第86回大会  (京都) 

    Presentation date: 2019.03

  • 無電解析出プロセスにおけるホルムアルデヒド及び次亜リン酸酸化反応の第一原理計算解析

    女部田勇介

    表面技術協会第139回講演大会  (神奈川) 

    Presentation date: 2019.03

  • Morphology control of Cu added Bi-Sb-Te films for micro thermoelectric devices

    C. Chen

    139th Meeting of the Surface Finishing Society of Japan  (Kanagawa) 

    Presentation date: 2019.03

  • 無電解析出プロセスにおけるホルムアルデヒド酸化反応過程のAIMDによる理論的解析

    篠崎高知

    表面技術協会第139回講演大会  (神奈川) 

    Presentation date: 2019.03

  • Zn アノード反応における ZnO 形成に対する添加剤効果の in situ ラマン分光解析

    安⽥哲也

    表面技術協会第139回講演大会  (神奈川) 

    Presentation date: 2019.03

  • ⾼純度シリカ精製における溶解プロセスに対するカチオン種効果の検討

    岡村雪広

    表面技術協会第139回講演大会  (神奈川) 

    Presentation date: 2019.03

  • Preparation of Solar Grade Silicon By Chemical and Ellectrochemial Processes

    T. Homma  [Invited]

    Joiny Symposium of Peking University & Waseda University on Energy and Nanomaterials  (Beijing) 

    Presentation date: 2019.01

  • Interfacial Analyses of Electrochemical System using Surface Enhanced Raman Spectroscopy with Plasmonic Sensor

    M. Kunimoto  [Invited]

    Joiny Symposium of Peking University & Waseda University on Energy and Nanomaterials  (Beijing) 

    Presentation date: 2019.01

  • Effects of Metal Additives on Morphological Evolution of Zinc Electrodeposition

    T. Otani

    Joiny Symposium of Peking University & Waseda University on Energy and Nanomaterials  (Beijing) 

    Presentation date: 2019.01

  • First-Principle Study of the Oxidation of Formaldehydeand Hypophosphite As Reducing Agents in Electroless Deposition

    Y. Onabuta

    Joiny Symposium of Peking University & Waseda University on Energy and Nanomaterials  (Beijing) 

    Presentation date: 2019.01

  • 電解・無電解めっきの基礎(Ⅱ)-反応メカニズムの理論的解析と機能特性・ナノ構造制御

    本間敬之  [Invited]

    表面処理基礎講座(Ⅱ)  (東京) 

    Presentation date: 2018.11

  • In-situ SERS Analysis of SEI Formation at Graphite Electrode in Li Ion Battery using Manipulated Plasmonic Sensor Element

    M. Kunimoto, M. Yanagisawa, T. Homma

    ECS and SMEQ Joint International Meeting (AiMES2018)  (Cancun) 

    Presentation date: 2018.10

  • Process Development and Analysis of Si Electrodeposition in Ionic Liquid

    T. Homma, Y. Tsuyuki, M. Kunimoto, Y. Fukunaka, P. Pianetta  [Invited]

    ECS and SMEQ Joint International Meeting (AiMES2018)  (Cancun) 

    Presentation date: 2018.10

  • Purification of Diatomaceous Earth using Leaching and Liquid-Liquid Extraction Processes to Produce High Purity Silica for Solar-Grade Silicon

    Yelchur Venkata Akash, Collen Takaza, M. Mimura, M. Kunimoto, Y. Fukunaka, T. Homma

    ECS and SMEQ Joint International Meeting (AiMES2018)  (Cancun) 

    Presentation date: 2018.10

  • First-Principles Study of Catalytic Activity of Cu, Ni and Pd Surface for Formaldehyde and Hypophosphite As Reducing Agents in Electroless Deposition

    Y. Onabuta, M. Kunimoto, K. Nakai, T. Homma

    ECS and SMEQ Joint International Meeting (AiMES2018)  (Cancun) 

    Presentation date: 2018.10

  • 電極表面形態に着目したZn負極アノード溶解とZnO形成過程の解析

    大谷智博, 工藤亮介, 福中康博, 本間敬之

    2018年電気化学秋季大会  (石川) 

    Presentation date: 2018.09

  • プラズモンセンサを利用したSERS測定によるLiイオン二次電池負極SEIの解析の試み

    國本雅宏, 柳沢雅広, 本間敬之

    2018年電気化学秋季大会  (石川) 

    Presentation date: 2018.09

  • Observation and classification of microorganisms using multi-modal surface-enhanced Raman microscopy

    M. Bertz, M. Yanagisawa, M. Kunimoto, T. Homma  [Invited]

    The 3rd International Symposium on Creation of Life Innovation Materials for Interdisciplinary and International Researcher Development (iLIM-3)  (Tokyo) 

    Presentation date: 2018.09

  • Znアノード反応におけるZnO析出過程のin situラマン分光法による解析

    安田哲也, 大谷智博, 國本雅宏, 柳沢雅広, 本間敬之

    表面技術協会 第138回講演大会  (北海道) 

    Presentation date: 2018.09

  • 無電解析出における還元剤酸化反応過程に対する溶媒効果の第⼀原理計算解析

    女部田勇介, 國本雅宏, 中井浩巳, 本間敬之

    表面技術協会 第138回講演大会  (北海道) 

    Presentation date: 2018.09

  • Review: Modeling Study on Gravitational Effects to Electrochemical Interfacial Phenomena during Charging/Discharging Operation with Cu-Electrodes Symmetry Cell

    Y. Fukunaka, M. Kunimoto, S. Wodarz, T. Homma  [Invited]

    70th Annual Meeting of the International Society of Electrochemistry  (Bologna) 

    Presentation date: 2018.09

  • Electrochemical Fabrication of Micro/nano Structured Plasmonic Sensors for Surface Enhanced Raman Scattering Analysis

    T. Homma, M. Kunimoto, M. Bertz, M. Saito, M. Yanagisawa  [Invited]

    69th Annual Meeting of the International Society of Electrochemistry  (Bologna) 

    Presentation date: 2018.09

  • Developing plasmonic sensors for surface enhanced Raman scattering microscopy for in situ analysis of electrochemical processes

    T. Homma, M. Bertz, M. Kunimoto, M. Saito, M. Yanagisawa  [Invited]

    The 12th International Symposium on Electrochemical Micro & Nano System Technologies (EMNT2018)  (Milano) 

    Presentation date: 2018.08

  • Analysis of Hydrogen Gas Evolution Phenomena on Micro-Patterned Ni Electrode during Alkaline Water Electrolysis

    T. Fujimura, W. Hikima, Y. Fukunaka, T. Homma

    The 12th International Symposium on Electrochemical Micro & Nano System Technologies (EMNT2018)  (Milano) 

    Presentation date: 2018.08

  • 電析FePtCuのL10規則化促進に向けた微細構造制御

    堤優也, 神戸茉奈, Giovanni Zangari, 本間敬之

    IEICE 磁気記録・ストレージ研究会(MRIS)  (東京) 

    Presentation date: 2018.07

  • Electrochemical micro/nano fabrication processes – Process development and mechanistic understanding –

    T. Homma  [Invited]

    11th International Workshop on Engineering of Functional Interfaces (EnFI 2018)  (Wittenberg) 

    Presentation date: 2018.07

  • 電解・無電解めっきの基礎

    本間敬之  [Invited]

    表面処理基礎講座(I)  (東京) 

    Presentation date: 2018.06

  • Observation and Classification of Microorganisms Using Multi-Modal Surface-Enhanced Raman Microscopy Based on Plasmonic Sensors

    M. Bertz, M. Yanagisawa, M. Kunimoto, T. Homma

    10th International Symposium on Organic Molecular Electronics (ISOME 2018)  (Saga) 

    Presentation date: 2018.05

  • Analysis of ZnO Growth Process and Effect of Li+ Additive on Zn Negative Electrode

    T. Otani, M. Nagata, Y. Fukunaka, T. Homma

    14 th International Fischer Symposium  (Seeon) 

    Presentation date: 2018.05

  • 理論化学計算とマイクロ空間計測による界面反応解析の実例

    國本雅宏  [Invited]

    電気化学界面シミュレーションコンソーシアム  (東京) 

    Presentation date: 2018.05

  • Molecular-Level Analysis of Surface Species for Electrochemical Deposition Processes Using Density Functional Theory Calculations and Surface Enhanced Raman Microscopy with Plasmonic Sensors

    T. Homma, M. Kunimoto, M. Bertz, M. Yanagisawa  [Invited]

    233 rd Meetnigs of the Electrochemical Society (233 rd ECS Meeting)  (Seattle) 

    Presentation date: 2018.05

  • Electrodeposition in Li in Non-Aqueous Solution

    Y. Fukunaka, T. Homma, T. Nishida, K. Nishikawa  [Invited]

    233 rd Meetnigs of the Electrochemical Society (233 rd ECS Meeting)  (Seattle) 

    Presentation date: 2018.05

  • Morphology Control of Electrodeposited ZnO Patterns for Micro Thermoelectric Devices

    K. Yoshitoku, H. Matsuo, M. Saito, H. Takahashi, I. Terasaki, T. Homma

    22nd Topical Meeting of the International Society of Electrochemistry  (Tokyo) 

    Presentation date: 2018.04

  • In-situ analysis for interaction of additives for electrodeposition in through silicon via using surface enhanced Raman scattering

    T. Yasuda, F. Yamaguchi, M. Kunimoto, M. Yanagisawa, T. Homma

    22nd Topical Meeting of the International Society of Electrochemistry  (Tokyo) 

    Presentation date: 2018.04

  • Effect of Metal Additives on Electrodeposited Bi-Sb- Te Films for Micro Thermoelectric Devices

    M. Sugie, M. Saito, H. Takahashi, I. Terasaki, T. Homma

    22nd Topical Meeting of the International Society of Electrochemistry  (Tokyo) 

    Presentation date: 2018.04

  • First-Principles Study of Reaction Mechanism of Reducing Agents on Ni and Cu in Electroless Deposition Processes

    Y. Onabuta, M. Kunimoto, H. Nakai, T. Homma

    22nd Topical Meeting of the International Society of Electrochemistry  (Tokyo) 

    Presentation date: 2018.04

  • Fabrication of plasmon sensor with Ag@TiO 2 core-shell nanoparticles for surface-enhanced Raman scattering

    Y. Kashimata, Y. Sato, M. Kunimoto, M. Yanagisawa, T. Homma

    22nd Topical Meeting of the International Society of Electrochemistry  (Tokyo) 

    Presentation date: 2018.04

  • Analysis of Electrodeposition Process of L1 0 -Ordered FePtCu Nanodot Arrays

    M. Kambe, S. Wodarz, S. Hashimoto, G. Zangari, T. Homma

    22nd Topical Meeting of the International Society of Electrochemistry  (Tokyo) 

    Presentation date: 2018.04

  • Development of Silica Microlens Array Sensor for in situ SERS Analysis of Electrode Reaction Processes

    A. Hayashi, Y. Sato, M. Kunimoto, M. Yanagisawa, T. Homma

    22nd Topical Meeting of the International Society of Electrochemistry  (Tokyo) 

    Presentation date: 2018.04

  • Influences of ZnO Formation on Morphological Evolution of Zn Negative Electrode

    T. Otani, M. Nagata, Y. Fukunaka, T. Homma

    22nd Topical Meeting of the International Society of Electrochemistry  (Tokyo) 

    Presentation date: 2018.04

  • Effect of electrolyte flow on the evolution of microsteps during zinc electrodeposition

    Y. Masuda, T. Otani, Y. Fukunaka, T. Homma

    22nd Topical Meeting of the International Society of Electrochemistry  (Tokyo) 

    Presentation date: 2018.04

  • Optimization of flow type reactor for efficient extraction of B for production of high purity silica のin situ SERS 解析

    Yelchur Venkata Akash, M. Mimura, M. Kunimoto, Y. Fukunaka, T. Homma

    The 98th CSJ Annual Meeting (2018)  (Funabashi) 

    Presentation date: 2018.03

  • Si 電析プロセスにおける還元反応機構に及ぼす微量水分 の影響の理論的解析

    大貫浩介, 真田歩, 國本雅宏, 中井 浩巳, 本間敬之

    表面技術協会第137回講演大会  (東京) 

    Presentation date: 2018.03

  • 表面増強ラマン計測による電極界面水素イオン濃度のin situ解析

    吉田悟, 國本雅宏, 柳沢雅広, 本間敬之

    表面技術協会第137回講演大会  (東京) 

    Presentation date: 2018.03

  • イオン液体中におけるAlおよびPドープSi薄膜電析と電気特性評価

    渡貫修永, 露木康博, 高井秀典, 福中康博, 本間敬之

    表面技術協会第137回講演大会  (東京) 

    Presentation date: 2018.03

  • N型及びp型酸化物電析膜を用いたマイクロ熱電変換素子 の作製

    井尻博之, 松尾日向子, 吉徳光一朗, 斎藤美紀子, 高橋英史, 寺崎一郎, 本間敬之

    表面技術協会第137回講演大会  (東京) 

    Presentation date: 2018.03

  • 透過型プラズモンセンサを用いた電極界面水素イオン濃度 のin situ SERS 解析

    佐藤祐太, 國本雅宏, 柳沢雅広, 本間敬之

    電気化学会第85回大会  (東京) 

    Presentation date: 2018.03

  • マイクロパターン電極を用いた水素電極反応への表面濡れ性の影響の解析

    引間稚菜, 藤村樹, 福中康博, 本間敬之

    電気化学会第85回大会  (東京) 

    Presentation date: 2018.03

  • 水電解反応における気泡成長挙動に着目した触媒電極形成とその解析

    藤村樹, 引間稚菜, 福中康博, 本間敬之

    第4回分科会ワークショップ『革新的エナジー・ハーべスティングに向けた材料・デバイス技術』  (東京) 

    Presentation date: 2018.03

  • Effect of metal additives on molphological evolution of zinc electrodeposition

    大谷智博, 福中康博, 本間敬之

    第4回分科会ワークショップ『革新的エナジー・ハーべスティングに向けた材料・デバイス技術』  (東京) 

    Presentation date: 2018.03

  • 宇宙用電池における微小重力下での安全評価手法開発のための電気化学界面現象の究明

    本間敬之, 福中康博, 曽根理嗣, 高橋哲哉, 國本雅宏, ヴォダルツジギー, ロッソマイケル, フランシアーヤン, アルカイアーリチャード

    第37回宇宙エネルギーシンポジウムプログラム  (神奈川) 

    Presentation date: 2018.03

  • 充放電操作と固液界面現象

    本間敬之, 福中康博, 國本雅宏, ヴォダルツジギー

    第 32 回 宇宙環境利用シンポジウム プログラム  (神奈川県相模原市) 

    Presentation date: 2018.01

  • ELECTRODEPOSITION OF SI THIN FILMS IN IONIC LIQUID WITH GROWTH CONTROL FROM INITIAL STAGES

    高井秀典, 露木康博, 藤村樹, 國本雅宏, 福中康博, P. Pianetta, 本間敬之

    早稲田大学ナノテクノロジーフォーラム 第 3 回分科会ワークショップ『環境問題と対策技術の最前線』  (東京) 

    Presentation date: 2017.12

  • ZnO電解析出を用いたマイクロ熱電変換素子の作製

    松尾日向子, 吉徳光一朗, 齋藤美紀子, 園部義明, 高橋英史, 寺崎一郎, 本間敬之

    早稲田大学ナノテクノロジーフォーラム 第 3 回分科会ワークショップ『環境問題と対策技術の最前線』  (東京) 

    Presentation date: 2017.12

  • プラズモンセンサ素子を用いた電極表面反応の解析

    國本雅宏, 柳沢雅広, 本間敬之  [Invited]

    表面技術協会 関東支部 第93回講演会  (長野) 

    Presentation date: 2017.12

  • Electrodeposition of Si Thin Films ㏌ Ionic Liquid with Growth Control from Initial Stages

    H. Takai, Y. Tsuyuki, T. Fujimura, M. Kunimoto, Y. Fukunaka, P. Pianetta, T. Homma

    5th DGIST-Waseda Workshop on Electrochemistry 2017  (Tokyo) 

    Presentation date: 2017.12

  • Effect of metal additives on molphological evolution of zinc electrodeposition

    T. Otani, Y. Fukunaka, T. Homma

    5th DGIST-Waseda Workshop on Electrochemistry 2017  (Tokyo) 

    Presentation date: 2017.12

  • Electrodeposition of ZnO from Acetate Bath for Thermoelectric Devices

    H. Matsuo, Y. Koichiro, D. Furuyama, M. Saito, T. Homma

    5th DGIST-Waseda Workshop on Electrochemistry 2017  (Tokyo) 

    Presentation date: 2017.12

  • Fabrication of Channel Type Mixing Devices for Efficient Solvent Extraction for High Purity Silica Production

    Yelchur Venkata Akash, M. Mimura, M. Kunimoto, Y. Fukunaka, T. Homma

    5th DGIST-Waseda Workshop on Electrochemistry 2017  (Tokyo) 

    Presentation date: 2017.12

  • 溶融CaCl2 中における液体Zn 陰極上でのSiO2 電解還元反応

    安田幸司, 馬元嘉, 井戸彬文, 萩原理加, 野平俊之, 本間敬之

    第41回電解技術討論会-ソーダ工業技術討論会-  (京都) 

    Presentation date: 2017.11

  • ELECTRODEPOSITION OF SI THIN FILMS IN IONIC LIQUID WITH GROWTH CONTROL FROM INITIAL STAGES

    H. Takai, Y. Tsuyuki, T. Fujimura, M. Kunimoto, Y. Fukunaka, P. Pianetta, T. Homma

    27 th International Photovoltaic Science and Engineering Conference (PVSEC-27)  (Shiga) 

    Presentation date: 2017.11

  • ZnO電解析出を用いたマイクロ熱電変換素子の作製

    松尾日向子, 吉徳光一朗, 齋藤美紀子, 園部義明, 高橋英史, 寺崎一郎, 本間敬之

    第7回CSJ化学フェスタ2017  (東京) 

    Presentation date: 2017.10

  • Znアノード反応におけるZnO形成と充放電挙動の解析

    永田雅人, 大谷智博, 福中康博, 本間敬之

    第7回CSJ化学フェスタ2017  (東京) 

    Presentation date: 2017.10

  • 水電解反応における気泡成長挙動に着目した触媒電極形成とその解析

    藤村樹, 引間稚菜, 福中康博, 本間敬之

    第7回CSJ化学フェスタ2017  (東京) 

    Presentation date: 2017.10

  • Surface Reactivity of a Tin Electrode in Organic Carbonate Electrolytes

    I. Hasa, I. Hasa, T. Otani, T. Homma, P. N. Ross, R. Kostecki

    232 nd ECS Meeting  (National Harbor) 

    Presentation date: 2017.10

  • Effect of Cu Addition and Annealing on Electrodeposited Bi-Te Films for Micro Thermoelectric Devices

    M. Sugie, D. Furuyama, M. Saito, Y. Sonobe, H. Takahashi, I. Terasaki, T. Homma

    232 nd ECS Meeting  (National Harbor) 

    Presentation date: 2017.10

  • Fabrication of Channel Type Mixing Devices for Efficient Solvent Extraction for High Purity Silica Production

    Yelchur Venkata Akash, M. Mimura, M. Kunimoto, Y. Fukunaka, T. Homma

    232 nd ECS Meeting  (National Harbor) 

    Presentation date: 2017.10

  • Gravitational Level Effects on the Coupling Phenomena between Mass Transfer and Morphorogical Variation Rate

    T. Nishida, K. Nishikawa, H. Matsushima, T. Homma, M. Rosso, Y. Fukunaka

    232 nd ECS Meeting  (National Harbor) 

    Presentation date: 2017.10

  • SERS Analysis on Interfacial Reaction of Rechargeable Battery Electrode using Plasmonic Sensor Element – SEI Formation at Graphite Electrode Surface

    M. Kunimoto, Y.Sun, M. Yanagisawa, T. Homma

    232 nd ECS Meeting  (National Harbor) 

    Presentation date: 2017.10

  • Preparation of Solar Grade Silicon by Interfacial and Electrochemical Processes

    T. Homma, M. Kunimoto, Y. Fukunaka, T. Nohira  [Invited]

    International Conference on Materials and Systems for Sustainability (ICMaSS2017)  (Nagoya) 

    Presentation date: 2017.09

  • 酢酸浴によるZnOの電析条件の検討と熱電変換素子への応用

    吉徳光一朗, 松尾日向子, 齋藤美紀子, 本間敬之

    表面技術協会第136回講演大会  (石川) 

    Presentation date: 2017.09

  • Si電析プロセスにおける還元種と有機溶媒の相互作用の理論的解析

    真田歩, 國本雅宏, 露木康博, 福中康博, 中井浩巳, 本間敬之

    2017年電気化学秋季大会  (長崎) 

    Presentation date: 2017.09

  • Analysis on Growth Process of Irregular Shaped Zn Electrodeposits and Roles of Metal Additives

    T. Otani, Y. Masuda, Y. Fukunaka, T. Homma

    68 th Annual Meeting of the International Society of Electrochemistry  (Providence, Rhode Island) 

    Presentation date: 2017.08

  • Dendrite Growth Rate of Li Electrodeposited in PC and Ionic Liquid

    Y. Fukunaka, T. Nishida, K. Nishikawa, T. Homma  [Invited]

    68 th Annual Meeting of the International Society of Electrochemistry  (Providence, Rhode Island) 

    Presentation date: 2017.08

  • Connecting Anodic Gas Evolution in Aqueous and High Temperature Molten Electrolyte Systems Via the Current Interrupt Technique

    B. Chmielowiec, T. Fujimura, T. Otani, K. Aoyama, T. Nohira, T. Homma, A. Allanore

    68 th Annual Meeting of the International Society of Electrochemistry  (Providence, Rhode Island) 

    Presentation date: 2017.08

  • ENHANCEMENT OF L10 ORDERING IN ELECTRODEPOSITED FePt NANODOT ARRAYS

    S. Wodarz, S. Hashimoto, M. Kambe, G. Zangari, T. Homma

    The 28th Magnetic Recording Conference (TMRC 2017)  (Tsukubn) 

    Presentation date: 2017.08

  • 電解析出法によるFePtナノドットアレイのL1 0 規則化の促進及び微細構造解析

    神戸茉奈, ヴォダルツジギー, 橋本尚吾, GiovanniZangari, 本間敬之

    磁気記録・ストレージ研究会  (東京) 

    Presentation date: 2017.07

  • 無電解めっきプロセスの理論的・実験的解析

    本間敬之, 國本雅宏, 柳沢雅広  [Invited]

    ナノプレーティング研究会 第62回例会  (神奈川) 

    Presentation date: 2017.06

  • 電解・無電解めっきの基礎

    本間敬之  [Invited]

    表面処理基礎講座(I)  (東京) 

    Presentation date: 2017.06

  • Electrochemical nano/micro Fabrication and Processing for Functional Structures, Devices and Materials - Process Development and Mechanistic Understanding

    T. Homma  [Invited]

    11 th European Symposium on Electrochemical Engineering  (Prague) 

    Presentation date: 2017.06

  • Theoretical Analysis of SiCl4 Reaction Mechanism for Si Electrodeposition Process in TMHA-TFSI as Ionic Liquids

    T. Fujimura, Y. Tsuyuki, M. Kunimoto, Y. Fukunka, T. Homma

    231 st ECS Meeting  (New Orleans) 

    Presentation date: 2017.05

  • Analysis of Cathodic Reaction Process of SiCl4 in Ionic Liquids

    Y. Tsuyuki, T. Fujimura, M. Kunimoto, Y. Fukunka, P. Pianetta, T. Homma

    231 st ECS Meeting  (New Orleans) 

    Presentation date: 2017.05

  • 透過型表面増強ラマンセンサを用いた埋もれた界面測定解析

    柳沢雅広, 齋藤美紀子, 國本雅宏, 本間敬之

    平成 29 年度日本分光学会年次講演会  (東京) 

    Presentation date: 2017.05

  • ラマン分光法を用いた炭素系ヘッド保護膜の耐熱性観察

    柳沢雅広, 國本雅宏, 齋藤美紀子, 本間敬之

    トライボロジー会議 2017春 東京  (東京) 

    Presentation date: 2017.05

  • ラマン分光法を用いた接触摺動界面の観察

    柳沢雅広, 國本雅宏, 齋藤美紀子, 本間敬之

    トライボロジー会議 2017春 東京  (東京) 

    Presentation date: 2017.05

  • ラマン分光法を用いたトライボロジーのオペランド観察:ドライ摩擦

    柳沢雅広, 國本雅宏, 齋藤美紀子, 本間敬之

    トライボロジー会議 2017春 東京  (東京) 

    Presentation date: 2017.05

  • ラマン分光法を用いたトライボロジーのオペランド観察:液体潤滑

    柳沢雅広, 國本雅宏, 齋藤美紀子, 本間敬之

    トライボロジー会議 2017春 東京  (東京) 

    Presentation date: 2017.05

  • テラワット級太陽光発電のためのプロセス技術革新

    本間敬之  [Invited]

    早稲田応用化学会 先進研究講演会 「応用化学最前線-教員からのメッセージ」  (東京) 

    Presentation date: 2017.04

  • 有機溶媒を用いたp型Si薄膜電析の検討

    岩田祥子, 露木康博, 続木南, 福中康博, 本間敬之

    電気化学会第84回大会  (東京) 

    Presentation date: 2017.03

  • CHO-k1生細胞の透過型プラズモンセンサを用いた表面増強ラマン分光計測の試み

    荒原涼人, Morten Bertz, 柳沢雅宏, 本間敬之

    電気化学会第84回大会  (東京) 

    Presentation date: 2017.03

  • 金属種添加効果に注目したZn mossy構造の電析過程の解析

    増田雄太, 大谷智博, 福中康博, 本間敬之

    電気化学会第84回大会  (東京) 

    Presentation date: 2017.03

  • 銅埋め込み電析における添加剤の拡散・吸着挙動のin situ顕微ラマン分光法による解析

    安田哲也, 山口楓太, 國本雅宏, 柳沢正広, 本間敬之

    電気化学会第84回大会  (東京) 

    Presentation date: 2017.03

  • パルス電析法を用いたFePtナノドットアレイ形成および微細構造解析

    神戸茉奈, ヴォダルツジギー, 齋藤学, 橋本尚吾, Giovanni Zangari, 本間敬之

    電気化学会第84回大会  (東京) 

    Presentation date: 2017.03

  • 溶融CaCl2中のSiO2直接電解還元で製造したSiの純度およびライフタイム測定

    鍾明, 安田幸司, 野平俊之, 本間敬之

    電気化学会第84回大会  (東京) 

    Presentation date: 2017.03

  • 無電解めっきプロセスの理論的・実験的解析

    本間敬之  [Invited]

    日本金属学会2017年春期(第160回)講演大会  (東京) 

    Presentation date: 2017.03

  • 無電解Cu析出プロセスにおけるホルムアルデヒドとチオ尿素の相互作用の理論的解析

    女部田勇介, 國本雅宏, 中井浩巳, 本間敬之

    表面技術協会第135回講演大会  (埼玉) 

    Presentation date: 2017.03

  • 酢酸イオン存在下でのZnO薄膜の電析と熱電変換材料への応用

    吉徳光一朗, 松尾日向子, 齋藤美紀子, 本間敬之

    表面技術協会第135回講演大会  (埼玉) 

    Presentation date: 2017.03

  • Bi-Te系電析膜に対するアニール処理の影響の解析および熱電変換素子への応用

    杉江美紗貴, 古山大貴, 齋藤美紀子, 園部義明, 高橋英史, 寺崎一郎, 本間敬之

    表面技術協会第135回講演大会  (埼玉) 

    Presentation date: 2017.03

  • Reduction Mechanism Analysis of SiCl4 during Si Electrodeposition in Ionic Liquids

    露木康博, 藤村樹, 國本雅宏, 福中康博, P. Pianetta, 本間敬之

    早稲田大学ナノテクノロジーフォーラム 第2回分科会ワークショップ 「エネルギー利用と蓄電池に関して」  (東京) 

    Presentation date: 2017.03

  • イオン液体を用いたSi電析プロセスにおけるSiCl4反応機構の理論的解析

    藤村樹, 内藤健博, 露木康博, 國本雅宏, 福中康博, 本間敬之

    早稲田大学ナノテクノロジーフォーラム 第2回分科会ワークショップ 「エネルギー利用と蓄電池に関して」  (東京) 

    Presentation date: 2017.03

  • Modeling and Spectroscopic Analysis of the Liquid-liquid Extraction of Boric Acid in Micro Channel Devices

    M. Kunimoto  [Invited]

    The 15 th Japanese-German International Workshop on Mathematical Fluid Dynamics(第15回日独流体数学国際研究集会)  (Tokyo) 

    Presentation date: 2017.01

  • Electrochemical nano/micro fablication processes for functional structures and devices - Process development and mecchanistic understanding

    T. Homma  [Invited]

    International Conference on Material Sciences (SCICON' 16)  (Coimbatore) 

    Presentation date: 2016.12

  • ラマン分光法を用いた動的機械物性と化学構造の同時測定: トライボロジー解析(第1報)

    柳沢雅広, 斎藤美紀子, 國本雅宏, 本間敬之

    第36回表面科学学術講演会  (愛知) 

    Presentation date: 2016.11

  • 2,2,4-Trimethyl-1,3-pentanediol (TMPD)を用いたホウ素の溶媒抽出反応における液液界面状態の解析

    鈴木隆, 國本雅宏, 福中康博, 本間敬之

    第6回CSJ化学フェスタ2016  (東京) 

    Presentation date: 2016.11

  • プラズモンセンサによる潤滑膜およびダイヤモンドカーボン膜の加熱挙動の観察

    柳沢雅広, 斎藤美紀子, 國本雅宏, 本間敬之

    トライボロジー会議2016秋 新潟  (新潟) 

    Presentation date: 2016.10

  • 新しいラマン分光法を用いたトライボロジー特性と化学構造の同時測定

    柳沢雅広, 斎藤美紀子, 國本雅宏, 本間敬之

    トライボロジー会議2016秋 新潟  (新潟) 

    Presentation date: 2016.10

  • Kinetic Studies on Direct Electrolytic Reduction of SiO2 Granules in Molten CaCl2

