Details of a Researcher - NORIMATSU, Wataru

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NORIMATSU, Wataru

Scopus Paper Info

Paper Count: 77 Citation Count: 1671 h-index: 20

Click to view the Scopus page. The data was downloaded from Scopus API in December 22, 2024, via http://api.elsevier.com and http://www.scopus.com .

Google Scholar Information (Citations per year)

Citation Count: 2288 h-index: 22 i10-index: 37

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Scopus Information

Affiliation

Faculty of Science and Engineering, School of Fundamental Science and Engineering

Job title

Professor

Homepage URL

https://www.nano.sci.waseda.ac.jp/

Research Experience

2023.04

-

Now

Waseda University Faculty of Fundamental Science Professor
2023.04

-

2024.03

Nagoya University Graduate School of Engineering Visiting Professor
2018.04

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2023.03

Nagoya University Graduate School of Engineering Chemical Systems Engineering 2 Associate professor
2017.04

-

2018.03

Nagoya University Graduate School of Engineering Biomolecular Engineering 1 Assistant Professor
2011.04

-

2017.03

Nagoya University Graduate School of Engineering Department of Applied Chemistry, Chemical Engineering and Biotechnology Chemistry of Inorganic Materials and Analytical Chemistry Assistant Professor
2008.05

-

2011.03

Nagoya University EcoTopia Science Institute Environmental Systems and Recycling Science Research Department Assistant Professor

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Research Areas

Thin film/surface and interfacial physical properties

Papers

Electrochemical lithium-ion insertion/extraction reactions of multilayered graphene with random twist angles

Satoshi Yamamoto, Ryotaro Sakakibara, Soichi Shima, Shinsuke Matsuura, Takeshi Yajima, Munekazu Motoyama, Wataru Norimatsu, Yuta Kimura, Koji Amezawa, Yasutoshi Iriyama

Chemical Communications 2024.11 [Refereed]

　View Summary

A multilayer graphene film with random twist angles between layers (TAGr) on SiC(0001̄) shows six pairs of redox peaks for Li⁺ insertion/extraction reaction.

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A Review on Carrier Mobilities of Epitaxial Graphene on Silicon Carbide

Wataru Norimatsu

Materials 16 ( 24 ) 7668 - 7668 2023.12 [Refereed] [Invited]

　View Summary

Graphene growth by thermal decomposition of silicon carbide (SiC) is a technique that produces wafer-scale, single-orientation graphene on an insulating substrate. It is often referred to as epigraphene, and has been thought to be suitable for electronics applications. In particular, high-frequency devices for communication technology or large quantum Hall plateau for metrology applications using epigraphene are expected, which require high carrier mobility. However, the carrier mobility of as-grown epigraphene exhibit the relatively low values of about 1000 cm2/Vs. Fortunately, we can hope to improve this situation by controlling the electronic state of epigraphene by modifying the surface and interface structures. In this paper, the mobility of epigraphene and the factors that govern it will be described, followed by a discussion of attempts that have been made to improve mobility in this field. These understandings are of great importance for next-generation high-speed electronics using graphene.

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4

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(Scopus)
Electrochemical Li⁺ Insertion/Extraction Reactions at LiPON/Epitaxial Graphene Interfaces

Satoshi Yamamoto, Munekazu Motoyama, Masahiko Suzuki, Ryotaro Sakakibara, Norikazu Ishigaki, Akichika Kumatani, Wataru Norimatsu, Yasutoshi Iriyama

ACS Nano 17 ( 17 ) 16448 - 16460 2023.08

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2

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(Scopus)
Step unbunching phenomenon on 4H-SiC (0001) surface during hydrogen etching

Ryotaro Sakakibara, Jianfeng Bao, Keisuke Yuhara, Keita Matsuda, Tomo-o Terasawa, Michiko Kusunoki, Wataru Norimatsu

Applied Physics Letters 123 ( 3 ) 2023.07 [Refereed]

　View Summary

We here report a step unbunching phenomenon, which is the inverse of the phenomenon of step bunching. When a 4H-SiC (0001) surface is annealed at a high temperature, step bunching arises due to the different velocities of the step motion in adjacent steps, resulting in steps with a height of more than several nanometers. We found that the bunched steps, thus, obtained by hydrogen etching in an Ar/H2 atmosphere were “unbunched” into lower height steps when annealed subsequently at lower temperatures. This unbunching phenomenon can be well explained by the consequence of the competition between energetics and kinetics. Our findings provide another approach for the surface smoothing of SiC by hydrogen etching and may give significant insight into the application of SiC power devices and two-dimensional materials growth techniques in general.

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3

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(Scopus)
Control of rotation angles of multilayer graphene on SiC (000 1‾ ) by substrate off-direction and angle

Ryotaro Sakakibara, Jianfeng Bao, Naoki Hayashi, Takahiro Ito, Hiroki Hibino, Wataru Norimatsu

Journal of Physics: Condensed Matter 35 ( 38 ) 385001 - 385001 2023.06 [Refereed]

　View Summary

Abstract

Graphene on SiC (000$\overline{1}$) tends to grow in multiple layers and does not have a single orientation relation with the SiC substrate. It has been considered impossible to control the rotation angle of multilayer graphene on SiC (000$\overline{1}$). In this study, we grew graphene on off-axis SiC substrates with various off angles from 0° to 8° and investigated their in-plane rotation and electronic structures systematically. As the off angle toward the [11$\overline{2}$0]_SiC direction increased, graphene rotated by 30° with respect to SiC became less dominant and instead, graphene rotated by 30 ± 2.5° appeared. We also found that the uniformity of the graphene rotation angle was relatively high on SiC substrates with a small off angle toward the [1$\overline{1}$00]_SiC direction. Our results suggest that the step-terrace structure defined by the substrate off-direction and angle plays an important role in the controllability of the rotation angle of graphene.

DOI
Microscopic mechanism of hydrogen intercalation: On the conversion of the buffer layer on SiC to graphene

Ryotaro Sakakibara, Wataru Norimatsu

PHYSICAL REVIEW B 105 ( 23 ) 2022.06

　View Summary

We report an investigation of the microscopic mechanism of hydrogen penetration and migration in the conversion process of the buffer layer on SiC into quasi-freestanding graphene. By systematically observing the initial stage, we found that hydrogen intercalation initiates locally and simultaneously throughout the terrace, followed by the expansion of the intercalated area, resulting in full graphenization of the buffer layer over the SiC surface. This suggests that hydrogen can penetrate the buffer layer. In addition, we found that the steps on the SiC surface can act as a migration barrier, hindering the migration of hydrogen at the interface across the steps. This series of experimental results provides important insights into the fundamental mechanism of hydrogen intercalation and may help to pave the way toward graphene electronics.

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5

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Observation of a flat band and bandgap in millimeter-scale twisted bilayer graphene

Keiju Sato, Naoki Hayashi, Takahiro Ito, Noriyuki Masago, Makoto Takamura, Mitsuru Morimoto, Takuji Maekawa, Doyoon Lee, Kuan Qiao, Jeehwan Kim, Keisuke Nakagahara, Katsunori Wakabayashi, Hiroki Hibino, Wataru Norimatsu

COMMUNICATIONS MATERIALS 2 ( 1 ) 2021.12

　View Summary

Magic-angle twisted bilayer graphene is interesting for its correlated superconducting and insulating states, but samples are typically micrometer-scale. Here, 3 x 5 mm(2) twisted bilayer graphene samples are fabricated, exhibiting a flat band and large bandgap revealed by angle-resolved photoemission spectroscopy.Magic-angle twisted bilayer graphene, consisting of two graphene layers stacked at a special angle, exhibits superconductivity due to the maximized density of states at the energy of the flat band. Generally, experiments on twisted bilayer graphene have been performed using micrometer-scale samples. Here we report the fabrication of twisted bilayer graphene with an area exceeding 3 x 5 mm(2) by transferring epitaxial graphene onto another epitaxial graphene, and observation of a flat band and large bandgap using angle-resolved photoemission spectroscopy. Our results suggest that the substrate potential induces both the asymmetrical doping in large angle twisted bilayer graphene and the electron doped nature of the flat band in magic-angle twisted bilayer graphene.

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15

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(Scopus)
Charge/Discharge Reactions via LiPON/Multilayer-Graphene Interfaces without Li+ Desolvation/Solvation Processes

Munekazu Motoyama, Keita Miyoshi, Satoshi Yamamoto, Ryotaro Sakakibara, Yuta Yamamoto, Takayuki Yamamoto, Wataru Norimatsu, Yasutoshi Iriyama

ACS APPLIED ENERGY MATERIALS 4 ( 10 ) 10442 - 10450 2021.09

　View Summary

Li+ desolvation process has been regarded as the rate-limiting process in Li+ insertion reaction with graphite anode in lithium-ion batteries. In contrast, Li+ desolvation process is absent in solid-state batteries. We fabricated thin-film all-solid-state cells by depositing lithium phosphorus oxynitride glass (LiPON) electrolyte onto a multilayer-graphene (MGr) film by RF magnetron sputtering and measured the charge/discharge performance of the cells. It was found that the charge transfer resistance at the LiPON/MGr interface was significantly small, although the LiPON/MGr interface was supposed to have inorganic solid electrolyte interphase resulting from the LiPON reduction decomposition. Consequently, the dominant factor for the overall overpotential was the ohmic loss for LiPON, and hence the capacity retention was still maintained at 60% even at nearly 900C when the LiPON film thickness was 4 mu m.

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5

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Photoluminescence Enhancement Exceeding 10-Fold from Graphene via an Additional Layer: Photoluminescence from Monolayer and Bilayer Graphene Epitaxially Grown on SiC

Kensuke Saito, Tomonari Koishi, Jianfeng Bao, Wataru Norimatsu, Michiko Kusunoki, Hideo Kishida, Takeshi Koyama

JOURNAL OF PHYSICAL CHEMISTRY C 125 ( 20 ) 11014 - 11022 2021.05

　View Summary

Graphene exhibits characteristic optical properties and has garnered significant attention for application in light-emitting devices. Bilayer graphene is expected to be more suitable than monolayer graphene for application because of its strong luminescence owing to weak substrate effects. To further investigate this, we analyze the femtosecond photoluminescence (PL) decay and time-resolved PL spectra of epitaxial monolayer and bilayer graphene on SiC. The bilayer graphene emits longer and more than 10-fold stronger PL compared with the monolayer graphene. The PL decay curves and spectra are analyzed using a three-temperature model. The time evolutions of the carrier temperature and coupling coefficients between the carriers of graphene and each of the phonons of graphene and the substrate are obtained. The carrier temperature in bilayer graphene after femtosecond laser pulse excitation is approximately 120 K higher than that in monolayer graphene under our experimental conditions, thereby explaining the longer and stronger PL from the bilayer graphene. This study demonstrates the superior ability of bilayer graphene as a light-emitting material compared with monolayer graphene and promotes research pertaining to graphene-based light-emitting devices.

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7

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Structure of quasi-free-standing graphene on the SiC (0001) surface prepared by the rapid cooling method

Tatsuya Sumi, Kazuki Nagai, Jianfeng Bao, Tomo-o Terasawa, Wataru Norimatsu, Michiko Kusunoki, Yusuke Wakabayashi

APPLIED PHYSICS LETTERS 117 ( 14 ) 2020.10

　View Summary

A systematic structural study of epitaxial graphene samples on the SiC (0001) surface has been performed by the surface x-ray diffraction method, which is a non-contact technique. For samples with only a buffer layer, one layer graphene, and multilayer graphene, the distances between the buffer layer and the surface Si atoms were found to be 2.3 angstrom. This value is the same as reported values. For quasi-free-standing graphene samples prepared by the rapid cooling method [Bao et al., Phys. Rev. Lett. 117, 205501 (2016)], there was no buffer layer and the distance between the quasi-free-standing graphene and the surface Si atoms was 3.5 angstrom, which is significantly shorter than the value in hydrogen-intercalated graphene and slightly longer than the interplane distance in graphite. The Si occupancy deviated from unity within 1nm of the SiC surface. The depth profile of the Si occupancy showed little sample dependence, and it was reproduced by a simple atomistic model based on random hopping of Si atoms.

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4

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(Scopus)
Controlled growth of boron-doped epitaxial graphene by thermal decomposition of a B4C thin film

Wataru Norimatsu, Keita Matsuda, Tomo-o Terasawa, Nao Takata, Atsushi Masumori, Keita Ito, Koji Oda, Takahiro Ito, Akira Endo, Ryoji Funahashi, Michiko Kusunoki

NANOTECHNOLOGY 31 ( 14 ) 2020.04

　View Summary

We show that boron-doped epitaxial graphene can be successfully grown by thermal decomposition of a boron carbide thin film, which can also be epitaxially grown on a silicon carbide substrate. The interfaces of B4C on SiC and graphene on B4C had a fixed orientation relation, having a local stable structure with no dangling bonds. The first carbon layer on B4C acts as a buffer layer, and the overlaying carbon layers are graphene. Graphene on B4C was highly boron doped, and the hole concentration could be controlled over a wide range of 2 x 10(13) to 2 x 10(15) cm(-2). Highly boron-doped graphene exhibited a spin-glass behavior, which suggests the presence of local antiferromagnetic ordering in the spin-frustration system. Thermal decomposition of carbides holds the promise of being a technique to obtain a new class of wafer-scale functional epitaxial graphene for various applications.

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11

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(Scopus)
Metal Deposition Using Solutions on High-Density and Well-Aligned CNTs

Mikiko Saito, Hiroyuki Kuwae, Jun Mizuno, Wataru Norimatsu, Michiko Kusunoki, Hiroshi Nishikawae

2020 IEEE 8TH ELECTRONICS SYSTEM-INTEGRATION TECHNOLOGY CONFERENCE (ESTC) 2020

　View Summary

The preparation processes of Co-Cu and Au-Ag electrodeposited films and electroless Au films, using high-density and highly orientated CNTs on a SiC substrate, were investigated. The attachment via electrochemical reduction of PVP to the CNTs/SiC resulted in a hydrophilic CNTs surface the water contact angle reduced from 110 degrees to 70 degrees. After Co-Cu electrodeposition, the D-band shifted to a lower wavenumber, that indicated an increase in the mass number as Co-Cu metals deposited on the CNTS/SiC. However, the morphology of this Co-Cu electrodeposited film was not related to its hydrophilicity. The CNTs worked well as cathode electrodes because of their high conductivity. During the Co-Cu electrodeposition process, high pH and a complex agent were used. This did not affect the nucleation generation rate, however, the diffusion velocity affected the reaction velocity. Meanwhile, the Au-Ag particle sizes formed with a Pt seed layer were smaller than with the CNTs/SiC substrate. The nucleation generation rates were also different since CNTs/SiC conductivity was smaller than that of Pt. The deposition bath constitution was also thought to be connected to the deposition mechanism. Therefore, to obtain small-sized particles, a higher conductivity of CNTs was needed. Lastly, to obtain more precise metal particles, electroless Au deposition was carried out. After oxygen plasma treatment, the oxidized surface and inner CNTs were displaced by deposited Au ions. The deposition of Au, with particle size approximately 5 nm, was confirmed by TEM analysis and EDS mapping. CNTs mixed electrodeposition and electroless deposition of metals were also investigated. It was confirmed that metal nanoparticles enhanced the deposition of well aligned and high-density CNTs/SiC, with a diameter of 5 nm.
Longitudinal strain of epitaxial graphene monolayers on SiC substrates evaluated by z-polarization Raman microscopy

Yuika Saito, Kenshiro Tokiwa, Takahiro Kondo, Jianfeng Bao, Tomo-o Terasawa, Wataru Norimatsu, Michiko Kusunoki

AIP ADVANCES 9 ( 6 ) 2019.06

　View Summary

Longitudinal strains in epitaxial monolayer graphene (EMG) grown on SiC substrates were evaluated by z-polarization Raman microscopy. Due to the covalent bonds formed at the interface between graphene and the substrate, strong compressive strains were loaded on the EMG, which were sensitively detected by Raman spectroscopy. Our polarization Raman microscope was specially designed for evaluating the longitudinal (z-polarization) strain, as well as the lateral (xy-polarization). Z-polarization Raman microscopy revealed the relationship between the fluctuation of the local strains and the sample morphology in the SiC-graphene through submicron spatial resolution mapping. The amount of strain estimated through Raman shift and its spatial inhomogeneity have critical influence on the mobility of electrons, which are essential for future device applications of EMG.

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4

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(Scopus)
Features and prospects for epitaxial graphene on SiC

Wataru Norimatsu, Tomo o. Terasawa, Keita Matsuda, Jianfeng Bao, Michiko Kusunoki

Handbook of Graphene 8 153 - 199 2019.03

　View Summary

Epitaxial graphene growth on SiC is the only technique available to obtain wafer-scale single-crystalline graphene directly on the insulating substrate. It is then suitable for electronics applications. Monolayer graphene covers the entire surface of the several millimeters square substrate. The carrier mobility of graphene on SiC increases with decreasing the carrier concentration, and it reaches as high as 46,000 cm2/Vs at 2 K, indicating the essential high quality of graphene on SiC. These features of graphene on SiC lead to possible applications in the field of high-frequency transistors, which are used for communication devices such as cell phones, broadcasting station, communication satellite, and radars. In this chapter, we summarize the basic features of graphene on SiC revealed by atomic force microscopy (AFM), Raman spectroscopy, transmission electron microscopy (TEM), angle-resolved photoemission spectroscopy (ARPES), and Hall-effect measurements. We also describe further techniques to improve the electrical properties and the prospects of graphene on SiC.
Carbon Nanotube Forests on SiC: Structural and Electrical Properties

Masafumi Inaba, Wataru Norimatsu, Michiko Kusunoki, Hiroshi Kawarada

Novel Structured Metallic and Inorganic Materials 605 - 620 2019 [Refereed]

DOI
Acceleration of Photocarrier Relaxation in Graphene Achieved by Epitaxial Growth: Ultrafast Photoluminescence Decay of Monolayer Graphene on SiC

Hirotaka Imaeda, Takeshi Koyama, Hideo Kishida, Kenji Kawahara, Hiroki Ago, Ryotaro Sakakibara, Wataru Norimatsu, Tomo-o Terasawa, Jianfeng Bao, Michiko Kusunoki

JOURNAL OF PHYSICAL CHEMISTRY C 122 ( 33 ) 19273 - 19279 2018.08

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Acceleration of photocarrier relaxation in graphene results in the enhancement of its properties for graphene-based ultrafast optical devices. The acceleration can be achieved by utilizing the relaxation paths outside the graphene to avoid bottlenecks in the graphene for photocarrier relaxation. In this study, we investigate photocarrier relaxation in epitaxial and transferred monolayer graphene on SiC with a buffer layer at room temperature by means of time-resolved photoluminescence spectroscopy. The photoluminescence decay at 0.7 eV in the epitaxial monolayer graphene is faster than that in the transferred monolayer graphene. On the basis of the three-temperature model calculation, it is found that the carrier-phonon interaction with phonons of the buffer layer for the epitaxial monolayer graphene is 3 times stronger than that for the transferred monolayer graphene. This study demonstrates that ultrafast photocarrier relaxation can be achieved in graphene by epitaxial growth.

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12

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(Scopus)
Electrical contact properties between carbon nanotube ends and a conductive atomic force microscope tip

Masafumi Inaba, Kazuyoshi Ohara, Megumi Shibuya, Takumi Ochiai, Daisuke Yokoyama, Wataru Norimatsu, Michiko Kusunoki, Hiroshi Kawarada

JOURNAL OF APPLIED PHYSICS 123 ( 24 ) 2018.06

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Understanding the electrical contact properties of carbon nanotube (CNT) ends is important to use the high conductance of CNTs in the CNT on-axis direction in applications such as through-silicon via structures. In this study, we experimentally evaluated the contact resistivity between single-/multi-walled CNT ends and a metal nanoprobe using conductive atomic force microscopy (C-AFM). To validate the measured end contact resistivity, we compared our experimentally determined value with that obtained from numerical calculations and reported values for side contact resistivity. The contact resistivity normalized by the length of the CNT ends was 0.6-2.4 x 10(6) Omega nm for single-walled CNTs. This range is 1-2 orders of magnitude higher than that determined theoretically. The contact resistivity of a single-walled CNT end with metal normalized by the contact area was 2-3 orders of magnitude lower than that reported for the resistivity of a CNT sidewall/metal contact. For multi-walled CNTs, the measured contact resistivity was one order of magnitude higher than that of a CNT forest grown by remote plasma-enhanced chemical vapor deposition, whereas the contact resistivity of a top metal electrode was similar to that obtained for a single-walled CNT forest. Published by AIP Publishing.

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5

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(Scopus)
Frequency dependent ac transport of films of close-packed carbon nanotube arrays

A. Endo, S. Katsumoto, K. Matsuda, W. Norimatsu, M. Kusunoki

Journal of Physics: Conference Series 969 ( 1 ) 2018.04 [Refereed]

　View Summary

We have measured low-Temperature ac impedance of films of closely-packed, highly-Aligned carbon nanotubes prepared by thermal decomposition of silicon carbide wafers. The measurement was performed on films with the thickness (the length of the nanotubes) ranging from 6.5 to 65 nm. We found that the impedance rapidly decreases with the frequency. This can be interpreted as resulting from the electric transport via capacitive coupling between adjacent nanotubes. We also found numbers of sharp spikes superposed on frequency vs. impedance curves, which presumably represent resonant frequencies seen in the calculated conductivity of random capacitance networks. Capacitive coupling between the nanotubes was reduced by the magnetic field perpendicular to the films at 8.2 mK, resulting in the transition from negative to positive magnetoresistance with an increase of the frequency.

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Preparation of Stable Silver Nanoparticles Having Wide Red-To-Near-Infrared Extinction

Shiori Kawamura, Kazuki Matsubara, Sotaro Sakai, Kazuhisa Sasaki, Masataro Saito, Kenji Saito, Masayuki Yagi, Wataru Norimatsu, Ryo Sasai, Michiko Kusunoki, Miharu Eguchi, Shu Yin, Yusuke Asakura, Tatsuto Yui

GLOBAL CHALLENGES 2 ( 3 ) 2018.03

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The synthesis of silver nanoparticles (AgNPs) within the interlayer space of transparent layered titania nanosheet (TNS) films is investigated. A considerable number of silver ions (approximate to 70% against the cation exchange capacity of the TNS) are intercalated in the TNS films using methyl-viologen-containing TNSs as a precursor. The silver ion (Ag+)-containing TNS films are treated with aqueous sodium tetrahydroborate (NaBH4), resulting in a gradual color change to bright blue. Various structural analyses clearly show that crystalline AgNPs are generated within the interlayer space of the TNSs. The NaBH4-treated films show intense and characteristic near-infrared (NIR) extinction spectra up to 1800 nm. The tability of the AgNPs within the TNS against oxygen and moisture is also investigated, and 96% and 82% of the AgNPs remain after standing in air for 1 month and 1 year, respectively. The NIR extinctions of the AgNP-containing TNS films are further extended by employing different preparation procedures, for example, using sintered TNS films as starting materials and irradiating the Ag+-containing TNSs with ultraviolet (UV) light. The obtained AgNP-containing TNS films exhibit photochemical activities in the production of hydrogen from ammonia borane under visible-light irradiation and the decomposition of nitrogen monoxide under UV-light irradiation.

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(Scopus)
Selective fabrication of free-standing ABA and ABC trilayer graphene with/without Dirac-cone energy bands

Katsuaki Sugawara, Norifumi Yamamura, Keita Matsuda, Wataru Norimatsu, Michiko Kusunoki, Takafumi Sato, Takashi Takahashi

NPG ASIA MATERIALS 10 2018.02

　View Summary

Graphene is a single-layer carbon sheet with a honeycomb structure, and bilayer graphene consists of two graphene sheets with AB stacking. In trilayer graphene, the third graphene sheet has two possible stacking sequences, A or C, when it is overlaid on bilayer graphene. It has been theoretically predicted that trilayer graphene exhibits a variety of novel electronic properties with/without a Dirac-cone band, depending on the stacking sequence. In this regard, trilayer graphene has a high potential for widening the capability of graphene-based electronic devices. However, the difficulty of selective fabrication has hindered the progress of research. Here, we report the first success in the selective fabrication of quasi-free-standing trilayer graphene with ABA or ABC stacking grown epitaxially on hydrogen-terminated silicon carbide. Angle-resolved photoemission spectroscopy (ARPES) clearly demonstrated that our trilayer graphene with ABA stacking has a massless Dirac-like band near the Fermi level, while that with ABC stacking shows a parabolic non-Dirac-like band dispersion.

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In-plane electrical conduction mechanisms of highly dense carbon nanotube forests on silicon carbide

Keita Matsuda, Wataru Norimatsu, Jianfeng Bao, Hiroshi Kawarada, Michiko Kusunoki

JOURNAL OF APPLIED PHYSICS 123 ( 4 ) 2018.01

　View Summary

We have investigated the length-dependence of the in-plane electrical resistivity of vertically aligned and highly dense carbon nanotube (CNT) films that were dense enough to conduct electrons. The in-plane conductivity is well accounted for by a combination of inter-tube hopping (variable range hopping, VRH) and graphitic conduction. VRH conduction was dominant in the thinner CNT films, and the films showed negative temperature dependence of resistivity. The dimension of the VRH component varied depending on the CNT length. In the thicker CNT films, the graphitic conduction appeared, and then, the localization length spread, leading to the positive temperature dependence of resistivity. This behavior can be explained by the presence of a labyrinthine arrangement of graphene walls among aligned CNTs, which was confirmed by transmission electron microscopy observations. Published by AIP Publishing.

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(Scopus)
Electrical integrity and anisotropy in dielectric breakdown of layered h-BN insulator

K. Nagashio, Y. Hattori, N. Takahashi, T. Taniguchi, K. Watanabe, J. Bao, W. Norimatsu, M. Kusunoki

ECS Transactions 79 ( 1 ) 91 - 97 2017 [Refereed]

　View Summary

We report the complete set of dielectric breakdown strength (EBD) for h-BN, that is, 12 MV/cm for out-of-plane EBD is four times higher than that for in-plane EBD and it is larger than that for diamond. The large anisotropy in dielectric constant (i.e., related with band gap) due to the layered structure causes this anisotropy.

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Photoinduced electron transfer in layer-by-layer thin solid films containing cobalt oxide nanosheets, porphyrin, and methyl viologen

R. Sasai, Y. Kato, W. Soontornchaiyakul, H. Usami, A. Masumori, W. Norimatsu, T. Fujimura, S. Takagi

Physical Chemistry Chemical Physics 19 ( 7 ) 5611 - 5616 2017

　View Summary

© 2017 the Owner Societies. The well-known layer-by-layer (LbL) method can be used to prepare solid thin films with a controlled electron transfer direction by appropriately stacking metal oxide nanosheets and functional organic ions. In this study, we prepared thin solid films consisting of cobalt oxide nanosheets (CoNSs) as the electron transfer medium, α,β,γ,δ-tetrakis(1-methylpyridinium-4-yl)porphyrin (TMPyP) as the electron donor, and 1,1′-dimethyl-4,4′-bipyridinium or methyl viologen (MV) as the electron acceptor. We investigated the photoinduced electron transfer phenomenon in these films by irradiating them with 450 nm light. Irradiating the LbL thin solid films prepared with the CoNS/TMPyP/CoNS/MV/CoNS sequence under reduced pressure led to the production of a one-electron reduction compound of MV. Hence, photoinduced electron transfer from TMPyP to MV bound to CoNSs occurred in these LbL thin solid films. However, the conduction band of CoNSs, as determined by the photoabsorption spectral and photoelectrochemical measurements, was much higher than the lowest unoccupied molecular orbital level of TMPyP. Our findings indicate that the observed equipotential photoinduced electron transfer was caused by the metallic electron conductivity of CoNSs, which show a unique charge arrangement of Co3+ and Co4+. Moreover, it was also found that the observed photoinduced charge separation state has a longer life-time (>5 h) under the reduced conditions.

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Two-carrier model on the magnetotransport of epitaxial graphene containing coexisting single-layer and bilayer areas

Akira Endo, Jianfeng Bao, Wataru Norimatsu, Michiko Kusunoki, Shingo Katsumoto, Yasuhiro Iye

PHILOSOPHICAL MAGAZINE 97 ( 21 ) 1755 - 1767 2017

　View Summary

We have performed low-temperature magnetotransport measurements on epitaxial graphene composed of domains of single-layer and bilayer areas simultaneously present on SiC(0001). Positive magnetoresistance that tends to saturate at high magnetic fields is observed for longitudinal component , while the Hall resistance exhibits sublinear behaviour. The lineshapes for both can be accounted for extremely well by the semiclassical magnetotransport model incorporating two types of carriers conducting in parallel. Two sets of mobilities and densities, corresponding to single-layer and bilayer regions, respectively, can be obtained by fitting the experimental traces to the two-carrier model formulae. From the carrier densities, in turn, the ratio of the single-layer to bilayer areas can be deduced, assuming the alignment of the Fermi levels in the two types of areas with differing dispersion relations and Dirac point energies. The ratio of areas thus obtained is consistent with the ratio directly observed in the atomic force micrograph.

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(Scopus)
Synthesis of Freestanding Graphene on SiC by a Rapid-Cooling Technique

Jianfeng Bao, Wataru Norimatsu, Hiroshi Iwata, Keita Matsuda, Takahiro Ito, Michiko Kusunoki

PHYSICAL REVIEW LETTERS 117 ( 20 ) 2016.11

　View Summary

Graphene has a negative thermal expansion coefficient; that is, when heated, the graphene lattice shrinks. On the other hand, the substrates typically used for graphene growth, such as silicon carbide, have a positive thermal expansion coefficient. Hence, on cooling graphene on SiC, graphene expands but SiC shrinks. This mismatch will physically break the atomic bonds between graphene and SiC. We have demonstrated that a graphenelike buffer layer on SiC can be converted to a quasifreestanding monolayer graphene by a rapid-cooling treatment. The decoupling of graphene from the SiC substrate was actually effective for reducing the electric carrier scattering due to interfacial phonons. In addition, the rapidly cooled graphene obtained in this way was of high-quality, strain-free, thermally stable, and strongly hole doped. This simple, classical, but quite novel technique for obtaining quasifreestanding graphene could open a new path towards a viable graphene-based semiconductor industry.

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Behavior of oxidized platinum nanoparticles on an aligned carbon nanotube forest

Keita Matsuda, Wataru Norimatsu, Shigeo Arai, Michiko Kusunoki

JOURNAL OF APPLIED PHYSICS 120 ( 14 ) 2016.10

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We observed and analyzed the behavior of platinum nanoparticles (PtNPs) supported on aligned-carbon nanotubes (CNTs) at high temperatures by X-ray photoelectron spectroscopy and high-resolution transmission electron microscope observations. We found that the PtNPs moved toward the inner-side along each CNT on which they were deposited. The mechanism of this behavior is related to the redox reaction of Pt with the carbon atoms in the CNT. We also performed in-situ observation of this process at a high temperature using an environmental transmission electron microscope under an oxygen atmosphere. We found that the PtNPs penetrated down into a high-density aligned CNT forest along the tube axis and that the PtNPs changed their shape to fit the structure of the CNTs during their movement. Published by AIP Publishing.

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Sequential control of step-bunching during graphene growth on SiC (0001)

Jianfeng Bao, Osamu Yasui, Wataru Norimatsu, Keita Matsuda, Michiko Kusunoki

APPLIED PHYSICS LETTERS 109 ( 8 ) 2016.08

　View Summary

We have investigated the relation between the step-bunching and graphene growth phenomena on an SiC substrate. We found that only a minimum amount of step-bunching occurred during the graphene growth process with a high heating rate. On the other hand, a large amount of step-bunching occurred using a slow heating process. These results indicated that we can control the degree of step-bunching during graphene growth by controlling the heating rate. We also found that graphene coverage suppressed step bunching, which is an effective methodology not only in the graphene technology but also in the SiC-based power electronics. Published by AIP Publishing.

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Thermoelectric properties of Nb-doped (Nd0.55Li0.36)TiO(3)bulk ceramics with superlattice structure

Yaoshuai Ba, Yifeng Wang, Chunlei Wan, Wataru Norimatsu, Michiko Kusunoki, Dechun Ba, Kunihito Koumoto

JOURNAL OF ALLOYS AND COMPOUNDS 664 487 - 491 2016.04

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We report the thermoelectric properties of Nb-doped (Nd0.55Li0.36)TiO3 bulk ceramics prepared by the conventional sintering method. Superlattice structure present throughout the crystalline grain was observed and a glass-like thermal conductivity (similar to 2 W/m.K) was obtained. The electrical properties of (Nd0.55Li0.36)TiO3 were improved due to the Ti-site-Nb-doping. The low solid solubility of Nb and the distortion of TiO6 octahedron impaired the electrical performance of Nb-doped (Nd0.55Li0.36)TiO3. The sample with 5 at% Nb gave the maximum ZT value of 0.05 at 650 K. This work is helpful for the design of novel oxide thermoelectric materials. (C) 2016 Elsevier B.V. All rights reserved.