    M. Zhong, X. Yang, K. Yasuda, T. Nohira, T. Homma

    PRiME 2016 (230th Meeting of The Electrochemical Society, 2016 Fall Meeting of The Electrochemical Society of Japan)  (Honolulu, Hawai) 

    Presentation date: 2016.10

  • Electrodeposition of Si Film from Water-Soluble KF-KCl Molten Salt and Gaseous SiCl4

    K. Yasuda, K. Saeki, K. Maeda, T. Nohira, R. Hagiwara, T. Homma

    PRiME 2016 (230th Meeting of The Electrochemical Society, 2016 Fall Meeting of The Electrochemical Society of Japan)  (Honolulu, Hawai) 

    Presentation date: 2016.10

  • Electrochemical Synthesis and Characterization of Fe-Ni-Pt Alloy Films

    S. Ge, S. Wodarz, S. Hashimoto, M. Saitou, T. Homma, G. Zangari

    PRiME 2016 (230th Meeting of The Electrochemical Society, 2016 Fall Meeting of The Electrochemical Society of Japan)  (Honolulu, Hawai) 

    Presentation date: 2016.10

  • Structural Control of Electrodeposited L10-FePt Nanodot Arrays Towards Reduction of Ordering Temperature

    S. Wodarz, S. Hashimoto, M. Saitou, G. Zangari, T. Homma  [Invited]

    PRiME 2016 (230th Meeting of The Electrochemical Society, 2016 Fall Meeting of The Electrochemical Society of Japan)  (Honolulu, Hawai) 

    Presentation date: 2016.10

  • Formation of Nanoporous Electrode on Aligned CNT Films Using Dealloying

    M. Saito, J. Mizuno, M. Kusunoki, H. Nishikawa

    PRiME 2016 (230th Meeting of The Electrochemical Society, 2016 Fall Meeting of The Electrochemical Society of Japan)  (Honolulu, Hawai) 

    Presentation date: 2016.10

  • In-situ Raman Spectroscopy Study on the Preferential Adsorption of Electrolyte Species on Electrode Surface of Lithium Ion Battery

    Y. Sun, M. Yanagisawa, T. Homma

    PRiME 2016 (230th Meeting of The Electrochemical Society, 2016 Fall Meeting of The Electrochemical Society of Japan)  (Honolulu, Hawai) 

    Presentation date: 2016.10

  • The Effect of Bath Condition on The Composition of Si thin Films Electrodeposited in Non-aqueous Solvents

    Y. Tsuyuki, M. Tsuzuki, Y. Fukunaka, T. Homma

    PRiME 2016 (230th Meeting of The Electrochemical Society, 2016 Fall Meeting of The Electrochemical Society of Japan)  (Honolulu, Hawai) 

    Presentation date: 2016.10

  • Electrodeposition of ZnO from Acetate Bath for Thermoelectric Devices

    H. Matsuo, K. Yoshitoku, D. Furuyama, M. Saito, T. Homma

    PRiME 2016 (230th Meeting of The Electrochemical Society, 2016 Fall Meeting of The Electrochemical Society of Japan)  (Honolulu, Hawai) 

    Presentation date: 2016.10

  • Growth Behavior of ZnO during Discharge of Zinc Negative Electrode

    T. Otani, M. Nagata, Y. Fukunaka, T. Homma

    PRiME 2016 (230th Meeting of The Electrochemical Society, 2016 Fall Meeting of The Electrochemical Society of Japan)  (Honolulu, Hawai) 

    Presentation date: 2016.10

  • A New Electrolytic Production Process of Silicon Using Liquid Zn Alloy Cathode in Molten Salt

    T. Nohira, A. Ido, T. Shimao, X. Yang, K. Yasuda, R. Hagiwara, T. Homma

    PRiME 2016 (230th Meeting of The Electrochemical Society, 2016 Fall Meeting of The Electrochemical Society of Japan)  (Honolulu, Hawai) 

    Presentation date: 2016.10

  • Development of Novel Process for Producing High-Purity Silicon through Designing Solid/Liquid Interfacial Reactions (2011-2016)

    T. Homma

    Nucleation & Growth Research Conference -international Workshop of Electrochemical/Materials Processong for Renewable Energy-  (Kyoto) 

    Presentation date: 2016.09

  • Theoretical Analysis of SiCl4 Reaction Mechanism for Si Electrodeposition Process in Ionic Liquids

    T. Fujimura, M. Kunimoto, T. Homma

    Nucleation & Growth Research Conference -international Workshop of Electrochemical/Materials Processong for Renewable Energy-  (Kyoto) 

    Presentation date: 2016.09

  • Reduction Mechanism Analysis of SiCl4 during Si Electrodeposition in Ionic Liquids

    Y. Tsuyuki, T. Fujimura, M. Kunimoto, Y. Fukunaka, P. Pianetta, T. Homma

    Nucleation & Growth Research Conference -international Workshop of Electrochemical/Materials Processong for Renewable Energy-  (Kyoto) 

    Presentation date: 2016.09

  • Effects of Metal Additives on Morphological Evolution of Zinc Electrodeposition

    T. Otani, Y. Fukunaka, T. Homma

    Nucleation & Growth Research Conference -international Workshop of Electrochemical/Materials Processong for Renewable Energy-  (Kyoto) 

    Presentation date: 2016.09

  • The Kinetic Study on the Direct Electrolytic Reduction of SiO2 Powder in Molten CaCl2

    M. Zhong, X. Yang, K. Yasuda, T. Nohira, T. Homma

    Nucleation & Growth Research Conference -international Workshop of Electrochemical/Materials Processong for Renewable Energy-  (Kyoto) 

    Presentation date: 2016.09

  • Bahavior of Direct Electrolytic Reduction of SiO2 in Molten CaCl2

    A. Ido, X. Yang, K. Yasuda, T. Nohira, R. Hagiwara, T. Homma

    Nucleation & Growth Research Conference -international Workshop of Electrochemical/Materials Processong for Renewable Energy-  (Kyoto) 

    Presentation date: 2016.09

  • Electrodeposition of Crystalline Silicon Films in Water-soluble KF-KCl Molten Salt

    K. Saeki, K. Yasuda, T. Nohira, R. Hagiwara, T. Homma

    Nucleation & Growth Research Conference -international Workshop of Electrochemical/Materials Processong for Renewable Energy-  (Kyoto) 

    Presentation date: 2016.09

  • Carbothermic Reduction Path of a Silica-Silicon Carbide Pellet Irradiated by Laser Beam

    Y. V. Akash, M. Kunimoto, T. Ishikawa, Y. Fukunaka, T. Homma

    Nucleation & Growth Research Conference -international Workshop of Electrochemical/Materials Processong for Renewable Energy-  (Kyoto) 

    Presentation date: 2016.09

  • Electrodeposition of Crystalline Silicon Films from Water-soluble KF-KCl Molten Salts

    T. Nohira, K. Saeki, K. Yasuda, R. Hagiwara, T. Homma

    Nucleation & Growth Research Conference -international Workshop of Electrochemical/Materials Processong for Renewable Energy-  (Kyoto) 

    Presentation date: 2016.09

  • Computational and Spectroscopic Study of Boron Extraction Reaction at Liquid-Liquid Interface

    M. Kunimoto, Y. Fukunaka, T. Homma

    Nucleation & Growth Research Conference -international Workshop of Electrochemical/Materials Processong for Renewable Energy-  (Kyoto) 

    Presentation date: 2016.09

  • 無電解Cu析出プロセスにおけるチオ尿素作用機構のSERSによる解析

    吉田悟, 國本雅宏, 柳沢雅広, 本間敬之

    表面技術協会第134回講演大会  (宮城) 

    Presentation date: 2016.09

  • Analysis on electrodeposition process of mossy shaped zinc

    T. Otani, M. Nagata, Y. Fukunaka, T. Homma

    EMNT2016  (Brussels) 

    Presentation date: 2016.08

  • DFT and SERS Study on the Effect of Thiourea for Electroless Cu Deposition Process

    M. Kunimoto, S. Yoshida, M. Yanagisawa, T. Homma

    EMNT2016  (Brussels) 

    Presentation date: 2016.08

  • Theoretical and In Situ SERS Analysis on the Electrochemical Micro/Nano Fabrication Processes

    T. Homma  [Invited]

    The 5th International Symposium on Materials Science Surface Technology 2016 (MSST2016)  (Yokohama) 

    Presentation date: 2016.08

  • 電解析出法による多層構造を有したFePtナノドットアレイの低温L10規則化の検討

    齋藤学, 橋本尚吾, ヴォダルツジギー, G. Zangari, 本間敬之

    磁気記録・情報ストレージ研究会(MR)  (東京) 

    Presentation date: 2016.07

  • 電解・無電解めっきの基礎

    本間敬之  [Invited]

    表面技術協会 夏季セミナー「表面処理基礎講座(Ⅰ)」  (東京) 

    Presentation date: 2016.06

  • Depth Profile Analysis of Chemical Structures Around Lubricant/Overcoat Interface Using Plasmonic Sensor

    M. Yanagisawa, T. Homma, M. Kunimoto

    ASME 2016 Conference on Information Storage and Processing Systems (ISPS2016)  (Santa Clara, CA) 

    Presentation date: 2016.06

  • Life Estimation of Carbon Overcoat on Magnetic Media for Heat-Assisted Magnetic Recording Using Novel Raman Spectroscopy

    M. Yanagisawa, T. Homma, M. Kunimoto

    ASME 2016 Conference on Information Storage and Processing Systems (ISPS2016)  (Santa Clara, CA) 

    Presentation date: 2016.06

  • Preparation of Solar-Grade Silicon By Chemical and Electrochemical Processes

    T. Homma, M. Kunimoto, X. Yang, K. Yasuda, Y. Fukunaka, T. Nohira

    229th Meeting of the Electrochemical Society  (San Diego) 

    Presentation date: 2016.06

  • DLC薄膜のレーザー加熱温度と熱劣化の同時測定および寿命推定

    國本雅宏, 本間敬之

    トライボロジー会議2016春 東京  (東京) 

    Presentation date: 2016.05

  • Theoretical and Experimental Analyses of Additive Effects in Electrochemical Deposition Processes

    M. Kunimoto, T. Homma

    3rd DGIST-WASEDA Workshop on electrochemistry  (Tokyo) 

    Presentation date: 2015.12

  • Electrodeposition of Si Thin Films in Ionic Liquids for Solar Cell Applications

    Y. Tsuyuki, M. Tsuzuki, Y. Fukunaka, T. Homma

    3rd DGIST-WASEDA Workshop on electrochemistry  (Tokyo) 

    Presentation date: 2015.12

  • Analysis of Initial Deposition Stage of Co-Pt Nanodot Arrays

    S. Wodarz, T. Homma

    3rd DGIST-WASEDA Workshop on electrochemistry  (Tokyo) 

    Presentation date: 2015.12

  • 電解・無電解めっきの基礎 (Ⅱ)-反応メカニズムの理論的解析と機能特性・ナノ構造制御

    本間敬之  [Invited]

    表面技術協会 冬季セミナー 「表面処理基礎講座(Ⅱ)」  (東京) 

    Presentation date: 2015.11

  • Study on chemical structure inside APTES SAMs by using SERS: depth profile and phase transition process

    Y. Sun, M. Yanagisawa, M. Kunimoto, M. Nakamura, T. Homma

    第5回CSJ化学フェスタ2015  (東京) 

    Presentation date: 2015.10

  • Carbothermic Reduction Path of a Silica-Silicon Carbide Pellet Irradiated by Laser Beam

    Y. Akash, M. Kunimoto, T. Ishikawa, Y. Fukunaka, T. Homma

    第5回CSJ化学フェスタ2015  (東京) 

    Presentation date: 2015.10

  • 高純度シリカ精製にむけた溶液処理プロセスにおける塩基性溶液の影響

    堀江舜介, 中嶋一輝, 國本雅宏, 福中康博, 本間敬之

    第5回CSJ化学フェスタ2015  (東京) 

    Presentation date: 2015.10

  • 高純度シリカ精製のための酸洗浄におけるpHの不純物除去率への影響

    中嶋一輝, 堀江舜介, 國本雅宏, 福中康博, 本間敬之

    第5回CSJ化学フェスタ2015  (東京) 

    Presentation date: 2015.10

  • Preparation of Transparent-Type Plasmonic Sensors By the Sol-Gel Process and Electrodeposition

    M. Saito, M. Mita, M. Yanagisawa, T. Homma

    228th Meeting of The Electrochemical Society (ECS)  (Arizona) 

    Presentation date: 2015.10

  • Coupling Phenomena Between Micromorphological Evolution and Ionic Mass Transfer Rate during Ag Electrodeposition in AgNO3 Aqueous Solution

    Y. Fukunaka, T. Wakatsuki, T. Homma

    228th Meeting of The Electrochemical Society (ECS)  (Arizona) 

    Presentation date: 2015.10

  • 電解析出法によるFePtナノドットアレイの超高密度化に向けた形成プロセスの検討

    齋藤学, 西家大貴, ヴォダルツジギー, G. Zangari, 本間敬之

    2015年電気化学秋季大会  (埼玉) 

    Presentation date: 2015.09

  • 有機溶媒中での電析Si薄膜の作製と組成評価

    続木南, 露木康博, P. Anh, 福中康博, 本間敬之

    2015年電気化学秋季大会  (埼玉) 

    Presentation date: 2015.09

  • 表面増強ラマン測定による電極界面水素イオン濃度解析

    佐々木萌, 花井智也, 國本雅宏, 柳沢雅広, 本間敬之

    2015年電気化学秋季大会  (埼玉) 

    Presentation date: 2015.09

  • 電極界面におけるpH測定系の開発に向けた理論的検討

    花井智也, 佐々木萌, 國本雅宏, 柳沢雅広, 中井浩己, 本間敬之

    表面技術協会第132回講演大会  (長野) 

    Presentation date: 2015.09

  • Electrodeposition of p-type Bi-Sb-Te alloys and fabrication of Π-structured micro-thermoelectric device

    D. Furuyama, K. Uda, M. Saito, Y. Sonobe, H. Takahashi, I. Terasaki, T. Homma

    The 6th NIMS/MANA-Waseda University International Symposium  (Tokyo) 

    Presentation date: 2015.07

  • パルス電析法を用いたFePtナノドットアレイの高保磁力化の検討

    西家大貴, ヴォダルツジギー, 謝承達, 齋藤学, 阿部純也, G. Zangari, 本間敬之

    磁気記録・情報ストレージ研究会  (東京) 

    Presentation date: 2015.07

  • 電解・無電解めっきの基礎

    本間敬之  [Invited]

    表面技術協会 夏季セミナー 「表面処理基礎講座(Ⅰ)」  (東京) 

    Presentation date: 2015.06

  • Growth Control of Electrodeposited Co-Pt Nanodot Arrays

    S. Wodarz, J. Abe, T. Homma

    13th International Fischer Symposium  (Lübeck) 

    Presentation date: 2015.06

  • Computational and Spectroscopic Study for Reaction Mechanism of Boric Acid Extraction in Micro-Channel Device

    M. Kunimoto, R. Tamura, T. Oyanagi, N. Matsuo, Y. Fukunaka, H. Nakai, T. Homma

    227th Meeting of The Electrochemical Society  (Chicago, IL) 

    Presentation date: 2015.05

  • Gravitational Level Effects on Coupling phenomena Between Morphological variations of Electrodeposited Film of ZnO and Mass Transfer Rates

    H. Osaki, T. Wakatsuki, T. Homma, Y. Fukunaka

    227th Meeting of The Electrochemical Society  (Chicago, IL) 

    Presentation date: 2015.05

  • シリカ溶液精製プロセスにおけるホウ素抽出反応機構の理論的解析

    田村理沙, 國本雅宏, 福中康博, 中井浩巳, 本間敬之

    電気化学会第82回大会  (神奈川) 

    Presentation date: 2015.03

  • 流路型リアクターを用いたホウ素抽出過程のラマン分光法によるin situ解析

    小柳高宏, 國本雅宏, 松尾伸史, 福中康博, 本間敬之

    電気化学会第82回大会  (神奈川) 

    Presentation date: 2015.03

  • 溶融CaCl2中における液体Si-Zn合金からのSi析出挙動

    安田幸司, 島尾武征, 楊肖, 野平俊之, 萩原理加, 一坪幸輝, 増田賢太, 本間敬之

    電気化学会第82回大会  (神奈川) 

    Presentation date: 2015.03

  • 新規な電気化学的ナノ構造形成プロセスの開拓と実践

    本間敬之  [Invited]

    電気化学会第82回大会  (神奈川) 

    Presentation date: 2015.03

  • p型Bi-Sb-Te薄膜のパターン電析および熱電変換素子作製

    古山大貴, 宇田和布, 齋藤美紀子, 園部義明, 高橋英史, 寺崎一郎, 本間敬之

    表面技術協会第131回講演大会  (神奈川) 

    Presentation date: 2015.03

  • 初期析出過程に着目した亜鉛電析挙動の解析

    大谷智博, 福中康博, 本間敬之

    表面技術協会第131回講演大会  (神奈川) 

    Presentation date: 2015.03

  • 水素電極反応に対するナトリウムの影響の理論的解析の試み

    横道拓哉, 國本雅宏, 中井浩巳, 本間敬之

    表面技術協会第131回講演大会  (神奈川) 

    Presentation date: 2015.03

  • ゾルゲル法と電解析出法による透過型プラズモンセンサの作製

    齋藤美紀子, 三田正弘, 柳沢雅広, 本間敬之

    表面技術協会第131回講演大会  (神奈川) 

    Presentation date: 2015.03

  • Growth Process of Electrodeposited Si Thin Films in Ionic Liquid for Solar Cell Applications

    Y. Tsuyuki, T. Anh Pham H, J. Komadina, Y. Fukunaka, T. Homma

    The 6th World Conference on Photovoltaic Energy Conversion  (Kyoto) 

    Presentation date: 2014.11

  • Depth profiling of APTES self-assembled monolayer using Surface-enhanced Confocal Raman Microspectroscopy

    Y. Sun, 柳沢雅広, 國本雅宏, 中村雅俊, 本間敬之

    第34回表面科学学術講演会  (島根) 

    Presentation date: 2014.11

  • Analysis of the Initial Stage of Co-Pt Electrodeposition Process at Nanopatterned Substrate

    S. Wodarz, T. Otani, H. Hagiwara, T. Homma

    10th International Symposium on Electrochemical Micro & Nanosystem Technology (EMNT2014)  (Okinawa) 

    Presentation date: 2014.11

  • Theoretical Analysis of Additive Effect of Heavy Metals in Au Electrodeposition

    M. Kunimoto, T. Yokomich, H. Nakai, T. Homma

    10th International Symposium on Electrochemical Micro & Nanosystem Technology (EMNT2014)  (Okinawa) 

    Presentation date: 2014.11

  • EQCM and XPS Analysis of SiCl4 Reduction in Ionic Liquids

    Y. Tsuyuki, T. Anh Pham H, J. Komadina, Y. Fukunaka, T. Homma

    10th International Symposium on Electrochemical Micro & Nanosystem Technology (EMNT2014)  (Okinawa) 

    Presentation date: 2014.11

  • In-situ temperature measurements on the phase change point of monolayer APTES by Surface-enhanced anti-Stokes and Stokes Raman scattering

    Y. Sun, M. Yanagisawa, M. Kunimoto, M. Nakamura, T. Homma

    The 7th International Symposium on Surface Science  (Shimane) 

    Presentation date: 2014.11

  • 高純度シリカ生成に向けた溶液処理による軽元素除去プロセスの検討

    石原貴史, 中嶋一輝, 松尾伸史, 福中康博, 本間敬之

    第4回CSJ化学フェスタ2014  (東京) 

    Presentation date: 2014.10

  • Reaction Mechanism of Thiourea as Suppressor in Electroless Cu Deposition Process

    M. Kunimoto, T. Naito, H. Nakai, T. Homma

    2014 ECS & SMEQ Joint International Meeting  (Cancun) 

    Presentation date: 2014.10

  • In Situ Surface Enhanced Raman Spectroscopy Analysis of the Electrochemical Deposition Processes Using Plasmon Antenna Sensors

    T. Homma, T. Yamamoto, M. Nakamura, M. Kunimoto, M. Saito, M. Yanagisawa  [Invited]

    2014 ECS & SMEQ Joint International Meeting  (Cancun) 

    Presentation date: 2014.10

  • Characterization of Electrodeposited Co-Pt Nano-Dot Array at Initial Deposition Stage

    S. Wodarz, T. Otani, H. Hagiwara, T. Homma

    2014 ECS & SMEQ Joint International Meeting  (Cancun) 

    Presentation date: 2014.10

  • The Study of Electrodeposition of Si in Tmhatfsi-SiCl4 analyzed by EQCM Method

    Y. Tsuyuki, T. Anh Pham H, J. Komadina, Y. Fukunaka, T. Homma

    2014 ECS & SMEQ Joint International Meeting  (Cancun) 

    Presentation date: 2014.10

  • Elimination of Boron from Soluble Silica Via Solvent Extraction with 2,2,4-Trimethyl-1,3-Pentanediol Using a Multistage Flow-Type Reactor

    N. Matsuo, T. Ishihara, T. Oyanagi, K. Nakajima, Y. Fukunaka, T. Homma

    2014 ECS & SMEQ Joint International Meeting  (Cancun) 

    Presentation date: 2014.10

  • A New Electrodeposition Process of Crystalline Silicon Utilizing Water-Soluble KF–KCl Molten Salt

    K. Maeda, K. Yasuda, T. Nohira, R. Hagiwara, T. Homma

    2014 ECS & SMEQ Joint International Meeting  (Cancun) 

    Presentation date: 2014.10

  • Fabrication of FePt and CoPt Magnetic Nanodot Arrays by Electrodeposition Process

    T. Homma, S. Wodarz, D. Nishiie, T. Otani  [Invited]

    2014 ECS & SMEQ Joint International Meeting  (Cancun) 

    Presentation date: 2014.10

  • 銅埋め込み電析における添加剤分布のin situ測定手法の開発

    中村雅俊, 柳沢雅広, 本間敬之

    2014年電気化学秋季大会  (札幌) 

    Presentation date: 2014.09

  • フッ化物-塩化物高温溶融塩を用いたシリコンの電気めっき法

    安田幸司, 前田一真, 野平俊之, 萩原理加, 本間敬之

    表面技術協会第130回講演大会  (京都) 

    Presentation date: 2014.09

  • CoPt電析プロセスにおける錯体の作用の理論的解析

    定岡佑典, 國本雅宏, 中井浩巳, 本間敬之

    表面技術協会第130回講演大会  (京都) 

    Presentation date: 2014.09

  • Bi-Te電析膜の微細構造制御およびマイクロ熱電変換素子への応用

    宇田和布, 古山大貴, 齋藤美紀子, 園部義明, 寺崎一郎, 本間敬之

    表面技術協会第130回講演大会  (京都) 

    Presentation date: 2014.09

  • Coupling Phenomena between Micromorphological Evolution and Ionic Mass Transfer Rate during Ag Electrodeposition in AgNO3 Aqueous Solution

    Y. Fukunaka, T. Wakatsuki, T. Homma

    65th International Society of Electrochemistry (ISE)  (Lausanne) 

    Presentation date: 2014.09

  • High Purity Silicon Materials Prepared Through Wet-chemical and Electrochemical Approaches

    T. Homma, Y. Fukunaka, T. Nohira  [Invited]

    65th International Society of Electrochemistry (ISE)  (Lausanne) 

    Presentation date: 2014.09

  • Redox Reaction Current on Multi-microdisc Electrode

    Y. Yamamoto, K. Fushimi, T. Nakanishi, Y. Hasegawa, M. Saito, T. Homma

    65th International Society of Electrochemistry (ISE)  (Lausanne) 

    Presentation date: 2014.09

  • 電析初期過程の解析に基づく超高記録密度ナノドットアレイの形成および高保磁力化

    萩原弘規, ヴォダルツジギー, 大谷智博, 西家大貴, G. Zangari, 本間敬之

    磁気記録・情報ストレージ研究会  (東京) 

    Presentation date: 2014.07

  • Chemical Analysis of Ultra-thin DLC Films and Lubricant/DLC Interface using Plasmonic Sensors

    M. Yanagisawa, M. Kunimoto, T. Homma

    ASME 2014 Conference on Information Storage and Processing Systems (ISPS2014)  (Santa Clara, CA) 

    Presentation date: 2014.06

  • DFT Analysis of Catalytic Reaction of H2PO2- as a Reductant for Electroless Deposition Process

    M. Kunimoto, H. Nakai, T. Homma  [Invited]

    Post-symposium of TOCAT7 (The 7th Tokyo Conference on Advanced Catalytic Science and Technology)  (Tokyo) 

    Presentation date: 2014.06

  • Gravitational Effects on the Initial Stage of Cu Electrodeposition

    H. Inari, Y. Konishi, R. Alkire, T. Homma, Y. Fukunaka

    225th Meeting of The Electrochemical Society (ECS)  (Orlando, FL) 

    Presentation date: 2014.05

  • 導波モードセンサによる水中鉛イオンの高感度検出

    山下幸太, 國本雅宏, 本間敬之, 大木義路, 藤巻真, 粟津浩一

    電気化学会第81回大会  (大阪) 

    Presentation date: 2014.03

  • 流路型デバイスを用いた2,2,4-Trimethyl-1,3-pentanediolによるシリカからの高効率ホウ素除去の検討

    小柳高宏, 松井雄希, 松尾伸史, 福中康博, 本間敬之

    電気化学会第81回大会  (大阪) 

    Presentation date: 2014.03

  • 強磁性FePt電析膜の高保磁力化及び高密度ナノドットアレイの形成

    西家大貴, 間庭佑太, G. Zangari, 本間敬之

    電気化学会第81回大会  (大阪) 

    Presentation date: 2014.03

  • 電析CoPtナノドットアレイの初期析出制御と磁気特性解析

    大谷智博, ヴォダルツジギー, 萩原弘規, 本間敬之

    電気化学会第81回大会  (大阪) 

    Presentation date: 2014.03

  • SiC基板上の高密度・高配向CNTへの電析膜の形成

    斎藤美紀子, 藤田隼, 楠美智子, 本間敬之, 川原田洋

    電気化学会第81回大会  (大阪) 

    Presentation date: 2014.03

  • Elimination of Boron from Silica with Solvent Extraction Using a Multistage Microchannel Device for High-Purity Source for Solar-Grade Silicon

    松尾伸史, 松井雄希, 石原貴史, 福中康博, 本間敬之

    NIMS-早稲田 ジョイントシンポジウム  (東京) 

    Presentation date: 2014.03

  • Electrodeposition Conditions of ZnO Thin Films from Zinc Acetate Bath for Thermo Electronic Devices

    A. A. Akhmaddireja, 齋藤美紀子, 福中康博, 本間敬之

    表面技術協会第129回講演大会  (千葉) 

    Presentation date: 2014.03

  • 多チャンネル微小電極アレイの作製とその電極特性評価

    山本悠大, 伏見公志, 中西貴之, 長谷川靖哉, 齋藤美紀子, 本間敬之

    表面技術協会第129回講演大会  (千葉) 

    Presentation date: 2014.03

  • 無電解Cu めっき反応に対するチオ尿素の添加効果の解析

    内藤健博, 國本雅宏, 中井浩巳, 本間敬之

    表面技術協会第129回講演大会  (千葉) 

    Presentation date: 2014.03

  • 無電解Ni-P めっき反応に対するチオ尿素の促進効果の理論的解析

    関健司, 國本雅宏, 中井浩巳, 本間敬之

    表面技術協会第129回講演大会  (千葉) 

    Presentation date: 2014.03

  • Elimination of incorporated boron in silica with precipitation control and solvent extraction using a microchannel device for high-purity source of solar-grade silicon

    N. Matsuo, Y. Matsui, T. Ishihara, Y. Fukunaka, T. Homma

    International Symposium on Integration of Chemistry and Bioscience  (Tokyo) 

    Presentation date: 2014.01

  • 電解・無電解めっきの基礎〈上級編〉 -反応メカニズムの理論的解析と機能特性・ナノ構造制御

    本間敬之  [Invited]

    2013年冬季セミナー 表面処理基礎講座〈上級編〉  (東京) 

    Presentation date: 2013.11

  • 電気化学的手法による超高記録密度強磁性ナノドットアレイの形成及び析出挙動の解析

    ヴォダルツジギー, 間庭佑太, 萩原弘規, 大谷智博, 西家大貴, G. Zangari, 本間敬之

    磁気記録・情報ストレージ研究会  (東京) 

    Presentation date: 2013.11

  • Electrolyte-Electrode Interfacial Study for Si Electrodeposition in Ionic Liquid

    J. Komadina, Y. Ishibashi, Y. Tsuyuki, Y. Zhang, Y. Fukunaka, P. A. Pianetta, T. Homma

    224th Meeting of the Electrochemical Society (ECS)  (San Francisco, CA) 

    Presentation date: 2013.10

  • Electrochemical Reduction Behavior of Granular SiO2 in Molten CaCl2

    X. Yang, K. Yasuda, T. Nohira, R. Hagiwara, K. Ichitsubo, K. Matsuda, T. Homma

    224th Meeting of the Electrochemical Society (ECS)  (San Francisco, CA) 

    Presentation date: 2013.10

  • DFT Analysis On Cathodic Reaction of Au Thiosulfate Complex At Au(111) Surface

    M. Kunimoto, H. Nakai, T. Homma

    224th Meeting of the Electrochemical Society (ECS)  (San Francisco, CA) 

    Presentation date: 2013.10

  • Influence of Incorporated Light Elements On Refining Process for High-Purity Silica Using Microchannel Device

    N. Matsuo, Y. Matsui, T. Ishihara, Y. Fukunaka, T. Homma

    224th Meeting of the Electrochemical Society (ECS)  (San Francisco, CA) 

    Presentation date: 2013.10

  • Electrochemical Fabrication of Magnetic Nanostructures- Analysis, Control, and Design of Deposition Processes

    T. Homma, S. Wodarz, B. Jiang, M. Kunimoto, M. Yanagisawa  [Invited]

    224th Meeting of the Electrochemical Society (ECS)  (San Francisco, CA) 