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Contact Conductivity of Uncapped Carbon Nanotubes Formed by Silicon Carbide Decomposition

Masafumi Inaba, Chih-Yu Lee, Kazuma Suzuki, Megumi Shibuya, Miho Myodo, Yu Hirano, Wataru Norimatsu, Michiko Kusunoki, Hiroshi Kawarada

JOURNAL OF PHYSICAL CHEMISTRY C 120 ( 11 ) 6232 - 6238 2016.03

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Understanding of the contact conductivity of carbon nanotubes (CNTs) will contribute to the further application of CNTs for electronic devices, such as thin film transistors whose channel or electrode is made of dispersed CNTs. In this study, we estimated the contact conductivity of a CNT/CNT interface from the in-plane conductivity of an uncapped CNT forest on SiC. Investigation of the electrical properties of dense CNT forests is also important to enable their electrical application. The in-plane conductivity of a dense CNT forest on silicon carbide normalized by its thickness was measured to be SO S/cm, which is two to three orders of magnitude lower than the conductivity of a CNT yarn. It was also found that both the CNT cap region and the CNT bulk region exhibit in-plane conductivity. The contact conductivity of CNTs was estimated from the in-plane conductivity in the bulk region. Dense and uncapped CNT forest can be approximated by a conductive mesh, in which each conductive branch corresponds to the CNT/CNT contact conductance. The evaluated contact conductivity was in good agreement with that calculated from the tunneling effect.

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Ohmic contact for silicon carbide by carbon nanotubes

Masafumi Inaba, Kazuma Suzuki, Yu Hirano, Wataru Norimatsu, Michiko Kusunoki, Hiroshi Kawarada

Materials Science Forum 858 561 - 564 2016 [Refereed]

　View Summary

The electrical contact properties of silicon carbide (SiC) and carbon nanotubes (CNTs) were measured by conductive atomic force microscopy (C-AFM). A CNT forest was synthesized by SiC surface decomposition. Trenches, which electrically separate the conduction area, were fabricated using a focused ion beam (FIB) without a cover layer, and the resistance of each island was measured by C-AFM. From the dependence of the resistance on the CNT forest island size, the contact resistance between the CNTs and the SiC substrate was measured. By varying the dopant density in the SiC substrate, the Schottky barrier height was evaluated to be ~0.5 eV. This is slightly higher than a previously reported result obtained from a similar setup with a metal covering the CNT forest. We assumed that the damaged region existed in the islands, which is due to the trench formation by the FIB. The commensurate barrier height was obtained with the length of the damaged region assumed to be ~3 μm. Here, we could estimate the resistivity of a CNT/SiC interface without a cover layer. This indicates that a CNT forest on SiC is useful as a brief contact electrode.

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Synthesis of copper nanoparticles within the interlayer space of titania nanosheet transparent films

Kazuhisa Sasaki, Kazuki Matsubara, Shiori Kawamura, Kenji Saito, Masayuki Yagi, Wataru Norimatsu, Ryo Sasai, Tatsuto Yui

JOURNAL OF MATERIALS CHEMISTRY C 4 ( 7 ) 1476 - 1481 2016

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We report the first in situ synthesis of copper nanoparticles (CuNPs) within the interlayer space of inorganic layered semiconductors (titania nanosheet films) through the following steps. A sintered titania nanosheet (s-TNS) film was synthesised, forming a transparent, layered semiconductor film (similar to 2 mu m thick). A considerable amount of copper ions (ca. 68% relative to the cation exchange capacity of TNSs) was intercalated in the s-TNSs using the methyl viologen-containing s-TNSs as the intermediate. The resultant copper-containing s-TNS (TNS/Cu2+) film was treated with an aqueous solution of NaBH4, resulting in a colour change. Extinction spectra of NaBH4-treated films exhibited a wide extinction band at lambda(max) (the extinction band maximum) = 683 nm. The spectral shapes and lambda(max) were similar to those for copper nanoparticles on TiO2 surfaces. Transmission electron microscopy analysis demonstrated the wide distribution of electron dense particles on the titania sheet of NaBH4-treated TNS/Cu2+. XRD analysis and absorption/extinction analysis with different amounts of TNSs suggest that CuNPs were formed within the interlayer space rather than the surface of TNSs through NaBH4 treatment. Repeatable oxidation and reduction behaviour, i.e. colouration and decolouration cycles of the copper species within TNS films, was investigated.

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Growth and Features of Epitaxial Graphene on SiC

Michiko Kusunoki, Wataru Norimatsu, Jianfeng Bao, Koichi Morita, Ulrich Starke

JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN 84 ( 12 ) 2015.12

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Recent progress of epitaxial graphene on SiC was reviewed, focusing on its growth and structural and electronic features. Homogeneous graphene can be grown on SiC(0001) on a wafer scale, however on SiC(000 (1) over bar) multilayer but rotationally stacked graphene with monolayer like electronic property grows. HRTEM revealed the formation mechanism and structural features of graphene on the both surfaces. The high structural and electronic quality of the grown graphene is monitored by Raman spectroscopy and magneto-transport characterization. High-resolution ARPES measurements of the electronic dispersion around the (K) over bar -point retrieved the ABA and ABC stacked trilayer graphene. The measurements also directly revealed that electronic structures of graphene were manipulated by transfer doping and atomic intercalation. In particular, p- and n-doped regions on a meso-scale and the p-n junctions prepared on SiC via controlling intercalation of Ge exhibited ballistic transport and Klein tunneling, which predicted novel potentials on to epitaxial graphene on SiC.

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Very low Schottky barrier height at carbon nanotube and silicon carbide interface

Masafumi Inaba, Kazuma Suzuki, Megumi Shibuya, Chih-Yu Lee, Yoshiho Masuda, Naoya Tomatsu, Wataru Norimatsu, Atsushi Hiraiwa, Michiko Kusunoki, Hiroshi Kawarada

APPLIED PHYSICS LETTERS 106 ( 12 ) 2015.03

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Electrical contacts to silicon carbide with low contact resistivity and high current durability are crucial for future SiC power devices, especially miniaturized vertical-type devices. A carbon nanotube (CNT) forest formed by silicon carbide (SiC) decomposition is a densely packed forest, and is ideal for use as a heat-dissipative ohmic contact in SiC power transistors. The contact resistivity and Schottky barrier height in a Ti/CNT/SiC system with various SiC dopant concentrations were evaluated in this study. Contact resistivity was evaluated in relation to contact area. The Schottky barrier height was calculated from the contact resistivity. As a result, the Ti/CNT/SiC contact resistivity at a dopant concentration of 3 x 10(18) cm(-3) was estimated to be similar to 1.3 x 10(-4) Omega cm(2) and the Schottky barrier height of the CNT/SiC contact was in the range of 0.40-0.45 eV. The resistivity is relatively low for SiC contacts, showing that CNTs have the potential to be a good ohmic contact material for SiC power electronic devices. (C) 2015 AIP Publishing LLC.

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Formation of a nitride interface in epitaxial graphene on SiC (0001)

Yoshiho Masuda, Wataru Norimatsu, Michiko Kusunoki

PHYSICAL REVIEW B 91 ( 7 ) 2015.02

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We report on a nitride interface structure formed between epitaxial graphene and SiC (0001). The nitride interface can be obtained by the pretreatment of SiC in an Ar/N-2 atmosphere at 1600 degrees C, followed by graphene growth in Ar at 1700 degrees C. Our detailed high-resolution transmission electron microscopy revealed a nitride atomic layer between the 0th carbon layer and the SiC substrate. Due to the nitride interface, the interface carrier scattering was reduced, which resulted in an improvement of the room temperature mobility of graphene, indicating that this is another technique to modify the electronic properties of graphene.

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Application of vertically aligned carbon nanotubes on burnishing slider in cleaning process of magnetic disk surfaces

Hiroshi Tani, Keisuke Konishi, Wataru Norimatsu, Michiko Kusunoki, Norio Tagawa

MICROSYSTEM TECHNOLOGIES-MICRO-AND NANOSYSTEMS-INFORMATION STORAGE AND PROCESSING SYSTEMS 21 ( 1 ) 295 - 300 2015.01

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The feasibility of using vertically aligned carbon nanotubes (CNTs) on a burnishing slider in the cleaning process of a magnetic disk surface was studied. Vertically aligned CNTs on SiC flat sliders were grown by the SiC surface decomposition method. Burnishing sliders with different CNT lengths were prepared for friction measurement on magnetic disks and for the burnishing test. Non-lubricated vertically aligned CNTs sliding on non-lubricated magnetic disks resulted in large friction; however, coating the CNTs and the disks with a perfluoropolyether lubricant film dramatically decreased the friction force. In addition, it was found that a specific amount of lubricant was needed on the CNTs to decrease the friction force and that the friction force depended on the CNT length. The particle burnishing test indicated that the 34-nm-long CNT burnishing slider with a rinsed lubricant film showed good burnishing performance.

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Growth of graphene from SiC{0001} surfaces and its mechanisms

Wataru Norimatsu, Michiko Kusunoki

SEMICONDUCTOR SCIENCE AND TECHNOLOGY 29 ( 6 ) 2014.06

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Graphene, a one-atom-layer carbon material, can be grown by thermal decomposition of SiC. On Si-terminated SiC(0001), graphene nucleates at steps and grows layer-by-layer, and as a result a homogeneous monolayer or bilayer can be obtained. We demonstrate this mechanism both experimentally and theoretically. On the C-face (000(1) over bar), multilayer graphene nucleates not only at steps, but also on the terraces. These differences reflect the distinct differences in the reactivity of these faces. Due to its high quality and structural controllability, graphene on SiC{0001} surfaces will be a platform for high-speed graphene device applications.

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Effects of Transition Metal Substitution on the Thermoelectric Properties of Metallic (BiS)(1.2)(TiS2)(2) Misfit Layer Sulfide

Yulia Eka Putri, Chunlei Wan, Feng Dang, Takao Mori, Yuto Ozawa, Wataru Norimatsu, Michiko Kusunoki, Kunihito Koumoto

JOURNAL OF ELECTRONIC MATERIALS 43 ( 6 ) 1870 - 1874 2014.06

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The misfit layer compounds (BiS)(1.2)(TiS2)(2), with a natural superlattice structures, are of substantial interest as thermoelectric materials. In this work we doped the Ti sites of (BiS)(1.2)(TiS2)(2) with a series of transition metal (TM) elements (V, Cr, Mn, Fe, Co, Ni, Cu, and Zn), to optimize its transport properties and thermoelectric performance. X-ray diffraction confirmed all the resulting compositions were single-phase. X-ray photoelectron spectroscopy revealed the valence states of the doping elements, indicating they behave as acceptors and reduce the carrier concentration; this was also apparent from Hall measurements. However, because of the non-parabolic band structure of (BiS)(1.2)(TiS2)(2), reduction of carrier concentration by doping with most of the TM elements did not improve the Seebeck coefficient. Exceptions were V and Cr. For these elements, the effective mass of electrons was maintained, or even enhanced, resulting in improvement of the Seebeck coefficient. Furthermore, the stacking disorder present in undoped (BiS)(1.2)(TiS2)(2) was not observed for the TM element-doped samples, resulting in increased lattice thermal conductivity. Although the power factor of these materials was not optimized, because of the large reduction in electronic thermal conductivity upon doping, the Cr-doped sample had a higher figure of merit than the undoped material.

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Structural features of epitaxial graphene on SiC {0001} surfaces

Wataru Norimatsu, Michiko Kusunoki

JOURNAL OF PHYSICS D-APPLIED PHYSICS 47 ( 9 ) 2014.03

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We investigated the atomic-scale structural properties of graphene epitaxially grown on SiC {0 0 0 1} surfaces by high-resolution transmission electron microscope observations. In this review paper, we summarize our results about the interface structure, the growth mechanisms and the growth techniques. Graphene on the Si-terminated surface has a buffer layer that is strongly bonded to the substrate and has a low carbon atom density. Multilayer graphene on the Si-face exhibited an ABC-stacking selectively. Graphene on the Si-face nucleates at the step-edge, and grows layer-by-layer over the upper terrace. Based on the mechanism, we succeeded in growing high-quality and homogeneous monolayer and bilayer graphene on the Si-terminated surface with low-height and low-density steps using our original technique. Graphene on the C-face has weaker bonds with the substrate, and the resulting multilayer contains the rotational stacking disorder. The origin of the rotational stacking is closely related to the growth mechanism, where graphene layers nucleate on a terrace at a lower temperature and grow in all directions on the surface.

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Growth mechanisms and selectivity for graphene or carbon nanotube formation on SiC (000(1)over-bar): A density-functional tight-binding molecular dynamics study

Noriyuki Ogasawara, Wataru Norimatsu, Stephan Irle, Michiko Kusunoki

CHEMICAL PHYSICS LETTERS 595 266 - 271 2014.03

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We have performed density-functional tight-binding simulations mimicking the thermal decomposition of the SiC (000 (1) over bar) surface to reproduce the experimentally observed growth of either graphene or carbon nanotubes. A graphene-like network was obtained from a layer-by-layer decomposition of the SiC surface. The interaction between graphene and SiC was found to be relatively weak. Meanwhile, carbon nanotubes grew when a five-membered ring was initially formed together with a carbon chain. The simulation results suggest that growth selectivity depends on the overall carbon network connectivity and carbon aggregation speed at the very initial stage of the decomposition process. (C) 2014 Elsevier B.V. All rights reserved.

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Epitaxial graphene on SiC{0001}: advances and perspectives

Wataru Norimatsu, Michiko Kusunoki

PHYSICAL CHEMISTRY CHEMICAL PHYSICS 16 ( 8 ) 3501 - 3511 2014

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We review here recent progress on epitaxial graphene grown on a SiC substrate. Epitaxial graphene can be easily grown by heating the SiC single crystal in a high vacuum or in an inert gas atmosphere. The SiC surfaces used for graphene growth contain Si- and C-terminated faces. On the Si- face, homogeneous and clean graphene can be grown with a controlled number of layers, and the carrier mobility reaches as high as several m(2) V s(-1), although this is reduced by the presence of the substrate steps. On the C-face, although the number of layers is not homogeneous, twisted bilayer graphene can be grown, which is expected to be the technique of choice to modify the electronic structure of graphene. From the application point of view, graphene on SiC will be the platform used to fabricate high-speed electronic devices and dense graphene nanoribbon arrays, which will be used to introduce a bandgap.

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151

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Enhanced thermoelectric performance of Nb-doped SrTiO3 by nano-inclusion with low thermal conductivity

Ning Wang, Haijun Chen, Hongcai He, Wataru Norimatsu, Michiko Kusunoki, Kunihito Koumoto

SCIENTIFIC REPORTS 3 2013.12

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Authors reported an effective path to increase the electrical conductivity while to decrease the thermal conductivity, and thus to enhance the ZT value by nano-inclusions. By this method, the ZT value of Nb-doped SrTiO3 was enhanced 9-fold by yttria stabilized zirconia (YSZ) nano-inclusions. YSZ inclusions, located inside grain and in triple junction, can reduce the thermal conductivity by effective interface phonon scattering, enhance the electrical conductivity by promoting the abnormal grain growth, and thus lead to the obvious enhancement of ZT value, which strongly suggests that, it is possible to not only reduce the thermal conductivity, but also increase the electrical conductivity by nano-inclusions with low thermal conductivity. This study will give some useful enlightenment to the preparation of high-performance oxide thermoelectric materials.

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Atom-by-atom simulations of graphene growth by decomposition of SiC (0001): Impact of the substrate steps

Masato Morita, Wataru Norimatsu, Hu-Jun Qian, Stephan Irle, Michiko Kusunoki

APPLIED PHYSICS LETTERS 103 ( 14 ) 2013.09

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The atomic-scale carbon rearrangement into graphene by the thermal decomposition of SiC (0001) was simulated by the density-functional tight-binding technique. By decomposing the terrace of the SiC (0001) surface, the carbon chains formed a three-dimensional structure, because the carbon atoms are released by losing their original contacts to silicon atom. On the other hand, in the step model, the silicon atoms at the step-edge act as trapping sites for the released carbon atoms, and the carbon network effectively nucleated and expanded. After nucleation at the step, graphene can grow by the further decomposition together with retreat of the step. (C) 2013 AIP Publishing LLC.

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Glass-like thermal conductivity of Nd2/3-xLi3xTiO3 bulk ceramics with nanochessboard superlattice structure

Yaoshuai Ba, Chunlei Wan, Yifeng Wang, Wataru Norimatsu, Michiko Kusunoki, Kunihito Koumoto

MATERIALS LETTERS 97 191 - 194 2013.04

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We report the thermal conductivity of bulk Nd2/3-xLi3xTiO3 (0.047 < x < 0.151) ceramics, prepared by a conventional solid-state reaction method. These materials possess a nanochessboard superlattice structure present in every crystallite, with a superperiodicity of similar to 4 nm along the [110] orientation. A glass-like low thermal conductivity (1-2 W/(mK)) was shown in the Nd2/3-xLi3xTiO3 system and it was almost temperature independent. Moreover, a shorter periodic length of the superlattice structure caused a lower thermal conductivity due to the increased interface phonon scattering. The low thermal conductivity is not always seen in oxide materials. In combination with the tunability of the electrical properties and the maintainability of the microstructure, we believe that this work provides an insight into the nanostructure design for the development of novel oxide thermoelectric materials. (C) 2013 Elsevier B.V. All rights reserved.

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High-quality graphene on SiC(000(1)over-bar) formed through an epitaxial TiC layer

Keisuke Kimura, Kentaro Shoji, Yuta Yamamoto, Wataru Norimatsu, Michiko Kusunoki

PHYSICAL REVIEW B 87 ( 7 ) 2013.02

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The formation of large-area homogeneous graphene on a C-terminated SiC (000 (1) over bar) surface was achieved via decomposition of the SiC (000 (1) over bar) surface covered with an ultrathin but much more stable TiC layer than the reactive SiC(000 (1) over bar). By heating the SiC (000 (1) over bar) surface with a mixed powder of TiO2 and carbon at 1500-1550 degrees C in vacuum, an extremely homogeneous, epitaxial 0.75-nm-thick TiC(111) layer was grown on the SiC(000 (1) over bar) surface over a millimeter-scale area. Graphitization of the TiC-masked SiC surface led to the growth of high-quality graphene layers, which consist of TiC- and SiC-derived carbon. High-resolution transmission electron microscopy revealed the presence of disordered stacking of graphene layers on SiC through an amorphous layer at the interface. This unique method will promise further progress of relatively high carrier mobility of graphene formed on the SiC (000 (1) over bar) surface. DOI: 10.1103/PhysRevB.87.075431

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New n-type silicide thermoelectric material with high oxidation resistance

Ryoji Funahashi, Yoko Matsumura, Tomonari Takeuchi, Hideaki Tanaka, Wataru Norimatsu, Emmanuel Combe, Ryosuke O. Suzuki, Chunlei Wan, Yifeng Wang, Michiko Kusunoki, Kunihito Koumoto

Materials Research Society Symposium Proceedings 1490 ( 1 ) 103 - 112 2013 [Refereed]

　View Summary

In order to achieve waste heat recovery using thermoelectric systems, thermoelectric materials showing high conversion efficiency over wide temperature range and high resistance against oxidation are indispensable. A silicide material with good n-type thermoelectric properties and oxidation resistance has been discovered. The composition and crystal structure of the silicide are found out Mn3Si4Al2 (abbreviated as 342 phase) and hexagonal CrSi2 structure, respectively. Element substitution of Mn with 3d transition metals is succeeded. Enhancement of Seebeck coefficient is observed in a Cr-substituted sample. The maximum dimensionless thermoelectric figure of merit ZT is 0.3 at 573 K in air for the Mn2.7Cr0.3Si4Al2 sample. Electrical resistivity of the Mn3Si4Al2 bulk sample holds constant value for 48 h at 873 K in air. This is due to formation of oxide passive layer on the surface of the bulk sample. The 342 phase is a promising n-type material with a good oxidation resistance in the middle temperature range of 500-800 K. © 2013 Materials Research Society.

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Thermoelectric properties of n-type Mn3-xCrxSi4Al2 in air

R. Funahashi, Y. Matsumura, H. Tanaka, T. Takeuchi, W. Norimatsu, E. Combe, R. O. Suzuki, Y. Wang, C. Wan, S. Katsuyama, M. Kusunoki, K. Koumoto

JOURNAL OF APPLIED PHYSICS 112 ( 7 ) 073713 2012.10 [Refereed]

　View Summary

A suicide material with a good n-type thermoelectric property has been discovered. This suicide possesses a composition of Mn3-xCrxSi4Al2 (0 <= x <= 0.7) and hexagonal CrSi2 structure. The a- and c-cell parameters decrease with increasing the amount of Cr substitution. The absolute values of Seebeck coefficient and electrical resistivity increase by Cr substitution up to 573 K because of reduction of carrier density. The dimensionless thermoelectric figure of merit ZT reaches 0.21 at 773 K for a non Cr substituted sample at the Mn site and 0.30 at 573 K for a Cr substituted one with x = 0.3. Since oxide passive layer is formed around the surface, electrical resistivity measured at 873 K is constant for 2 days in air, which indicates good oxidation resistance in air of this material. The Mn3-xCrxSi4Al2 is a promising n-type material with a good oxidation resistance in the middle temperature range. A thermoelectric module consisting of 64 pairs of legs has been fabricated using MnSi1.7 and non Cr substituted Mn3Si4Al2 devices as p- and n-type legs, respectively. Output power reaches 9.4W, which corresponds to 2.3 kW/m(2) of power density against surface area of the substrate, for a heat source temperature of 873 K in air. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4755793]

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Transport Properties of Closely-Packed Carbon Nanotubes Film on SiC Tuned by Si-Doping

Wataru Norimatsu, Takehiro Maruyama, Kenta Yoshida, Koichi Takase, Michiko Kusunoki

APPLIED PHYSICS EXPRESS 5 ( 10 ) 2012.10

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Here, we reveal origins of the planar electrical transport of closely-packed carbon nanotubes (CNTs) and silicon-doped CNTs (Si-CNTs) films. Their electrical resistivities increased with decreasing temperature, but exhibit a plateau below 60 K. This phenomenon can be well described using the simple-two-band model, which is often used to understand the electronic properties of graphite. Cryogenic energy-filtered transmission electron microscopy visualizes Si atoms dispersed finely in CNTs, preserving the structural features of CNTs. These Si atoms induced effective carriers above 150 K, while three-dimensional variable range hopping and weak localization are dominant in their transport below 50 and 10 K, respectively. (C) 2012 The Japan Society of Applied Physics

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Band alignment of a carbon nanotube/n-type 6H-SiC heterojunction formed by surface decomposition of SiC using photoelectron spectroscopy

Takahiro Maruyama, Satoshi Sakakibara, Shigeya Naritsuka, Wataru Norimatsu, Michiko Kusunoki, Hiroyuki Yamane, Nobuhiro Kosugi

APPLIED PHYSICS LETTERS 101 ( 9 ) 2012.08

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Energy band alignment at the interface between carbon nanotubes (CNTs) and n-type 6H-SiC formed by the surface decomposition of SiC was investigated using high-resolution photoelectron spectroscopy (PES). Valence band spectra of the CNT films showed a Fermi edge, indicating metallic character. PES results revealed that a Schottky barrier was formed at the interface and the barrier height was 1.38 eV. Current-voltage measurements of the interface showed rectifying behavior, which was consistent with the PES results. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4748792]

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Epitaxial growth of boron-doped graphene by thermal decomposition of B4C

Wataru Norimatsu, Koichiro Hirata, Yuta Yamamoto, Shigeo Arai, Michiko Kusunoki

JOURNAL OF PHYSICS-CONDENSED MATTER 24 ( 31 ) 2012.08

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We grew graphene by thermal decomposition of B4C and investigated its features by high-resolution transmission electron microscope observations. At temperatures higher than 1600 degrees C in a vacuum, B4C decomposes and graphene forms epitaxially on its surface. The number and the morphology of the graphene layers depend on the surface orientation. An electron diffraction technique revealed the presence of a superstructure with a two-times larger unit cell, which is consistent with the structure of BC3. We have directly confirmed boron in the graphene layers by electron energy loss spectroscopy measurements and boron-mapping experiments.

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Effects of alkaline earth doping on the thermoelectric properties of misfit layer sulfides

Yulia Eka Putri, Chunlei Wan, Yifeng Wang, Wataru Norimatsu, Michiko Kusunoki, Kunihito Koumoto

SCRIPTA MATERIALIA 66 ( 11 ) 895 - 898 2012.06

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The substitutional doping of magnesium into the host layers (TiS2), calcium and strontium into phonon barrier layers (BiS) was attempted to improve the thermoelectric performance of (BiS)(1.2)(TiS2)(2) misfit layer sulfides by decreasing the carrier concentration. The substitutional doping did reduce the carrier concentration; however, the Seebeck coefficient decreased slightly due to the decrease in the effective mass of carrier electrons. Meanwhile, the lattice thermal conductivity was increased by the formation of an ordered or commensurate structure. (C) 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

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Near-Edge X-Ray Absorption Fine Structure Study of Vertically Aligned Carbon Nanotubes Grown by the Surface Decomposition of SiC

Takahiro Maruyama, Yuki Ishiguro, Shigeya Nartitsuka, Wataru Norimatsu, Michiko Kusunoki, Kenta Amemiya, Hideshi Ishii, Toshiaki Ohta

JAPANESE JOURNAL OF APPLIED PHYSICS 51 ( 5 ) 2012.05

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Vertically aligned carbon nanotubes (CNTs) grown by the surface decomposition of SiC were studied by angular-dependent C K-edge near-edge X-ray absorption fine structure spectroscopy (NEXAFS) with a linearly polarized X-ray beam. The NEXAFS spectra measured in total electron yield mode showed a distinct angular dependence on pi* and sigma* resonances and the orientation parameter was tentatively estimated to be 0.38, which is fairly larger than those reported for other vertically aligned CNTs grown by chemical vapor deposition. The high order of the vertical alignment of CNTs grown by the surface decomposition of SiC was demonstrated by NEXAFS measurements for the first time. (C) 2012 The Japan Society of Applied Physics

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Nitrate-ion-selective exchange ability of layered double hydroxide consisting of Mg-II and Fe-II

Ryo Sasai, Wataru Norimatsu, Yukitaka Matsumoto

JOURNAL OF HAZARDOUS MATERIALS 215 311 - 314 2012.05

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In this study, layered double hydroxide (LDH) consisting of Mg-II and Fe-III (Mg/Fe-LDH) was synthesized by using a combination of coprecipitation with hydrothermal aging, and its anion-exchange properties were investigated. Through various analyses, the chemical formula of the proposed Mg/Fe-LDH was determined to be [Mg0.76Fe0.24(OH)(2)](Cl-)(0.21)(CO32-)(0.02)center dot 0.76H(2)O. Furthermore, amorphous Fe-III impurities were contained in the present Mg/Fe-LOH. The proposed Mg/Fe-LDH exhibited clear selectivity for nitrate ions dissolved in water. This selectivity for nitrate ions can be explained by an anion-sieve effect by the existence of amorphous Fe-III impurities. Our findings suggest that it is possible to synthesize LDHs with high selectivity for various anions by effective hybridizing Fe-III impurities. (C) 2012 Elsevier B.V. All rights reserved.

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Nanoscale stacking faults induced low thermal conductivity in thermoelectric layered metal sulfides

Chunlei Wan, Yifeng Wang, Wataru Norimatsu, Michiko Kusunoki, Kunihito Koumoto

APPLIED PHYSICS LETTERS 100 ( 10 ) 2012.03

　View Summary

Layered metal sulfides (MS)(1+x)(TiS2)(2) (M - Pb, Sn, Bi) with alternative stacking of MS layers and TiS2 layers (a natural superlattice) have been proposed as thermoelectric materials. In this paper, various nanoscale stacking faults have been found in these materials, including the translational disorder in (SnS)(1.2)(TiS2)(2) and the staging disorder in (BiS)(1.2)(TiS2)(2). The lattice thermal conductivities along the layers are systematically and significantly reduced by these stacking faults which are only a few unit cells apart, without deteriorating the electron mobility, demonstrating a "phonon-blocking, electron-transmitting" scenario. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.3691887]

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Plan-View of Few Layer Graphene on 6H-SiC by Transmission Electron Microscopy

Jun Kuroki, Wataru Norimatsu, Michiko Kusunoki

E-JOURNAL OF SURFACE SCIENCE AND NANOTECHNOLOGY 10 396 - 399 2012

　View Summary

We firstly performed plan-view transmission electron microscope (TEM) observations along SiC [0001] direction to analyze the in-plane structure of graphene on Si- and C-faces of SiC. A fast Fourier transformation (FFT) of the TEM images and the reconstructed inverse FFT (iFFT) images enabled to investigate the stacking structure. The FFT patterns of several graphene layers on Si- and C-faces show one and multiple sets of six-fold 1100 spots, respectively. These mean that within a same grain graphene layers on the Si-face stack without rotation, while graphene layers on the C-face stack with rotation.

DOI

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9

Citation

(Scopus)
Development and Application of Carbon Nanotube Films Produced by SiC Surface Decomposition

Michiko Kusunoki, Wataru Norimatsu, Motohiro Yamamoto, Hatsuhiko Usami, Koji Miyake

JOURNAL OF JAPANESE SOCIETY OF TRIBOLOGISTS 57 ( 10 ) 682 - 687 2012
Patterning of Aligned CNT Films Using SiO2 Particles Monolayer as a Mask

Keita Matsuda, Wataru Norimatsu, Michiko Kusunoki

E-JOURNAL OF SURFACE SCIENCE AND NANOTECHNOLOGY 10 198 - 202 2012

　View Summary

We developed a new simple method to fabricate periodic CNTs array. The new method has a series of processes, which consists of forming monolayer of SiO2 particles on close-packed-CNT film formed by surface decomposition of SiC, Pt deposition, removing of the SiO2 particles and heat treatment in the air. This method enables us to fabricate the periodic CNTs array without expensive apparatuses and complicated processes.

DOI

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3

Citation

(Scopus)
First Principles Calculations of Close-Packed and Doped Carbon Nanotubes

Noriyuki Ogasawara, Wataru Norimatsu, Michiko Kusunoki

E-JOURNAL OF SURFACE SCIENCE AND NANOTECHNOLOGY 10 411 - 413 2012

　View Summary

The electronic structures of doped carbon nanotubes (CNTs) need to be investigated. We have studied boron and nitrogen-doped, close-packed, aligned, single-walled carbon nanotubes (SWCNTs) using first principles calculations based on density functional theory (DFT). The total energy and density of states (DOS) for doped (10,0) SWCNTs were calculated. From these results, we found that it is more energetically favorable to dope boron atoms than nitrogen atoms. We also found that the electronic structure of close-packed and zigzag-type (10,0) SWCNTs changed to that of a p-type semiconductor and metal by doping boron and nitrogen atoms, respectively.

DOI

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Formation mechanism of graphene layers on SiC (000(1)over-bar) in a high-pressure argon atmosphere

Wataru Norimatsu, Juji Takada, Michiko Kusunoki

PHYSICAL REVIEW B 84 ( 3 ) 2011.07

　View Summary

Graphene layers were grown on a C-terminated SiC (000 (1) over bar) surface in a high-pressure Ar atmosphere. Their growth mechanism was investigated using high-resolution transmission electron microscopy (TEM). First at a low temperature, local areas of SiC surface are decomposed, and several layers of graphene nucleus are formed in the resulting craters. Then graphene layers grow in all directions laterally, keeping their number of layers invariant. These results indicate that control of the number of graphene layers require precise control of the first stage of decomposition. After the graphene layers cover the surface completely, SiC decomposition occurs at a higher temperature along the [0001](SiC) direction, and the number of graphene layers increase. The formation of local wrinkles accompanies the increase of the number of layers. In addition we propose that the formation mechanism strongly affects the rotational stacking, which is characteristic of multilayer graphene on the C-face of SiC.

DOI

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55

Citation

(Scopus)
Intercalation: Building a Natural Superlattice for Better Thermoelectric Performance in Layered Chalcogenides

Chunlei Wan, Yifeng Wang, Ning Wang, Wataru Norimatsu, Michiko Kusunoki, Kunihito Koumoto

JOURNAL OF ELECTRONIC MATERIALS 40 ( 5 ) 1271 - 1280 2011.05

　View Summary

A natural superlattice with composition (SnS)(1.2)(TiS2)(2), built by intercalating a SnS layer into the van der Waals gap of layered TiS2, has been directly observed by high-resolution transmission electron microscopy (HRTEM). The thermoelectric performance is improved in the direction parallel to the layers because the electron mobility is maintained while simultaneously suppressing phonon transport, which is attributed to softening of the transverse sound velocities due to weakened interlayer bonding. In the direction perpendicular to the layers, the lattice thermal conductivity of (SnS)(1.2)(TiS2)(2) is even lower than the predicted minimum thermal conductivity, which may be caused by phonon localization due to the translational disorder of the SnS layers parallel to the layers. Moreover, we propose a large family of misfit-layer compounds (MX)(1+x) (TX2) (n) (M = Pb, Bi, Sn, Sb, rare-earth elements; T = Ti, V, Cr, Nb, Ta; X = S, Se; n = 1, 2, 3) with a natural superlattice structure as possible candidate high-performance thermoelectric materials.