    Presentation date: 2013.10

  • 電解析出法を用いた高保磁力Fe-Pt ナノドットパターンの形成

    間庭佑太, 萩原弘規, G. Zangari, 本間敬之

    第3回CSJ化学フェスタ 2013  (東京) 

    Presentation date: 2013.10

  • 流路型デバイスを用いたシリカ中からの軽元素除去プロセスの高効率化

    松井雄希, 石原貴史, 松尾伸史, 福中康博, 本間敬之

    2013年電気化学秋季大会  (東京) 

    Presentation date: 2013.09

  • 室温イオン液体を用いた電析法によるSiナノ構造体の作製

    石橋瑶子, 露木康博, J. Komadina, 福中康博, 本間敬之

    2013年電気化学秋季大会  (東京) 

    Presentation date: 2013.09

  • 顕微ラマン分光法によるスルーホール内部における添加剤の挙動の観察

    加藤晃, 柳澤雅広, 本間敬之

    表面技術協会第128回講演大会  (福岡) 

    Presentation date: 2013.09

  • 金電析過程における重金属添加効果の理論的解析

    横道拓哉, 國本雅宏, 中井浩巳, 本間敬之

    表面技術協会第128回講演大会  (福岡) 

    Presentation date: 2013.09

  • 電気化学的手法により形成した超高記録密度強磁性ナノドットアレイの初期析出過程の解析及び特性評価

    ヴォダルツジギー, 間庭佑太, 萩原弘規, 本間敬之

    磁気記録・情報ストレージ研究会  (東京) 

    Presentation date: 2013.07

  • Πstructured Bi-Te micro-thermoelectric device fabricated by electrodeposition process

    K. Uda, Y. Seki, M. Saito, Y. Sonobe, Y. Hsieh, H. Takahashi, I. Terasaki, T. Homma

    The 32nd International Conference on Thermoelectrics  (Kobe) 

    Presentation date: 2013.07

  • Electrolyte-Electrode Interface and Si Deposition in Ionic Liquid

    J. Komadina, T. Akiyoshi, Y. Ishibashi, Y. Fukunaka, P. Pianetta, T. Homma

    223rd Meeting of The Electrochemical Society (ECS)  (Toronto, Ontario) 

    Presentation date: 2013.05

  • Electrodeposition process to form patterned Si nanostructures

    T. Homma, Y. Fukunaka, Y. Ishibashi, J. Komadina  [Invited]

    The 13th Topical Meeting of the International Society of Electrochemistry  (Pretoria) 

    Presentation date: 2013.04

  • Nanoindentation analysis for mechanical properties of electroless NiP imprinting mold replicated from self-assembled monolayer modified patterns

    林政平, 齋藤美紀子, 本間敬之

    電気化学会第80回大会  (宮城) 

    Presentation date: 2013.03

  • 高保磁力Fe-Pt電析膜の薄膜化及びナノドットアレイの形成

    間庭佑太, 高見淳, G. Zangari, 本間敬之

    電気化学会第80回大会  (宮城) 

    Presentation date: 2013.03

  • 電析浴組成制御による高保磁力CoPtナノドットアレイ精密形成の検討

    萩原弘規, ヴォダルツジギー, 高見淳, 本間敬之

    電気化学会第80回大会  (宮城) 

    Presentation date: 2013.03

  • ナノドットパターンに対するCoPt電析初期過程の解析

    ヴォダルツジギー, 萩原弘規, 高見淳, 本間敬之

    電気化学会第80回大会  (宮城) 

    Presentation date: 2013.03

  • マイクロ流路を用いた2-ethyl-hexanediolによるシリカからのホウ素抽出プロセスの検討

    石原貴史, 松井雄希, 松尾伸史, 福中康博, 本間敬之

    電気化学会第80回大会  (宮城) 

    Presentation date: 2013.03

  • イオン液体からのSi電析薄膜の析出過程および形成状態の解析

    露木康博, 石橋瑶子, 秋吉貴裕, J. Komadina, 福中康博, 本間敬之

    電気化学会第80回大会  (宮城) 

    Presentation date: 2013.03

  • p 型Bi-Te 系薄膜の電析および熱電変換素子の作製

    宇田和布, 関佑太, 齋藤美紀子, 園部義明, 謝育秦, 高橋英史, 寺崎一郎, 本間敬之

    第60回応用物理学会学術講演会  (神奈川) 

    Presentation date: 2013.03

  • 酸性無電解NiPめっき浴におけるチオ尿素の作用機構の理論的解析

    関健司, 國本雅宏, 中井浩巳, 本間敬之

    表面技術協会第127回講演大会  (埼玉) 

    Presentation date: 2013.03

  • Theoretical Analysis of the Solvation Effect on the Adsorption of Hypophosphite Ion on Pd and Cu Surfaces

    K. Seki, M. Kunimoto, H. Nakai, T. Homma

    The 5th International Workshop on Advanced Electrochemical Power Sources (WAEPS-5)  (Kumamoto) 

    Presentation date: 2012.11

  • 電気化学的手法による超高密度強磁性ナノドットアレイの形成及び特性評価

    高見淳, 間庭佑太, ヴォダルツジギー, 萩原弘規, 本間敬之

    磁気記録・情報ストレージ研究会(MR)  (東京) 

    Presentation date: 2012.11

  • Silicon Bonding State in Films Electrodeposited from SiCl4 in Ionic Liquid

    J. Komadina, T. Akiyoshi, Y. Ishibashi, X. Wang, Y. Fukunaka, P. Pianetta, T. Homma

    PRiME 2012 (222nd Meeting of The Electrochemical Society, 2012 Fall Meeting of The Electrochemical Society of Japan)  (Honolulu, Hawaii) 

    Presentation date: 2012.10

  • Fundamental Study of Li Dendrite Growth in Ionic Liquid

    T. Nishida, K. Nishikawa, T. Homma, Y. Fukunaka, M. Rosso

    PRiME 2012 (222nd Meeting of The Electrochemical Society, 2012 Fall Meeting of The Electrochemical Society of Japan)  (Honolulu, Hawaii) 

    Presentation date: 2012.10

  • Raman and DFT Study of Reductant Adsorption on Metal Surfaces in Electroless Deposition Process

    B. Jiang, M. Kunimoto, M. Yanagisawa, T. Homma

    PRiME 2012 (222nd Meeting of The Electrochemical Society, 2012 Fall Meeting of The Electrochemical Society of Japan)  (Honolulu, Hawaii) 

    Presentation date: 2012.10

  • Theoretical Analysis of the Solvent Effect on Hypophosphite Ion Adsorption on Pd and Cu Surfaces

    M. Kunimoto, K. Seki, H. Nakai, T. Homma

    PRiME 2012 (222nd Meeting of The Electrochemical Society, 2012 Fall Meeting of The Electrochemical Society of Japan)  (Honolulu, Hawaii) 

    Presentation date: 2012.10

  • The Effect of the Deposition Conditions on the Electrodeposition of Si Nanopillars in TMHATFSI

    Y. Ishibashi, T. Akiyoshi, J. Komadina, Y. Fukunaka, T. Homma

    PRiME 2012 (222nd Meeting of The Electrochemical Society, 2012 Fall Meeting of The Electrochemical Society of Japan)  (Honolulu, Hawaii) 

    Presentation date: 2012.10

  • Solvent Extraction Using Microchannel System for High Purification of Silica

    N. Matsuo, Y. Matsui, Y. Fukunaka, T. Homma

    PRiME 2012 (222nd Meeting of The Electrochemical Society, 2012 Fall Meeting of The Electrochemical Society of Japan)  (Honolulu, Hawaii) 

    Presentation date: 2012.10

  • Fundamental Study on Reduction Rate for Electrolytic Reduction of SiO2 Powder in Molten CaCl2

    T. Toba, K. Yasuda, T. Nohira, R. Hagiwara, K. Ichitsubo, K. Masuda, T. Homma

    PRiME 2012 (222nd Meeting of The Electrochemical Society, 2012 Fall Meeting of The Electrochemical Society of Japan)  (Honolulu, Hawaii) 

    Presentation date: 2012.10

  • マイクロ流路を用いた溶媒抽出法によるシリカ精製プロセスに関する検討

    松井雄希, 松尾伸史, 福中康博, 本間敬之

    表面技術協会第126回講演大会  (北海道) 

    Presentation date: 2012.09

  • 室温イオン液体からのSi電析薄膜形成プロセスの検討

    秋吉貴裕, 石橋瑶子, J. Komadina, 福中康博, 本間敬之

    表面技術協会第126回講演大会  (北海道) 

    Presentation date: 2012.09

  • 金表面におけるチオ硫酸錯体のカソード反応の理論的解析

    國本雅宏, 島照人, 中井浩巳, 本間敬之

    表面技術協会第126回講演大会  (北海道) 

    Presentation date: 2012.09

  • Theoretical Analysis of the Effect of Surface Defects on the Reaction of Hypophosphite Ion as a Reducing Agent for Electroless Deposition Process

    M. Kunimoto, H. Nakai, T. Homma

    9th International Symposium on Electrochemical Micro & Nanosystem Technology (EMNT2012)  (Linz) 

    Presentation date: 2012.08

  • Electrodeposition of Si nanopatterns from ionic liquid

    T. Homma  [Invited]

    9th International Symposium on Electrochemical Micro & Nanosystem Technology (EMNT2012)  (Linz) 

    Presentation date: 2012.08

  • 電析法によるL10規則化Fe-Pt磁性薄膜の作製及びナノドットパターンの形成

    間庭佑太, 高見淳, G. Zangari, 本間敬之

    東北大通研-早大ナノ機構 第2回研究会  (東京) 

    Presentation date: 2012.07

  • Electrochemical Fabrication of Magnetic Nanodot Arrays - analysis and design of deposition processes

    T. Homma, A. Takami, M. Kunimoto  [Invited]

    12th International Fischer Symposium  (Lübeck) 

    Presentation date: 2012.06

  • Optical Observation of Li Dendrite Growth in Ionic Liquid

    T. Nishida, K. Nishikawa, T. Homma, Y. Fukunaka

    221st Meeting of The Electrochemical Society (ECS)  (Seattle, WA) 

    Presentation date: 2012.05

  • Progress in Nanowire Growth and Mechanistic Analysis of Silicon Electrodeposition in Ionic Liquid

    J. Komadina, T. Akiyoshi, Y. Ishibashi, Y. Fukunaka, P. Pianetta, T. Homma

    221st Meeting of The Electrochemical Society (ECS)  (Seattle, WA) 

    Presentation date: 2012.05

  • 溶融CaCl2中での粉末状SiO2の電解還元における還元速度向上の検討

    鳥羽哲也, 安田幸司, 野平俊之, 萩原理加, 一坪幸輝, 増田賢太, 本間敬之

    電気化学会第79回大会  (浜松) 

    Presentation date: 2012.03

  • 金属ナノ粒子電解生成における微細構造制御

    齋藤美紀子, 石井智紘, 藤原英道, 本間敬之

    電気化学会第79回大会  (浜松) 

    Presentation date: 2012.03

  • ナノギャップ電極を用いたポリジアセチレン超分子の電気特性解析

    天野諭, 松尾伸史, Y. Choi, D.-J. Ahn, 本間敬之

    電気化学会第79回大会  (浜松) 

    Presentation date: 2012.03

  • 電析法によるL10規則化Fe-Pt磁性薄膜の作製及びナノドットパターン形成

    間庭佑太, 小西洋平, Giovanni Zangari, 本間敬之

    電気化学会第79回大会  (浜松) 

    Presentation date: 2012.03

  • ラテラル方向への金めっき優先成長に添加剤が与える影響の検討

    加藤晃, 小林千秋, 齋藤美紀子, 本間敬之

    電気化学会第79回大会  (浜松) 

    Presentation date: 2012.03

  • 二種還元剤を用いた無電解析出反応系のSERS法による解析

    ヴォダルツジギー, 嶋野直史, 大友彬, 國本雅広, 柳沢雅宏, 本間敬之

    電気化学会第79回大会  (浜松) 

    Presentation date: 2012.03

  • 電解析出法によるBiTe系熱電変換素子形成プロセスの検討

    関佑太, 富田元紀, 山本智之, 齋藤美紀子, 園部義明, 高橋英史, 寺崎一郎, 本間敬之

    第59回応用物理学関係連合講演会  (東京) 

    Presentation date: 2012.03

  • 無電解析出プロセスにおける次亜リン酸の金属表面吸着に対する溶媒効果の理論的解析

    関健司, 國本雅宏, 中井浩巳, 本間敬之

    表面技術協会第125回講演大会  (東京) 

    Presentation date: 2012.03

  • Cu表面におけるヒドラジンの酸化反応に対する次亜リン酸の影響の理論的解析

    大友彬, 嶋野直史, 國本雅宏, 中井浩巳, 本間敬之

    表面技術協会第125回講演大会  (東京) 

    Presentation date: 2012.03

  • 金表面におけるチオ硫酸の錯解離性の理論的解析

    島照人, 國本雅宏, 中井浩巳, 本間敬之

    表面技術協会第125回講演大会  (東京) 

    Presentation date: 2012.03

  • ウェットプロセスによるナノ・マイクロ構造の形成

    本間敬之  [Invited]

    4大学ナノ・マイクロファブリケーションコンソーシアム拠点形成シンポジウム  (川崎) 

    Presentation date: 2012.03

  • 機能ナノ構造・デバイス形成のためのめっき技術

    本間敬之  [Invited]

    神奈川科学技術アカデミー教育講座  (川崎) 

    Presentation date: 2012.01

  • Fabrication of 80 nm-scale imprinting mold by detaching electroless-deposited NiP from SAM modified SiO2 master mold

    C.-P. Lin, 齋藤美紀子, 本間敬之

    第1回CSJ化学フェスタ  (東京) 

    Presentation date: 2011.11

  • ラテラル方向へのめっき成長促進と分子ワイヤの特性評価への応用

    小林千秋, 青山裕, 若山裕, 齋藤美紀子, 本間敬之

    第1回CSJ化学フェスタ  (東京) 

    Presentation date: 2011.11

  • Templated electrodeposition of Si nanowires from ionic liquid

    T. Homma, J. Komadina, Y. Nakano, T. Akiyoshi, Y. Ishibashi, Y. Nishimura, T. Nishida, Y. Fukunaka  [Invited]

    220th Meeting of The Electrochemical Society (ECS)  (Boston, MA) 

    Presentation date: 2011.10

  • 無電解析出反応における還元剤水素化ホウ素の反応活性発現のための分子-表面間軌道相互作用の解析

    國本雅宏, 中井浩巳, 本間敬之

    表面技術協会第124回講演大会  (愛知) 

    Presentation date: 2011.09

  • Electrochemical Fabrication of Functional Micro/Nano Structures

    T. Homma, J. Komadina, M.Kunimoto, Y. Fukunaka

    International Symposium on Renewable Energy & Materials Tailoring (REMT2011)  (Kyoto) 

    Presentation date: 2011.09

  • Theoretical study of additive effects on reactions in electroless deposition processes

    M. Kunimoto, H. Nakai, T. Homma

    International Symposium on Renewable Energy & Materials Tailoring (REMT2011)  (Kyoto) 

    Presentation date: 2011.09

  • Observation of reductants on copper surface in electroless deposition process with nano-scale resolution using surface enhanced raman spectroscopy

    B.-Jiang, N. Shimano, T. Ouchi, M. Yanagisawa, T. Homma

    International Symposium on Renewable Energy & Materials Tailoring (REMT2011)  (Kyoto) 

    Presentation date: 2011.09

  • DFT Analysis on Orbital Interaction between Hypophosphite Ion and Metal Surfaces in Electroless Deposition Process

    M. Kunimoto, H. Nakai, T. Homma

    International Society of Electrochemistry (ISE, 62nd Annual Meeting)  (Nigata) 

    Presentation date: 2011.09

  • I-V Characterization of Molecular Architecture Change in Polydiacetylene Supermolecules

    N. Matsuo, Y. Choi, C. Kobayashi, C. Cui, D.-J. Ahn, T. Homma

    International Society of Electrochemistry (ISE, 62nd Annual Meeting)  (Nigata) 

    Presentation date: 2011.09

  • Fabrication of electrodeposited Co-Pt nano dot arrays and analysis of its initial deposition process

    Y. Konishi, A. Takami, T. Ouchi, T. Homma

    International Society of Electrochemistry (ISE, 62nd Annual Meeting)  (Nigata) 

    Presentation date: 2011.09

  • Fabrication and initial deposition analysis of electroless Ni alloy nanoimprinting mold replicated from SAM modified nanopatterns

    C.-P. Lin, M. Saito, T. Homma

    International Society of Electrochemistry (ISE, 62nd Annual Meeting)  (Nigata) 

    Presentation date: 2011.09

  • High Coercivity Magnetic Thin Films Deposited from Simplified Electroless Bath System

    T. Homma, T. Ouchi, N. Shimano  [Invited]

    International Society of Electrochemistry (ISE, 62nd Annual Meeting)  (Nigata) 

    Presentation date: 2011.09

  • ラテラル方向へのめっき優先成長を用いた分子ワイヤー特性評価法の検討

    青山裕, 小林千秋, 若山裕, 齋藤美紀子, 本間敬之

    2011年電気化学秋季大会(第52回化学センサ研究発表会)  (新潟) 

    Presentation date: 2011.09

  • Theoretical Study on Catalytic Activity of Metal Surfaces on P-H Bond Cleavage of Hypophosphite Ion

    M. Kunimoto, H. Nakai, T. Homma

    7th Congress of the International Society for Theoretical Physics (ISTCP-VII)  (Tokyo) 

    Presentation date: 2011.09

  • Mechanical properties and initial deposition analysis of electroless Ni alloy nanoimprinting mold replicated from SAM modified nanopatterns

    C.-P. Lin, M. Saito, T. Homma

    (STAC5-AMDI2) Joint Conference of The Fifth International Conference on the Science and Technology for Advanced Ceramics  (Yokohama) 

    Presentation date: 2011.06

  • Investigation of Effects on Organic Additives for Laterally-Enhanced Growth of Au Electrodeposition Presenters

    C. Kobayashi, S. Yoshida, M. Saito, T. Homma

    219th Meeting of The Electrochemical Society (ECS)  (Montreal, QC) 

    Presentation date: 2011.05

  • マルチセンサアレイによる極薄DLC膜、潤滑膜の耐熱特性測定・解析

    柳沢雅広

    トライボロジー学会トライボロジー会議  (東京) 

  • The Degradation of Carbon Electrode for Rechargeable Zinc-Air Battery at an Initial State of Cycling Revealed By in-Situ Raman Measurement

    T. Wang

    239th ECS Meeting with the 18th International Meeting on Chemical Sensors (IMCS 2021)  (オンライン) 

  • Observation of Polymer Additive Absorption on Substrates for STI CMP Slurries

    S. Nomura

    239th ECS Meeting with the 18th International Meeting on Chemical Sensors (IMCS 2021)  (オンライン) 

  • Deep Learning Combined with Surface-Enhanced Raman Spectroscopy for Chemical Sensing and Recognition

    M. Bertz

    239th ECS Meeting with the 18th International Meeting on Chemical Sensors (IMCS 2021)  (オンライン) 

  • DFT Analyses of the Facilitating Effect of Water on Interfacial Reactions

    M. Kunimoto  [Invited]

    Materials Research Meeting 2021  (Kanagawa) 

  • Surface Enhanced Raman Scattering Measurements and Theoretical Analyses for Mechanistic Understanding of Electrolytic/Electroless Depositions

    國本雅宏  [Invited]

    2023年度日本材料科学会学術講演大会  (神奈川) 

  • 炭化水素系潤滑油のトライボ触媒反応(3)

    柳沢雅広

    トライボロジー会議2023春東京  (東京) 

  • カーボン材料のトライボ触媒反応(1)

    柳沢雅広

    トライボロジー会議2023春東京  (東京) 

  • フッ素系潤滑油のトライボ触媒反応

    柳沢雅広

    トライボロジー会議2023春東京  (東京) 

  • 次世代超高記録密度磁気ディスク用単層グラフェン保護膜と潤滑膜の化学構造解析

    柳沢雅広

    IIP2023  (福岡) 

  • Fabrication of SERS Plasmonic Sensor for Electrochemical Analysis Using Electroless Deposition Process

    Zhengke Tu

    74th Annual ISE Meeting  (France) 

  • 高角形比を有するCoPt/Pt多層垂直磁化膜の電析法による作製

    荒木大輝

    第47回 日本磁気学会学術講演会  (大阪) 

  • Application of Surface-Enhanced Raman Spectroscopy to Interface Analysis on Tribology using Plasmonic Sensor

    Masahiro Yanagisawa

    ITC Fukuoka 2023  (福岡) 

▼display all

Research Projects

  • Electrochemical Processing and Multi-scale Modeling of Zinc Electrodes for Large-scale Energy Storage System

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research

    Project Year :

    2021.04
    -
    2026.03
     

  • Multi-scale, high resolution operando analysis of material destruction processes using mechano-chemical interactive measurements

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research

    Project Year :

    2018.06
    -
    2021.03
     

    Homma Takayuki

     View Summary

    Purpose of the study was development of new tools with capability to analyze mechanical deformation and fracture of materials with mechanical properties and molecular structure. Developed tool was composed of multi beam SERS (Surface-Enhanced Raman Scattering) spectrometer with plasmonic sensor and tension tester. Operando measurement in tensile test was carried out, i.e. kinetic changes of molecular structure mapping in plain, fracture propagation, and so on. Multi-scale from nanometer range to millimeter scale was analyzed in materials. Rubber material was examined for tensile test. The following results were gained. Although surface layer revealed plastic deformation, deep component showed elastic deformation. Operando observation in crack propagation showed that double bond in rubber molecules was decomposed at around fracture position.

  • Development of 3-dimensional-structure sensors with molecular-level resolution and their application to solid/liquid interface analysis on biocells.

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research

    Project Year :

    2014.04
    -
    2017.03
     

    HOMMA Takayuki

     View Summary

    A novel measurement tool, which is capable to analyze chemical structures of ultra-thin films or interfaces, has been developed, based on surface enhanced Raman scattering with newly developed “plasmon sensors,” which enhances local intensity of the Raman signals. Various types of the plasmon sensors have been developed, and as a result, ultra-thin organic films, i.e. self-assembled monolayers, lipid bilayers, cell membranes, were successfully analyzed. Particularly, inner chemical structure of the films was measured with a depth resolution of 0.1nm. Developed methodology is expected to apply wide areas such as diagnostics of various types of cells (e.g., cancer cells) as well as fundamental researches for biomedical field

  • Electrochemical processing of initial nucleation control for large scale energy storage devices

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research

    Project Year :

    2013.04
    -
    2016.03
     

    Homma Takayuki, FUKUNAKA Yasuhiro, SAITO Mikiko, KUNIMOTO Masahiro

     View Summary

    It is indispensable for the development of large scale advanced energy storage devices to control the surface nanostructures of the electrode during charging and discharging operations. In this work, analysis and modeling of the electrodeposition process were carried out from experimental and theoretical approaches to establish the precise methodology to analyze and control the process from single grain nucleation level. As for the electrode material for the large scale energy storage devices, potentiostatic electrodeposition of Zn electrode was conducted in aqueous alkaline solution, and the morphology evolution process, such as formation of mossy structures, is investigated in detail to elucidate its formation mechanism

  • Development of in-situ Electrochemical Imaging Plate for Interfacial Reaction and Its Application to Estimation of Residual Lifetime of Metallic Materials

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research

    Project Year :

    2013.04
    -
    2016.03
     

    Fushimi Koji, HOMMA Takayuki, SAITO Mikiko, LEE Jun-Seob, TAKABATAKE Yu, YANAGISAWA Kei, JIN Misako, YAMAMOTO Yudai

     View Summary

    A 16x16ch Au multielectrode array with a diameter of 10 um and an inter-electrode distance of 100 um was fabricated. Electrochemical measurements using a made-to-order 64 ch multichannel potentiostat revealed that all microelectrodes operated as an individual microelectrode, although their properties varied widely. Polarization of 8x8ch microelectrodes in the array showed an interference of diffusion layer formed on the microelectrodes. The interference was also successfully simulated with a FEM numerical modeling of three-dimensional diffusion problem. The degree of interference during the dynamic polarization of the array could be normalized by the geometry of microelectrode diameter and inter-electrode distance

  • 分子分解能を有する3次元構造センサの開発と細胞固液界面構造解析への応用

    科学研究費助成事業(早稲田大学)  科学研究費助成事業(挑戦的萌芽研究)

    Project Year :

    2014
    -
    2016
     

  • Development of 3-dimensional-structure sensors with molecular-level resolution and their application to solid/liquid interface analysis on biocells.

    Project Year :

    2014
    -
    2016
     

     View Summary

    A novel measurement tool, which is capable to analyze chemical structures of ultra-thin films or interfaces, has been developed, based on surface enhanced Raman scattering with newly developed “plasmon sensors,” which enhances local intensity of the Raman signals. Various types of the plasmon sensors have been developed, and as a result, ultra-thin organic films, i.e. self-assembled monolayers, lipid bilayers, cell membranes, were successfully analyzed. Particularly, inner chemical structure of the films was measured with a depth resolution of 0.1nm. Developed methodology is expected to apply wide areas such as diagnostics of various types of cells (e.g., cancer cells) as well as fundamental researches for biomedical field

  • 大規模エネルギー変換貯蔵デバイスの電気化学プロセシングにおける核発生成長制御

    科学研究費助成事業(早稲田大学)  科学研究費助成事業(基盤研究(A))

    Project Year :

    2013
    -
    2015
     

     View Summary

    情報関連機器や自動車用電源として二次電池の一層の高性能化が求められている。さらに昨今のエネルギー事情から、再生可能エネルギーを基幹電力ネットワークと連系させるため、より安価で資源的リスクが少なくかつ安定した充放電特性を示す大規模エネルギー変換貯蔵デバイスの開発が急務となっている。このようなデバイスにおいては、充放電反応操作に伴う電極表面変化の制御、すなわち表面状態と直結した電池可逆性の保証が重要となる。従来充放電挙動に関する検討は膨大に重ねられているが、それに伴う金属種の析出/溶解プロセスの詳細については未だ不明点も多い。そこで本研究ではこのような電気化学反応による金属核発生の解析およびその制御に着目し、反応プロセスを実験的・理論的アプローチから系統的に解析すると共に、マルチスケールでの解析を可能とするモデルの構築を目指している。
    初年度である本年度は、研究に必要な種々の要素技術の確立を中心に検討を進めた。まず初期析出過程の基礎解析として、研究者らが従来より検討を進めているCoPt系電析プロセスの成果を踏まえ、析出のごく初期すなわち単結晶子が核発生したレベルからの解析を可能とする手法を確立した。同様に、非水溶媒系からの電析プロセスについて、水晶振動子マイクロバランス法を用いて解析する手法の検討を進めた。またごく微小な初期核発生状態の試料を大気暴露による酸化の影響なく解析可能とするための雰囲気遮断試料交換器を導入し、Si電析系を適用し立ち上げを行った。さらに電極表面における反応プロセスについても、種々の表面吸着化学種が関与する系、例えば電池電極反応の鍵を握る表面被膜(SEI:Solid Electrolyte Interface)の形成に関わる挙動および表面の原子レベル欠陥の影響などについて、顕微ラマン分光法および理論解析を用いて解析する手法を確立すべく基礎的な検討を進めた。

  • Development of in-situ analysis method for solid-liquid interfaces with ultra-high resolution using plasmon antenna sensors

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research

    Project Year :

    2011.04
    -
    2014.03
     

    HOMMA Takayuki, YANAGISAWA Masahiro, SAITO Mikiko, KUNIMOTO Masahiro

     View Summary

    A molecular analysis system at liquid/solid interface utilizing Surface-enhanced Raman Scattering (SERS) was developed using two kinds of plasmonic sensors, a concentric-circled groove type and transparent substrate with nano-particles made of Au, Ag, and Cu. For application examples, adsorption behavior of hydrazine and hypophosphate as a reducing agent at the Cu/liquid interface in the atomistic level. The decomposition reaction with an electric field for Janus Green B (JGB) as a deposition inhibitor was observed at Au/liquid interface. Molecular structure of lubricant molecules on a Diamond-Like Carbon (DLC) film for hard disk media was successfully measured in the depth resolution of 0.1 nm

  • Development of in-situ analysis method for solid-liquid interfaces with ultra-high resolution using plasmon antenna sensors

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research

    Project Year :

    2011.04
    -
    2014.03
     

    HOMMA Takayuki, YANAGISAWA Masahiro, SAITO Mikiko, KUNIMOTO Masahiro

     View Summary

    A molecular analysis system at liquid/solid interface utilizing Surface-enhanced Raman Scattering (SERS) was developed using two kinds of plasmonic sensors, a concentric-circled groove type and transparent substrate with nano-particles made of Au, Ag, and Cu. For application examples, adsorption behavior of hydrazine and hypophosphate as a reducing agent at the Cu/liquid interface in the atomistic level. The decomposition reaction with an electric field for Janus Green B (JGB) as a deposition inhibitor was observed at Au/liquid interface. Molecular structure of lubricant molecules on a Diamond-Like Carbon (DLC) film for hard disk media was successfully measured in the depth resolution of 0.1 nm

  • Development of in-situ analysis method for solid-liquid interfaces with ultra-high resolution using plasmon antenna sensors

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research

    Project Year :

    2011
    -
    2013
     

    HOMMA Takayuki, YANAGISAWA Masahiro, SAITO Mikiko, KUNIMOTO Masahiro

     View Summary

    A molecular analysis system at liquid/solid interface utilizing Surface-enhanced Raman Scattering (SERS) was developed using two kinds of plasmonic sensors, a concentric-circled groove type and transparent substrate with nano-particles made of Au, Ag, and Cu. For application examples, adsorption behavior of hydrazine and hypophosphate as a reducing agent at the Cu/liquid interface in the atomistic level. The decomposition reaction with an electric field for Janus Green B (JGB) as a deposition inhibitor was observed at Au/liquid interface. Molecular structure of lubricant molecules on a Diamond-Like Carbon (DLC) film for hard disk media was successfully measured in the depth resolution of 0.1 nm.

  • Establishment of Electrochemical Device Engineering

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research

    Project Year :

    2008
    -
    2012
     

    OSAKA Tetsuya, MOMMA Toshiyuki, SHOJI Shuichi, SUGIYAMA Atsushi, NAKANISHI Takuya, HOMMA Takayuki, MATSUKATA Masahiko, MIZUNO Jun, SEKIGUCHI Tetsushi, YOSHINO Masahiro, TOMINAKA Satoshi

     View Summary

    Based on the researches for development of functional materials with the control of solid-liquid interface and for development of devices with the practical use of nano- and meso-structures and phenomena at the interface, the establishment of Electrochemical Device Engineering was promoted. To establish Electrochemical Device Engineering on the basis of Electrochemical Nanotechnology, the practical devices utilizing the outcome of research and the dimensions for appearance of function and design of solid-liquid interface were set as the warp and weft of this academic discipline.

  • Electrochemical tailoring of semiconductor nanowire arrays and their application to photo-energy devices

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research

    Project Year :

    2009
    -
    2011
     

    HOMMA Takayuki

     View Summary

    Novel process for the electrodeposition of Si thin film from ionic liquid electrolyte has been developed and the initial stage of the deposition process was investigated using EQCM, TEM, and Raman Spectroscopy. It was found that amorphous Si was electrodeposited while a certain amount of ionic liquid was included in the films. Moreover, uniform array of Si nanodots was successfully electrodeposited using 150 nm diameter dot array patterns fabricated by UV nanoimprinting lithography.

  • Electrochemical tailoring of semiconductor nanowire arrays and their application to photo-energy devices

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research

    Project Year :

    2009
    -
    2011
     

    HOMMA Takayuki

     View Summary

    Novel process for the electrodeposition of Si thin film from ionic liquid electrolyte has been developed and the initial stage of the deposition process was investigated using EQCM, TEM, and Raman Spectroscopy. It was found that amorphous Si was electrodeposited while a certain amount of ionic liquid was included in the films. Moreover, uniform array of Si nanodots was successfully electrodeposited using 150 nm diameter dot array patterns fabricated by UV nanoimprinting lithography

  • A study on lubrication technology for future magnetic disks using a lubricant flow in a small gap

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research

    Project Year :

    2008
    -
    2010
     

    YANAGISAWA Masahiro, HOMMA Takayuki, SUGIYAMA Atsushi, YOSHINO Masahiro

     View Summary

    We proposed a lubricant reserver system in which lubricants supplied from a small gap between a hub and a disk plate to disk surfaces. A flow of Perfluorinated Polyether (PFPE) lubricant was examined with cylindrical lens which enable to prepare nanometer scale gaps. As a result, the flow rate parabolically decreases with the decreased gap. Further, it was found that the PFPE lubricant molecule adsorbed on a substrate surface at a functional group, phosphazene, in the molecule with a Surface Enhanced Raman Scattering (SERS) technique

  • Novel electrochemical nanofabrication process for developing precise micro-chemical analytical systems

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research

    Project Year :

    2006
    -
    2008
     

    HOMMA Takayuki

  • Development of Biological Sample Separation/Extraction and Preparation Microsystems for High Performance Biosensing

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research

    Project Year :

    2004
    -
    2006
     

    SHOJI Shuichi, FUNATSU Takashi, HOMMA Takayuki, ARAKAWA Takahiro

     View Summary

    In recent one of the most active area of Micro Total Analysis Systems (μTAS) or Lab-on-a-Chip (LOC), DNA, Protein analysis methods and devices have been improved. However, traditional sample preparations before analysis are required in many cases. In order to realize high speed and high throughput analysis in μTAS, sample separations/extractions are requested to be obtained in microfluidic devices/systems. We applied MEMS technologies and nano technologies and fabricated micro fluidic devices and systems of nl or pl in volume.Biomolecules sorting systems using so-gel transformation of the thermo-sensitive hydrogel as the carrier fluid were developed. High speed one inlet and two outlets sorter is realized by optimizing the channel structures and the flow behaviors. Very fast sorting within 5 msec was also realized. One inlet and 9 outlets sorting system is realized in a matrix microchannel using IR light illumination projected by the PC controlled DMD. A micro chamber integrated with an extremely low dead volume reagent injector for real-time monitoring of living cell was developed. In order to realize specific introduction of the reagent, we also developed the 3D sheath flow scanner. For high throughput analysis, a prototype of 8 diagnostic micro chambers having passive distributing facilitates simultaneous cell injection. On the other hand, microfluidic systems using sheath flow behavior in the microchannel for biological cell sorting were also developed. The flow system can sort two different cells to 16 outlet microchambers. To realize high efficient reaction of DNA and protein, two phase micro droplets of organic/water and three phase micro droplets of organic/water/air genelation fluidic devices were proposed

  • Development of Novel electrochemical Nanofabrication Processes through Controlling Non-linear Diffusion

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research

    Project Year :

    2003
    -
    2005
     

    HOMMA Takayuki, SHOJI Shuichi

     View Summary

    The objective of this research was to develop novel nanofabrication processes of metal nanostructures trough electrochemical approaches. Especially, control and utilization of the nonlinear diffusion of the species, which is unique to the electrochemical processes, were emphasized. In the first year of the research, preferential electrochemical deposition of metal species at the nano-defect sites on Si wafer surface was confirmed, and by utilizing this, fabrication process of metal nanostructure was developed. Also, quantitative analysis was made for the reaction of reductant species at the surface of metal cluster using ab-initio molecular orbital calculation. In addition, attempt on the application of illumination-assisted anodization process was made to develop Si nanofabrication process, and by controlling the illumination condition using aperture-like structure, which controls nonlinear diffusion of holes to the reaction sites, uniform formation of macro pore array was achieved. In the second year, the fabrication process of metal nanostructure onto Si wafer surface was improved to achieve further precision control for various metal species. The modification of the Si macro pore array was attempted to fabricate pico-liter volume glass tube array which is applicable as microreactors. The single-batch process to fabricate the pore array and its filling to form metal-needle array was also developed. In addition, theoretical analysis on the chemical properties of strained Si surface, which is key material for fabricating high-performance ULSI, was also attempted and the correlation between the surface reactivity and "degree of strain" was quantitatively evaluated. In the final year, fabrication process for through-hole to the tip of the glass tube was developed to form "nano-nozzle" array. This process was achieved by controlling the nonlinear diffusion of etchant species. By using this process, fabrication of filter devices and other systems was attempted. In addition, quantitative evaluation procedure of the reactivity of reductant for electroless deposition process was established using quantum chemical calculation approaches. As described, novel electrochemical processes for precision nanofabrication have been developed and detailed mechanism of the reaction processes has elucidated

  • 界面電荷移動反応制御による新規ウェット系インテグレーションプロセスの開発

    科学研究費助成事業(早稲田大学)  科学研究費助成事業(特定領域研究)

    Project Year :

    2002
    -
    2003
     

     View Summary

    次世代超高機能デバイス・システム形成のためのナノファブリケーション技術として、電解・無電解法などのウェットプロセスは今後一層重票となるが、本手法は固液界面反応の関る複雑な系であるため不明点が多く、本分野において広く用いられるには至っていない。そこで本研究では、本プロセス特有の因子である固液界面電荷移動反応を理論的・実験的アプローチから素過程レベルで解析すると共に、これに基づいたナノレベルの精度の新規ファブリケーションプロセスの開発を目的とした。
    まず、無電解析出法による金属ナノ構造体形成について、非経験的分子軌道法を用いた素過レベルからの解析を試みた。01年度において無電解Cu析出系に関する検討を行い、02年度には次々世代の極微細配線材料と目されているAg系の検討にも着手し、その反応経路に関する基礎的知見を得た。これらの成果を基に、本年度はCu、Pd、Ag表面における種々の還元剤系について系統的な検討を進め、金属表面の触媒活性を考える上で、表面に吸着した種の電子放出過程が最も重要であることを示唆する定量的結果を得た。
    さらに、電気化学マイクロリアクター用の三次元微小櫛歯電極配列をNi電解析出とAu無電解析出の組み合わせにより形成するプロセスを開発すると共に、超高感度X線画像センサー用のマイクロカロリメータ吸収体アレイの一括形成を、Sn電解法を用いたプロセスにより実現した。
    以上のように、本研究では、新規インテグレーションシステム形成のためのウェット系プロセスについて、理論、実験双方の見地から検討を進め、種々のデバイスおよびその形成のためのプロセスを確立することが出来た。本研究により得られた成果は、各々実デバイス形成への展開をはかりつつあるところであり、その推進と共に、反応過程の理論解析と連携させながら、ウェット系プロセス全体の体系化も進めていく予定である。

  • 酵素、抗体、DNAアッセイのための分子認識・半導体マルチセンシングデバイスの構築

    科学研究費助成事業(早稲田大学)  科学研究費助成事業(萌芽研究)

    Project Year :

    2002
    -
    2003
     

     View Summary

    個々の生体分子の認識および生体反応に基づく分子レベルの反応解析等を照準とした超高感度な集積化マイクロバイオセンシングデバイスの構築を目的として、申請者らは、電極部において構造規制された機能性有機単分子膜を生体分子固定用のテンプレート表面として活用し、そこでの生体反応に伴う表面電位変化を電界効果トランジスタで直接的に電気信号検出する新規センシングテバイスの構築に関する研究を推進した。このようなデバイスをオンチップで作製するために必要となる「単分子テンプレート」すなわち、異なる種類の官能基を有する単分子膜を各電極上に位置選択的に形成させた生体物質固定場の構築を昨年度より行ってきた。テンプレートはSiO2/Si基板上に修飾分子として、アルキル系、フッ化アルキル系、アミノ基末端を有するシラン分子を主に用いて形成した。その修飾表面のバルクでのpH応答特性ついて検討を行ったところ、アミノ修飾表面は良好なpH応答性を示し、一方でアルキル系、フッ化アルキル系分子修飾基板はpH応答性を示さないことが確認された。本年度においては、上記テンプレート形成技術を活用し、溶液耐性を有する有機単分子膜修飾電界効果トランジスタを作製したところ、アミノ基修飾デバイスはイオン感応性トランジスタとして、アルキル系、フッ化アルキル系分子修飾デバイスは参照用トランジスタとして動作することを見出した。一方で、フッ化アルキル分子をフィールド層とし、マイクロ・ナノスケールの局所場にアミン分子を形成したテンプレート上へDNAの固定化を試みたところ、アミノ分子修飾された局所場上にのみ、高い位置・反応選択的に固定化させることに成功した。上記成果は高精度な生体物質検出のためのオンチップイオン・バイオセンシングデバイスの構築に有用であると考えられる。

  • Analysis and control of the fluids, interfaces of liquid-liquid and liquid-solid in microchannels

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research

    Project Year :

    2001
    -
    2003
     

    SHOJI Shuichi, HOMMA Takayuki, FUNATSU Takashi

     View Summary

    Nano/micro flow systems open up the new possibilities for chemical and biochemical analysis and synthesis. For the design of nano/micro flow systems LSI designing concepts is applicable considering the symmetries between the electric devices and the flow devices. Nano/micro flow devices and elements which have micro meter scale sizes and nano liter volumes developed so far are described. Microvalves of negligible leakage and dead volumes were developed for chemical/biochemical applications. Micro mixers and sample injectors were obtained by using microfluidic behaviors in micro scale channels. In channel micro filters and electrochemical biosensors were fabricated using high aspect ratio UV photolithographic technologies. 3D metal electrodes implanted PDMS microflow cell was fabricated using 3D assembly method. Biological cell observation micro cell integrated on chip microvalve for regent injection was fabricated on Si substrate using deep RIE. Biomolecules sorting microsystems were. also realized using sol-gel transfer of hydrogels

  • 微生物機能を利用した資源循環型水環境プロセスの構築

    文部科学省 

    Project Year :

    1999
    -
    2003
     

  • Studies on sorting and fixing of. Bioiooiecules for high performance micro chemical/biochemical analysis systems

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research

    Project Year :

    2000
    -
    2002
     

    SHOJI Shuichi, HONMA Takayuki, FUNATSU Takashi

     View Summary

    Biomolecles handling microsystemsMicro biomolecules handling flow cell using 3-D sheath flow was fabricated. It uses the simple micro structure designed by MEMS CAD system. On the other hand, cross-linked methyl cellulose (MC) changes its state from liquid to gel by elevating the temperature up to 55 ℃. In order to realize micro flow control, we applied this phenomenon to realize micro flow switch for cell sorting. To achieve high speed sorting, we fabricated a PC controlled flow system consists of an automatic fluorescence sample detector, focused IR laser sorce, and two galvanometer mirrors for switching and scanning of the laser. The detection and switching time of 120 msec is achieved.Micro flow cell for multi-analyse bioaffinity assayA micro flow cell for the multi-analyse bioaffinity assay system was designed. It has two Teflon micro check values. Some different antibodies for clinical diagnostic were immobilized on center surface of the channel as bioaffinity probes, which realizes sequential multi-analyse assay. An efficient reaction with small sample volume is expected.Micro mixer/reactor using multilayer laminar flowAn efficient micromixer using nonhomogeneous multilaer in laminar flow regime was fabricated. To increase the mixing efficiency, the CFD simulation was used to optimize the width of the multilayers. It is estimated that the reagents mixing is proceeded much faster compared to previous multiplayer micro mixers.Metal electrodes implanted PDMS micro cellMetal electrodes or heaters implanted PDMS structures were proposed and fabricated. Prototype micro flow cell having two pairs of the parallel electrodes in order to control the electric field or the temperature is fabricated and evaluated

  • 固液界面電荷移動反応制御によるウェット系インテグレーション新プロセスの開発

    科学研究費助成事業(早稲田大学)  科学研究費助成事業(特定領域研究(A))

    Project Year :

    2001
     
     
     

     View Summary

    本研究はグローバルインテグレーションの要素技術であるウェットプロセスによる極微細金属構造体の形成において,本系に特有である固液界面電荷移動反応を理論的・実験的観点から素過程レベルで解明し,これに基づいた原子レベル界面制御を可能とする新規プロセスへと展開することを目的とした.特に高集積デバイス・回路配線形成のための無電解Cu析出プロセスを中心に検討した.
    まず無電解析出反応において電子放出過程を担う還元剤分子種の,金属表面サイトにおける反応について検討した.(111)結晶表面を想定したクラスタに還元剤分子種を配したモデル系を構築し,これ用いて非経験的分子軌道法により反応素過程の解析を行った.還元剤分子種として,無電解析出反応系に典型的に用いられる次亜リン酸,ジメチルアミンボラン,ヒドラジンおよびホルムアルデヒドを選定し,各々について系統的な検討を行った.その結果,各還元剤の吸脱着エネルギーバリアおよび反応バリアの差から,還元剤分子種の「還元能」および金属表面サイトの「触媒活性」を定量的に評価することが可能であることを明らかとした.さらにPd等の原子についても同様な解析を行い,Cuにおける結果との比較検討から,Cu析出のための還元剤種の選定には,反応中間体の吸脱着エネルギーの影響の考慮が重要であることを明らかとした.このような知見を基に,新規還元剤の探索を行った.特にナノ領域への均一・無欠陥形成を考慮し,微量不純物の混入が極力抑制され,かつ水素発生を伴わない系を中心に検討を行い,新たな無電解浴系を開発した.

  • 傾斜機能材料の電気的・磁気的性質

    科学研究費助成事業(京都工芸繊維大学)  科学研究費助成事業(重点領域研究)

    Project Year :

    1996
    -
    1998
     

     View Summary

    1. 傾斜機能誘電体基板の研究では,バリウムチタネイトを主体とした多孔体に液体状態のケイ素源を拡散含浸処理後,最終焼成を行うことによって,従来から困難とされていた1mm前後の領域での傾斜機能化が達成できた.
    2. 傾斜構造を有するエネルギー変換材料の研究では,傾斜機能焦重体サンプルを作製し,積層方向およびそれと垂直な方向での焦電特性を,我が国で初めて明らかにした.
    3. 傾斜機能圧電材料の研究では,作製プロセスを改良した傾斜型圧電アクチュエータを試作し,昨年度までの応力緩和計算シュミレーション結果が有効であることを確認した.
    4. 電気メッキ法による傾斜機能磁性薄膜の研究では,磁気特性に直接関係する薄膜断面の微細構造解析,膜析出挙動解析,並びにリング型記録ヘッドの磁界分布を念頭に置いた性能の評価を行い,理論的予測と一致することを確認した.
    5. 高周波用傾斜機能磁性材料の研究では,鉄-ニッケル合金とフエライトの傾斜機能磁性材料をクラックなしで焼結させ,10MNzまでの高周波磁気特性を評価できた.
    6. 傾斜機能化電極・固体電解質の研究では,電子・イオン混合導電体電極内の酸素イオン拡散特性の評価を行い,混合導電体電極の単セル試験によって性能評価を行った.
    7. 強誘電体・強磁性体傾斜機能材料の研究では,レーザMBE法によって作製した強誘電体/強磁性体傾斜機能材料の格子歪み,化学結合,強相関電子系パラメータ制御によって,電場によるスピン制御,低磁場での巨大磁気抵抗の出現などを確認できた.
    8. 傾斜的磁性制御の研究では,フェロ-フェリ混合分子磁性薄膜を作製し,磁気光学的および非線形光学的挙動を明らかにした.

  • 強磁性ナノ結晶集合体の高次構造形成過程のin situ解析と機能発現機構の解明

    科学研究費助成事業(早稲田大学)  科学研究費助成事業(奨励研究(A))

    Project Year :

    1996
     
     
     

     View Summary

    本研究では,ナノ結晶が集合し高次構造を形成する過程のin situ解析を試みることにより,高次構造の形成メカニズムやその機能特性発現機構を解明すると共に,これを基に高次構造制御による新規機能材料の創製を試み,このような新しい観点からの材料設計手法を拓くことを目的とした.
    まず申請者が従来検討を進めてきた,無電解析出法による非導電表面上へのNiPアモルファス薄膜およびCo系垂直磁気異方性薄膜の析出過程について,タッピングモード原子間力顕微鏡(TMAFM)を用いてnmレベルの定量解析を行った.TMAFMは試料表面に与えるダメ-ジが極めて小さいため,初期核発生時からμmオーダー厚程度までの成長過程の連続的観察が可能である.得られた像よりRMSラフネス値を算出し,これを基にスケーリング解析を行った.その結果,膜成長状態は初期の核発生密度に大きく依存し,その差異により高次構造形成モードが変化することが明らかとなった.このような核発生密度の差異について,析出基板表面の電気化学的触媒活性度という観点から詳細に検討を加え,その影響を明らかにすると共に,化学的処理プロセスにより触媒活性度の積極的制御が可能であることを明らかとした。
    一方,このような初期析出時においては,核発生密度によらず,膜成長と共にRMSラフネスが減少する,即ちレベリング作用が生じていることが明らかとなった.これは通常の手法(スパッタ・MBE等)における薄膜成長とは全く異なる,非導電基板上への無電解析出特有の現象であり,今後このような特徴を利用したナノレベル微細構造制御の糸口が得られた.

  • 高機能強磁性ナノ結晶集合体の電気化学的創製およびその集合体形成メカニズムの解析

    科学研究費助成事業(早稲田大学)  科学研究費助成事業(奨励研究(A))

    Project Year :

    1995
     
     
     

     View Summary

    本研究ではナノ結晶集合体の形成機構およびそれに影響を与える諸因子の解明,さらに集合状態と微少領域における機能特性の相関性を解明することを目的に,機能特性が極めて構造敏感なことが従来の申請者の検討により確認されている,無電解Co系垂直磁気異方性薄膜(二次元ナノ結晶集合体)を中心に検討を行った.
    まず組成が極めて単純かつ常温での形成が可能な無電解CoNiP浴系を開発した.この系においてはpH値により膜の磁気特性が大きく変化し,最適点では保磁力2500Oeという高い機能特性を示すものが得られることが確認された.またin situ STM解析を行った結果,10nm径程度のナノ結晶が集合し数十nm径程度の粒子群を形成しながら成長していることが明らかとなった.一方無電解析出薄膜においては従来微細構造変化は浴中の金属イオンの錯体形成状態によるとされていたが,in situ UV-Vis解析により浴中の錯状態を検討したところ膜微細構造との相関性は認められず,基板表面でのadatom拡散状態等が膜微細構造形成を支配していることが示された.
    次に,微少領域における機能特性の解析について磁気力顕微鏡(MFM)を用いて詳細な解析を行った.この検討には,特異な磁化状態の形成がこれまでの申請者の検討で確認されている,無電解析出複合薄膜(CoNiReP/CoB系およびCoNiReP/CoNiP系)を用いた.まず各薄膜に同一磁界強度で微少磁化領域形成を行い,その状態をMFM観察した結果,複合型薄膜は単層薄膜より強く磁化されると共に,磁化転移領域の磁界勾配も急峻となるのが認められた.ここで両複合型媒体においても微少磁化状態に差異がみられたため,これらについて更に磁化強度を変化させて系統的検討を行ったところ,微少磁化モードは下層部の保磁力(Hc_<(u)>)値の影響を強く受けることが明らかとなった.このような磁化転移状態は申請者のグループを始めとした内外の研究グループにより予想されていたが,今回初めて直接的に確認されると共に,その定量的評価がnmオーダーで可能となった.

  • 電気化学的手法による高機能薄膜作製におけるエピタキシ-制御手法の確立

    科学研究費助成事業(早稲田大学)  科学研究費助成事業(奨励研究(A))

    Project Year :

    1994
     
     
     

     View Summary

    本研究は,電気化学的手法による機能薄膜作製において,特に“エピタキシ-"に着目し,これに影響を与える諸因子を明らかにすると共に,それらを利用したエピタキシ-制御手法を確立することを目的に研究を行った.その際,特に本手法独特の成膜因子を制御パラメータの中心とし,蒸着,スパッタ等の物理成膜法では不可能な,本成膜法ならではの高度な膜微細構造制御手法の確立を念頭に検討を進めた.
    まず申請者が従来より検討対象としてきた無電解析出法のよるCo合金薄膜を対象に検討を進めた.c軸が基板面に垂直に配向したhcp構造を有する無電解CoNiReP薄膜を同軸が面内配向した無電解CoP薄膜上に直接成膜したところ,通常のエピタキシ-効果によりCoNiReP上層は両内配向構造となり,またその磁気特性もCoP膜に類似のものとなった.両層間に数nm厚程度の中間層を付与したところ膜成長のエピタキシ-は断ち切れたが,同時に両層間の磁気的相互作用(交換結合)も断ち切られた.そこで,CoP下地表面に,無電解折出反応に対し高い触媒能を示すPdを付与したところ,その吸着量は0.5ML以下であるものの表面の優先析出(エピタキシャル成長)サイトに効果的にクラスタを形成する結果,磁気的相互作用を保ったままでエピタキシャル成長を抑制可能であることが明らかとなった.このような手法を用いて,従来は作製不可能であった垂直面内複合型磁気ディスクを得,その記録再生特性が極めて良好であることを明かとし,このようなエピタキシ-制御手法の有効性を確認した.さらに主々の因子の与える影響の詳細な解析の推進が可能な新浴系を開発すると同時に種々の電気化学的パラメータの影響を検討し,従来通説とされていた,金属イオンの錯状態の影響は必ずしも一義的なものでないことを明らかにした.
    以上の検討より得られた結果を基に,次のステップとして,より高度な機能を発現する薄膜(多層膜,人工超格子膜等)材料創製への展開を目指す予定である.

  • 無電解析出法による高機能薄膜生成機構の走査トンネル顕微鏡によるin situ解析

    日本学術振興会  科学研究費助成事業

    Project Year :

    1992
     
     
     

    本間 敬之

  • 電気学的手法による高機能磁性薄膜材料の創製

    科学研究費助成事業(早稲田大学)  科学研究費助成事業(重点領域研究)

    Project Year :

    1992
     
     
     

     View Summary

    本研究は、電気化学的手法を用いて機能性薄膜材料を創製する際の基礎的材料設計指針を得ることを目的とし、代表的電気化学成膜法である無電解めっき法による高機能磁性薄膜を中心に研究を行うものである。本年度は、まず前年度に開発した無電解CoNiP垂直磁気記録媒体の機能特性と微細構造の相関性について詳細な検討を行った。この膜はc軸が基板面に対し垂直配向したhcp構造をとる結果垂直異方性が発現することが確認されているが、平均膜組成はNiリッチであり、CoNiバルク合金の平衡状態においてはfcc構造のみが安定な領域である。そこで、熱処理法およびスピンエコー^<59>Co-NMR法により検討を行った結果、この膜は成膜時において組成不均一であり、特にCoリッチな成分が存在することにより高Hcなどの特性が発現していることが明かとなった。次にこのようなCoリッチ成分の膜中での存在状態を確認するため選択化学エッチング法を用いた解析を行い、Coリッチな強磁性微粒子が非磁性領域に分散偏析した微細構造をとる結果、超高分解能・超高密度記録に適した機能特性が発現いていることが明かとなった。
    続いて前年度に開発いた無電解CoB軟磁性薄膜について、更なる特性向上という観点から種々の検討を試みたが、特に成膜後の磁場中然処理が有効であることが明かとなった。成膜後に2k0e程度の外部磁界を印加しながら真空中にて30min程度熱処理することにより異方性磁界Hkが減少すると共に、透磁率μの上昇が見られた。μ上昇は処理温度により異なるが、150^゚C熱処理において最大値(2000以上)が得られた。

  • 電気化学的手法による高機能薄膜析出素過程および機能発現機構の解明

     View Summary

    電気化学的成膜法(電析法・無電解析出法など)は,物理的成膜法(蒸着・スパッタ等)では困難な精密成膜が原理的に可能であるが,析出過程が複雑で不明点が多い.そこで本研究では電気化学的手法による薄膜析出過程を素過程レベルから解析すると共に,形成された膜の機能発現機構を明らかにすることにより,本手法による機能薄膜材料分野に新たな可能性を拓くことを目的としている.前年度の検討より析出反応機構素過程の分子軌道論的モデルおよび薄膜物性(微細構造と機能特性の相関)に関する基本的知見が得られているので.本年はこれらをより精密化させながら,得られた結果全体の体系化を目指した.まず無電解析出反応柔過程(特に還元剤分子種の酸化反応過程)の非経験的分子軌道法のよる解析について,次亜リン酸や三塩化チタンなどの分子種を対象に検討を行った.その結果,次亜リン酸の場合,前年度検討を行ったジメチルアミンボランと同様に,5配位型の中間体構造をとりながら進行する反応素過程がエネルギー的に安定であることが明らかとなった.一方,三塩化チタンについては,電子放出が反応の最終段でおこることが示唆された.次に,これらの反応に対し触媒性を有する,析出表面における活性サイトについて,原子間力顕微鏡(AFM)によるキャラクタリゼーションを試みた,前年度行った無電解NiP薄膜系の結果を基に,無電解CiNiP磁性膜を対象に検討した.その結果,活性サイトの活性度には,溶液中に存在する遊離アンモニウムイオンの濃度が影響し,これが高い場合,サイトに対するブロッキングが起こり,結晶粒成長が阻害される結果,微細な粒子から成る保磁力の低い膜が成長することが明らかとなった.以上得られた結果を総合して,無電解析出反応〜膜成長〜機能特性発現の相関を系統的に明らかにし,新しい機能を有する無電解薄膜材料を設計する指針を得た

  • ウェットデバイスプロセスにおけるシリコン表面反応素過程の電気化学的手法による解明

     View Summary

    本研究は,ITインフラストラクチャーの基盤技術であるシリコンデバイスプロセスにおいて重要な位置を占める液相系(ウェット)デバイスプロセスにおいて,特にシリコン表面での化学反応に関して,液相中の反応種の状態やシリコン表面の電気化学的および物理的・化学的性質の原子レベルからのキャラクタライゼーションを行い,これらの関与する反応を素過程レベルで解明すると伴に,得られた知見を基に新規デバイスプロセス設計の方法論を確立することを目的とした.昨年度の研究により,シリコンウェハ表面に存在するナノ欠陥部位において,局所的に電位が卑(カソード側)にシフトしていることを見出し,このようなサイトが金属の還元析出反応に対し高い活性を有しているということを明らかとした.今年度はこれに基づき,種々のレベルの欠陥における電位シフトの状態について検討し,両者の相関に対する系統的知見を得た.さらに,固液界面反応に大きく関わる溶存酸素の影響について,超純水中における極微量金属イオン種(Cu,Fe)のウェハ表面への析出反応についても詳細な検討を進めた.その結果,ppbレベル以下の極希薄濃度領域において,溶存酸素が存在する場合にはこれら金属種は主にシリコン表面酸化膜中に酸化物または水酸化物として取り込まれること,また溶存酸素を除去すると,Cuは電気化学的還元反応によりメタリックな状態でウェハ表面に極微小粒状に析出するのに対し,Feはそのような析出状態は示さないことを見出した.そして,このような差異の原因が,CuとFeの電気化学的酸化還元電位にあることを明らかとした.以上の結果は,今後要求される超清浄シリコンウェハ表面を実現するためのプロセス反応設計に重要な指針を与えるものである

  • シリコン表面ナノ領域の電気化学的特性解析と新規ウェットプロセスへの展開

     View Summary

    液相中でウェハ表面を処理するウェットプロセスは,表面の超清浄化やULSIチップ内部の微細銅配線形成など,デバイスプロセスの重要な部分を担っている.本研究はこのウェットプロセスに着目し,シリコン単結晶表面の電気化学的特性をnmレベルの分解能で定量的に解析し,これを基にした新規ウェットデバイスプロセス(シリコン表面微細加工・微細修飾など)の開発を目的とした.前年度の研究において,ウェハ表面におけるナノレベルの欠陥をナノインデンテーション法により精密に形成する手法およびその特性を表面電位顕微鏡(SPoM)により定量的に測定する手法を開発した.これを基に,本年度は種々のナノ構造を形成可能なプロセスの確立を試みた.まず,ナノインデンテーション法による表面欠陥形成手法を改良し,ウェハ表面にナノ欠陥領域,すなわち析出活性領域をパターン形成する手法を開発した.次にこのようなパターンを有する表面を金属イオン種を含む溶液に浸せきすることにより,金属ナノ構造体を一括形成可能とするプロセスを開発した.Cu, Ag, Auなどの導電体およびCo系磁性体のナノ構造を高い選択性で自在に形成できるプロセスを開発することができた.これらのプロセスは現行のフォトリソグラフィー法のような複雑な手順や装置は一切必要としない,極めて単純かつ低環境負荷なものである.さらに,これらの成果を基にした,電子機能・磁気的機能・化学的機能(反応制御)を有するナノデバイス・システム,例えば集積回路内の受動型埋込部品(微細抵抗回路など)や,上記各種機能を有するナノドットアレイの選択的形成などへの本プロセスの適用に着手した.今後はこれらをさらに進展させ.本成果をさらに発展させる予定である

▼display all

Misc

  • Fabrication of magnetic nanodot array using electrochemical deposition processes

    Takanari Ouchi, Yuki Arikawa, Yohei Konishi, Takayuki Homma

    ELECTROCHIMICA ACTA   55 ( 27 ) 8081 - 8086  2010.11  [Refereed]

     View Summary

    We investigated fabrication processes of magnetic nanodot arrays for the ultra-high density magnetic recording media by using an electrodeposition A CoZrNb underlayer was sputter-deposited on a glass disk substrate as a soft magnetic underlayer (SUL) Nano-patterns were formed on the substrate by UV-nanoimprint lithography (UV-NIL) and CoPt was electrodeposited into the nano-patterns For obtaining uniform CoPt nanodot arrays with high perpendicular coercivities we applied thin Cu intermediate layer on CoZrNb SUL and minimized its thickness As a result we obtained CoPt nanodot arrays with 150-nm diameter 300-nm pitches and 20-nm heights which have uniform structures on the substrates with the construction of Cu (1-2 nm)/CoZrNb (100 nm)/Cr (5 nm)/glass disk The perpendicular coercivity of the CoPt nanodot arrays was as high as 5 4 kOe From these results we showed that the Cu intermediate layer with even 1-2 nm thick considerably improved the deposition condition on the substrates with CoZrNb SUL to successfully fabricate CoPt nanodot arrays with the diameter and pitches of 80 nm and 160 nm with sufficient uniformity (C) 2010 Elsevier Ltd All rights reserved

    DOI

  • Electrochemical Fabrication and Characterization of CoPt Bit Patterned Media: Towards a Wetchemical, Large-Scale Fabrication

    Takanari Ouchi, Yuki Arikawa, Taisuke Kuno, Jun Mizuno, Shuichi Shoji, Takayuki Homma

    IEEE TRANSACTIONS ON MAGNETICS   46 ( 6 ) 2224 - 2227  2010.06

     View Summary

    This paper describes the fabrication process of CoPt nandot arrays on a glass disk substrate with a CoZrNb underlayer as a soft magnetic underlayer (SUL) by using an electrochemical process, and also the analysis on the magnetic properties of these fabricated CoPt nanodot arrays. We formed nano-patterned substrates by UV-nanoimprint lithography (UV-NIL) on the glass disk substrate. CoPt was electrodeposited into the nano-patterned substrates optimizing the electrodeposition condition and bath composition as well as a Cu intermediate layer. The construction of the nanodot arrays were CoPt nanodot arrays (20 nm)/Cu (5 nm)/CoZrNb (100 nm)/Cr (5 nm)/Glass disk. Magnetic signals were clearly observed on the dc magnetized state and multi domain were observed in each nanodot on the ac magnetized state by magnetic force microscopy (MFM). The perpendicular coercivity of the CoPt nanodot arrays was 430 kA/m. These results showed electrochemical process can be used for the manufacture of magnetic recording media.