DOI

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94

Citation

(Scopus)
Chemical State Analysis of Si-Doped CNT on SiC by Hard X-Ray Photoelectron Spectroscopy

Jin-Young Son, Masatake Machida, Hiroshi Oji, Yoshio Watanabe, Takehiro Maruyama, Wataru Norimatsu, Michiko Kusunoki

E-JOURNAL OF SURFACE SCIENCE AND NANOTECHNOLOGY 9 54 - 57 2011

　View Summary

The carbon nanotubes (CNTs) on 6H-SiC and Si-doped CNTs on 6H-SiC were analyzed by hard x-ray photoelectron spectroscopy to identify the chemical bonding character of the doped Si in the CNT layer. We performed the depth profiling of the sample by changing photoelectron's take-off-angle (TOA). The spectral component associated with the doped Si is clearly seen in the Si 1s photoelectron spectra of Si-doped CNTs on 6H-SiC. The Si 1s peak shifts toward lower kinetic energy side from TOA = 80 degrees (bulk-sensitive) to 8 degrees (surface-sensitive), which implies the formation of the sp(2)-like structure in Si-doped CNTs

DOI

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2

Citation

(Scopus)
Development of novel thermoelectric materials by reduction of lattice thermal conductivity

Chunlei Wan, Yifeng Wang, Ning Wang, Wataru Norimatsu, Michiko Kusunoki, Kunihito Koumoto

SCIENCE AND TECHNOLOGY OF ADVANCED MATERIALS 11 ( 4 ) 2010.08

　View Summary

Thermal conductivity is one of the key parameters in the figure of merit of thermoelectric materials. Over the past decade, most progress in thermoelectric materials has been made by reducing their thermal conductivity while preserving their electrical properties. The phonon scattering mechanisms involved in these strategies are reviewed here and divided into three groups, including (i) disorder or distortion of unit cells, (ii) resonant scattering by localized rattling atoms and (iii) interface scattering. In addition, we propose construction of a 'natural superlattice' in thermoelectric materials by intercalating an MX layer into the van der Waals gap of a layered TX2 structure which has a general formula of (MX)(1+x) (TX2)(n) (M = Pb, Bi, Sn, Sb or a rare earth element; T = Ti, V, Cr, Nb or Ta; X = S or Se and n = 1, 2, 3). We demonstrate that one of the intercalation compounds (SnS)(1.2)(TiS2)(2) has better thermoelectric properties compared with pure TiS2 in the direction parallel to the layers, as the electron mobility is maintained while the phonon transport is significantly suppressed owing to the reduction in the transverse phonon velocities.

DOI

Scopus

158

Citation

(Scopus)
Transmission Electron Microscope Observation of Interface Structures of Graphene on 6H-SiC

Wataru Norimatsu, Michiko Kusunoki

JOURNAL OF NANOSCIENCE AND NANOTECHNOLOGY 10 ( 6 ) 3884 - 3889 2010.06

　View Summary

High-resolution transmission electron microscopic cross-sectional observations of graphene-on-SiC(0001) were carried out to directly observe the interface structure. A first principles calculation allowed us to understand the interface structures and their electronic states. Our observations revealed a metastable transitional interface structure formed by decomposition of a single SiC bilayer as well as complete honeycomb graphene formed by the decomposition of three SiC bilayers. The calculations further showed that the differences in the interface structures should strongly influence the electronic states, producing either metallic or semiconducting behavior. These results may help to resolve the controversy over the electronic states of graphene-on-SiC, and promote more accurate band-gap engineering via surface decomposition.

DOI

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17

Citation

(Scopus)
Selective formation of ABC-stacked graphene layers on SiC(0001)

Wataru Norimatsu, Michiko Kusunoki

PHYSICAL REVIEW B 81 ( 16 ) 2010.04

　View Summary

An investigation using high-resolution transmission electron microscopy of the stacking sequence of several layers of graphene formed on SiC (0001) shows that graphene layers selectively exhibit an ABC-type stacking. Using the well-known Slonczewski-Weiss-McClure model based on the tight-binding method, we suggest that a gamma(5)-like interatomic interaction, which corresponds to the formation of a linear trimer of ABA type stacking, is spontaneously weakened by the interaction between graphene and SiC. This can lead to the destabilization of the ABA stacking and to the formation of the ABC stacking, indicating the possibility of bandgap tuning by an electric field in more than three layers of graphene on SiC.

DOI

Scopus

100

Citation

(Scopus)
Fabrication of a multi-layered carbon nanotube/SiC stack structure

Takehiro Maruyama, Wataru Norimatsu, Michiko Kusunoki

PHYSICA E-LOW-DIMENSIONAL SYSTEMS & NANOSTRUCTURES 42 ( 4 ) 767 - 770 2010.02

　View Summary

A multi-layered carbon nanotube (CNT)/SiC stack structure was fabricated by repeated alternate deposition and surface decomposition of SiC. The newly deposited 3C-SiC layer on the CNT film had good crystallinity; the CNTs produced by the decomposition of the 3C-SiC were as mostly aligned as the CNTs produced from pristine 6H-SiC. By appropriate choice of deposition and decomposition conditions we demonstrated that it is possible to produce alternating CNT and SiC layers with a controlled thickness. (C) 2009 Elsevier B.V. All rights reserved.

DOI

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4

Citation

(Scopus)
Novel upgraded method of recycling spent SiC abrasive powders to CNT particles

Ryo Sasai, Takayuki Morishita, Wataru Norimatsu, Motohiro Yamamoto, Akihiro Ichikawa, Michiko Kusunoki

JOURNAL OF THE CERAMIC SOCIETY OF JAPAN 117 ( 1367 ) 815 - 818 2009.07

　View Summary

To encourage the recycling of spent SiC abrasive powders, we investigated the synthesis of CNTs from several types of powders. The surface decomposition method was applied to as-received powders, and graphite was observed on the SiC surface but CNTs were not. This could be caused by the turbulence of the crystal structure and Fe contaminants on the SiC surface. On the other hand, from TEM observations we found that particle covered of CNTs could be synthesized by applying the surface decomposition method to powders pretreated by acid and heat, because the turbulence of the crystal structure on the surface could be improved and Fe contaminants could be removed. Consequently, the spent SiC abrasive powders pretreated by acid and heat could be used as a resource for synthesizing CNT particles. (C) 2009 The Ceramic Society of Japan. All rights reserved.

DOI

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4

Citation

(Scopus)
Transitional structures of the interface between graphene and 6H-SiC (0001)

Wataru Norimatsu, Michiko Kusunoki

CHEMICAL PHYSICS LETTERS 468 ( 1-3 ) 52 - 56 2009.01

　View Summary

Direct cross-sectional observations of graphene-on-SiC (0001) by high-resolution transmission electron microscopy have revealed the presence of a metastable transitional structure formed by decomposition of a single SiC bilayer as well as fully-packed honeycomb graphene as an interface structure between graphene and SiC. A first principles calculation studied in parallel has clarified that the metastable transitional state exhibits the metallic behavior, while the fully-packed honeycomb graphene exhibits the semiconducting behavior. (C) 2008 Elsevier B. V. All rights reserved.

DOI

Scopus

100

Citation

(Scopus)
Crystallographic features of the orbital-ordered state in the layered perovskite manganite Sr2-xPrxMnO4

Wataru Norimatsu, Go Shindo, Yasumasa Koyama

PHYSICA B-CONDENSED MATTER 403 ( 5-9 ) 1585 - 1586 2008.04

　View Summary

The crystallographic features of Sr2-xPrxMnO4 samples, prepared by a coprecipitation method, have been investigated by transmission electron microscopy to understand their electronic States for 0.10 <= x <= 0.30. The orbital-ordered (OO) state lacking charge ordering existed for 0.10 <= x <= 0.25, and accompanied C-type antiferromagnetic (CAF) ordering at lower temperatures. It was also found that the suppression of CAF ordering occurred in a variant with smaller orthorhombicity, which is one of two variants forming a banded domain structure in the OO state. (C) 2007 Elsevier B.V. All rights reserved.

DOI

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5

Citation

(Scopus)
Stability of electronic states in the layered perovskite Sr2-xNdxMnO4

Wataru Norimatsu, Yasumasa Koyama

PHYSICA C-SUPERCONDUCTIVITY AND ITS APPLICATIONS 463 115 - 119 2007.10

　View Summary

The electronic system in the layered perovskite Sr2-xNdxMnO4 is characterized as a two-dimensional e(g)-electron system. In order to understand the stability of electronic states in the Nd-content region of 0 <= x <= 0.50, the crystallographic features of this manganite have been investigated by transmission electron microscopy. The increase in the Nd-content led to the orbital ordered state in 0.10 <= x <= 0.25 and the charge and orbital ordered state in 0.25 <= x < 0.45. In particular, it was found that the orbital ordering accompanied the C-type antiferromagnetic ordering at lower temperatures, and that the transition to the charge and orbital ordered states was strongly suppressed in x > 0.35. (C) 2007 Elsevier B.V. All rights reserved.

DOI

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8

Citation

(Scopus)
Crystallographic features of the orbital-ordered, and charge-and-orbital-ordered states in Sr2-xNdxMnO4

Wataru Norimatsu, Yasumasa Koyama

PHYSICAL REVIEW B 75 ( 23 ) 2007.06

　View Summary

The crystallographic features of the orbital-ordered and charge-and-orbital-ordered states in Sr2-xNdxMnO4 have been investigated by in situ observations, using a transmission electron microscope, in an attempt to understand the distinct characteristics of their electronic states. In the orbital-ordered state with orthorhombic symmetry, there exist four banded-domain-structure states, that is, two orthorhombic variant states (O-I+O-II) accompanying the C-type antiferromagnetic ordering at lower temperatures and (DT+O-I) coexistence and (O-I+O-II) states lacking magnetic ordering at higher temperatures, where DT represents the disordered tetragonal state and O-I and O-II the two orthorhombic variants. On the other hand, the stability of the charge-and-orbital-ordered state present for 0.25 <= x <= 0.43 is strongly suppressed when x > 0.38. As a result of the strong suppression, the charge-exchange-type charge-and-orbital-ordered state is absent for x=0.5. The important features of the charge-and-orbital-ordered state are that it is basically characterized by incommensurate structural modulations and that round-shaped domains separated by disordered regions appear for 0.38 < x <= 0.43 near the DT state. On the basis of these data, the origin of the appearance of the four banded-structure states in the orbital-ordered state was attributed to a coupling between the local Jahn-Teller distortion and the long-range distortions, including a dilational one. In addition, we propose a model for the ground-state change between the orbital-ordered and charge-and-orbital-ordered states in terms of orbital degree of freedom.

DOI

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11

Citation

(Scopus)
Domain-structure relaxation in the tetragonal-to-orthorhombic phase transition of the layered perovskite Sr1.8La0.2Mn1-yFeyO4

Wataru Norimatsu, Yasumasa Koyama

PHYSICAL REVIEW B 75 ( 10 ) 2007.03

　View Summary

An in situ observation of the tetragonal-to-orthorhombic phase transition in Fe-substituted Sr1.8La0.2MnO4 by transmission electron microscopy revealed that the domain structure changes, as a relaxation phenomenon, took place during the aging for the formation of the orbital ordered state. At each aging temperature, the final banded domain structure could be produced from any starting state. The characteristic features of the domain-structure relaxation found in this study are also discussed in terms of a coupling between the local Jahn-Teller and long-range dilational distortions.

DOI

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9

Citation

(Scopus)
Evolution of orthorhombic domain structures during the tetragonal-to-orthorhombic phase transition in the layered perovskite Sr2-xLaxMnO4

Wataru Norimatsu, Yasumasa Koyama

PHYSICAL REVIEW B 74 ( 8 ) 2006.08

　View Summary

When Sr2+ ions in Sr2MnO4 containing only Mn4+ ions were partially replaced by La3+, a new phase having orthorhombic symmetry appeared around an La content of x=0.15 between the tetragonal I4/mmm (T) phase and the charge and orbital ordered (COO) phase, accompanying the introduction of Mn3+ ions. Our in situ observation using a transmission electron microscope revealed that the orthorhombic (O) phase could be identified as an orbital ordered state without charge ordering, and that its microstructure is characterized by an alternating array of two banded-shape variants with different orthorhombicities, O-I and O-II. It was also found that the T-to-O phase transition exhibited a unique evolution of domain structures, which resulted in the above-mentioned banded microstructure. In particular, the domain-structure evolution consisted of three steps: the appearance of the (T+O-I) and then the (O-I+O-II) coexisting states, followed by the annihilation of the interface between the O-I and O-II variants. The evidence suggests that this unique pattern of evolution is due to coupling between the short-wavelength Jahn-Teller (JT) distortion, associated with the Mn3+ ion, and the long-wavelength O distortion.

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20

Citation

(Scopus)

▼display all

Presentations

グラフェン/SiC系を基盤とした低次元物質科学研究（招待講演）

乗松航、 [Invited]

凝縮系物質科学研究所シンポジウム (早稲田大学)

Presentation date： 2023.05
4H-SiC基板表面におけるステップアンバンチング現象

榊原涼太郎、乗松航

第70回応用物理学会春季学術講演会 (上智大学)

Presentation date： 2023.03
SiC基板上ツイスト2層グラフェンの作製と電子状態（招待講演）

乗松航、 [Invited]

第35回QLCセミナー (名古屋大学)

Presentation date： 2022.12
Observation of flat band in millimetre-scale magic-angle twisted bilayer graphene (Invited talk)

Wataru Norimatsu, [Invited]

6th International Symposium on Frontiers in Materials Science (FMS2022) (Phu Quoc Island, Kien Giang, Vietnam)

Presentation date： 2022.11
グラフェン形成によるTaC薄膜の超伝導転移温度向上とそのメカニズム

近藤大斗、榊原涼太郎、林直輝、伊藤孝寛、遠藤彰、鈴木舞奈佳、石井祐太、若林裕助、乗松航

第83回応用物理学会秋季学術講演会 (東北大学)

Presentation date： 2022.09
固体電解質/グラフェン/SiCにおける電気化学的リチウム挿入脱離機構

乗松航、山本智士、本山宗主、入山泰寿、

第69回応用物理学会春季学術講演会 (オンライン)

Presentation date： 2022.03
Observation of flat band in millimetre-scale magic-angle twisted bilayer graphene

Wataru Norimatsu, Keiju Sato, Takahiro Ito, Keisuke Nakagahara, Katsunori Wakabayashi, and Hiroki Hibino,

International Symposium on Novel maTerials and quantum Technologies (ISNTT 2021) (online)

Presentation date： 2021.12
Microscopic Mechanism of Hydrogen Intercalation in Graphene/SiC (0001)

Ryotaro Sakakibara and Wataru Norimatsu,

International Symposium on Novel maTerials and quantum Technologies (ISNTT 2021) (online)

Presentation date： 2021.12
SiC上グラフェンを用いた表面構造物性の新展開（招待講演）

乗松航、 [Invited]

第40回電子材料シンポジウム (オンライン)

Presentation date： 2021.10
Enhancement of the superconducting transition temperature of the TaC thin film by graphene coverage

Daito Kondo, Takahiro Ito, Akira Endo, and Wataru Norimatsu,

Graphene Week 2021

Presentation date： 2021.09
Observation of a flat band in millimetre-scale magic angle twisted bilayer graphene

Wataru Norimatsu, Takahiro Ito, Keiju Sato, Noriyuki Masago, Mitsuru Moritomo, Takuji Maekawa, Doyoon Lee, Kuan Qiao, Jeehwan Kim, Keisuke Nakagahara, Katsunori Wakabayashi, and Hiroki Hibino,

Graphene Week 2021 (online)

Presentation date： 2021.09
Novel function and its mechanism realized at the graphene/substrate interface （Invited Talk）

Wataru Norimatsu、 [Invited]

2021年日本物理学会春季大会シンポジウム (online)

Presentation date： 2021.09
ミリメートルスケール魔法角ツイスト2層グラフェンにおけるフラットバンドの観測

乗松航、伊藤孝寛、佐藤京樹、眞砂紀之、森本満、前川拓滋、Lee Doyoon、Qiao Kuan、Kim Jeehwan、中川原圭祐、若林克法、日比野浩樹

第82回応用物理学会秋季学術講演会 (オンライン)

Presentation date： 2021.09
固体電解質/大面積単一方位グラフェンにおけるリチウム挿入脱離機構

乗松航、山本智士、本山宗主、入山泰寿、

第82回応用物理学会秋季学術講演会 (オンライン)

Presentation date： 2021.09
水素インターカレーションによる SiC上グラフェン形成のメカニズム

榊原涼太郎、乗松航、

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
SiC上グラフェン研究の進展と展望（招待講演）

乗松航、 [Invited]

第68回応用物理学会春季学術講演会シンポジウム (オンライン)

Presentation date： 2021.03
Hex-Au(001)基板上のグラフェンのエネルギーギャップの起源

寺澤知潮、保田諭、松永和也、林直輝、田中慎一郎、乗松航、伊藤孝寛、町田真一、朝岡秀人、

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
グラフェン/SiC 界面を利用した新機能開拓（招待講演）

乗松航、 [Invited]

第13回九大2D物質研究会 (オンライン)

Presentation date： 2021.02
水素インターカレーションによるSiC上グラフェン形成の初期過程

榊原涼太郎、乗松航、

第19回日本表面真空学会中部支部学術講演会 (オンライン)