    DOI CiNii

  • Magnetization Reversal Process of Hard/Soft Nano-Composite Structures Formed by Ion Irradiation

    M. Aniya, A. Shimada, Y. Sonobe, K. Sato, T. Shima, K. Takanashi, Simon J. Greaves, T. Ouchi, T. Homma

    IEEE TRANSACTIONS ON MAGNETICS   46 ( 6 ) 2132 - 2135  2010.06

     View Summary

    Discrete track media (DTM) and bit-patterned media (BPM) are being extensively studied as routes to achieve higher density hard disk drives. In the DTM and BPM, it is essential to isolate the data tracks or bits with non-magnetic materials to reduce the magnetic noise from adjacent tracks or bits. In contrast to the conventional procedure of physically etching the media, we attempted to isolate the tracks or bits with soft regions using an area-selective ion irradiation method. We prepared hard and soft nano-composite structures by nanoimprinting, followed by ion irradiation. In this study, we confirmed the magnetic reversal process of the hard and soft regions of the nano-composite structure using magnetic force microscopy (MFM) with various external applied magnetic fields. The analysis of the magnetization reversal process of patterned Coupled Granular Continuous (CGC) films with weak exchange coupling confirmed the validity of this novel approach for the fabrication of DTM and BPM.

    DOI CiNii

  • Electrochemical etching process to tune the diameter of arrayed deep pores by controlling carrier collection at a semiconductor-electrolyte interface

    Hirotaka Sato, Takuya Yamaguchi, Tetsuhiko Isobe, Shuichi Shoji, Takayuki Homma

    ELECTROCHEMISTRY COMMUNICATIONS   12 ( 6 ) 765 - 768  2010.06

     View Summary

    An approach to control the diameter of high-aspect-ratio pores formed into a silicon wafer by an electrochemical etching process is reported. Hole (h(+)) was involved in the etching reaction and the collection of the h(+) was the key factor. Artificial micro-cavities were fabricated on the silicon surface prior to the etching. The depth of the space charge region (SCR), Schottky barrier on the silicon-electrolyte interface, was adjusted regarding the depth of the micro-cavities by applied overpotential and specific resistance of the silicon wafer. The collection of h at the tip of the cavity site was widely controlled by the adjusted SCR. Consequently the electrochemically etched domain at the cavity site was actively tuned, and then high-aspect-ratio pore with the controlled diameter was formed. The diameter was tuned by the SCR depth which was controlled by the overpotential and the specific resistance. The diameter tuning mechanism worked under the mask-free condition. (C) 2010 Elsevier B.V. All rights reserved.

    DOI CiNii

  • Synchrotron radiation-induced total reflection X-ray fluorescence analysis

    F. Meirer, A. Singh, G. Pepponi, C. Streli, T. Homma, P. Pianetta

    TRAC-TRENDS IN ANALYTICAL CHEMISTRY   29 ( 6 ) 479 - 496  2010.06

    Book review, literature introduction, etc.  

     View Summary

    Synchrotron radiation-induced total reflection X-ray fluorescence (SR-TXRF) analysis is a high sensitive analytical technique that offers limits of detection in the femtogram range for most elements. Besides the analytical aspect, SR-TXRF is mainly used in combination with angle-dependent measurements and/or X-ray absorption near-edge structure (XANES) spectroscopy to gain additional information about the investigated sample. In this article, we briefly discuss the fundamentals of SR-TXRF and follow with several examples of recent research applying the above-mentioned combination of techniques to analytical problems arising from industrial applications and environmental research. (C) 2010 Elsevier Ltd. All rights reserved.

    DOI

  • Transient mass transfer rate of Cu2+ ion caused by copper electrodeposition with alternating electrolytic current

    S. Kawai, M. Ogawa, K. Ishibashi, Y. Kondo, T. Matsuoka, T. Homma, Y. Fukunaka, S. Kida

    ELECTROCHIMICA ACTA   55 ( 12 ) 3987 - 3994  2010.04

     View Summary

    Copper electrolysis is carried out in a stagnant 0.05 M CuSO4 aqueous electrolyte under alternating current (AC) condition. Transient mass transfer rate of Cu2+ ion caused by copper electrodeposition with AC is studied theoretically and experimentally with the holographic interferometer. The effect of buoyancy convection developing along the vertical plane electrodes on the transient concentration boundary layer (CBL) structure accompanying with AC is focused on. Two different electrode configurations, the horizontal cathode over anode and the vertical electrode settings, are employed for this purpose. The CBL thickness tends to increase over long duration time in the former configuration, while it converges to a steady-state value in the latter. Both calculated and measured concentration profiles in the vertical electrode configuration exhibit the characteristic transient behaviors composed of the pulsating CBL (PCBL) in the vicinity of the cathode surface and the stationary CBL (SCBL) outside the PCBL The appearance of the SCBL is ascribed to mass transfer by advection, and the overall CBL thickness depends on the hydrodynamic conditions such as the magnitude of buoyancy convection. (C) 2010 Elsevier Ltd. All rights reserved.

    DOI CiNii

  • Effect of Tl-codeposition on Au Electrodeposition from Non-Cyanide Bath

    M. Saito, K. Inoue, K. Shiokawa, T. Homma

    FUNDAMENTALS OF ELECTROCHEMICAL GROWTH: FROM UPD TO MICROSTRUCTURES - SYMPOSIUM IN MEMORY OF PROF. EVGENI BUDEVSKI   25 ( 34 ) 87 - 96  2010

     View Summary

    Effect of Tl on the electrodeposition behavior of Au was investigated by electrochemical analysis, total-reflection X-ray fluorescene analysis, XRD, glow discharge optical emission spectrometer (GD-OES) and hardness measurement. The deposition rate increased with an increase in the amount of Tl addition to the bath. Tl was co-deposited at the interface between the seed layer and the Au films, as well as in the films. In as-deposited condition, the Tl contained films exhibited higher hardness compared with the Tl-free films, while both of them showed almost the same hardness after annealing. It was suggested that the hardness is correlated with the crystal orientation of the grains.

    DOI

  • High Perpendicular Coercivity Electroless Cobalt Alloy Films with 25 nm Thicknesses

    T. Ouchi, Y. Arikawa, T. Kuno, T. Homma

    ELECTRODEPOSITION OF NANOENGINEERED MATERIALS AND DEVICES 3   25 ( 41 ) 125 - 134  2010

     View Summary

    This paper describes the development of Co alloy films thinner than 50 nm with high perpendicular magnetic coercivity using an electroless deposition process. In order to obtain these films, we used a Cu underlayer for a heteroepitaxial growth of the Co alloys and an optimized bath composition which included sodium hypophosphite and hydrazine as reductants. As a results, the perpendicular coercivity of the films turned to be higher 3000 Oe at the initial deposition stage with the thickness lower than 80 nm. In particular, the high perpendicular magnetic coercivity of the film as thin as 25 nm thick was obtained. These results indicate that electroless deposition is applicable for formation of the films with high perpendicular magnetic coercivity by optimizing the deposition conditions.

    DOI

  • Fabrication of Nanogap Electrodes using Electrodeposition Process

    C. Kobayashi, S. Yoshida, M. Saito, Y. Wakayama, T. Homma

    ELECTRODEPOSITION OF NANOENGINEERED MATERIALS AND DEVICES 3   25 ( 41 ) 29 - 40  2010

     View Summary

    Laterally-enhanced growth of Au using electrochemical deposition from an electrode onto SiO2 surface modified with organic molecules for fabrication of nanogap electrodes was investigated. After modifying the SiO2 surface with self-assembled monolayers (SAMs) or dendrimer, electrodeposition was carried out and the enhanced lateral deposition was observed from the edge of Au electrode onto the SiO2 surface. In order to analyze the surface states modified with SAMs or dendrimer, X-ray photoelectron spectroscopy (XPS) were conducted and the existence of the organic molecules and Au ions on the SiO2 surface was confirmed. It was suggested that the enhanced lateral deposition was induced by the adsorbed Au ions. Furthermore, we tried to measure the electrical property of phthalocyanine molecular wire using the gap electrodes. In order to improve the contact state between the wire and the electrodes, electrodeposition was applied. As a result, improvement of contact state was observed from Current-Voltage characterization.

    DOI

  • Microstructure Formation within Films of Silicon using Electrochemical Anodization

    J. B. Ratchford, M. Saito, T. Homma

    Trans, Mat. Res. Soc.   35 ( 1 ) 69 - 72  2010

     View Summary

    The electrochemical anodization of silicon films in aqueous solutions containing hydrofluoric acid was investigated. The films were deposited onto fused quartz chips from poly-crystalline, phosphorous doped silicon using magnetron physical vapor deposition in argon plasma. X-ray diffraction from these films showed that the atomic structure of silicon was amorphous. Current-potential profiles of the films in hydrofluoric acid solutions showed a linear increase in current with increasing anodic potential, unlike the diffusion limited profiles obtained from arsenic-doped silicon (100) crystals. In order to form microstructures within selected regions of the silicon, an epoxy resin was lithographically patterned onto the surface of the silicon prior to anodization. Three-dimensional profiles of the film's surface after removal of the resin revealed that the regions of silicon protected by the resin had formed microstructures.

    DOI CiNii

  • In Situ Observation of Dendrite Growth of Electrodeposited Li Metal

    Kei Nishikawa, Takeshi Mori, Tetsuo Nishida, Yasuhiro Fukunaka, Michel Rosso, Takayuki Homma

    JOURNAL OF THE ELECTROCHEMICAL SOCIETY   157 ( 11 ) A1212 - A1217  2010

     View Summary

    The dendrite growth behavior of Li metal galvanostatically electrodeposited on Ni substrate in a LiClO(4)-propylene carbonate electrolyte solution was in situ observed by a laser scanning confocal microscope with a metallographic microscope. A Li dendrite precursor is stochastically evolved on Ni substrate probably through a solid electrolyte interphase layer produced by the surface chemical reaction between a reduced Li metal and an organic electrolyte. The measured length of randomly growing Li dendrite arms was statistically analyzed. The initiation period of the dendrite precursor becomes shorter with increasing current density and decreasing LiClO(4) concentration. Once it has been initiated, the ionic mass transfer rate starts to govern the growth process of the dendrite arm length, exceeding over the surface chemistry controlling step. The dendrite arm length averaged over the substrate surface grows linearly proportional to the square root of time. The lower the concentration of LiClO(4), the steeper the inclination of the line at 5 mA cm(-2), whereas the concentration dependence of inclination is not evident at 0.5 mA cm(-2). (C) 2010 The Electrochemical Society. [DOI: 10.1149/1.3486468] All rights reserved.

    DOI CiNii

  • Magnetic Properties of Patterned CGC Perpendicular Films With Soft Magnetic Fillings

    M. Aniya, A. Mitra, A. Shimada, Y. Sonobe, T. Ouchi, Simon J. Greaves, T. Homma

    IEEE TRANSACTIONS ON MAGNETICS   45 ( 10 ) 3539 - 3542  2009.10

     View Summary

    To increase the areal density of hard disk drives (HDDs), discrete track media (DTM) and bit-patterned media (BPM) are being extensively studied. In the DTM and BPM, it is essential to isolate data tracks or bits. Unlike isolating the data tracks or bits using the conventional procedure involving physical etching, we attempted to isolate the tracks or bits with a soft guard band using an area-selective ion irradiation method. We prepared hard and soft (H/S) patterned films by nanoimprinting followed by ion irradiation. We confirmed the magnetic isolation of tracks and bits using magnetic force microscopy (MFM) images and magnetooptical Kerr effect (MOKE) signals. The results of an analysis of the magnetic properties of patterned coupled granular continuous (CGC) films with weak exchange coupling confirmed the validity of this novel approach for the fabrication of DTM and BPM.

    DOI CiNii

  • Electrochemical Fabrication of CoPt Nanodot Arrays on Glass Disks by UV Nanoimprint Lithography

    T. Ouchi, Y. Arikawa, J. Mizuno, S. Shoji, T. Homma

    Electrochem. Soc. Trans.   16 ( 45 ) 79 - 84  2009

    DOI

  • Electrochemical Evaluation and Finite Element Structural Analysis of Si Wafer Surface under Mechanical Stress

    K. Sakata, T. Homma

    Electrochem. Soc. Trans.   16 ( 40 ) 79 - 84  2009

    DOI

  • Preparation of electrodeposited Pt nano patterned electrode using UV-nano imprinting lithography

    M. Saito, J. Mizuno, H. Nishikubo, H. Fujiwara, T. Homma

    ECS Transactions   16 ( 25 ) 131 - 136  2009

     View Summary

    We attempt to prepare the patterned electrode for the formation of nano particles using electrochemical deposition with the cathode whose surface has nano dot patterns. In particular, we applied electrodeposition of Pt and UV nano imprinting lithography (UV-NIL) to prepare the nano patterned electrode. In order to achieve higher activity, the deposition condition of Pt was optimized using additives such as polyethylene glycol (PEG). The surface activity of the Pt films was affected by molecular weight of PEG. It was revealed that the surface activity of the films deposited with the order of thousands of molecular weight of PEG indicated the highest effective current density among the examined films. The Pt films, which exhibited the highest current density, were adapted to fabricate nano-patterned electrode with 400 nm pith periodic structure using UV-NIL. ©The Electrochemical Society.

    DOI

  • Raman Microscopy and Scanning Surface Potential Microscopy Analysis of Nanoscale Defects on Si Wafer Surfaces

    Takayuki Homma, Masahiro Kato, Nobuhiro Kubo, Kaoruho Sakata, Masahiro Yanagisawa

    JOURNAL OF THE ELECTROCHEMICAL SOCIETY   156 ( 6 ) H475 - H478  2009

     View Summary

    Nanometer-scale defects on the surface of a Si wafer, fabricated by nanoindentation technique, were examined using Raman microscopy and scanning surface potential microscopy to determine the quantitative relation between surface potential shift and Raman shift. Formation of cracks has not observed at the defect sites, indicating that the plastic and elastic deformations were a major issue and that the residual stress from the plastic deformation was observed. The Raman peak of the array of defects formed by nanoindentation shifted to a lower wavenumber as the indentation force was increased. The results indicated that the amount of tensile strain increased with the indentation force, that is, tensile stress was dominant over the condition in the surrounded area, in the indentation-induced defects. Correspondingly, the surface potential of the defect arrays shifted to the negative direction with an increase in indentation force. These results suggest that the tensile stress at the defect site, indicated by the Raman shift, causes the negative shift in the surface potential, which is related to chemical reactivity. Furthermore, Raman shift of a single indent on a silicon-on-insulator (SOI) wafer was observed, which revealed an enhancement in the source-to-noise ratio of the Raman spectrum at the Si defect site, because the ratio of the volume of the defect site to that of the unstrained site increased due to the thin Si layer on the SOI wafer.

    DOI CiNii

  • Effect of Cu Seed Layers on the Properties of Electroplated Sn-Cu Films

    M. Saito, H. Sasaki, K. Katou, T. Toba, T. Homma

    JOURNAL OF THE ELECTROCHEMICAL SOCIETY   156 ( 5 ) E86 - E90  2009

     View Summary

    Sn-Cu films were electroplated on Cu seed layers of various thicknesses. The velocity of the diffusion of Cu atoms from a seed layer into the electroplated Sn-Cu film was investigated, focusing on the effect of microstructural properties of the film. It was found that the diffusion velocity of Cu from a Cu seed layer into the electroplated Sn-Cu film increased with a decrease in the thickness of the Cu seed layer. Moreover, the film microstructure was influenced by the thickness of the Cu seed layer. When the crystalline quality of the Cu seed layer was inferior, a large lattice mismatch developed at the interface between the electroplated Sn-Cu film and the Cu seed layer. As a result of this lattice mismatch, many lattice defects and stress may exist at the interface between the electroplated Sn-Cu films and the Cu seed layers. Therefore, the lattice mismatch was considered to be related to the high-diffusion velocity of Cu from the Cu seed layer. Furthermore, the high-diffusion velocity of Cu was found to cause whisker formation. (C) 2009 The Electrochemical Society. [DOI: 10.1149/1.3090179] All rights reserved.

    DOI CiNii

  • Fabrication of CoPt magnetic nanodot arrays by electrodeposition process

    Takanari Ouchi, Yuki Arikawa, Takayuki Homma

    JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS   320 ( 22 ) 3104 - 3107  2008.11

     View Summary

    We attempted to fabricate patterned media using the electrochemical deposition process along with nanopatterned substrates prepared by the electron beam lithography (EBL), UV nanoimprint lithography (UV-NIL), and spin-on-glass nanoimprint lithography (SOG-NIL) approaches. CoPt was electrodeposited into the nanopatterned substrates and chemical mechanical polishing was carried out to planarize the surface. It was clarified that CoPt nanodot arrays were successfully deposited into the patterned nanopores fabricated by UV-NIL and SOG-NIL as well as by EBL with high area selectivity and uniformity. The density of the CoPt nanodot arrays deposited into the nanopores fabricated by EBL was equal up to an areal recording density of 250 Gbit/in(2). (C) 2008 Elsevier B. V. All rights reserved.

    DOI CiNii

  • Fabrication of catalyst-functionalized three-dimensional micromesh structures

    Satoshi Keino, Hironobu Sato, Takayuki Homma, Shuichi Shoji

    JAPANESE JOURNAL OF APPLIED PHYSICS   47 ( 6 ) 5204 - 5207  2008.06

     View Summary

    We present fabrication methods of functional three-dimensional (3-D) micromesh structures coated with titanium dioxide (TiO(2)) microparticles and biocatalysts. The 3-D micromesh structures are useful for fabricating highly efficient microreactors because of their large surface area. In this study, TiO(2)-embedded SU-8 micromesh structures were formed by coating a TiO(2)/SU-8 mixture onto the surface of SU-8 micromesh structures. Biocatalyst-immobilized micromesh structures were also formed by coating a biocatalyst/photopolymer mixture onto SU-8 micromesh structures.

    DOI

  • Characterization of the surface layer on a strained Si wafer by electrochemical methods

    Kaoruho Sakata, Masahiro Kato, Nobuhiro Kubo, Takeshi Senda, Koji Izunome, Takayuki Homma

    JOURNAL OF PHYSICAL CHEMISTRY C   112 ( 10 ) 3785 - 3788  2008.03

     View Summary

    To assess the surface reactivity of strained Si wafers, open circuit potential (ocp) measurement and scanning surface potential microscopy (SPoM) were carried out. Surface conditions of the wafers were varied by changing the structure of the wafers, i.e., the Ge content of the SiGe underlayer and the thickness of the strained Si layer. The ocp value of the strained Si was negative compared with that of nonstrained Si, and it shifted in the negative direction with an increase in Ge content of the SiGe layer and/or in the thickness of the strained Si layer, indicating that the degree of strain and/or the density of defects at the Si wafer surface affect its reactivity. In addition, the ocp value shifted in the positive direction to reach the value of the nonstrained Si, possibility due to stress relaxation, when the thickness of strained Si exceeds a certain value, which is expected to be the "critical" thickness. The SPoM analysis confirmed that the negative potential shift takes place locally at the surface, whose contrast was associated with the crosshatchlike surface morphology, suggesting that there is nanoscopic difference in strain at the strained surface.

    DOI CiNii

  • Estimation of redox potential of strained Si by density functional theory calculation

    Sakata, Kaoruho, Ishizaki, Shoji, Nakai, Hiromi, Homma, Takayuki

    Journal of Physical Chemistry C   112 ( 10 ) 3538 - 3542  2008

    DOI CiNii

  • Self-aligned formation of nano-holes to arrayed micro glass tubes

    Hirotaka Sato, Takuya Yamaguchi, Tetsuhiko Isobe, Takayuki Homma, Shuichi Shoji

    ELECTROCHIMICA ACTA   53 ( 1 ) 200 - 204  2007.11

     View Summary

    Microreactors and micro-fluidic devices require micro-tube structures to reserve and manipulate extremely small volume of liquid specimen, and nano-hole on the micro-tube is useful for its injection, aspiration and filtration, etc. In the present study, we attempted to develop a precise etching process to form nano-hole to the edge part of the micro glass tube by controlling SiO2 etching conditions with diluted aqueous HF solution. The arrayed micro-glass-tubes were fabricated by electrochemical etching of Si wafer followed by wet-thermal oxidation. The bottoms of arrayed micro-glass-tubes were exposed from Si wafer, which possessed pyramid-shape edges. The etching with optimized concentration of HF formed uniform nano-holes only at every bottom edge, indicating self-alignment of the etching process. The diameter of the nano-holes was controllable in the range of ca. 100-500 nm by adjusting the immersion duration and thickness of the glass tube. Nonlinear diffusion of fluoride species to the bottom edges could be the origin of the self-aligned formation of nano-holes at the bottom edges. (C) 2007 Elsevier Ltd. All rights reserved.

    DOI

  • Fabrication of metallic nanopatterns using the vacuum type UV-NIL equipment

    Makoto Fukuhara, Jun Mizuno, Mikiko Saito, Takayuki Homma, Shuichi Shoji

    IEEJ TRANSACTIONS ON ELECTRICAL AND ELECTRONIC ENGINEERING   2 ( 3 ) 307 - 312  2007.05

     View Summary

    Nanoscale dot patterns of cobalt alloy were formed on a silicon substrate using the ultra-violet nanoimprint lithography (UV-NIL) technology in combination with an electrodeposition process. We developed an improved UV-NIL equipment that can evacuate the chamber during imprinting. Using this equipment, we successfully imprinted 240-nm dot patterns with 500 nm pitch on a photocurable resin with high dimensional accuracy. Thickness control of the resin and imprinting under vacuum are important issues to obtain fine nanopatterns. Using these resin patterns as a mask layer, 300-nm cobalt alloy patterns are successfully formed by the electrodeposition process. (c) 2007 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

    DOI CiNii

  • Fabrication of magnetic nanodot arrays for patterned magnetic recording media

    Hirotaka Sato, Takayuki Homma

    JOURNAL OF NANOSCIENCE AND NANOTECHNOLOGY   7 ( 1 ) 225 - 231  2007.01

    Book review, literature introduction, etc.  

     View Summary

    Fabrication processes of arrayed magnetic nanodots for the use of patterned magnetic recording media were reviewed. One candidate for the patterned media is ordered assemble of magnetic nanoparticles, and the other is patterned magnetic thin films fabricated using various micro/nano scale machining processes. For the formation of patterned masks and molds, lithography processes as well as self-organized pattern formation are utilized. For the deposition processes of magnetic dots, electrochemical deposition processes were widely used. These fabrication processes are reviewed mainly from recent reports. The recording systems for the patterned media including probe-type-recording are also overviewed.

    DOI PubMed CiNii

  • Molecular orbital study on the oxidation mechanism of hydrazine and hydroxylamine as reducing agents for electroless deposition process

    Takuya Shimada, Amiko Tamaki, Hiromi Nakai, Takayuki Homma

    ELECTROCHEMISTRY   75 ( 1 ) 45 - 49  2007.01

     View Summary

    The oxidation mechanism of hydrazine and hydroxylamine were investigated using molecular orbital (MO) calculation. Two pathways for their reactions were verified. One is initiated by hydrogen elimination from the reducing agent, followed by coordination of hydroxyl group to center nitrogen atom accompanied with electron emission. Another is initiated by coordination of hydroxyl group to hydrogen atom to form H2O, which is eliminated later, followed by electron emission. The calculated results indicated that the oxidation reactions of hydrazine preferentially proceeded via the second pathway. It was also indicated that only the first electron emission steps of the hydrazine oxidation took place on Cu surface, while the following reactions proceeded at near the solid/liquid interface. The oxidation of hydroxylamine also proceeded via the elimination reaction of H2O. After the oxidation, calculated heats of reactions suggested that OH radical, generated from N2O as a product, decomposed hydroxylamine.

    DOI

  • Density functional theory study on the reaction mechanism of reductants for electroless Ag deposition process

    Takuya Shimada, Hiromi Nakai, Takayuki Homma

    JOURNAL OF THE ELECTROCHEMICAL SOCIETY   154 ( 4 ) D273 - D276  2007

     View Summary

    Oxidation reaction mechanisms of reductants for electroless Ag deposition process were investigated using density functional theory calculation, focusing upon behavior of the reaction intermediate species. It was indicated that the oxidation processes of reductants, such as dimethylamine borane, formaldehyde, and hypophosphite ion, on the Ag surface are initiated by addition of OH- and proceed via five-coordinate intermediate species. Catalytic activity of the Ag surface for the oxidation reaction of the reductants was investigated by using energy density analysis, focusing upon the local interaction of the species. The results indicated that the adsorption of the reductants onto the Ag surface is driven by destabilization of the reductant and stabilization of the Ag surface. It was also indicated that the destabilization of the five-coordinate intermediate species at the Ag surface is a key factor of the "catalytic activity" for the oxidation reaction. In the case of the reaction of formaldehyde, in which the Ag surface acts as catalyst, the intermediates were considerably activated at the Ag surface, whereas such an effect was not clearly seen with the hypophosphite ion, for which the Ag surface is not catalytic. It was also suggested that the activation of the intermediates is affected by coordination behavior of OH- species. (c) 2007 The Electrochemical Society.

    DOI CiNii

  • Electrochemical formation of intermediate layer for Co/Pd multilayered media

    Jun Kawaji, Koji Kimura, Toru Asahi, Takayuki Homma, Tetsuya Osaka

    JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS   303 ( 2 ) E128 - E132  2006.08

     View Summary

    Pd nanocluster seeds were formed on a soft magnetic underlayer (SUL) using an electrochemical substitution reaction, and were utilized as an intermediate layer for a Co/Pd multilayered ([Co/Pd](n)) perpendicular magnetic recording medium. A CoNiFeB film prepared with electroless deposition was used as SUL, which was immersed into a PdCl2 solution for the formation of Pd seeds. The Pd seeds were found to effectively reduce the size of magnetic domains in the [Co/Pd](n) film deposited on them. The optimization of the concentration of the PdCl2 solution and the use of the pretreatment process with a SnCl2 solution were effective to obtain the smooth SUL surface with fine Pd seeds as small as 5 nm. The 20 nm-thick [Co/Pd] n film deposited on the optimized Pd seeds/CoNiFeB SUL exhibited a high coercivity of 7.8 kOe and a small magnetic domain size of 69 nm. These results indicated that the combination of the Pd seeds and the electroless-deposited SUL was desirable in terms of the improvement not only in the magnetic properties of [Co/Pd] n media but also in the mass productivity of the underlayer. (C) 2006 Elsevier B.V. All rights reserved.

    DOI

  • Fabrication of high-aspect-ratio arrayed structures using Si electrochemical etching

    Hirotaka Sato, Takayuki Homma

    SCIENCE AND TECHNOLOGY OF ADVANCED MATERIALS   7 ( 5 ) 468 - 474  2006.07

    Book review, literature introduction, etc.  

     View Summary

    This paper reviews microscale processes to fabricate three-dimensional structures, in particular, high-aspect-ratio arrayed structures, using precise electrochemical etching process. Array of sharp micropits were pre-formed on the front side surface of Si wafer and the electrochemical etching was carried out using aqueous HF solution, with the back side illumination to generate holes, which diffused to the edge of the micropits to proceed the dissolution of Si with fluoride species. In order to form high-aspect-ratio pores at selected areas, a shade mask pattern was fabricated on the back side surface to align the illumination to the pre-patterned area on the front side surface. The parameters, such as HF concentration, current density and hole diffusion length, were optimized and uniform array of straight pores was formed into the designed area of Si wafer.
    Subsequently the surface of the pores was thermally oxidized to form SiO2 layers, and arrayed glass tubes with picoliter volume were fabricated. On the other hand, the pore filling with metal was attempted using electrodeposition to obtain array of the metal needles. For this, the "single batch" process was developed to form the pore array and metal filling with single electrolyte, and array of metal micro needles was successfully formed. These processes demonstrated capability and possibility of the electrochemical processes for microscale fabrication, and further precise processes can be developed using these approaches. (c) 2006 NIMS and Elsevier Ltd. All rights reserved.

    DOI CiNii

  • Adsorption of organic molecules by photochemical reaction on Cl : Si(111) and H : Si(111) evaluated by HREELS

    Katsuhiko Nishiyama, Yosuke Tanaka, Hiroshi Harada, Taro Yamada, Daisuke Niwa, Tomoyuki Inoue, Takayuki Homma, Tetsuya Osaka, Isao Taniguchi

    SURFACE SCIENCE   600 ( 10 ) 1965 - 1972  2006.05

     View Summary

    The covalent attachment of alkyl groups to silicon surfaces, via carbon-silicon bond formation, has been attempted using gas-surface reactions starting from Cl-terminated Si(111) or H:Si(111) under ultraviolet light irradiation. The formation of Cl-terminated Si(111) and its resulting stability were examined prior to deposition of organic molecules. High-resolution electron energy loss spectroscopy (HREELS) was utilized for detecting surface-bound adsorbates. The detection of photo-deposited organic species on CI:Si(111) from gas-phase CH4 or CH2=CH2 was not significant. On H:Si(111), it was evident that after the photoreaction with gas-phase C2H5Cl, C2H5 groups were chemically bonded to the surface Si atoms through single covalent bonds. The C2H5 groups were thermally stable at temperatures below 600 K. Alkyl monolayers prepared on silicon surfaces by dry process will lead to a new prospective technology of nanoscale fabrication and biochemical applications. (c) 2006 Elsevier B.V. All rights reserved.

    DOI CiNii

  • Evaluation of 256-pixel TES microcalorimeter arrays with electrodeposited Bi absorbers

    U Morita, Y Yamakawa, T Fujimori, Y Ishisaki, T Ohashi, Y Takei, K Yoshida, T Yoshino, K Mitsuda, NY Yamasaki, R Fujimoto, H Sato, Y Minoura, N Takahashi, T Homma, S Shoji, Y Kuroda, M Onishi

    NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT   559 ( 2 ) 539 - 541  2006.04

     View Summary

    We succeeded in fabricating 256-pixel arrays of Ti/Au transition edge sensor (TES) microcalorimeters with electrodeposited microabsorbers made of Bi, and report on their test results. We confirmed till pixels tested so far were alive, however most of the microabsorbers were stripped off during cooling cycles. We investigated some pixels by irradiating with 5.9 keV X-rays, and confirmed that they actually worked as microcalorimeters. The X-ray pulses are represented by a sum of two components with different decay times. The ratio of the two components fluctuates from pulse to pulse, which limits the energy resolution to similar to 200 eV. We discuss the pulse shape of two decay-time components considering thermal conductivities, i.e., inside microabsorbers, between microabsorbers and TES. (c) 2005 Elsevier B.V. All rights reserved.

    DOI

  • Density functional theory study on the oxidation mechanisms of aldehydes as reductants for electroless Cu deposition process

    T Shimada, K Sakata, T Homma, H Nakai, T Osaka

    ELECTROCHIMICA ACTA   51 ( 5 ) 906 - 915  2005.11

     View Summary

    The oxidation mechanism of aldehydes, which are commonly used as reductants for an electroless deposition process, was studied by using Density Functional Theory (DFT) calculations. The reaction pathway of the three aldehydes, i.e., formaldehyde, acetaldehyde and glyoxylic acid, with different functional groups, were examined by calculating energy profiles of all intermediate species. It was indicated that the pathway in an isolated system proceeds via dianion-free intermediate species. Taking the solvation effect into consideration, it was indicated that the oxidation reactions of the three aldehydes preferably proceed at the solid/liquid interface. In combination with a Cu metal cluster as a model of metal surface, it was also indicated that the oxidation reactions proceed preferentially at the Cu surface. It was expected that the adsorption/desorption energy at the Cu surface of glyoxylic acid, which has an electron-accepting carboxyl group, was smaller and substituent effect lead to its high reducibility. (C) 2005 Elsevier Ltd. All rights reserved.

    DOI

  • Preparation and characterization of electroplated amorphous gold-nickel alloy film for electrical contact applications

    N Togasaki, Y Okinaka, T Homma, T Osaka

    ELECTROCHIMICA ACTA   51 ( 5 ) 882 - 887  2005.11

     View Summary

    A process for electroplating amorphous gold-nickel alloy with the atomic ratio of unity was developed. The plating bath was prepared by adding potassium cyanoaurate(I) into a known plating bath which produces amorphous nickel-tungsten alloy. At a sufficiently high gold concentration, the alloy deposit did not contain any tungsten. The amorphous nature of the Au-Ni alloy produced in the new bath was confirmed by using TEM and THEED. Hardness, resistivity, and contact resistance of this new alloy were determined, and the results are discussed for applications as an electrical contact material. (C) 2005 Elsevier Ltd. All rights reserved.

    DOI

  • Fabrication of patterned nanostructures with various metal species on Si wafer surfaces by maskless and electroless process

    N Kubo, T Homma, Y Hondo, T Osaka

    ELECTROCHIMICA ACTA   51 ( 5 ) 834 - 837  2005.11

     View Summary

    Maskless and electroless fabrication was demonstrated to form patterned nanostructures of various metal species, based upon the process previously developed by the authors. In this process, the metallic nanostructures were formed on the surface of clean, hydrogen terminated p-(1 0 0) Si wafer with pre-patterned nanoscopic defects, which were confirmed to possess higher activity for the reductive deposition reaction of the metal ion species. The deposition was achieved spontaneously and selectively at the defect sites on the wafer surface by immersing into dilute aqueous fluoride solution containing trace amount of metal ion species. By optimizing the formation condition of the patterned defects and composition of the solution, fabrication of patterned nanostructures of various metallic species such as Au, Ag, and Co, was achieved. Formation of the patterned nanostructures to 10 mu m(2) in extent, as well as control of the feature size of the deposits by adjusting the formation condition of the pattemed defects were also attempted. (C) 2005 Elsevier Ltd. All rights reserved.

    DOI

  • Electrochemical analysis of zincate treatments for Al and Al alloy films

    M Saito, T Maegawa, T Homma

    ELECTROCHIMICA ACTA   51 ( 5 ) 1017 - 1020  2005.11

     View Summary

    Electrochemical behavior of At and At alloy films in zincate solution was investigated to elucidate the effect of the zincate pretreatment for electroless NiP deposition, which is used for under bump metallization for LSI interconnects. The immersion potential for AlCu and AlSiCu, immediately reached to constant, which was almost equal potential to zinc reference electrode. The corrosion current for the AlCu and AlSiCu films was larger than that of the At and AlSi films in the zincate solution. It was also confirmed that the deposited Zn at the surface of AlCu and AlSiCu films possessed smaller grain size and larger amount of nucleation, resulted in the formation of flat NiP films. (C) 2005 Elsevier Ltd. All rights reserved.

    DOI

  • Characterization of strained Si wafer surface by density functional theory analysis

    K Sakata, T Homma, H Nakai, T Osaka

    ELECTROCHIMICA ACTA   51 ( 5 ) 1000 - 1003  2005.11

     View Summary

    Using first-principles total energy calculations within density functional theory (131717), we investigated the surface properties, especially focusing upon the surface reactivity, of strained Si layer deposited onto SiGe underlayer, in comparison with normal (non-strained) Si surface. We used a cluster model as the surface of the strained Si and normal Si, and results of our calculation indicate that, when the Si possessed strained condition, the total energy is destabilized and the value of the gap between HOMO and LUMO became smaller than that of normal Si. In addition, we estimated the reactivity of the strained Si and normal Si surfaces with trace metal ion species in solution. As a result of the adsorption energy calculation of Cu2+, Ni2+ and Fe2+ to Si (100) surface, it was suggested that the adsorption energy of the metal ion species to the strained Si surface is more stable than that of the normal Si. (C) 2005 Elsevier Ltd. All rights reserved.

    DOI

  • Picoliter volume glass tube array fabricated by Si electrochemical etching process

    H Sato, T Homma, K Mori, T Osaka, S Shoji

    ELECTROCHIMICA ACTA   51 ( 5 ) 844 - 848  2005.11

     View Summary

    Fabrication process for picoliter volume SiO2 glass tube array partially embedded in Si wafer was developed. As a template for the glass tubes, macropore array was formed at the surface of n-Si(1 0 0) wafer by photo-assisted electrochemical etching process. The area-selective formation of the array was achieved by applying Au/Cr micropatterns formed at the back-side surface of the substrate as the shade mask, which controls the illumination condition to optimize the etching reaction conditions. Subsequently, surface of the macropores was wet-thermally oxidized to form glass layer, and the bulk Si region was removed by alkaline etching, remaining the "glass tubes". As a result of complete removal of the bulk Si, released glass tubes were obtained. By partial removal of the bulk Si part, the glass tubes were exposed, fixed in the remaining Si substrate in the form of well-ordered array. It was confirmed that the depth, the exposed region and the wall thickness of each glass tube were controllable by adjusting the parameters such as the duration of the Si electrochemical etching, the alkaline etching and the wet-thermal oxidation, respectively. In order to demonstrate microreaction in the glass tube, aqueous rhodamine B solution was injected into the tubes and excitation light was irradiated to them. As a result, the fluorescence of rhodamine B was clearly detected, confirming the applicability of the glass tubes for various kinds of devices and systems such as microreactors. (C) 2005 Elsevier Ltd. All rights reserved.

    DOI

  • Density functional theory study on the oxidation mechanisms of aldehydes as reductants for electroless Cu deposition process

    T Shimada, K Sakata, T Homma, H Nakai, T Osaka

    ELECTROCHIMICA ACTA   51 ( 5 ) 906 - 915  2005.11

     View Summary

    The oxidation mechanism of aldehydes, which are commonly used as reductants for an electroless deposition process, was studied by using Density Functional Theory (DFT) calculations. The reaction pathway of the three aldehydes, i.e., formaldehyde, acetaldehyde and glyoxylic acid, with different functional groups, were examined by calculating energy profiles of all intermediate species. It was indicated that the pathway in an isolated system proceeds via dianion-free intermediate species. Taking the solvation effect into consideration, it was indicated that the oxidation reactions of the three aldehydes preferably proceed at the solid/liquid interface. In combination with a Cu metal cluster as a model of metal surface, it was also indicated that the oxidation reactions proceed preferentially at the Cu surface. It was expected that the adsorption/desorption energy at the Cu surface of glyoxylic acid, which has an electron-accepting carboxyl group, was smaller and substituent effect lead to its high reducibility. (C) 2005 Elsevier Ltd. All rights reserved.

    DOI

  • Preparation and characterization of electroplated amorphous gold-nickel alloy film for electrical contact applications

    N Togasaki, Y Okinaka, T Homma, T Osaka

    ELECTROCHIMICA ACTA   51 ( 5 ) 882 - 887  2005.11

     View Summary

    A process for electroplating amorphous gold-nickel alloy with the atomic ratio of unity was developed. The plating bath was prepared by adding potassium cyanoaurate(I) into a known plating bath which produces amorphous nickel-tungsten alloy. At a sufficiently high gold concentration, the alloy deposit did not contain any tungsten. The amorphous nature of the Au-Ni alloy produced in the new bath was confirmed by using TEM and THEED. Hardness, resistivity, and contact resistance of this new alloy were determined, and the results are discussed for applications as an electrical contact material. (C) 2005 Elsevier Ltd. All rights reserved.

    DOI

  • Fabrication of patterned nanostructures with various metal species on Si wafer surfaces by maskless and electroless process

    N Kubo, T Homma, Y Hondo, T Osaka

    ELECTROCHIMICA ACTA   51 ( 5 ) 834 - 837  2005.11

     View Summary

    Maskless and electroless fabrication was demonstrated to form patterned nanostructures of various metal species, based upon the process previously developed by the authors. In this process, the metallic nanostructures were formed on the surface of clean, hydrogen terminated p-(1 0 0) Si wafer with pre-patterned nanoscopic defects, which were confirmed to possess higher activity for the reductive deposition reaction of the metal ion species. The deposition was achieved spontaneously and selectively at the defect sites on the wafer surface by immersing into dilute aqueous fluoride solution containing trace amount of metal ion species. By optimizing the formation condition of the patterned defects and composition of the solution, fabrication of patterned nanostructures of various metallic species such as Au, Ag, and Co, was achieved. Formation of the patterned nanostructures to 10 mu m(2) in extent, as well as control of the feature size of the deposits by adjusting the formation condition of the pattemed defects were also attempted. (C) 2005 Elsevier Ltd. All rights reserved.

    DOI

  • Electrochemical analysis of zincate treatments for Al and Al alloy films

    M Saito, T Maegawa, T Homma

    ELECTROCHIMICA ACTA   51 ( 5 ) 1017 - 1020  2005.11

     View Summary

    Electrochemical behavior of At and At alloy films in zincate solution was investigated to elucidate the effect of the zincate pretreatment for electroless NiP deposition, which is used for under bump metallization for LSI interconnects. The immersion potential for AlCu and AlSiCu, immediately reached to constant, which was almost equal potential to zinc reference electrode. The corrosion current for the AlCu and AlSiCu films was larger than that of the At and AlSi films in the zincate solution. It was also confirmed that the deposited Zn at the surface of AlCu and AlSiCu films possessed smaller grain size and larger amount of nucleation, resulted in the formation of flat NiP films. (C) 2005 Elsevier Ltd. All rights reserved.

    DOI

  • Characterization of strained Si wafer surface by density functional theory analysis

    K Sakata, T Homma, H Nakai, T Osaka

    ELECTROCHIMICA ACTA   51 ( 5 ) 1000 - 1003  2005.11

     View Summary

    Using first-principles total energy calculations within density functional theory (131717), we investigated the surface properties, especially focusing upon the surface reactivity, of strained Si layer deposited onto SiGe underlayer, in comparison with normal (non-strained) Si surface. We used a cluster model as the surface of the strained Si and normal Si, and results of our calculation indicate that, when the Si possessed strained condition, the total energy is destabilized and the value of the gap between HOMO and LUMO became smaller than that of normal Si. In addition, we estimated the reactivity of the strained Si and normal Si surfaces with trace metal ion species in solution. As a result of the adsorption energy calculation of Cu2+, Ni2+ and Fe2+ to Si (100) surface, it was suggested that the adsorption energy of the metal ion species to the strained Si surface is more stable than that of the normal Si. (C) 2005 Elsevier Ltd. All rights reserved.

    DOI

  • Picoliter volume glass tube array fabricated by Si electrochemical etching process

    H Sato, T Homma, K Mori, T Osaka, S Shoji

    ELECTROCHIMICA ACTA   51 ( 5 ) 844 - 848  2005.11

     View Summary

    Fabrication process for picoliter volume SiO2 glass tube array partially embedded in Si wafer was developed. As a template for the glass tubes, macropore array was formed at the surface of n-Si(1 0 0) wafer by photo-assisted electrochemical etching process. The area-selective formation of the array was achieved by applying Au/Cr micropatterns formed at the back-side surface of the substrate as the shade mask, which controls the illumination condition to optimize the etching reaction conditions. Subsequently, surface of the macropores was wet-thermally oxidized to form glass layer, and the bulk Si region was removed by alkaline etching, remaining the "glass tubes". As a result of complete removal of the bulk Si, released glass tubes were obtained. By partial removal of the bulk Si part, the glass tubes were exposed, fixed in the remaining Si substrate in the form of well-ordered array. It was confirmed that the depth, the exposed region and the wall thickness of each glass tube were controllable by adjusting the parameters such as the duration of the Si electrochemical etching, the alkaline etching and the wet-thermal oxidation, respectively. In order to demonstrate microreaction in the glass tube, aqueous rhodamine B solution was injected into the tubes and excitation light was irradiated to them. As a result, the fluorescence of rhodamine B was clearly detected, confirming the applicability of the glass tubes for various kinds of devices and systems such as microreactors. (C) 2005 Elsevier Ltd. All rights reserved.

    DOI

  • High efficiency electrochemical immuno sensors using 3D comb electrodes

    N Honda, M Inaba, T Katagiri, S Shoji, H Sato, T Homma, T Osaka, M Saito, J Mizuno, Y Wada

    BIOSENSORS & BIOELECTRONICS   20 ( 11 ) 2306 - 2309  2005.05

     View Summary

    To realize highly sensitive electrochemical immunoassays, a micro-fabricated three-dimensional (313) electrode was fabricated and applied to enzyme immuno assay based on production of a redox species. The dimensions of the electrodes are 10 mu m in width and 30 mu m in height, with 20 mu m spacing in between, and the 30 pairs of anode and cathode electrodes made up a single sensor. This structure lead to enhancement of the electrochemical reaction, nearly 100% of trap ratio of redox species. It can be applied to highly sensitive enzyme immuno sensing based on p-aminophenylphosphate (PAPP). Applicability of this technique to the immuno assay for one of the clinical diagnostic marker proteins (alpha-fetoprotein; AFP) from 6 to 500 ng/mL was demonstrated. (c) 2004 Elsevier B.V. All rights reserved.

    DOI PubMed CiNii

  • High efficiency electrochemical immuno sensors using 3D comb electrodes

    N Honda, M Inaba, T Katagiri, S Shoji, H Sato, T Homma, T Osaka, M Saito, J Mizuno, Y Wada

    BIOSENSORS & BIOELECTRONICS   20 ( 11 ) 2306 - 2309  2005.05

     View Summary

    To realize highly sensitive electrochemical immunoassays, a micro-fabricated three-dimensional (313) electrode was fabricated and applied to enzyme immuno assay based on production of a redox species. The dimensions of the electrodes are 10 mu m in width and 30 mu m in height, with 20 mu m spacing in between, and the 30 pairs of anode and cathode electrodes made up a single sensor. This structure lead to enhancement of the electrochemical reaction, nearly 100% of trap ratio of redox species. It can be applied to highly sensitive enzyme immuno sensing based on p-aminophenylphosphate (PAPP). Applicability of this technique to the immuno assay for one of the clinical diagnostic marker proteins (alpha-fetoprotein; AFP) from 6 to 500 ng/mL was demonstrated. (c) 2004 Elsevier B.V. All rights reserved.

    DOI PubMed CiNii

  • Surface conductivity in methyl-monolayer/Si heterojunction structure in the presence of water

    Daisuke Niwa, Hiroshi Fukunaga, Takayuki Homma, Tetsuya Osaka

    Chemistry Letters   34 ( 4 ) 520 - 521  2005.04

     View Summary

    The heterojunction between Si(111) semiconductor and the well-ordered methyl monolayer was formed to investigate the channel conduction at the surface in the heterojunction structure. With the presence of water, the methyl monolayer/Si heterojunction structure showed switching action with a high trance-conductance of 2.8 × 10-3 A/V under the application of bias voltage, while without the presence of water, such a switching behavior was not observed. The methyl monolayer/Si heterojunction structure worked as a p-type mode with the presence of water at the modified surface. Copyright © 2005 The Chemical Society of Japan.

    DOI CiNii

  • Electrochemical formation process of Si macropore and metal filling for high aspect ratio metal microstructure using single electrolyte system

    H Sato, T Homma, K Mori, T Osaka, S Shoji

    ELECTROCHEMISTRY   73 ( 4 ) 275 - 278  2005.04

     View Summary

    Array of macropores filled with electrodeposited Ni was formed on Si substrate applying the novel process, which consists of Si electrochemical etching and Ni electrodeposition using single electrolyte. This electrolyte contained HF as Si dissolution agent and Ni(OSO2NH2)(2) 4H(2)O as Ni2+ source for Ni electrodeposition. First, array of macropores was formed on Si (100) substrate by applying anodic current. The formation was carried out area-selectively by applying Au/Cr micropatterns formed at the back side surface of the substrate as the shade mask, which enables to control the illumination condition for hole generation condition. Subsequently, the applied bias was switched to cathodic current, and Ni was filled into c.a. 200 mu m depth Si macropores without void-like defects. Array of Ni needles with smooth surface was formed area-selectively by removal of the Si region of the Ni filled specimen with 25 wt% tetramethylammonium hydroxide (TMAH) aqueous solution at 90 degrees C.

  • Area-selective formation of macropore array by anisotropic electrochemical etching on an n-Si(100) surface in aqueous HF solution

    T Homma, H Sato, K Mori, T Osaka, S Shoji

    JOURNAL OF PHYSICAL CHEMISTRY B   109 ( 12 ) 5724 - 5727  2005.03

     View Summary

    A photoassisted anodization process to fabricate arrays of uniform and straight macropores at selected areas of a Si wafer surface was developed. The front- and backside surfaces of n-type Si(100) wafers were coated with a thin Si3N4 layer, and the frontside layer was micro-patterned using photolithography and reactive ion etching to form an array of microscopic openings at selected areas. The inverted pyramid-shape micropits were formed at these openings by anisotropic etching using aqueous KOH solution; these pits act as the initiation sites for the anodization to form macropores. The electrochemical etching was carried out in aqueous HF solution under illumination from the backside of the wafer, on which Au/Cr electric contact was formed following removal of the Si3N4 layer. To improve the uniformity of the formation condition of the macropores at the selected area, holes were area-selectively generated by controlling the illumination condition during the anodization. For this, micropatterns were formed on the Au/Cr layer at the backside surface, which were aligned to those at the frontside surface. The parameters, such as HF concentration, current density, and wafer thickness, i.e., hole diffusion length, were optimized, and the arrays of uniform and high-aspect-ratio macropores were formed at the selected area of the domain at the silicon surface.

    DOI CiNii

  • Area-selective formation of macropore array by anisotropic electrochemical etching on an n-Si(100) surface in aqueous HF solution

    T Homma, H Sato, K Mori, T Osaka, S Shoji

    JOURNAL OF PHYSICAL CHEMISTRY B   109 ( 12 ) 5724 - 5727  2005.03

     View Summary

    A photoassisted anodization process to fabricate arrays of uniform and straight macropores at selected areas of a Si wafer surface was developed. The front- and backside surfaces of n-type Si(100) wafers were coated with a thin Si3N4 layer, and the frontside layer was micro-patterned using photolithography and reactive ion etching to form an array of microscopic openings at selected areas. The inverted pyramid-shape micropits were formed at these openings by anisotropic etching using aqueous KOH solution; these pits act as the initiation sites for the anodization to form macropores. The electrochemical etching was carried out in aqueous HF solution under illumination from the backside of the wafer, on which Au/Cr electric contact was formed following removal of the Si3N4 layer. To improve the uniformity of the formation condition of the macropores at the selected area, holes were area-selectively generated by controlling the illumination condition during the anodization. For this, micropatterns were formed on the Au/Cr layer at the backside surface, which were aligned to those at the frontside surface. The parameters, such as HF concentration, current density, and wafer thickness, i.e., hole diffusion length, were optimized, and the arrays of uniform and high-aspect-ratio macropores were formed at the selected area of the domain at the silicon surface.

    DOI CiNii

  • Microstructure of a Co/Pd multilayered perpendicular recording medium with Pd seeds prepared by electrochemical process

    M Tanaka, J Kawaji, K Kimura, T Asahi, T Homma, S Matsunuma, T Osaka

    JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS   287   188 - 192  2005.02

     View Summary

    Effects of the Pd seeds formed by an electrochemical process on the microstructures of Co/Pd multilayered perpendicular recording media were investigated. By immersing a CoZrNb soft magnetic underlayer (SUL) into PdCl2 aqueous solution, island-like Pd clusters were deposited on the SUL, resulting from the electrochemical substitution reaction. Transmission electron microscopic observations revealed that the columnar Co/Pd multilayered grains with clear boundaries grew on the SUL with the Pd clusters. The clear grain boundaries, where the densities of Co and Pd elements were low, were thought to cause the magnetic exchange decoupling between the Co/Pd grains, leading to an increase of perpendicular coercivity and a decrease of magnetic cluster size of Co/Pd multilayered film. Consequently, lower medium noise was obtained for the Co/Pd multilayered medium with the Pd clusters than for that with a sputter-deposited Pd seedlayer. From these investigations, it was clarified that the SUL surface with Pd clusters provided the effective nucleation sites for a well-defined Co/Pd multilayered grain growth. (C) 2004 Elsevier B.V. All rights reserved.

    DOI CiNii

  • Area selective formation of magnetic nanodot arrays on Si wafer by electroless deposition

    J Kawaji, F Kitaizumi, H Oikawa, D Niwa, T Homma, T Osaka

    JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS   287   245 - 249  2005.02

     View Summary

    Electroless deposition process for fabricating magnetic dot arrays was studied. A patterned Si substrate with a SiO2 resist was produced by processes combined with electron-beam lithography and reactive ion etching. By immersing the patterned Si substrate into a CoNiP electroless deposition bath, CoNiP was deposited only into the patterned pores, demonstrating a satisfactory area selectivity of the deposition. Excellent uniformity on the CoNiP deposition into the patterned pores with diameter less than 100 nm and high aspect ratio (&gt; 5) was achieved by applying chemical activation processes using a Pd solution prior to the deposition. The CoNiP dot arrays exhibited higher perpendicular squareness ratio than that of CoNiP continuous film and showed a clear magnetization state at DC-magnetized state, which originated from the shape anisotropy caused by high aspect ratio of the dot patterns. (C) 2004 Elsevier B.V. All rights reserved.

    DOI CiNii

  • Microstructure of a Co/Pd multilayered perpendicular recording medium with Pd seeds prepared by electrochemical process

    M Tanaka, J Kawaji, K Kimura, T Asahi, T Homma, S Matsunuma, T Osaka

    JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS   287   188 - 192  2005.02

     View Summary

    Effects of the Pd seeds formed by an electrochemical process on the microstructures of Co/Pd multilayered perpendicular recording media were investigated. By immersing a CoZrNb soft magnetic underlayer (SUL) into PdCl2 aqueous solution, island-like Pd clusters were deposited on the SUL, resulting from the electrochemical substitution reaction. Transmission electron microscopic observations revealed that the columnar Co/Pd multilayered grains with clear boundaries grew on the SUL with the Pd clusters. The clear grain boundaries, where the densities of Co and Pd elements were low, were thought to cause the magnetic exchange decoupling between the Co/Pd grains, leading to an increase of perpendicular coercivity and a decrease of magnetic cluster size of Co/Pd multilayered film. Consequently, lower medium noise was obtained for the Co/Pd multilayered medium with the Pd clusters than for that with a sputter-deposited Pd seedlayer. From these investigations, it was clarified that the SUL surface with Pd clusters provided the effective nucleation sites for a well-defined Co/Pd multilayered grain growth. (C) 2004 Elsevier B.V. All rights reserved.

    DOI CiNii

  • Area selective formation of magnetic nanodot arrays on Si wafer by electroless deposition

    J Kawaji, F Kitaizumi, H Oikawa, D Niwa, T Homma, T Osaka

    JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS   287   245 - 249  2005.02

     View Summary

    Electroless deposition process for fabricating magnetic dot arrays was studied. A patterned Si substrate with a SiO2 resist was produced by processes combined with electron-beam lithography and reactive ion etching. By immersing the patterned Si substrate into a CoNiP electroless deposition bath, CoNiP was deposited only into the patterned pores, demonstrating a satisfactory area selectivity of the deposition. Excellent uniformity on the CoNiP deposition into the patterned pores with diameter less than 100 nm and high aspect ratio (&gt; 5) was achieved by applying chemical activation processes using a Pd solution prior to the deposition. The CoNiP dot arrays exhibited higher perpendicular squareness ratio than that of CoNiP continuous film and showed a clear magnetization state at DC-magnetized state, which originated from the shape anisotropy caused by high aspect ratio of the dot patterns. (C) 2004 Elsevier B.V. All rights reserved.

    DOI CiNii

  • Deposition behavior of Ni on Si(100) surfaces in an aqueous alkaline solution

    Daisuke Niwa, Takayuki Homma, Tetsuya Osaka

    Journal of the Electrochemical Society   152 ( 2 ) C54 - C59  2005

     View Summary

    The spontaneous deposition of Ni on Si(100) surface in aqueous alkaline solution was investigated under various conditions. In a 0.1 M NiSO4 solution containing 0.2-0.5 M (NH4)2SO4, the optimum pH for the homogeneous deposition at 60-80°C at each set of operating conditions shifted in the high-pH direction as both (NH 4)2SO4 concentration and the operating temperature were decreased. The potential at which the deposition terminates and the deposition duration were determined from electrochemical open-circuit potential profiles. The different behaviors, observed at different pH levels, are discussed in terms of these potential measurements. Ultraviolet-visible absorption spectra of various Ni solutions used indicated that the deposition behavior was strongly affected by the composition of the Ni complex and the reactivity of Si surface. The deposition reaction efficiently proceeded when the Ni complex was present in a specific composition. The anodic reaction rate of Si decreased steeply when the solution temperature was lowered. The optimum condition for the homogeneous deposition was greatly affected by the reactivity of the Si surface rather man the composition of the complex, the higher pH favoring the overall reaction. © 2004 The Electrochemical Society. All rights reserved.