Presentation date： 2020.12
エピタキシャルグラフェン被覆による超伝導体TaC 薄膜の転移温度向上

近藤大斗、林直樹、伊藤孝寛、遠藤彰、乗松航、

第19回日本表面真空学会中部支部学術講演会 (オンライン)

Presentation date： 2020.12
エピタキシャルグラフェンによる超伝導体薄膜の転移温度向上

乗松航、近藤大斗、伊藤孝寛、

学際・国際的高度人材育成ライフイノベーションマテリアル創製共同研究プロジェクト第5回公開討論会 (オンライン)

Presentation date： 2020.11
ミリメートルスケールツイスト2層グラフェンにおけるフラットバンド

佐藤京樹、林直樹、伊藤孝寛、眞砂紀之、森本満、前川拓滋、Kuan Qiao、Jeehwan Kim、若林克法、日比野浩樹、乗松航、

第81回応用物理学会秋季学術講演会 (オンライン)

Presentation date： 2020.09
超伝導体TaC薄膜のグラフェン被覆による転移温度向上

近藤大斗、林直樹、伊藤孝寛、遠藤彰、乗松航、

第81回応用物理学会秋季学術講演会 (オンライン)

Presentation date： 2020.09
SiC(000-1)面上多層グラフェンの回転角制御

乗松航、包建峰、林直樹、伊藤孝寛、眞砂紀之、前川拓滋、森本満、日比野浩樹

第81回応用物理学会秋季学術講演会 (オンライン)

Presentation date： 2020.09
SiC表面分解法によるカーボンナノチューブ成長への水の影響

鈴木航、乗松航、

第81回応用物理学会秋季学術講演会 (オンライン)

Presentation date： 2020.09
Nd-Fe-B系磁石材料の構造・物性相関解析

乗松航、包建峰、山下誠司、北英紀、川原田洋、井上靖秀、小山泰正、柳内克昭、

学際・国際的高度人材育成ライフイノベーションマテリアル創製共同研究プロジェクト第4回公開討論会 (東京ガーデンパレス, 東京)

Presentation date： 2020.03
B4C熱分解によるグラフェンの成長と物性

乗松航、川原田洋、

学際・国際的高度人材育成ライフイノベーションマテリアル創製共同研究プロジェクト第4回公開討論会 (東京ガーデンパレス, 東京)

Presentation date： 2020.03
グラフェン/SiC系における構造制御と電子状態（招待講演）

乗松航、 [Invited]

第12回九大2D物質研究会 (コープイン京都, 京都)

Presentation date： 2020.01
SiC上グラフェンにおける高圧水素インターカレーションとそのメカニズム

榊原涼太郎、乗松航、

第18回日本表面真空学会中部支部学術講演会 (名古屋大学ベンチャービジネスラボラトリ, 名古屋)

Presentation date： 2019.12
エピタキシャルグラフェンの電子状態に与える界面の影響

佐藤京樹、榊原涼太郎、河原憲治、吾郷浩樹、林直樹、伊藤孝寛、乗松航、

第18回日本表面真空学会中部支部学術講演会 (名古屋大学ベンチャービジネスラボラトリ, 名古屋)

Presentation date： 2019.12
SiC上エピタキシャルグラフェンの成長と構造・物性制御（招待講演）

乗松航、 [Invited]

グラフェン・酸化グラフェン合同シンポジウム (TKPガーデンシティPREMIUM秋葉原, 東京)

Presentation date： 2019.12
Growth of functional epitaxial graphene (Invited talk)

Wataru Norimatsu, [Invited]

Joint 5th International Symposium on Frontiers in Materials Science and 3rd International Symposium on Nano-materials (Technology and Applications, Duy Tan University, Danang, Vietnam)

Presentation date： 2019.11
Functional epitaxial graphene grown by thermal decomposition of carbide materials

Wataru Norimatsu,

International Conference on Materials and Systems for Sustainability (Nagoya University, Japan)

Presentation date： 2019.11
Growth of epitaxial graphene by thermal decomposition of carbides (Invited talk)

Wataru Norimatsu, [Invited]

International Conference on Materials and Systems for Sustainability (Nagoya University, Japan)

Presentation date： 2019.11
Electronic states of graphene transferred onto the buffer layer on SiC

Keiju Sato, Ryotaro Sakakibara, Kenji Kawahara, Hiroki Ago, Naoki Hayashi, Takahiro Ito, and Wataru Norimatsu,

International Symposium on Epi-Graphene 2019 (TU Chemnitz, Germany)

Presentation date： 2019.08
Functional epitaxial graphene grown by thermal decomposition of carbides (Invited talk)

Wataru Norimatsu, [Invited]

International Symposium on Epi-Graphene 2019 (TU Chemnitz, Germany)

Presentation date： 2019.08
Quasi-free-standing graphene formed under high-pressure hydrogen

Ryotaro Sakakibara and Wataru Norimatsu,

International Symposium on Epi-Graphene 2019 (TU Chemnitz, Germany)

Presentation date： 2019.08
Quasi-freestanding epitaxial graphene obtained under high-pressure hydrogen

Ryotaro Sakakibara and Wataru Norimatsu,

第1回低次元物質科学セミナー (名古屋大学)

Presentation date： 2019.08
Electronic states of epitaxial graphene and CVD graphene transferred onto the buffer layer

Keiju Sato, Ryotaro Sakakibara, Kenji Kawahara, Hiroki Ago, Naoki Hayashi, Takahiro Ito, and Wataru Norimatsu,

第1回低次元物質科学セミナー (名古屋大学)

Presentation date： 2019.08
4H-SiC(000-1)上TaC薄膜のグラフェン化

清水一矢、林直輝、伊藤孝寛、乗松航、

第66回応用物理学会春季学術講演会 (東京工業大学大岡山キャンパス, 東京)

Presentation date： 2019.03
SiC上グラフェンの電子物性に対する界面の影響

佐藤京樹、榊原涼太郎、河原憲治、吾郷浩樹、林直輝、伊藤孝寛、乗松航、

第66回応用物理学会春季学術講演会 (東京工業大学大岡山キャンパス, 東京)

Presentation date： 2019.03
Hex-Au(100)再構成表面上でのグラフェンの電子バンド構造の変調

寺澤知潮、保田諭、林直輝、乗松航、伊藤孝寛、町田真一、矢野雅大、斉木幸一郎、朝岡秀人、

第66回応用物理学会春季学術講演会 (東京工業大学大岡山キャンパス, 東京)

Presentation date： 2019.03
SiC上エピタキシャル炭化物からのグラフェン成長

乗松航、

第11回九大2D物質研究会 (九州大学西新プラザ, 博多)

Presentation date： 2019.02
エピタキシャルグラフェン研究の10年

乗松航、

第3回早稲田大学凝縮系物質科学研究所シンポジウム (早稲田大学, 東京)

Presentation date： 2019.01
Electronic properties of epitaxial graphene and its application

Wataru Norimatsu, Michiko Kusunoki,

The 3rd International Symposium on Creation of Life Innovation Materials for Interdisciplinary and International Researcher Development (Tokyo Garden Palace, Tokyo)

Presentation date： 2018.09
SiC上グラフェンの移動度に及ぼす界面の影響

榊原涼太郎、河原憲治、吾郷浩樹、乗松航、

第79回応用物理学会秋季学術講演会 (名古屋国際会議場)

Presentation date： 2018.09
Ni intercalation between graphene and silicon carbide

Wataru Norimatsu, Tomo-o Terasawa, Yutaro Ouchi, Takahiro Ito, and Michiko Kusunoki,

Graphene Week 2018 (Kursaal Conference Center, San Sebastian, Spain)

Presentation date： 2018.09
Interface engineering of epitaxial graphene (Plenary)

Wataru Norimatsu, [Invited]

1st Tianjin International Symposium on Epitaxial Graphene (TISEG-1) (Tianjin University, Tianjin, China)

Presentation date： 2018.07
Interface engineering of epitaxial graphene on SiC (Invited)

Wataru Norimatsu, [Invited]

6th International Symposium on Graphene Devices (ISGD-6) (ITMO University, St. Petersburg, Russia)

Presentation date： 2018.07
エピタキシャルグラフェン研究の展開

乗松航、

第1回JEX-2014研究会 (東北大学東京分室, 東京)

Presentation date： 2018.06
エピタキシャル炭化アルミニウム薄膜の成長及びその熱分解によるグラフェン形成

松田敬太、福井舞、乗松航、楠美智子、

第65回応用物理学会春季学術講演会 (早稲田大学)

Presentation date： 2018.03
Formation of zigzag graphene nanoribbons on vicinal SiC (0001)

Yota Harada, Keita Matsuda, K. Higuchi, Wataru Norimatsu, and Michiko Kusunoki,

International Symposium on Epitaxial Graphene 2017 (ISEG-2017) (Nagoya University)

Presentation date： 2017.11
Morphology control of epitaxial graphene by Ar flow rate in large-scale

Tomo-o Terasawa, Wataru Norimatsu, and Michiko Kusunoki,

International Symposium on Epitaxial Graphene 2017 (ISEG-2017) (Nagoya University)

Presentation date： 2017.11
Fabrication of the carbon nanotubes/graphene composite film on silicon carbide

Yoshito Nagae, Wataru Norimatsu, and Michiko Kusunoki,

International Symposium on Epitaxial Graphene 2017 (ISEG-2017) (Nagoya University)

Presentation date： 2017.11
Epitaxial growth of two-dimensional GaN film on SiC substrates

Seina Nakao, Wataru Norimatsu, and Michiko Kusunoki,

International Symposium on Epitaxial Graphene 2017 (ISEG-2017) (Nagoya University)

Presentation date： 2017.11
Negative-thermal-expansion-induced graphenization of buffer layer on SiC

Jianfeng Bao, Wataru Norimatsu, Keita Matsuda, and Michiko Kusunoki,

International Symposium on Epitaxial Graphene 2017 (ISEG-2017) (Nagoya University)

Presentation date： 2017.11
Carrier mobility of graphene on SiC: influence of the substrates

Wataru Norimatsu, Jianfeng Bao, Tomo-o Terawasa, and Michiko Kusunoki,

International Symposium on Epitaxial Graphene 2017 (ISEG-2017) (Nagoya University)

Presentation date： 2017.11
Step unbunching phenomenon of the SiC surface

Wataru Norimatsu, Keisuke Yuhara, Jianfeng Bao, Tomo-o Terasawa, and Michiko Kusunoki,

International Symposium on Epitaxial Graphene 2017 (ISEG-2017) (Nagoya University)

Presentation date： 2017.11
Characterization of Ni intercalated graphene film on SiC (0001)

Yutaro Ouchi, Wataru Norimatsu, Takahiro Ito, Ryoji Funahashi, and Michiko Kusunoki,

International Symposium on Epitaxial Graphene 2017 (ISEG-2017) (Nagoya University)

Presentation date： 2017.11
Characterization of boron doped graphene derived from epitaxial B4C thin film on SiC substrate

Nao Takata, Wataru Norimatsu, Takahiro Ito, and Michiko Kusunoki,

International Symposium on Epitaxial Graphene 2017 (ISEG-2017) (Nagoya University)

Presentation date： 2017.11
Fabrication of SiC/B4C nano-composite film and subsequent graphitization

Keita Matsuda, Wataru Norimatsu, and Michiko Kusunoki,

International Symposium on Epitaxial Graphene 2017 (ISEG-2017) (Nagoya University)

Presentation date： 2017.11
Toward mobility improvement of epitaxial graphene

Ryotaro Sakakibara, Wataru Norimatsu, and Michiko Kusunoki,

International Symposium on Epitaxial Graphene 2017 (ISEG-2017) (Nagoya University)

Presentation date： 2017.11
Epitaxial Al4C3 growth on SiC substrate and subsequent graphenization

Keita Matsuda, Mai Fukui, Wataru Norimatsu, Tomo-o Terasawa, and Michiko Kusunoki,

International Symposium on Epitaxial Graphene 2017 (ISEG-2017) (Nagoya University)

Presentation date： 2017.11
Relation between thermal resistance and deformation of vertically aligned carbon nanotubes on SiC

Yosuke Tsukiyama, Wataru Hoshino, Yusaku Nakamura, Isami Nitta, Wataru Norimatsu, and Michiko Kusunoki,

International Symposium on Epitaxial Graphene 2017 (ISEG-2017) (Nagoya University)

Presentation date： 2017.11
Effect of oxygen gas on diameter of carbon nanotubes formed by SiC surface decomposition

Yuka Matsuyama, Wataru Norimatsu, and Michiko Kusunoki,

International Symposium on Epitaxial Graphene 2017 (ISEG-2017) (Nagoya University)

Presentation date： 2017.11
Synthesis of epitaxial graphene quantum dots along periodic steps of SiC

Michiko Kusunoki, Satsuki Nakano, Yota Harada, Wataru Norimatsu, and Y. Nishikawa,

International Symposium on Epitaxial Graphene 2017 (ISEG-2017) (Nagoya University)

Presentation date： 2017.11
Low-temperature magnetotransport of inhomogeneous epitaxial graphene grown on SiC

Akira Endo, Shingo Katsumoto, Jianfeng Bao, Wataru Norimatsu, and Michiko Kusunoki,

International Symposium on Epitaxial Graphene 2017 (ISEG-2017) (Nagoya University)

Presentation date： 2017.11
Time-resolved photoluminescence from epitaxial and transferred monolayer graphene on SiC substrate

Hirotaka Imaeda, Takeshi Koyama, Hideo Kishida, Kenji Kawahara, Hiroki Ago, Jianfeng Bao, Tomo-o Terasawa, Wataru Norimatsu, and Michiko Kusunoki,

International Symposium on Epitaxial Graphene 2017 (ISEG-2017) (Nagoya University)

Presentation date： 2017.11
Angle-resolved photoemission study of p-doped graphene with Cu-intercalation

Takahiro Ito, Kouki Yamamoto, Masato Imai, Wataru Norimatsu, and Michiko Kusunoki,

International Symposium on Epitaxial Graphene 2017 (ISEG-2017) (Nagoya University)

Presentation date： 2017.11
Effect of impurities in Ar gas on growth of epitaxial graphene

Tomo-o Terasawa, Wataru Norimatsu, and Michiko Kusunoki,

International Symposium on Epitaxial Graphene 2017 (ISEG-2017) (Nagoya University)

Presentation date： 2017.11
Tuning of Cu intercalation between graphene and SiC (0001)

Tomo-o Terasawa, Masato Imai, Wataru Norimatsu, and Michiko Kusunoki,

International Symposium on Epitaxial Graphene 2017 (ISEG-2017) (Nagoya University)

Presentation date： 2017.11
Effect of gas phase conditions on growth of epitaxial graphene

Tomo-o Terasawa, Wataru Norimatsu, and Michiko Kusunoki,

Graphene Week 2017 (Athens, Greece)

Presentation date： 2017.09
Graphene growth by thermal decomposition of Al4C3 on SiC

Wataru Norimatsu, Mai Fukui, Keita Matsuda, Tomo-o Terasawa, and Michiko Kusunoki,

Graphene Week 2017 (Athens, Greece)

Presentation date： 2017.09
Nano-graphene formation by thermal decomposition of sea-island structured SiC/B4C nano-composite

Keita Matsuda, Wataru Norimatsu, and Michiko Kusunoki,

Graphene Week 2017 (Athens, Greece)

Presentation date： 2017.09
SiC熱分解によるグラフェン成長における不純物の影響

寺澤知潮、乗松航、楠美智子、

第78回応用物理学会秋季学術講演会 (福岡国際会議場)

Presentation date： 2017.09
SiC(0001)上グラフェンにおけるNiインターカレーション

大内勇太郎、乗松航、伊藤孝寛、舟橋良次、楠美智子、

第78回応用物理学会秋季学術講演会 (福岡国際会議場)

Presentation date： 2017.09
SiCステップ上グラフェン量子ドットのプラズモン発光現象

原田頌太、中野さつき、乗松航、西川洋太、河野行雄、楠美智子、

第78回応用物理学会秋季学術講演会 (福岡国際会議場)

Presentation date： 2017.09
B4C薄膜の熱分解によるホウ素ドープグラフェンの作製

高田奈央、乗松航、伊藤孝寛、楠美智子、

第78回応用物理学会秋季学術講演会 (福岡国際会議場)

Presentation date： 2017.09
Interface Engineering of Epitaxial Graphene Grown on SiC (Invited talk)

Wataru Norimatsu, [Invited]

Nagoya Univ.-Tsinghua Univ.-Toyota Motor Corp.-Hokkaido Univ. Joint Symposium (NTTH-2017) (Takayama Municipal Cultural Hall, Japan)

Presentation date： 2017.07
Interface engineering of epitaxial graphene on SiC (Invited talk)

Wataru Norimatsu, [Invited]

Collaborative Conference on Materials Research (CCMR) 2017 (International Convention Center Jeju, South Korea)

Presentation date： 2017.06
エピタキシャルグラフェンの界面制御（招待講演）

乗松航、楠美智子、 [Invited]

6大学連携プロジェクト「文科省学際国際的高度人材育成ライフイノベーションマテリアル創製共同研究プロジェクト」第1回公開討論会 (名古屋大学)

Presentation date： 2017.03
SiC上単層グラフェンの時間分解発光

今枝寛雄、小山剛史、岸田英生、包建峰、乗松航、楠美智子、

第72回日本物理学会年会 (大阪大学豊中キャンパス)

Presentation date： 2017.03
SiC表面分解によるグラフェン成長のAr流量による制御

寺澤知潮、乗松航、楠美智子、

第64回応用物理学会春季学術講演会 (パシフィコ横浜)

Presentation date： 2017.03
海島構造をもつSiC/B4Cナノコンポジット膜の作製とそのナノグラフェン化

松田敬太、乗松航、楠美智子、

第64回応用物理学会春季学術講演会 (パシフィコ横浜)

Presentation date： 2017.03
エピタキシャルグラフェンの界面制御と角度分解光電子分光測定（依頼講演）

乗松航、伊藤孝寛、楠美智子、 [Invited]

第6回名古屋大学シンクロトロン光研究センターシンポジウム (名古屋大学)

Presentation date： 2017.03
SiC上グラフェンの課題と界面制御（招待講演）

乗松航、楠美智子、 [Invited]

第9回九大2次元物質研究会 (九州大学応用力学研究所, 福岡)

Presentation date： 2017.01
銅インターカレート処理したSiC(0001)上グラフェンの角度分解光電子分光

山本功樹、伊藤孝寛、今井雅人、乗松航、楠美智子、

第30回日本放射光学会年会 (神戸芸術センター)

Presentation date： 2017.01
SiC上へのAl4C3薄膜の作製とグラフェン化

福井舞、乗松航、楠美智子、

第16回表面科学会中部支部学術講演会 (名古屋大学)

Presentation date： 2016.12
炭化アルミニウムの熱分解によるアルミニウムドープグラフェンの作製

福井舞、乗松航、楠美智子、

第36回表面科学学術講演会 (名古屋国際会議場)

Presentation date： 2016.11
SiC粉末の表面分会によるCNT合成

横山理徳、乗松航、楠美智子、

第36回表面科学学術講演会 (名古屋国際会議場)

Presentation date： 2016.11
パルスレーザー堆積法による大面積TiC薄膜のグラフェン化

鶴田遥香、乗松航、楠美智子、

第36回表面科学学術講演会 (名古屋国際会議場)

Presentation date： 2016.11
SiC上グラフェン量子ドットの作製と特性評価

中野さつき、乗松航、楠美智子、

第36回表面科学学術講演会 (名古屋国際会議場)

Presentation date： 2016.11
Interface modification of epitaxial graphene on SiC (Invited talk)

Wataru Norimatsu, [Invited]

International Conference on Technologically Advanced Materials and Asian Meeting on Ferroelectrics (ICTAM-AMF10) (University of Delhi、India)

Presentation date： 2016.11
Formation of graphene on SiC in nitrogen atmosphere and its interface structure

Michiko Kusunoki, and Wataru Norimatsu,

The International Symposium on Visualization in Joining & Welding Science through Advanced Measurements and Simulation (Visual-JW 2016) (Hotel Hankyu Expo Park, Osaka)

Presentation date： 2016.10
Carrier-type control of close-packed carbon nanotube film on SiC

Wataru Norimatsu, Keita Matsuda, and Michiko Kusunoki,

The International Symposium on Visualization in Joining & Welding Science through Advanced Measurements and Simulation (Visual-JW 2016) (Hotel Hankyu Expo Park, Osaka)

Presentation date： 2016.10
バッファー層急冷グラフェンの電子状態と物性

乗松航、包建峰、山本功樹、伊藤孝寛、舟橋良次、楠美智子、

第77回応用物理学会秋季学術講演会 (朱鷺メッセ, 新潟)

Presentation date： 2016.09
SiC上高濃度ホウ素ドープグラフェンの物性

乗松航、増森淳史、舟橋良次、遠藤彰、楠美智子、

第77回応用物理学会秋季学術講演会 (朱鷺メッセ, 新潟)

Presentation date： 2016.09
パルスレーザー堆積法による大面積TiC薄膜の作製とそのグラフェン化

鶴田遥香、乗松航、楠美智子、

第77回応用物理学会秋季学術講演会 (朱鷺メッセ, 新潟)

Presentation date： 2016.09
Controlling the stacking rotation of multilayer graphene on SiC (000-1)

Keita Matsuda, Wataru Norimatsu, Jun Kuroki, and Michiko Kusunoki,

5th International Symposium on Graphene Devices (ISGD-5) (Brisbane, Australia)

Presentation date： 2016.07
Negative-thermal-expansion-induced graphenization of buffer layer on SiC

Wataru Norimatsu, Jianfeng Bao, Takahiro Ito, and Michiko Kusunoki,

5th International Symposium on Graphene Devices (ISGD-5) (Brisbane, Australia)

Presentation date： 2016.07
Negative-thermal-expansion-induced graphenization of buffer layer on SiC

Wataru Norimatsu, Jianfeng Bao, Takahiro Ito, and Michiko Kusunoki,

Graphene Week 2016 (Warsaw, Poland)

Presentation date： 2016.06
Negative thermal expansion induced graphenization of buffer layer on SiC (Invited talk)

Wataru Norimatsu and Michiko Kusunoki, [Invited]

2-D Materials Meeting (San Sebastian, Spain)

Presentation date： 2016.05
単層・2層が共存するエピタクシャルグラフェンの磁気抵抗の2キャリアモデルによる解析

遠藤彰、包建峰、乗松航、楠美智子、

第71回日本物理学会年次大会 (東北学院大学, 仙台)

Presentation date： 2016.03
成長後急冷型バッファー層フリーグラフェンの角度分解光電子分光

山本功樹、伊藤孝寛、包建峰、乗松航、松田敬太、楠美智子、

第71回日本物理学会年次大会 (東北学院大学, 仙台)

Presentation date： 2016.03
SiC基板上高密度CNT配向膜における電気伝導機構の解明

松田敬太、乗松航、楠美智子、

第63回応用物理学会春季学術講演会 (名古屋国際会議場)

Presentation date： 2016.03
Growth of epitaxial graphene on SiC and its interface modification (Invited talk)

Wataru Norimatsu and Michiko Kusunoki, [Invited]

2nd Annual World Congress of Smart Materials (WCSM-2016) (Singapore)

Presentation date： 2016.03
負の熱膨張を利用したバッファー層の急冷処理によるグラフェン化（招待講演）

乗松航、 [Invited]

第8回九大グラフェン研究会「原子層物質の成長と物性」 (九州大学)

Presentation date： 2016.01
SiC上均質グラフェンの特性と今後の展望（招待講演）

楠美智子、乗松航、 [Invited]

NanoTech 2016 (東京ビッグサイト)

Presentation date： 2016.01
SiC(000-1)上B4C薄膜の熱分解によるホウ素ドープグラフェンの創製

増森淳史、乗松航、楠美智子

第15回日本表面科学会中部支部学術講演会 (名古屋工業大学)

Presentation date： 2015.12
負の熱膨張率を利用したSiC基板上フリースタンディンググラフェンの形成

包建峰、乗松航、楠美智子

第15回日本表面科学会中部支部学術講演会 (名古屋工業大学)

Presentation date： 2015.12
Growth and functionalization of epitaxial graphene on SiC (Invited talk)

Wataru Norimatsu and Michiko Kusunoki, [Invited]

Collaborative Conference on Crystal Growth (3CG) (Hong Kong)

Presentation date： 2015.12
TiC/SiC単結晶の表面分解によるグラフェンの作製と観察

宮本玄生、乗松航、楠美智子

平成27年度日本セラミックス協会東海支部学術研究発表会 (名古屋大学)

Presentation date： 2015.12
SiC上CNT配向膜の伝導特性

松田敬太、乗松航、楠美智子

平成27年度日本セラミックス協会東海支部学術研究発表会 (名古屋大学)

Presentation date： 2015.12
SiC上へのB4C薄膜の形成と特性評価

増森淳史、乗松航、楠美智子

平成27年度日本セラミックス協会東海支部学術研究発表会 (名古屋大学)

Presentation date： 2015.12
Novel interface modification in epitaxial graphene on SiC (Invited talk)

Michiko Kusunoki and Wataru Norimatsu, [Invited]

EMN Hong Kong Meeting 2015 (Hong Kong)

Presentation date： 2015.12
Epitaxial graphene growth on SiC and its interface modification (Invited talk)

Wataru Norimatsu and Michiko Kusunoki, [Invited]

第1回「炭化珪素系へテロ構造を用いた物質創成と応用展開」研究会 (東北大学)

Presentation date： 2015.11
Electrical Transport Properties of Close-Packed and Well-aligned Carbon Nanotube Films Depending on Length

Keita Matsuda, Wataru Norimatsu and Michiko Kusunoki,

2nd International Symposium on Frontiers in Materials Science (Waseda University)

Presentation date： 2015.11
Epitaxial graphene growth and its electronic functionalization (Invited talk)

Wataru Norimatsu and Michiko Kusunoki, [Invited]

2nd International Symposium on Frontiers in Materials Science (Waseda University)

Presentation date： 2015.11
SiC(000-1)上B4C薄膜の熱分解によるホウ素ドープグラフェンの創製

増森淳史、乗松航、楠美智子、

第76回応用物理学会秋季学術講演会 (名古屋国際会議場)

Presentation date： 2015.09
SiC上グラフェン量子ドットの作製と特性評価

中野さつき、乗松航、楠美智子、

第76回応用物理学会秋季学術講演会 (名古屋国際会議場)

Presentation date： 2015.09
銅インターカレーションしたSiC(0001)上グラフェンのTEM観察

今井雅人、乗松航、楠美智子、

第76回応用物理学会秋季学術講演会 (名古屋国際会議場)

Presentation date： 2015.09
カーボンナノチューブ間の接触抵抗

稲葉優文、李智宇、鈴木和真、平野優、費文茜、乗松航、楠美智子、川原田洋、

第76回応用物理学会秋季学術講演会 (名古屋国際会議場)

Presentation date： 2015.09
SiC 上カーボンナノチューブフォレストのメタルフリーCVD 成長におけるCNT 端面の調査

平野優、稲葉優文、鈴木和真、費文茜、乗松航、楠美智子、川原田洋、

第76回応用物理学会秋季学術講演会 (名古屋国際会議場)

Presentation date： 2015.09
Growth of graphene and novel 2D film on SiC (Invited talk)

Wataru Norimatsu and Michiko Kusunoki, [Invited]

The Second Symposium on 2D electronic Materials (Joint ACCGE/OMVPE) (Big Sky, Montana, USA)

Presentation date： 2015.08
Novel Interface modification in epitaxial graphene on SiC (Invited talk)

Michiko Kusunoki and Wataru Norimatsu, [Invited]

The 8th Nagoya Univ.-Tsinghua Univ.-Toyota Motor Corp.-Hokkaido Univ.- XinJiang Normal Univ.(NTTHX) Joint Symposium (Urumuqi, Xinjiang, China)

Presentation date： 2015.08
SiC上グラフェンの構造制御と輸送特性（招待講演）

乗松航、 [Invited]

日本セラミックス協会第49回基礎科学部会セミナー (ウィンク愛知)

Presentation date： 2015.07
Electronic properties of the closely-packed aligned carbon nanotube film

Wataru Norimatsu, Hayato Fujita, Koji Oda, and Michiko Kusunoki,

The Sixteenth International Conference on the Science and Application of Nanotubes (NT16) (Nagoya University)

Presentation date： 2015.06
Creation of Boron-Doped Graphene by thermal decomposition of B4C

Atsushi Masumori, Wataru Norimatsu, and Michiko Kusunoki,

The Sixteenth International Conference on the Science and Application of Nanotubes (NT16) (Nagoya University)

Presentation date： 2015.06
Intercalation of copper atoms under graphene film on SiC (0001)

Masato Imai, Wataru Norimatsu, and Michiko Kusunoki,

The Sixteenth International Conference on the Science and Application of Nanotubes (NT16) (Nagoya University)

Presentation date： 2015.06
Quasi-free-standing graphene formation on SiC (0001) by the post-growth rapid-cooling

Jianfeng Bao, Wataru Norimatsu, and Michiko Kusunoki,

The Sixteenth International Conference on the Science and Application of Nanotubes (NT16) (Nagoya University)

Presentation date： 2015.06
Interface modifications in epitaxial graphene on SiC (0001)

Yoshiho Masuda, Wataru Norimatsu, and Michiko Kusunoki,

The Sixteenth International Conference on the Science and Application of Nanotubes (NT16) (Nagoya University)

Presentation date： 2015.06
TEM observation of copper intercalation in graphene on SiC (0001)

Masato Imai, Wataru Norimatsu, and Michiko Kusunoki,

Graphene Week 2015 (University of Manchester, UK)

Presentation date： 2015.06
Buffer-layer-free graphene on SiC (0001) by rapid cooling

Jianfeng Bao, Wataru Norimatsu, and Michiko Kusunoki,

Graphene Week 2015 (University of Manchester, UK)

Presentation date： 2015.06
Interplay between step-bunching and graphene growth on 6H-SiC (0001)

Wataru Norimatsu, Osamu Yasui, Jianfeng Bao, and Michiko Kusunoki,

Graphene Week 2015 (University of Manchester, UK)

Presentation date： 2015.06
SiC上の高均質グラフェン・ナノチューブ膜の可能性

楠美智子、乗松航、

第19回液晶化学研究会シンポジウム (名古屋大学)

Presentation date： 2015.05
ホウ素ドープ最密充填カーボンナノチューブ膜の電気伝導測定

乗松航、小田晃司、藤田隼人、楠美智子、

第62回応用物理学会春季学術講演会 (東海大学)

Presentation date： 2015.03
無触媒CVD成長したカーボンナノチューブの評価

平野優、稲葉優文、渋谷恵、鈴木和真、李智宇、明道三穂、平岩篤、乗松航、楠美智子、川原田洋、

第62回応用物理学会春季学術講演会 (東海大学)

Presentation date： 2015.03
SiC上のカーボンナノチューブのパターニング形成のための耐超高温ZnO/Cマスク

稲葉優文、李智宇、鈴木和真、渋谷恵、明道三穂、平野優、乗松航、楠美智子、川原田洋、

第62回応用物理学会春季学術講演会 (東海大学)

Presentation date： 2015.03
SiCグラフェン成長とステップバンチングの関係

安井理、乗松航、楠美智子、

第62回応用物理学会春季学術講演会 (東海大学)

Presentation date： 2015.03
急冷法によるSiC(0001)上バッファー層フリーグラフェンの作製

包建峰、乗松航、楠美智子、

第62回応用物理学会春季学術講演会 (東海大学)

Presentation date： 2015.03
SiC(0001)基板の様々なステップ高さにおけるグラフェン形成メカニズム

安井理、乗松航、楠美智子、

第53回セラミックス基礎科学討論会 (京都テルサ)

Presentation date： 2015.01
SiC初期酸化膜の周期構造とそのグラフェン化

宮田将大、乗松航、楠美智子、

第53回セラミックス基礎科学討論会 (京都テルサ)

Presentation date： 2015.01
グラフェン成長におけるSiC基板のステップ方位及びoff角依存性

柚原敬介、乗松航、楠美智子、

第14回日本表面科学会中部支部学術講演会 (名古屋大学)

Presentation date： 2014.12
SiC初期酸化膜の周期制御とそのグラフェン化に与える影響

宮田将大、乗松航、楠美智子、

第14回日本表面科学会中部支部学術講演会 (名古屋大学)

Presentation date： 2014.12
SiC(0001)面上エピタキシャルグラフェンの形状評価と電気特性

内山貴文、乗松航、楠美智子、

平成26年度日本セラミックス協会東海支部学術研究発表会 (名古屋工業大学)

Presentation date： 2014.12
熱分解グラフェン成長におけるSiC基板off角依存性

柚原敬介、乗松航、楠美智子、

平成26年度日本セラミックス協会東海支部学術研究発表会 (名古屋工業大学)

Presentation date： 2014.12
精密SiC表面で実現する高品質グラフェン成長とその展開（招待講演）

乗松航、楠美智子、 [Invited]

第3回表面創成工学の新展開研究会 (ホテルグランド天空、秋田県田沢湖)

Presentation date： 2014.11
Nitrogen induced modification of interface in epitaxial graphene on SiC

Wataru Norimatsu, Yoshiho Masuda and Michiko Kusunoki,

International Symposium on Graphene Devices 2014 (Hilton Bellevue, Washington)