    DOI CiNii

  • Surface Conductivity in Methyl- Monolayer/Si Heterojunction Structure in the Presence of Water

    D. Niwa, K. Omichi, N. Motohashi, T. Homma, T. Osaka

    Chem.Lett.   34 ( 4 ) 520 - 521  2005

    DOI CiNii

  • Nucleation and growth of copper nanoparticles on silicon surfaces

    A. Singh, K. Luening, S. Brennan, T. Homma, N. Kubo, P. Pianetta

    PHYSICA SCRIPTA   T115   714 - 716  2005

     View Summary

    The recent adoption of copper interconnect technology by the semiconductor industry, has led to great interest in understanding the mechanisms of copper metal deposition onto silicon wafer surfaces from ultra pure water (UPW) solutions. We have studied these processes by using total reflection X-ray fluorescence (TXRF) and X-ray absorption near edge spectroscopy (XANES) in a grazing incidence geometry to determine the surface concentration and chemical state of copper atoms on intentionally contaminated Si surfaces. These measurements established that in deoxygenated UPW, copper is deposited on the silicon surface in the form of metallic nanoparticles with sizes up to 16 nm. However, in non-deoxygenated UPW, the copper is incorporated uniformly into the silicon surface oxide as Cu oxide.

    DOI

  • Electrochemical formation process of Si macropore and metal filling for high aspect ratio metal microstructure using single electrolyte system

    H. Sato, T. Homma, K. Mori, T. Osaka, S. Shoji

    Electrochemistry   73 ( 4 ) 275 - 278  2005

    CiNii

  • Deposition behavior of Ni on Si(100) surfaces in an aqueous alkaline solution

    Daisuke Niwa, Takayuki Homma, Tetsuya Osaka

    Journal of the Electrochemical Society   152 ( 2 ) C54 - C59  2005

     View Summary

    The spontaneous deposition of Ni on Si(100) surface in aqueous alkaline solution was investigated under various conditions. In a 0.1 M NiSO4 solution containing 0.2-0.5 M (NH4)2SO4, the optimum pH for the homogeneous deposition at 60-80°C at each set of operating conditions shifted in the high-pH direction as both (NH 4)2SO4 concentration and the operating temperature were decreased. The potential at which the deposition terminates and the deposition duration were determined from electrochemical open-circuit potential profiles. The different behaviors, observed at different pH levels, are discussed in terms of these potential measurements. Ultraviolet-visible absorption spectra of various Ni solutions used indicated that the deposition behavior was strongly affected by the composition of the Ni complex and the reactivity of Si surface. The deposition reaction efficiently proceeded when the Ni complex was present in a specific composition. The anodic reaction rate of Si decreased steeply when the solution temperature was lowered. The optimum condition for the homogeneous deposition was greatly affected by the reactivity of the Si surface rather man the composition of the complex, the higher pH favoring the overall reaction. © 2004 The Electrochemical Society. All rights reserved.

    DOI CiNii

  • Nucleation and growth of copper nanoparticles on silicon surfaces

    A. Singh, K. Luening, S. Brennan, T. Homma, N. Kubo, P. Pianetta

    Physica Scripta T   T115   714 - 716  2005

     View Summary

    The recent adoption of copper interconnect technology by the semiconductor industry, has led to great interest in understanding the mechanisms of copper metal deposition onto silicon wafer surfaces from ultra pure water (UPW) solutions. We have studied these processes by using total reflection x-ray fluorescence (TXRF) and x-ray absorption near edge spectroscopy (XANES) in a grazing incidence geometry to determine the surface concentration and chemical state of copper atoms on intentionally contaminated Si surfaces. These measurements established that in deoxygenated UPW, copper is deposited on the silicon surface in the form of metallic nanoparticles with sizes up to 16nm. However, in non-deoxygenated UPW, the copper is incorporated uniformly into the silicon surface oxide as Cu oxide. © Physica Scripta 2005.

    DOI

  • Deposition mechanism of Ni on Si(100) surfaces in aqueous alkaline solution

    D Niwa, T Homma, T Osaka

    JOURNAL OF PHYSICAL CHEMISTRY B   108 ( 28 ) 9900 - 9904  2004.07

     View Summary

    The spontaneous deposition process of Ni on Si(100) surface in aqueous alkaline solution was investigated by electrochemical measurements and in situ attenuated total reflection Fourier transform infrared spectroscopy (ATR FTIR). The open circuit potential (OCP) profile revealed that the deposition reaction was self-terminated as the potential steeply shifted in the positive direction after a certain immersion time. Auger depth profiles of specimens after the termination of the deposition reaction indicated that the surface was not completely covered by Ni. To clarify the deposition behavior, anodic reaction of Si in an aqueous alkaline solution containing no Ni ions was investigated by in situ ATR FTIR and electrochemical measurements. It was found that the deposition reaction was initiated by the formation of suboxide species of Si at the surface. This suboxide species served as "reductant" for Ni ions. Subsequently, the anodic reactions such as the oxidation of suboxide species and the anisotropic etching to (111) direction proceeded spontaneously. When (111) oriented microfacets were formed, the surface was passivated with silicon dioxide. Because of the silicon dioxide insulating properties, the electron generation by Si oxidation is inhibited, and then, the OCP sharply shifted in the positive direction. Apparently, the formation of (I 11) oriented microfacets at the surface led to the self-termination of the Ni deposition process. This study shows that the overall deposition reaction of Ni is significantly affected by the anodic reaction of Si, including the oxidation and the anisotropic etching.

    DOI CiNii

  • Deposition mechanism of Ni on Si(100) surfaces in aqueous alkaline solution

    D Niwa, T Homma, T Osaka

    JOURNAL OF PHYSICAL CHEMISTRY B   108 ( 28 ) 9900 - 9904  2004.07

     View Summary

    The spontaneous deposition process of Ni on Si(100) surface in aqueous alkaline solution was investigated by electrochemical measurements and in situ attenuated total reflection Fourier transform infrared spectroscopy (ATR FTIR). The open circuit potential (OCP) profile revealed that the deposition reaction was self-terminated as the potential steeply shifted in the positive direction after a certain immersion time. Auger depth profiles of specimens after the termination of the deposition reaction indicated that the surface was not completely covered by Ni. To clarify the deposition behavior, anodic reaction of Si in an aqueous alkaline solution containing no Ni ions was investigated by in situ ATR FTIR and electrochemical measurements. It was found that the deposition reaction was initiated by the formation of suboxide species of Si at the surface. This suboxide species served as "reductant" for Ni ions. Subsequently, the anodic reactions such as the oxidation of suboxide species and the anisotropic etching to (111) direction proceeded spontaneously. When (111) oriented microfacets were formed, the surface was passivated with silicon dioxide. Because of the silicon dioxide insulating properties, the electron generation by Si oxidation is inhibited, and then, the OCP sharply shifted in the positive direction. Apparently, the formation of (I 11) oriented microfacets at the surface led to the self-termination of the Ni deposition process. This study shows that the overall deposition reaction of Ni is significantly affected by the anodic reaction of Si, including the oxidation and the anisotropic etching.

    DOI CiNii

  • Development of Bi electrodeposition process for fabricating microabsorber array for high sensitive X-ray imaging sensor

    H Sato, H Kobayashi, H Kudo, T Izumi, T Homma, T Osaka, S Shoji, Y Ishisaki, R Fujimoto, K Mitsuda

    ELECTROCHEMISTRY   72 ( 6 ) 424 - 426  2004.06

     View Summary

    Microscale Bi electrodeposition process was developed to fabricate the array of mushroom-shaped absorbers for the high sensitive X-ray imaging sensor, so called X-ray microcalorimeter array. The bath composition and operating conditions for Bi electrodeposition was optimized, and sufficient bath stability and surface smoothness of the deposits were achieved by applying the additives such as diethylenetriamine pentaacetic acid and sodium n-dodecyl sulfate with appropriate concentration. By applying the two-step exposure steps for the "stem" part and the "roof" part, the mold to deposit the mushroom-shaped microstructure was formed from single-layered photoresist coating. The absorber array was successfully fabricated by the sequential processes of Bi electrodeposition into the mold, precise polishing, and mold removal.

  • Development of Bi electrodeposition process for fabricating microabsorber array for high sensitive X-ray imaging sensor

    H Sato, H Kobayashi, H Kudo, T Izumi, T Homma, T Osaka, S Shoji, Y Ishisaki, R Fujimoto, K Mitsuda

    ELECTROCHEMISTRY   72 ( 6 ) 424 - 426  2004.06

     View Summary

    Microscale Bi electrodeposition process was developed to fabricate the array of mushroom-shaped absorbers for the high sensitive X-ray imaging sensor, so called X-ray microcalorimeter array. The bath composition and operating conditions for Bi electrodeposition was optimized, and sufficient bath stability and surface smoothness of the deposits were achieved by applying the additives such as diethylenetriamine pentaacetic acid and sodium n-dodecyl sulfate with appropriate concentration. By applying the two-step exposure steps for the "stem" part and the "roof" part, the mold to deposit the mushroom-shaped microstructure was formed from single-layered photoresist coating. The absorber array was successfully fabricated by the sequential processes of Bi electrodeposition into the mold, precise polishing, and mold removal.

  • Performance analyse's of TES microcalorimeters with mushroom shaped X-ray absorbers made of Sn or Bi

    Y Ishisaki, U Morita, T Koga, K Shinozaki, K Sato, N Takai, T Ohashi, T Arakawa, H Kudo, H Sato, H Kobayashi, T Izumi, S Ohtsuka, K Mori, S Shoji, T Osaka, T Homma, K Mitsuda, NY Yamasaki, R Fujimoto, N Iyomoto, T Oshima, K Futamoto, Y Takei, T Ichitsubo, T Fujimori, K Yoshida, Y Kuroda, M Onishi, M Goto, F Beppu

    NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT   520 ( 1-3 ) 452 - 455  2004.03

     View Summary

    Performance of microcalorimeters with a Ti/Au transition-edge sensor (TES) and an electrodeposited absorber has been investigated. The absorbers are in a mushroom-shape made of Sn or Bi. With an Sn absorber we observed a long time scale component of 1.8 ms for X-ray pulses, which is due presumably to recombination of quasiparticles into phonons. As a result, the energy resolution is not good with the Sn absorber. Better energy resolution of 28 +/- 1 eV was obtained with an incomplete-shaped Bi absorber, although the long component was also seen with smaller level. A calorimeter with only a neck of the An seed layer for the electrodeposition had the best energy resolution of 6.3 +/- 0.4 eV in spite of saturated pulses and relatively high transition temperature of 210 mK. (C) 2003 Elsevier B.V. All rights reserved.

    DOI

  • Fabrication of multi-pixel TES microcalorimeters with an electrodeposited Sn absorber and Bi absorber

    T Arakawa, H Kudo, H Sato, H Kobayashi, T Izumi, S Ohtsuka, K Mori, S Shoji, T Osaka, T Homma, K Mitsuda, N Yamasaki, R Fujimoto, N Iyomoto, Y Ishisaki, U Morita, T Koga, K Shinozaki, K Sato, N Takai, T Ohashi, Y Kuroda, M Onishi, M Goto, F Beppu

    NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT   520 ( 1-3 ) 456 - 459  2004.03

     View Summary

    We have developed multi-pixel TES microcalorimeters in order to realize high-energy resolution and X-ray imaging. A Sn absorber and a Bi absorber were formed on Si3N4 and SiO2 membrane using two-step exposure photolithography and electrodeposition. A FEM analysis was carried out to investigate the performance of the X-ray microabsorbers. In addition, a superconducting through-wafer interconnection was demonstrated considering the future X-ray imager using microcalorimeters. Detail of the fabrication techniques, characteristics and simulation results of two types of the microabsorbers, as well as those of the calorimeters are described. (C) 2003 Elsevier B.V. All rights reserved.

    DOI

  • TES microcalorimeter development for future Japanese X-ray astronomy missions

    R Fujimoto, K Mitsuda, NY Yamasaki, N Iyomoto, T Oshima, Y Takei, K Futamoto, T Ichitsubo, T Fujimori, K Yoshida, Y Ishisaki, U Morita, T Koga, K Shinozaki, K Sato, N Takai, T Ohashi, H Kudo, H Sato, T Arakawa, H Kobayashi, T Izumi, S Ohtsuka, K Mori, S Shoji, T Osaka, T Homma, Y Kuroda, M Onishi, M Goto, F Beppu, T Tanaka, T Morooka, S Nakayama, K Chinone

    NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT   520 ( 1-3 ) 431 - 434  2004.03

     View Summary

    We are developing a Ti/Au TES microcalorimeter array for future Japanese X-ray astronomy missions. The goal is an energy resolution of 2-5 eV at 6 keV, and an array of 100-1000 pixels to achieve a geometrical area of &gt;1 cm(2) and a moderate spatial resolution simultaneously. The energy resolution was improved to similar to6 eV at 6 keV with a very fast time constant (&lt;100 mus). To achieve a high coverage fraction, it is necessary to fabricate mushroom-shaped X-ray microabsorbers. We are developing an electrodeposition fabrication technique that is suitable for our process. Sn was used as absorber material, but the energy resolution was not good due to the existence of long-lived quasiparticles. Bi is also used, and the process is under optimization now. The readout strategy is to multiplex signals in the frequency domain, using a bridge circuit. So far, we succeeded in multiplexing two pixels modulated with 50 and 20 kHz at 440 mK. The energy resolution obtained at 110 mK was 33 eV (25 kHz). (C) 2003 Elsevier B.V. All rights reserved.

    DOI

  • High sensitive X-ray microcalorimeter using Bi-Au microabsorber for imaging applications

    H Kudo, T Arakawa, S Ohtsuka, T Izumi, S Shoji, H Sato, H Kobayashi, K Mori, T Homma, T Osaka, N Iyomoto, R Fujimoto, K Mitsuda, NY Yamasaki, T Oshima, K Futamoto, Y Takei, T Ichitsubo, T Fujimori, Y Ishisaki, U Morita, T Koga, K Shinozaki, K Sato, T Ohashi, Y Kuroda, M Onishi, K Otake, F Beppu

    JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS   43 ( 3 ) 1190 - 1195  2004.03

     View Summary

    An X-ray microcalorimeter is a cryogenic energy-dispersive spectrometer, which has an energy resolution almost comparable to that of conventional wavelength-dispersive spectrometers. Using a transition edge sensor (TES) as a temperature sensor, the energy resolution can be further improved. We have developed a new method of achieving an array of TES microcalorimeters for the purpose of X-ray imaging. To achieve this, mushroom-shaped X-ray microabsorbers formed using electrodeposition were applied. The temperature of the TES, which is easily degraded by thermal diffusion, was kept sufficiently low throughout the process to achieve practical use. On the bases of this new method, a 2 x 2 (x 4) array of TES microcalorimeters was fabricated and tested. A high energy resolution of 13.0 eV at 6 keV was achieved and the filling factor was improved to 83%. Although several issues still need to be investigated, we verified that our method is useful for fabricating a Ti-Au TES microcalorimeter array.

    DOI

  • Formation of molecular templates for fabricating on-chip biosensing devices

    D Niwa, Y Yamada, T Homma, T Osaka

    JOURNAL OF PHYSICAL CHEMISTRY B   108 ( 10 ) 3240 - 3245  2004.03

     View Summary

    Formation of organosilane monolayers having various functional groups on silicon oxide surfaces for fabricating on-chip biosensing devices was investigated. Alkyl and perfluoro-alkyl functionalized monolayers were prepared by a chemical vapor deposition, and amino functionalized monolayers were formed by a liquid phase reaction. Each monolayer was confirmed to be closely packed and composed of single moiety species. A molecular patterning process using these organic monolayers was performed. The monolayer patterns were uniformly formed on the substrate by using ultraviolet light patterning and oxygen plasma ashing processes. The pH responsibility at the liquid/modified electrode interface was examined by using capacitor profiles of the structure of monolayer/silicon oxide/silicon. The amino modified surface showed good pH sensitivity of -44 mV/pH. This value was similar to that of the silicon nitride surface. On the other hand, the potential was not changed in any pH solutions in the case of the alkyl and perfluoro-alkyl monolayer-modified surface. It was demonstrated that the pH response of these surfaces was greatly affected by the variation of the functional group. Furthermore, by using the patterned monolayers, fabrication of a multichannel electrode for multiple detection of pH response was achieved.

    DOI CiNii

  • Electrochemical behavior of methyl- and butyl-terminated Si(111) in aqueous solution

    D Niwa, T Inoue, H Fukunaga, T Akasaka, T Yamada, T Homma, T Osaka

    CHEMISTRY LETTERS   33 ( 3 ) 284 - 285  2004.03

     View Summary

    Formation of the methyl- and n-butyl monolayer on (Cl)Si(I 11) surfaces by using the Grignard reaction and their electro-chemical behavior was investigated. The modified Si(I 11) surfaces were indicated to be closely packed with a single moiety species. The methyl-modified Si(I 11) surface was composed of (I x 1) adlattice structure. The methyl-modified surface was stable in aqueous solution, and showed essentially good electrical conductive property with p-n junction like behavior.

    DOI CiNii

  • Performance analyse's of TES microcalorimeters with mushroom shaped X-ray absorbers made of Sn or Bi

    Y Ishisaki, U Morita, T Koga, K Shinozaki, K Sato, N Takai, T Ohashi, T Arakawa, H Kudo, H Sato, H Kobayashi, T Izumi, S Ohtsuka, K Mori, S Shoji, T Osaka, T Homma, K Mitsuda, NY Yamasaki, R Fujimoto, N Iyomoto, T Oshima, K Futamoto, Y Takei, T Ichitsubo, T Fujimori, K Yoshida, Y Kuroda, M Onishi, M Goto, F Beppu

    NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT   520 ( 1-3 ) 452 - 455  2004.03

     View Summary

    Performance of microcalorimeters with a Ti/Au transition-edge sensor (TES) and an electrodeposited absorber has been investigated. The absorbers are in a mushroom-shape made of Sn or Bi. With an Sn absorber we observed a long time scale component of 1.8 ms for X-ray pulses, which is due presumably to recombination of quasiparticles into phonons. As a result, the energy resolution is not good with the Sn absorber. Better energy resolution of 28 +/- 1 eV was obtained with an incomplete-shaped Bi absorber, although the long component was also seen with smaller level. A calorimeter with only a neck of the An seed layer for the electrodeposition had the best energy resolution of 6.3 +/- 0.4 eV in spite of saturated pulses and relatively high transition temperature of 210 mK. (C) 2003 Elsevier B.V. All rights reserved.

    DOI

  • Fabrication of multi-pixel TES microcalorimeters with an electrodeposited Sn absorber and Bi absorber

    T Arakawa, H Kudo, H Sato, H Kobayashi, T Izumi, S Ohtsuka, K Mori, S Shoji, T Osaka, T Homma, K Mitsuda, N Yamasaki, R Fujimoto, N Iyomoto, Y Ishisaki, U Morita, T Koga, K Shinozaki, K Sato, N Takai, T Ohashi, Y Kuroda, M Onishi, M Goto, F Beppu

    NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT   520 ( 1-3 ) 456 - 459  2004.03

     View Summary

    We have developed multi-pixel TES microcalorimeters in order to realize high-energy resolution and X-ray imaging. A Sn absorber and a Bi absorber were formed on Si3N4 and SiO2 membrane using two-step exposure photolithography and electrodeposition. A FEM analysis was carried out to investigate the performance of the X-ray microabsorbers. In addition, a superconducting through-wafer interconnection was demonstrated considering the future X-ray imager using microcalorimeters. Detail of the fabrication techniques, characteristics and simulation results of two types of the microabsorbers, as well as those of the calorimeters are described. (C) 2003 Elsevier B.V. All rights reserved.

    DOI

  • TES microcalorimeter development for future Japanese X-ray astronomy missions

    R Fujimoto, K Mitsuda, NY Yamasaki, N Iyomoto, T Oshima, Y Takei, K Futamoto, T Ichitsubo, T Fujimori, K Yoshida, Y Ishisaki, U Morita, T Koga, K Shinozaki, K Sato, N Takai, T Ohashi, H Kudo, H Sato, T Arakawa, H Kobayashi, T Izumi, S Ohtsuka, K Mori, S Shoji, T Osaka, T Homma, Y Kuroda, M Onishi, M Goto, F Beppu, T Tanaka, T Morooka, S Nakayama, K Chinone

    NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT   520 ( 1-3 ) 431 - 434  2004.03

     View Summary

    We are developing a Ti/Au TES microcalorimeter array for future Japanese X-ray astronomy missions. The goal is an energy resolution of 2-5 eV at 6 keV, and an array of 100-1000 pixels to achieve a geometrical area of &gt;1 cm(2) and a moderate spatial resolution simultaneously. The energy resolution was improved to similar to6 eV at 6 keV with a very fast time constant (&lt;100 mus). To achieve a high coverage fraction, it is necessary to fabricate mushroom-shaped X-ray microabsorbers. We are developing an electrodeposition fabrication technique that is suitable for our process. Sn was used as absorber material, but the energy resolution was not good due to the existence of long-lived quasiparticles. Bi is also used, and the process is under optimization now. The readout strategy is to multiplex signals in the frequency domain, using a bridge circuit. So far, we succeeded in multiplexing two pixels modulated with 50 and 20 kHz at 440 mK. The energy resolution obtained at 110 mK was 33 eV (25 kHz). (C) 2003 Elsevier B.V. All rights reserved.

    DOI

  • High sensitive X-ray microcalorimeter using Bi-Au microabsorber for imaging applications

    H Kudo, T Arakawa, S Ohtsuka, T Izumi, S Shoji, H Sato, H Kobayashi, K Mori, T Homma, T Osaka, N Iyomoto, R Fujimoto, K Mitsuda, NY Yamasaki, T Oshima, K Futamoto, Y Takei, T Ichitsubo, T Fujimori, Y Ishisaki, U Morita, T Koga, K Shinozaki, K Sato, T Ohashi, Y Kuroda, M Onishi, K Otake, F Beppu

    JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS   43 ( 3 ) 1190 - 1195  2004.03

     View Summary

    An X-ray microcalorimeter is a cryogenic energy-dispersive spectrometer, which has an energy resolution almost comparable to that of conventional wavelength-dispersive spectrometers. Using a transition edge sensor (TES) as a temperature sensor, the energy resolution can be further improved. We have developed a new method of achieving an array of TES microcalorimeters for the purpose of X-ray imaging. To achieve this, mushroom-shaped X-ray microabsorbers formed using electrodeposition were applied. The temperature of the TES, which is easily degraded by thermal diffusion, was kept sufficiently low throughout the process to achieve practical use. On the bases of this new method, a 2 x 2 (x 4) array of TES microcalorimeters was fabricated and tested. A high energy resolution of 13.0 eV at 6 keV was achieved and the filling factor was improved to 83%. Although several issues still need to be investigated, we verified that our method is useful for fabricating a Ti-Au TES microcalorimeter array.

    DOI

  • Formation of molecular templates for fabricating on-chip biosensing devices

    D Niwa, Y Yamada, T Homma, T Osaka

    JOURNAL OF PHYSICAL CHEMISTRY B   108 ( 10 ) 3240 - 3245  2004.03

     View Summary

    Formation of organosilane monolayers having various functional groups on silicon oxide surfaces for fabricating on-chip biosensing devices was investigated. Alkyl and perfluoro-alkyl functionalized monolayers were prepared by a chemical vapor deposition, and amino functionalized monolayers were formed by a liquid phase reaction. Each monolayer was confirmed to be closely packed and composed of single moiety species. A molecular patterning process using these organic monolayers was performed. The monolayer patterns were uniformly formed on the substrate by using ultraviolet light patterning and oxygen plasma ashing processes. The pH responsibility at the liquid/modified electrode interface was examined by using capacitor profiles of the structure of monolayer/silicon oxide/silicon. The amino modified surface showed good pH sensitivity of -44 mV/pH. This value was similar to that of the silicon nitride surface. On the other hand, the potential was not changed in any pH solutions in the case of the alkyl and perfluoro-alkyl monolayer-modified surface. It was demonstrated that the pH response of these surfaces was greatly affected by the variation of the functional group. Furthermore, by using the patterned monolayers, fabrication of a multichannel electrode for multiple detection of pH response was achieved.

    DOI CiNii

  • Electrochemical behavior of methyl- and butyl-terminated Si(111) in aqueous solution

    D Niwa, T Inoue, H Fukunaga, T Akasaka, T Yamada, T Homma, T Osaka

    CHEMISTRY LETTERS   33 ( 3 ) 284 - 285  2004.03

     View Summary

    Formation of the methyl- and n-butyl monolayer on (Cl)Si(I 11) surfaces by using the Grignard reaction and their electro-chemical behavior was investigated. The modified Si(I 11) surfaces were indicated to be closely packed with a single moiety species. The methyl-modified Si(I 11) surface was composed of (I x 1) adlattice structure. The methyl-modified surface was stable in aqueous solution, and showed essentially good electrical conductive property with p-n junction like behavior.

    DOI CiNii

  • Formation of micro and nanoscale patterns of monolayer templates for position selective immobilization of oligonucleotide using ultraviolet and electron beam lithography

    D Niwa, K Omichi, N Motohashi, T Homma, T Osaka

    CHEMISTRY LETTERS   33 ( 2 ) 176 - 177  2004.02

     View Summary

    Formation of organosilane monolayer templates using ultraviolet and electron-beam (EB) lithography was investigated. The oligonucleotides were covalently immobilized with high selectivity only to the amino-monolayer modified regions locally formed on the template surfaces at micro and nanometer scale. By using EB lithography, patterned immobilization in nanometer scale, as small as 20nm, was achieved.

    DOI CiNii

  • Formation of micro and nanoscale patterns of monolayer templates for position selective immobilization of oligonucleotide using ultraviolet and electron beam lithography

    D Niwa, K Omichi, N Motohashi, T Homma, T Osaka

    CHEMISTRY LETTERS   33 ( 2 ) 176 - 177  2004.02

     View Summary

    Formation of organosilane monolayer templates using ultraviolet and electron-beam (EB) lithography was investigated. The oligonucleotides were covalently immobilized with high selectivity only to the amino-monolayer modified regions locally formed on the template surfaces at micro and nanometer scale. By using EB lithography, patterned immobilization in nanometer scale, as small as 20nm, was achieved.

    DOI CiNii

  • Ab Initio Molecular Orbital Study of the Electron Emission Mechanism of TiCl3 as a Reductant for an Electroless Deposition Process

    T. Shimada, I. Komatsu, T. Homma, H. Nakai, T. Osaka

    Electrochemistry   72 ( 6 ) 462 - 465  2004

  • Formation of Pd Nanocluster Seeds by Electrochemical Process for Control of Magnetic Properties in Co/Pd Multilayered Film

    J. Kawaji, M. Tanaka, K. Kimura, T. Asahi, T. Homma, T. Osaka

    IEEE Trans. Magn.   40 ( 4 ) 2473 - 2475  2004  [Refereed]

    DOI CiNii

  • Fabrication of organic monolayer modified ion-sensitive field effect transistors with high chemical durability

    D Niwa, T Homma, T Osaka

    JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS   43 ( 1A-B ) L105 - L107  2004.01

     View Summary

    Fabrication of ion-sensitive field effect transistor (FET) with modified SiO2 gate by various organosilane monolayers was investigated. By precise control of the fabrication processes, the FETs modified with various functional monolayers were successfully formed on the same substrate. Each modified device indicates typical transistor property with a good stability in aqueous solution. The transistor with amino monolayer modified gate showed good pH sensitivity of 58 mV/pH, whereas the profiles of transistor with the perfluoro-alkyl monolayer modified gate kept constant in any pH solutions. These monolayer-modified devices are expected to be applied as an ion-sensitive and a reference electrode for sensing devices in the solution.

    DOI CiNii

  • Ab Initio Molecular Orbital Study of the Electron Emission Mechanism of TiCl3 as a Reductant for an Electroless Deposition Process

    T. Shimada, I. Komatsu, T. Homma, H. Nakai, T. Osaka

    Electrochemistry   72 ( 6 ) 462 - 465  2004

  • Formation of Pd Nanocluster Seeds by Electrochemical Process for Control of Magnetic Properties in Co/Pd Multilayered Film

    J. Kawaji, M. Tanaka, K. Kimura, T. Asahi, T. Homma, T. Osaka

    IEEE Trans. Magn.   40 ( 4 ) 2473 - 2475  2004  [Refereed]

    DOI CiNii

  • Fabrication of organic monolayer modified ion-sensitive field effect transistors with high chemical durability

    D Niwa, T Homma, T Osaka

    JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS   43 ( 1A-B ) L105 - L107  2004.01

     View Summary

    Fabrication of ion-sensitive field effect transistor (FET) with modified SiO2 gate by various organosilane monolayers was investigated. By precise control of the fabrication processes, the FETs modified with various functional monolayers were successfully formed on the same substrate. Each modified device indicates typical transistor property with a good stability in aqueous solution. The transistor with amino monolayer modified gate showed good pH sensitivity of 58 mV/pH, whereas the profiles of transistor with the perfluoro-alkyl monolayer modified gate kept constant in any pH solutions. These monolayer-modified devices are expected to be applied as an ion-sensitive and a reference electrode for sensing devices in the solution.

    DOI CiNii

  • Sn electrodeposition process for fabricating microabsorber arrays for an X-ray microcalorimeter

    T Homma, H Sato, H Kobayashi, T Arakawa, H Kudo, T Osaka, S Shoji, Y Ishisaki, T Oshima, N Iyomoto, R Fujimoto, K Mitsuda

    JOURNAL OF ELECTROANALYTICAL CHEMISTRY   559 ( 1 ) 143 - 148  2003.11  [Refereed]

     View Summary

    Sn electrodeposition was employed for fabricating an array of microabsorbers with a 'mushroom-shaped' microstructure for a precision X-ray microdetector, the so called X-ray microcalorimeter. A deposition process for flat and smooth Sn films, which was suitable for the use of the absorber material, was developed by optimizing the conditions of additives such as o-cresol-4-sulfonic acid and polyethyleneglycol (PEG) to the Sn bath. The Sn films exhibited suitable properties, i.e. a higher superconducting transition temperature than the operating temperature of the X-ray microcalorimeter. The mushroom-shaped absorber array was successfully fabricated by Sn electrodeposition in combination with a photolithographic technique. (C) 2002 Elsevier Science B.V. All rights reserved.

    DOI CiNii

  • Molecular orbital study on the reaction process of dimethylamine borane as a reductant for electroless deposition

    T Homma, A Tamaki, H Nakai, T Osaka

    JOURNAL OF ELECTROANALYTICAL CHEMISTRY   559 ( 1 ) 131 - 136  2003.11  [Refereed]

     View Summary

    The oxidation mechanism of dimethylantine borane (DMAB), which acts as a reductant in the electroless deposition process, was studied using ab initio molecular orbital approaches such as Hartree-Fock (HF) and second order Moller-Plesset (MP2) calculations. The overall oxidation process of the DMAB was divided into each elementary reaction in which OH- substitutes H one by one and eventually forms B(OH)(4)(-). The oxidation mechanism of DMAB in the isolated state, which was previously proposed by us, was refined using more accurate basis sets, and the effects of solvation and interaction with metal surface sites on the oxidation mechanism were also studied. Taking the solvation effect into consideration using the self-consistent reaction field method with an isodensity polarized continuum model (SCRF-IPCM), the heat of oxidation was transferred to an exothermic reaction with decreasing dielectric constant. This indicated that the reaction preferably proceeds at the solid \ liquid interface. Combined with Cu(111) and Pd(111) neutral cluster models as metal surface sites, it was found that the oxidation reaction proceeds preferentially at the metal surface sites. It was also suggested that the catalytic activity of the deposited metal is caused by its electron acceptivity. (C) 2003 Elsevier Science B.V. All rights reserved.

    DOI CiNii

  • Survey of the metal nucleation processes on silicon surfaces in fluoride solutions: from dilute HF to concentrated NH4F solutions

    M Chemla, T Homma, Bertagna, V, R Erre, N Kubo, T Osaka

    JOURNAL OF ELECTROANALYTICAL CHEMISTRY   559 ( 1 ) 111 - 123  2003.11  [Refereed]

     View Summary

    As is well known, contamination of the silicon surface by trace metal impurities is responsible for detrimental effects in the production of ULSI circuits. An extensive experimental study of the factors influencing the spontaneous metal nucleation from fluoride solutions on Si substrates was undertaken. In acidic media (dilute HF solution) only noble metals can be deposited. The mechanism for the formation of Cu element nuclei was chosen as a model example. The first stage was the appearance of Cu crystals of a nanoscopic scale, observed by AFM microscopy. These nuclei soon induce corrosion pits due to the formation of a short-circuited electrochemical cell. In concentrated NH4F solutions, the open circuit potential (ocp) of Si samples is highly negative and provides an efficient driving force for nucleation even for common metals like Fe. Our results show that the deposition of Fe is hardly observable when Fe only is present, but in the presence of Cu, a catalytic effect is observed leading to the co-deposition of Fe + Cu nuclei. In all cases surface defects on the Si substrate are generated by the corrosion pits. (C) 2002 Elsevier Science B.V. All rights reserved.

    DOI CiNii

  • Sn electrodeposition process for fabricating microabsorber arrays for an X-ray microcalorimeter

    T Homma, H Sato, H Kobayashi, T Arakawa, H Kudo, T Osaka, S Shoji, Y Ishisaki, T Oshima, N Iyomoto, R Fujimoto, K Mitsuda

    JOURNAL OF ELECTROANALYTICAL CHEMISTRY   559 ( 1 ) 143 - 148  2003.11  [Refereed]

     View Summary

    Sn electrodeposition was employed for fabricating an array of microabsorbers with a 'mushroom-shaped' microstructure for a precision X-ray microdetector, the so called X-ray microcalorimeter. A deposition process for flat and smooth Sn films, which was suitable for the use of the absorber material, was developed by optimizing the conditions of additives such as o-cresol-4-sulfonic acid and polyethyleneglycol (PEG) to the Sn bath. The Sn films exhibited suitable properties, i.e. a higher superconducting transition temperature than the operating temperature of the X-ray microcalorimeter. The mushroom-shaped absorber array was successfully fabricated by Sn electrodeposition in combination with a photolithographic technique. (C) 2002 Elsevier Science B.V. All rights reserved.

    DOI CiNii

  • Molecular orbital study on the reaction process of dimethylamine borane as a reductant for electroless deposition

    T Homma, A Tamaki, H Nakai, T Osaka

    JOURNAL OF ELECTROANALYTICAL CHEMISTRY   559 ( 1 ) 131 - 136  2003.11  [Refereed]

     View Summary

    The oxidation mechanism of dimethylantine borane (DMAB), which acts as a reductant in the electroless deposition process, was studied using ab initio molecular orbital approaches such as Hartree-Fock (HF) and second order Moller-Plesset (MP2) calculations. The overall oxidation process of the DMAB was divided into each elementary reaction in which OH- substitutes H one by one and eventually forms B(OH)(4)(-). The oxidation mechanism of DMAB in the isolated state, which was previously proposed by us, was refined using more accurate basis sets, and the effects of solvation and interaction with metal surface sites on the oxidation mechanism were also studied. Taking the solvation effect into consideration using the self-consistent reaction field method with an isodensity polarized continuum model (SCRF-IPCM), the heat of oxidation was transferred to an exothermic reaction with decreasing dielectric constant. This indicated that the reaction preferably proceeds at the solid \ liquid interface. Combined with Cu(111) and Pd(111) neutral cluster models as metal surface sites, it was found that the oxidation reaction proceeds preferentially at the metal surface sites. It was also suggested that the catalytic activity of the deposited metal is caused by its electron acceptivity. (C) 2003 Elsevier Science B.V. All rights reserved.

    DOI CiNii

  • Survey of the metal nucleation processes on silicon surfaces in fluoride solutions: from dilute HF to concentrated NH4F solutions

    M Chemla, T Homma, Bertagna, V, R Erre, N Kubo, T Osaka

    JOURNAL OF ELECTROANALYTICAL CHEMISTRY   559 ( 1 ) 111 - 123  2003.11  [Refereed]

     View Summary

    As is well known, contamination of the silicon surface by trace metal impurities is responsible for detrimental effects in the production of ULSI circuits. An extensive experimental study of the factors influencing the spontaneous metal nucleation from fluoride solutions on Si substrates was undertaken. In acidic media (dilute HF solution) only noble metals can be deposited. The mechanism for the formation of Cu element nuclei was chosen as a model example. The first stage was the appearance of Cu crystals of a nanoscopic scale, observed by AFM microscopy. These nuclei soon induce corrosion pits due to the formation of a short-circuited electrochemical cell. In concentrated NH4F solutions, the open circuit potential (ocp) of Si samples is highly negative and provides an efficient driving force for nucleation even for common metals like Fe. Our results show that the deposition of Fe is hardly observable when Fe only is present, but in the presence of Cu, a catalytic effect is observed leading to the co-deposition of Fe + Cu nuclei. In all cases surface defects on the Si substrate are generated by the corrosion pits. (C) 2002 Elsevier Science B.V. All rights reserved.

    DOI CiNii

  • Maskless and electroless fabrication of patterned metal nanostructures on silicon wafers by controlling local surface activities

    T Homma, N Kubo, T Osaka

    ELECTROCHIMICA ACTA   48 ( 20-22 ) 3115 - 3122  2003.09

     View Summary

    Attempt was made to develop novel maskless and electroless fabrication process of metal nanostructures by controlling local surface activity for the deposition reaction at silicon wafer surfaces. P-Si(100) wafers were cleaned to obtain hydrogen-terminated surface and nanoscopic patterns were formed on the surface by nanoindentation technique using a scanning probe microscope (SPM) with a diamond probe. By controlling the parameters such as the indentation force (within the order of 1 - 10 muN), nanoscopic patterns with different degrees of defects were formed. The scanning surface potential microscopy (SPoM) analysis clarified that these sites locally possessed negative shift in potential, i.e., higher activity for the reductive deposition of metal ions, which increased with an increase in the degree of defect. In order to achieve spontaneous (electroless) and selective deposition at those patterns, conditions of the solution were optimized and the formation of metal nanostructures, such as Cu nanodot arrays and wires, has been achieved. Capability of the present process to form nanostructures whose feature size is as small as 50 nm was demonstrated. (C) 2003 Elsevier Ltd. All rights reserved.

    DOI

  • Maskless and electroless fabrication of patterned metal nanostructures on silicon wafers by controlling local surface activities

    T Homma, N Kubo, T Osaka

    ELECTROCHIMICA ACTA   48 ( 20-22 ) 3115 - 3122  2003.09

     View Summary

    Attempt was made to develop novel maskless and electroless fabrication process of metal nanostructures by controlling local surface activity for the deposition reaction at silicon wafer surfaces. P-Si(100) wafers were cleaned to obtain hydrogen-terminated surface and nanoscopic patterns were formed on the surface by nanoindentation technique using a scanning probe microscope (SPM) with a diamond probe. By controlling the parameters such as the indentation force (within the order of 1 - 10 muN), nanoscopic patterns with different degrees of defects were formed. The scanning surface potential microscopy (SPoM) analysis clarified that these sites locally possessed negative shift in potential, i.e., higher activity for the reductive deposition of metal ions, which increased with an increase in the degree of defect. In order to achieve spontaneous (electroless) and selective deposition at those patterns, conditions of the solution were optimized and the formation of metal nanostructures, such as Cu nanodot arrays and wires, has been achieved. Capability of the present process to form nanostructures whose feature size is as small as 50 nm was demonstrated. (C) 2003 Elsevier Ltd. All rights reserved.

    DOI

  • Substrate (Ni)-catalyzed electroless gold deposition from a noncyanide bath containing thiosulfate and sulfite - I. Reaction mechanism

    M Kato, J Sato, H Otani, T Homma, Y Okinaka, T Osaka, O Yoshioka

    JOURNAL OF THE ELECTROCHEMICAL SOCIETY   149 ( 3 ) C164 - C167  2002.03

     View Summary

    Electroless gold deposition is known to take place on Ni-based substrates even when the conventional reducing agent is excluded from the autocatalytic bath containing thiosulfate and sulfite as ligands for gold ions. It is shown in this paper that the reaction of gold deposition from this bath on electroless Ni-B substrate is not autocatalytic but, instead, proceeds primarily by the mechanism of substrate catalysis with galvanic displacement playing a secondary role. It was established that sulfite serves as the reducing agent for the substrate-catalyzed gold deposition reaction. (C) 2002 The Electrochemical Society.

    DOI CiNii

  • Substrate (Ni)-catalyzed electroless gold deposition from a noncyanide bath containing thiosulfate and sulfite - II. Deposit characteristics and substrate effects

    J Sato, M Kato, H Otani, T Homma, Y Okinaka, T Osaka, O Yoshioka

    JOURNAL OF THE ELECTROCHEMICAL SOCIETY   149 ( 3 ) C168 - C172  2002.03

     View Summary

    Characteristics of the gold deposit produced by the substrate (Ni)-catalyzed process in the thiosulfate-sulfite bath described in Part I of this series of papers are profoundly affected by bath composition and the composition and pretreatment of the substrate. This paper, Part II of a series of two, describes effects of those variables on the appearance, uniformity, morphology, and porosity of the gold deposit. (C) 2002 The Electrochemical Society.

    DOI CiNii

  • Substrate (Ni)-catalyzed electroless gold deposition from a noncyanide bath containing thiosulfate and sulfite - I. Reaction mechanism

    M Kato, J Sato, H Otani, T Homma, Y Okinaka, T Osaka, O Yoshioka

    JOURNAL OF THE ELECTROCHEMICAL SOCIETY   149 ( 3 ) C164 - C167  2002.03

     View Summary

    Electroless gold deposition is known to take place on Ni-based substrates even when the conventional reducing agent is excluded from the autocatalytic bath containing thiosulfate and sulfite as ligands for gold ions. It is shown in this paper that the reaction of gold deposition from this bath on electroless Ni-B substrate is not autocatalytic but, instead, proceeds primarily by the mechanism of substrate catalysis with galvanic displacement playing a secondary role. It was established that sulfite serves as the reducing agent for the substrate-catalyzed gold deposition reaction. (C) 2002 The Electrochemical Society.

    DOI CiNii

  • Substrate (Ni)-catalyzed electroless gold deposition from a noncyanide bath containing thiosulfate and sulfite - II. Deposit characteristics and substrate effects

    J Sato, M Kato, H Otani, T Homma, Y Okinaka, T Osaka, O Yoshioka

    JOURNAL OF THE ELECTROCHEMICAL SOCIETY   149 ( 3 ) C168 - C172  2002.03

     View Summary

    Characteristics of the gold deposit produced by the substrate (Ni)-catalyzed process in the thiosulfate-sulfite bath described in Part I of this series of papers are profoundly affected by bath composition and the composition and pretreatment of the substrate. This paper, Part II of a series of two, describes effects of those variables on the appearance, uniformity, morphology, and porosity of the gold deposit. (C) 2002 The Electrochemical Society.

    DOI CiNii

  • CoCrPtTa and Co/Pd perpendicular magnetic recording media with amorphous underlayers

    T Onoue, T Asahi, K Kuramochi, J Kawaji, T Homma, T Osaka

    IEEE TRANSACTIONS ON MAGNETICS   37 ( 4 ) 1592 - 1594  2001.07  [Refereed]

     View Summary

    The effect of amorphous carbon underlayers on magnetic properties and read-write characteristics of Co73Cr18Pt6Ta3 single layer and Co/Pd multilayer perpendicular magnetic recording media were investigated. The increase in H-c and decrease in alpha, defined as 4 pi (dM/dH)(H=Hc), were observed by increasing the underlayer thickness for both Co-73 Cr18Pt6Ta3 and Co/Pd media. The media with a low alpha value, suggesting a decrease in the exchange coupling, exhibited the higher coercivity and the improvement of S/N ratio. In read-write experiments, the improvement of S/N ratio for the Co/Pd media was achieved up to 400 kFRPI or even higher in the recording density by increasing carbon underlayer thickness, while that for the Co73Cr18Pt6Ta3 media was obtained up to ca. 250 kFRPI.

    DOI CiNii

  • CoCrPtTa and Co/Pd perpendicular magnetic recording media with amorphous underlayers

    T Onoue, T Asahi, K Kuramochi, J Kawaji, T Homma, T Osaka

    IEEE TRANSACTIONS ON MAGNETICS   37 ( 4 ) 1592 - 1594  2001.07  [Refereed]

     View Summary

    The effect of amorphous carbon underlayers on magnetic properties and read-write characteristics of Co73Cr18Pt6Ta3 single layer and Co/Pd multilayer perpendicular magnetic recording media were investigated. The increase in H-c and decrease in alpha, defined as 4 pi (dM/dH)(H=Hc), were observed by increasing the underlayer thickness for both Co-73 Cr18Pt6Ta3 and Co/Pd media. The media with a low alpha value, suggesting a decrease in the exchange coupling, exhibited the higher coercivity and the improvement of S/N ratio. In read-write experiments, the improvement of S/N ratio for the Co/Pd media was achieved up to 400 kFRPI or even higher in the recording density by increasing carbon underlayer thickness, while that for the Co73Cr18Pt6Ta3 media was obtained up to ca. 250 kFRPI.

    DOI CiNii

  • Mechanism of Sulfur Inclusion in Soft Gold Electrodeposited from the Thiosulfate-Sulfite Bath

    T. Osaka, M. Kato, J. Sato, K. Yoshizawa, T. Homma, Y. Okinaka, O. Yoshioka

    J. Electrochem. Soc   148 ( 10 ) C659 - C662  2001

    DOI CiNii

  • Improvement of Signal to Noise Ratio for Co/Pd Multilayer Perpendicular Magnetic Recording Media by Addition of an Underlayer

    T. Onoue, T. Asahi, K. Kuramochi, J. Kawaji, T. Homma, T. Osaka

    J. Magn. Magn. Matter   235 ( 1 ) 40 - 44  2001  [Refereed]

    DOI CiNii

  • Molecular orbital study on the reaction mechanisms of electroless deposition processes

    Homma, T, Komatsu, I, Tamaki, A, Nakai, H, Osaka, T

    Electrochimica Acta   47 ( 1-2 ) 47 - 53  2001  [Refereed]

    DOI CiNii

  • Ab initio molecular orbital study of the oxidation mechanism of hypophosphite ion as a reductant for an electroless deposition process

    Nakai, H, Homma, T, Komatsu, I, Osaka, T

    Journal of Physical Chemistry B   105 ( 9 ) 1701 - 1704  2001

    DOI CiNii

  • Mechanism of Sulfur Inclusion in Soft Gold Electrodeposited from the Thiosulfate-Sulfite Bath

    T. Osaka, M. Kato, J. Sato, K. Yoshizawa, T. Homma, Y. Okinaka, O. Yoshioka

    J. Electrochem. Soc   148 ( 10 ) C659 - C662  2001

    DOI CiNii

  • Improvement of Signal to Noise Ratio for Co/Pd Multilayer Perpendicular Magnetic Recording Media by Addition of an Underlayer

    T. Onoue, T. Asahi, K. Kuramochi, J. Kawaji, T. Homma, T. Osaka

    J. Magn. Magn. Matter   235 ( 1 ) 40 - 44  2001  [Refereed]

    DOI CiNii

  • Molecular orbital study on the reaction mechanisms of electroless deposition processes

    Homma, T, Komatsu, I, Tamaki, A, Nakai, H, Osaka, T

    Electrochimica Acta   47 ( 1-2 ) 47 - 53  2001  [Refereed]

    DOI CiNii

  • Ab initio molecular orbital study of the oxidation mechanism of hypophosphite ion as a reductant for an electroless deposition process

    Nakai, H, Homma, T, Komatsu, I, Osaka, T

    Journal of Physical Chemistry B   105 ( 9 ) 1701 - 1704  2001

    DOI CiNii

  • Electrochemical studies on the deposition process of electroless CoNiP films with graded magnetic properties

    Takayuki Homma, Yosuke Kita, Tetsuya Osaka

    Journal of the Electrochemical Society   147 ( 11 ) 4138 - 4141  2000.11

     View Summary

    In order to clarify the origin of the graded magnetic properties by the substrate rotational speed for electroless CoNiP films, electrochemical characteristics such as mixed potential and polarization behaviors were investigated. The results of mixed potential analysis revealed that the cathodic and anodic partial reactions in this system were diffusion- and reaction-controlled state, respectively. It was shown that the mixed potential of the CoNiP deposition with the substrate rotational speed was dominated mainly by the deposition reaction of Co. The results of the polarization curves for each metal ion clarified that the Co deposition is in the diffusion-controlled state, whereas such a tendency did not appear for the deposition of Ni. This suggests that such a difference in deposition behaviors between Co and Ni with respect to the rotational speed of the substrate results in the formation of graded film properties.

    DOI CiNii

  • Electrochemical studies on the deposition process of electroless CoNiP films with graded magnetic properties

    Takayuki Homma, Yosuke Kita, Tetsuya Osaka

    Journal of the Electrochemical Society   147 ( 11 ) 4138 - 4141  2000.11

     View Summary

    In order to clarify the origin of the graded magnetic properties by the substrate rotational speed for electroless CoNiP films, electrochemical characteristics such as mixed potential and polarization behaviors were investigated. The results of mixed potential analysis revealed that the cathodic and anodic partial reactions in this system were diffusion- and reaction-controlled state, respectively. It was shown that the mixed potential of the CoNiP deposition with the substrate rotational speed was dominated mainly by the deposition reaction of Co. The results of the polarization curves for each metal ion clarified that the Co deposition is in the diffusion-controlled state, whereas such a tendency did not appear for the deposition of Ni. This suggests that such a difference in deposition behaviors between Co and Ni with respect to the rotational speed of the substrate results in the formation of graded film properties.

    DOI CiNii

  • Evaluation of Substrate (Ni)-Catalyzed Electroless Gold Plating Process

    T. Osaka, T. Misato, J. Sato, H. Akiya, T. Homma, M. Kato, Y. Okinaka, O. Yoshioka

    J. Electrochem. Soc.   147 ( 3 ) 1059 - 1064  2000.03  [Refereed]

    DOI CiNii

  • Evaluation of Substrate (Ni)-Catalyzed Electroless Gold Plating Process

    T. Osaka, T. Misato, J. Sato, H. Akiya, T. Homma, M. Kato, Y. Okinaka, O. Yoshioka

    J. Electrochem. Soc.   147 ( 3 ) 1059 - 1064  2000.03  [Refereed]

    DOI CiNii

  • Microstructural Study on the Functionally Graded Magnetic Thin Films Prepared by Electroless Deposition

    T. Homma, Y. Kita, T. Osaka

    J. Electrochem. Soc.   147 ( 1 ) 160 - 163  2000.01  [Refereed]

    DOI CiNii

  • Microstructural Study on the Functionally Graded Magnetic Thin Films Prepared by Electroless Deposition

    T. Homma, Y. Kita, T. Osaka

    J. Electrochem. Soc.   147 ( 1 ) 160 - 163  2000.01  [Refereed]

    DOI CiNii

  • Effect of deposition site condition on the initial growth process of electroless CoNiP films

    Kunimasa Itakura, Takayuki Homma, Tetsuya Osaka

    Electrochimica Acta   44 ( 21 ) 3707 - 3711  1999.06  [Refereed]

     View Summary

    Effect of deposition site condition on the growth process of electroless CoNiP films was investigated by employing the intermediate 'treatment' step during the deposition. The effect of chemical species in the bath on the deposition sites, i.e., the film growth process, was examined using scanning electron microscopy (SEM) and atomic force microscopy (AFM). By changing the pH of the solutions for the 'treatment' step, it was found that the 'treatment' with higher pH solution resulted in the formation of smaller grains which possess lower perpendicular coercivity, Hc(⊥). From these results, ammonia in the deposition bath results in the inhibition of the growth of crystallites, which leads lower Hc(⊥). Based upon this, a model of the growth process of the CoNiP films was proposed.

    DOI CiNii

  • Ab Initio Molecular Orbital Study on the Oxidation Mechanism for Dimethylamine Borane as a Reductant for an Electroless Deposition Process

    T. Homma, H. Nakai, M. Onishi, T. Osaka

    J. Phys.Chem. B   103 ( 10 ) 1774 - 1778  1999

    DOI CiNii

  • Effect of deposition site condition on the initial growth process of electroless CoNiP films

    K Itakura, T Homma, T Osaka

    ELECTROCHIMICA ACTA   44 ( 21-22 ) 3707 - 3711  1999  [Refereed]

     View Summary

    Effect of deposition site condition on the growth process of electroless CoNiP films was investigated by employing the intermediate 'treatment' step during the deposition. The effect of chemical species in the bath on the deposition sites, i.e., the film growth process, was examined using scanning electron microscopy (SEM) and atomic force microscopy (AFM). By changing the pH of the solutions for the 'treatment' step, it was found that the 'treatment' with higher pH solution resulted in the formation of smaller grains which possess lower perpendicular coercivity, Hc(perpendicular to). From these results, ammonia in the deposition bath results in the inhibition of the growth of crystallites, which leads lower Hc(perpendicular to). Based upon this, a model of the growth process of the CoNiP films was proposed. (C) 1999 Elsevier Science Ltd. All rights reserved.

    DOI CiNii

  • Ab initio molecular orbital study on the oxidation mechanism for dimethylamine borane as a reductant for an electroless deposition process

    Homma, T, Nakai, H, Onishi, M, Osaka, T

    Journal of Physical Chemistry B   103 ( 10 ) 1774 - 1778  1999

    DOI CiNii

  • Nucleation of Trace Copper on the H-Si(111) Surface in Aqueous Fluoride Solutions

    T. Homma, C.P.Wade, C.E.D.Chidsey

    J. Phys.Chem. B   102 ( 41 ) 7919 - 7922  1998.10

    DOI CiNii

  • 表面技術便覧

    本間敬之

    日刊工業新聞     1613 - 1622  1998.02  [Refereed]

  • Gradient Control of Magnetic Properties in Electroless Deposited CoNiP Films

    T. Homma, M.Suzuki, T.Osaka

    J.Electrochem.Soc.   145 ( 1 ) 134 - 138  1998.01  [Refereed]

    DOI CiNii

  • Nucleation of Trace Copper on the H-Si(111) Surface in Aqueous Fluoride Solutions

    T. Homma, C.P.Wade, C.E.D.Chidsey

    J. Phys.Chem. B   102 ( 41 ) 7919 - 7923  1998

    DOI CiNii

  • Gradient control of magnetic properties in electroless-deposited CoNiP thin films

    Takayuki Homma, Mitsuru Suzuki, Tetsuya Osaka

    Journal of the Electrochemical Society   145 ( 1 ) 134 - 138  1998

     View Summary

    In order to establish the methodology for the preparation of the magnetic recording medium whose properties graded along the head field distribution, an intentional gradient control of coercivity, Hc, in electroless-deposited CoNiP thin films was attempted. Microstructure and Hc of the films changed significantly with the rotational speed of the substrate during deposition. Based upon these results, the gradient control of Hc was achieved by employing a programmed variation of the rotational speed of the substrate during the deposition. It was confirmed that not only "single-gradient" but also "dual-gradient" control of Hc in the direction of film thickness can be realized. This method is expected to be a useful technique for preparing a recording medium with magnetic propterties most suitable for recording system parameters such as head properties.

    DOI CiNii

  • Gradient control of magnetic properties in electroless-deposited CoNiP thin films

    Takayuki Homma, Mitsuru Suzuki, Tetsuya Osaka

    Journal of the Electrochemical Society   145 ( 1 ) 134 - 138  1998

     View Summary

    In order to establish the methodology for the preparation of the magnetic recording medium whose properties graded along the head field distribution, an intentional gradient control of coercivity, Hc, in electroless-deposited CoNiP thin films was attempted. Microstructure and Hc of the films changed significantly with the rotational speed of the substrate during deposition. Based upon these results, the gradient control of Hc was achieved by employing a programmed variation of the rotational speed of the substrate during the deposition. It was confirmed that not only "single-gradient" but also "dual-gradient" control of Hc in the direction of film thickness can be realized. This method is expected to be a useful technique for preparing a recording medium with magnetic propterties most suitable for recording system parameters such as head properties.

    DOI CiNii

  • Tapping Mode Atomic Force Microscopy Analysis of the Growth Process of Electroless Nickel-Phosphorus Films on Nonconducting Surfaces

    T. Homma, M. Tanabe, K. Itakura, T. Osaka

    J.Electrochem.Soc.   144 ( 12 ) 4123 - 4127  1997.12  [Refereed]

    DOI CiNii

  • Tapping Mode Atomic Force Microscopy Analysis of the Growth Process of Electroless Nickel-Phosphorus Films on Nonconducting Surfaces

    T. Homma, M. Tanabe, K. Itakura, T. Osaka

    J.Electrochem.Soc.   144 ( 12 ) 4123 - 4127  1997.12  [Refereed]

    DOI CiNii

  • Electrodeposition of Soft Gold From a Thiosulfate-Sulfite Bath for Electronics Applications

    T. Osaka, A. Kodera, T. Misato, T. Homma, Y. Okinaka

    J.Electrochem.Soc.   144 ( 10 ) 3462 - 3469  1997.10  [Refereed]

    DOI CiNii

  • Electrodeposition of Soft Gold From a Thiosulfate-Sulfite Bath for Electronics Applications

    T. Osaka, A. Kodera, T. Misato, T. Homma, Y. Okinaka

    J.Electrochem.Soc.   144 ( 10 ) 3462 - 3469  1997.10  [Refereed]

    DOI CiNii

  • Noise Properties of an Electroless-deposited CoNiReP Perpendicular Magnetic Prcording Medium and a Perpendicular / Longitudinal Composite Medium

    J. Hokkyo, T. Osaka, T. Homma, T. Onoue, N. Miyamoto

    J.Magn.Soc.Jpn.   21 ( S2 ) 525 - 528  1997.09  [Refereed]

  • Noise Properties of an Electroless-deposited CoNiReP Perpendicular Magnetic Prcording Medium and a Perpendicular / Longitudinal Composite Medium

    J. Hokkyo, T. Osaka, T. Homma, T. Onoue, N. Miyamoto

    J.Magn.Soc.Jpn.   21 ( S2 ) 525 - 528  1997.09  [Refereed]

  • Noise Properties of an Electroless-deposited CoNiReP Perpendicular Magnetic Prcording Medium and a Perpendicular / Longitudinal Composite Medium

    J. Hokkyo, T. Osaka, T. Homma, T. Onoue, N. Miyamoto

    J.Magn.Soc.Jpn.   21 ( S2 ) 525 - 528  1997.09

  • 垂直面内複合型媒体の記録再生特性

    黒川義昭, 本間敬之, 逢坂哲彌

    日本応用磁気学会誌   21 ( 6 ) 977 - 982  1997.06  [Refereed]

     View Summary

    The recording characteristics of a composite medium with a longitudinal magnetization recording layer as a underlayer of a perpendicular magnetization recording layer were evaluated by using ring-type heads. The results suggest that the residual magnetization mode of the medium is a phase synchronization mode, which forms a horseshoe-shaped magnetization region composed of the strong perpendicular magnetization region of the perpendicular layer and the longitudinal magnetization region of the underlayer. The reproduced voltage of the medium is higher than that obtained by simple superposition of the outputs of the perpendicular top layer and the longitudinal under-layer, and the waveform of the medium shows an almost single-peaked pulse. The recording density response and peak shift characteristics are not restricted by the characteristics of the underlayer. The magnetization state of the medium can be controlled by the medium and head parameters, indicating the importance of optimizing these parameters.

    CiNii

  • リングヘッド-垂直面内複合型媒体系におけるスペーシングの影響

    黒川義昭, 長崎 顕, 本間敬之, 逢坂哲彌

    日本応用磁気学会誌   21 ( S1 ) 163 - 168  1997.04  [Refereed]

  • CoCrTa/Cr磁性薄膜におけるSi基板前処理効果の検討

    逢坂哲彌, 本間敬之, 黒川義昭, 田口智一, 瀧澤敦尚

    日本応用磁気学会誌   21 ( 4 ) 213 - 216  1997.04  [Refereed]

     View Summary

    CoCrTa/Cr magnetic films on Si(100) substrates with and without HF pre-treatment were prepared by dc magnetron sputtering. It was found that the coercivity was increased by HF pre-treatment of the Si substrate for Cr underlayers of various thicknesses. The microstructure analyses of the magnetic films using XRD. FE-SEM,and TEM showedthat the crystallinity and the orientation of the c-axis in the film plane were enhanced and that the grain size was increased by HF pre-treatment.