Presentation date： 2014.09
SiC上のカーボンナノチューブを下地としたカーボンナノチューブフォレストのクローニング成長

平野優、稲葉優文、渋谷恵、鈴木和真、李智宇、明道三穂、平岩篤、乗松航、楠美智子、川原田洋、

第75回応用物理学会秋季学術講演会 (北海道大学)

Presentation date： 2014.09
SiC上に形成した稠密カーボンナノチューブフォレストの面内方向伝導性評価

稲葉優文、李智宇、鈴木和真、渋谷恵、明道三穂、平野優、平岩篤、乗松航、楠美智子、川原田洋、

第75回応用物理学会秋季学術講演会 (北海道大学)

Presentation date： 2014.09
SiC (000-1)上B4C薄膜のエピタキシャル成長

増森淳史、乗松航、楠美智子、

第75回応用物理学会秋季学術講演会 (北海道大学)

Presentation date： 2014.09
グラフェンナノパターニングに向けたSiC初期酸化膜の周期構造

宮田将大、乗松航、楠美智子、

第75回応用物理学会秋季学術講演会 (北海道大学)

Presentation date： 2014.09
TiCマスクをしたSiC基板の表面分解によるグラフェン形成

宮本玄生、乗松航、楠美智子、

第47回フラーレン・ナノチューブ・グラフェン学会総合シンポジウム (名古屋大学)

Presentation date： 2014.09
Electronic and structural properties of B-doped carbon-nanotube film on SiC

乗松航、小田晃司、藤田隼人、楠美智子、

第47回フラーレン・ナノチューブ・グラフェン学会総合シンポジウム (名古屋大学)

Presentation date： 2014.09
Nitrogen-induced interface improvement in epitaxial graphene on SiC

乗松航、増田佳穂、楠美智子、

第47回フラーレン・ナノチューブ・グラフェン学会総合シンポジウム (名古屋大学)

Presentation date： 2014.09
SiC上カーボンナノチューブフォレスト向け高温マスクパターニング

稲葉優文、李智宇、鈴木和真、渋谷恵、平野優、明道三穂、平岩篤、乗松航、楠美智子、川原田洋、

第47回フラーレン・ナノチューブ・グラフェン学会総合シンポジウム (名古屋大学)

Presentation date： 2014.09
トップコンタクト電極を用いたCNT/SiC界面の接触抵抗及びSchottky障壁高さの評価

鈴木和真、稲葉優文、李智宇、鈴木和真、渋谷恵、平野優、明道三穂、平岩篤、乗松航、楠美智子、川原田洋、

第47回フラーレン・ナノチューブ・グラフェン学会総合シンポジウム (名古屋大学)

Presentation date： 2014.09
SiC上グラフェンへの銅インターカレーション

今井雅人、乗松航、楠美智子、

第47回フラーレン・ナノチューブ・グラフェン学会総合シンポジウム (名古屋大学)

Presentation date： 2014.09
Homogeneous graphene growth on SiC (000-1)

Wataru Norimatsu, Honami Ohara and Michiko Kusunoki,

IUMRS-ICA 2014 (Fukuoka Univ.)

Presentation date： 2014.08
Interface modification by nitrogen in epitaxial graphene on SiC

Wataru Norimatsu, Yoshiho Masuda and Michiko Kusunoki,

IUMRS-ICA 2014 (Fukuoka Univ.)

Presentation date： 2014.08
Interface improvement by nitrogen in epitaxial graphene on SiC

Wataru Norimatsu, Yoshiho Masuda and Michiko Kusunoki,

7th NTTH Symposium (Hokkaido Univ.)

Presentation date： 2014.07
Interface modification by nitrogen in epitaxial graphene on SiC

Wataru Norimatsu, Yoshiho Masuda and Michiko Kusunoki,

Graphene Week 2014 (Goteborg, Sweden)

Presentation date： 2014.06
Growth and structural/electronic properties of epitaxial graphene on SiC (Invited talk)

Wataru Norimatsu and Michiko Kusunoki, [Invited]

2014 EMN Meeting (Cancun, Mexico)

Presentation date： 2014.06
SiC表面上グラフェンの窒素処理による界面構造改質

乗松航、増田佳穂、楠美智子、

日本顕微鏡学会第70回記念学術講演会 (幕張メッセ)

Presentation date： 2014.05
トップコンタクト電極を用いたCNT/SiC界面の接触抵抗及びSchottky障壁高さの評価

鈴木和真、稲葉優文、渋谷恵、李智宇、明道三穂、平岩篤、増田佳穂、乗松航、楠美智子、川原田洋、

応用物理学会第61回春季学術講演会 (青山学院大学)

Presentation date： 2014.03
高配向・高密度カーボンナノチューブへのカルボラン内包

藤田隼、乗松航、楠美智子、

応用物理学会第61回春季学術講演会 (青山学院大学)

Presentation date： 2014.03
エピタキシャルグラフェンの構造解析（招待講演）

乗松航、楠美智子、 [Invited]

東北大学通研共同プロジェクト講演会 (東北大学)

Presentation date： 2014.03
半絶縁性シリコンカーバイド上の高密度カーボンナノチューブフォレストの面内電導

稲葉優文、李智宇、鈴木和真、平岩篤、増田佳穂、乗松航、楠美智子、川原田洋、

第46回フラーレン・ナノチューブ・グラフェン学会総合シンポジウム (東京大学)

Presentation date： 2014.03
カーボンナノチューブ／シリコンカーバイド界面の接触抵抗及びSchottky障壁高さの評価

鈴木和真、李智宇、稲葉優文、平岩篤、増田佳穂、乗松航、楠美智子、川原田洋、

第46回フラーレン・ナノチューブ・グラフェン学会総合シンポジウム (東京大学)

Presentation date： 2014.03
窒素雰囲気下で形成されるグラフェン／SiCの界面構造

増田佳穂、乗松航、楠美智子、

第46回フラーレン・ナノチューブ・グラフェン学会総合シンポジウム (東京大学)

Presentation date： 2014.03
高配向・高密度カーボンナノチューブ膜へのカルボラン内包

藤田隼、乗松航、楠美智子、

第46回フラーレン・ナノチューブ・グラフェン学会総合シンポジウム (東京大学)

Presentation date： 2014.03
透過型電子顕微鏡によるエピタキシャルグラフェンの結晶学的研究（招待講演）

乗松航、楠美智子、 [Invited]

第6回グラフェン研究会 (九州大学)

Presentation date： 2014.01
高配向・高密度カーボンナノチューブ膜へのカルボラン内包とその評価

藤田隼、乗松航、楠美智子、

第13回日本表面科学会中部支部学術講演会 (名古屋工業大学)

Presentation date： 2013.12
SiC(000-1)C面を用いた均一な大面積グラフェンの作製

大原穂波、乗松航、楠美智子、

平成25年度日本セラミックス協会東海支部学術研究発表会 (名城大学)

Presentation date： 2013.12
高配向・高密度カーボンナノチューブへのカルボラン内包とその評価

藤田隼、乗松航、楠美智子、

平成25年度日本セラミックス協会東海支部学術研究発表会 (名城大学)

Presentation date： 2013.12
Structures and Transport Properties of Zigzag-Type CNT Films Doped by Si (Invited)

Michiko Kusunoki, Naoya Tomatsu, Wataru Norimatsu, Koichi Takase [Invited]

2013 MRS Fall Meeting (Boston Massachusetts)

Presentation date： 2013.12
Graphene growth from solid-state amorphous carbon on various substrates

Fumitaka Asai, Wataru Norimatsu, and Michiko Kusunoki,

3rd CAMPUS Asia Symposium on Chemistry and Materials (Seoul National University, Korea)

Presentation date： 2013.11
Epitaxial Graphene Growth by Thermal Decomposition of SiC (Invited talk)

Wataru Norimatsu, and Michiko Kusunoki, [Invited]

3rd CAMPUS Asia Symposium on Chemistry and Materials (Seoul National University, Korea)

Presentation date： 2013.11
高濃度ドープによるCNT/SiC界面の接触抵抗の低減

鈴木和真、稲葉優文、渋谷恵、明道三穂、平岩篤、増田佳穂、乗松航、楠美智子、川原田洋、

応用物理学会第74回学術講演会 (同志社大学)

Presentation date： 2013.09
窒素ガス雰囲気下におけるSiC上グラフェン形成とその界面構造

増田佳穂、乗松航、楠美智子、

応用物理学会第74回学術講演会 (同志社大学)

Presentation date： 2013.09
SiC(000-1)上グラフェンのTEMによる面内構造解析

乗松航、黒木淳、楠美智子、

応用物理学会第74回学術講演会 (同志社大学)

Presentation date： 2013.09
Homogeneous graphene on SiC (000-1) formed via an epitaxial TiC layer

K. Kimura, K. Shoji, W. Norimatsu, and Michiko Kusunoki,

5th International Conference on Recent Progress in Graphene Research 2013 (Tokyo Institute of Technology, Japan)

Presentation date： 2013.09
In-plane structural features of graphene on SiC revealed by TEM observations

Jun Kuroki, Wataru Norimatsu, and Michiko Kusunoki,

20th International Conference on Electronic Properties of Two-Dimensional Systems (EP2DS-10) (Wroclaw University of Technology, Poland)

Presentation date： 2013.07
Growth of boron-doped graphene by thermal decomposition of B4C

Wataru Norimatsu, K. Hirata and Michiko Kusunoki,

20th International Conference on Electronic Properties of Two-Dimensional Systems (EP2DS-10) (Wroclaw University of Technology, Poland)

Presentation date： 2013.07
In-plane structural properties of graphene on SiC revealed by TEM observations

Jun Kuroki, Wataru Norimatsu, and Michiko Kusunoki,

Graphene Week 2013 (Chemnitz City Hall, Germany)

Presentation date： 2013.06
High quality graphene growth on SiC (000-1) via an epitaxial TiC layer

Wataru Norimatsu, K. Shoji, K. Kimura and Michiko Kusunoki,

Graphene Week 2013 (Chemnitz City Hall, Germany)

Presentation date： 2013.06
SiC(000-1)表面上グラフェンの成長機構解明

乗松航、楠美智子、

第3回6大学6研究所連携プロジェクト公開討論会 (名古屋大学)

Presentation date： 2013.03
窒素ガスがSiC上エピタキシャルグラフェン形成に及ぼす影響

増田佳穂、乗松航、楠美智子、

日本表面科学会中部支部第12回学術講演会 (名古屋大学)

Presentation date： 2012.12
窒素ガスがSiC表面分解反応に及ぼす影響

増田佳穂、乗松航、楠美智子、

日本セラミックス協会東海支部学術研究発表会 (名古屋大学)

Presentation date： 2012.12
SiC(000-1)C面上における均一な大面積グラフェンの作製

大原穂波、乗松航、楠美智子、

日本セラミックス協会東海支部学術研究発表会 (名古屋大学)

Presentation date： 2012.12
TEM観察によるSiC表面分解グラフェンの面内構造解析

黒木淳、乗松航、楠美智子、

日本セラミックス協会東海支部学術研究発表会 (名古屋大学)

Presentation date： 2012.12
Homogeneous Graphene Growth on SiC (0001) with Step-height Lower Than 1 nm

Wataru Norimatsu, and Michiko Kusunoki,

3rd International Symposium on Graphene Devices (ISGD-2012) (Synchrotron SOLEIL, Saint-Aubin, France)

Presentation date： 2012.11
In-plane Structural Analysis of Graphene Layers on SiC by TEM Observation

Jun Kuroki, Wataru Norimatsu, and Michiko Kusunoki,

The 5th International Symposium on Designing (Hotel Nikko Toyohashi, Aichi)

Presentation date： 2012.11
Early stage of CNT formation by surface decomposition of SiC revealed by DFTB/MD simulations

Noriyuki Ogasawara, Wataru Norimatsu, Michiko Kusunoki, and S. Irle

The 5th International Symposium on Designing (Hotel Nikko Toyohashi, Aichi)

Presentation date： 2012.11
Growth of boron doped graphene by thermal decomposition of boron carbide

Wataru Norimatsu, Koichiro Hirata, and Michiko Kusunoki,

3rd International Symposium on Graphene Devices (ISGD-2012) (Synchrotron SOLEIL, Saint-Aubin, France)

Presentation date： 2012.11
Formation Mechanism of CNTs by Surface Decomposition of SiC Revealed by DFTB/MD Simulations

Noriyuki Ogasawara, Wataru Norimatsu, and Michiko Kusunoki, Stephan Irle,

IUMRS-ICEM 2012 (Pacifico Yokohama, Japan)

Presentation date： 2012.09
Electric properties of closely-packed CNTs film controlled by doping (Invited talk)

Wataru Norimatsu, Takehiro Maruyama, Koji Oda, and Michiko Kusunoki, [Invited]

IUMRS-ICEM 2012 (Pacifico Yokohama, Japan)

Presentation date： 2012.09
In-plane Structural Analysis of Graphene Layers on SiC (0001) and (000-1)

Jun Kuroki, Wataru Norimatsu, and Michiko Kusunoki,

IUMRS-ICEM 2012 (Pacifico Yokohama, Japan)

Presentation date： 2012.09
Growth of graphene on C-face (000-1) of SiC with the controlled number of layers in large area

Honami Ohara, Wataru Norimatsu, and Michiko Kusunoki,

IUMRS-ICEM 2012 (Pacifico Yokohama, Japan)

Presentation date： 2012.09
Interaction of metal nano-particles with graphene on SiC

Tomohiro Sakashita, Wataru Norimatsu, and Michiko Kusunoki,

IUMRS-ICEM 2012 (Pacifico Yokohama, Japan)

Presentation date： 2012.09
SiC surface decomposition in the N2 atmosphere

Yoshiho Masuda, Wataru Norimatsu, and Michiko Kusunoki,

IUMRS-ICEM 2012 (Pacifico Yokohama, Japan)

Presentation date： 2012.09
Epitaxial growth of graphene on various carbides

Wataru Norimatsu, Koichiro Hirata, Keisuke Kimura, and Michiko Kusunoki,

IUMRS-ICEM 2012 (Pacifico Yokohama, Japan)

Presentation date： 2012.09
金属ナノ粒子とSiC上グラフェンの相互作用

坂下智啓、乗松航、楠美智子、

日本セラミックス協会第25回秋季シンポジウム (名古屋大学)

Presentation date： 2012.09
窒素ガス雰囲気下におけるSiC表面分解反応

増田佳穂、乗松航、楠美智子、

日本セラミックス協会第25回秋季シンポジウム (名古屋大学)

Presentation date： 2012.09
DFTB/MDシミュレーションによるSiC表面分解グラフェンの成長機構解析

小笠原徳之、乗松航、楠美智子、Stephan Irle、

応用物理学会第73回学術講演会 (松山大学)

Presentation date： 2012.09
層数制御された大面積SiC(000-1)C面上グラフェンの作製

大原穂波、乗松航、楠美智子、

応用物理学会第73回学術講演会 (松山大学)

Presentation date： 2012.09
デバイス応用に適したSiC(0001)表面上グラフェン成長条件の探索

乗松航、楠美智子、

応用物理学会第73回学術講演会 (松山大学)

Presentation date： 2012.09
Epitaxial growth of boron-doped graphene by thermal decomposition of B4C

Wataru Norimatsu, Koichiro Hirata, Yuta Yamamoto, Shigeo Arai, and Michiko Kusunoki,

Graphene Week 2012 (Delft University of Technology, Netherland)

Presentation date： 2012.06
SiC表面上カーボンナノチューブ配向膜へのボロンドープ

乗松航、小田晃司、山本悠太、荒井重勇、楠美智子、

日本顕微鏡学会第68回学術講演会 (つくば国際会議場)

Presentation date： 2012.05
炭化ホウ素の熱分解によるグラフェン成長とその特徴

乗松航、平田浩一郎、山本悠太、荒井重勇、楠美智子、

日本顕微鏡学会第68回学術講演会 (つくば国際会議場)

Presentation date： 2012.05
高配向カーボンナノチューブ膜の真実接触面観察

月山陽介、小島傑、新田勇、乗松航、楠美智子、

トライボロジー会議2012春 (国立オリンピック記念青少年総合センター)

Presentation date： 2012.05
Crystallographic features of boron-doped graphene grown by thermal decomposition of B4C

Wataru Norimatsu, Koichiro Hirata, and Michiko Kusunoki,

The 3rd International Symposium on Advanced Microscopy and Theoretical Calculations (AMTC3) (Nagaragawa Convention Center, Gihu)

Presentation date： 2012.05
Stacking structures of graphene layers on SiC (0001) and (000-1)

Jun Kuroki, Wataru Norimatsu, and Michiko Kusunoki,

The 3rd International Symposium on Advanced Microscopy and Theoretical Calculations (AMTC3) (Nagaragawa Convention Center, Gihu)

Presentation date： 2012.05
B4Cの熱分解によるグラフェン成長とその特徴

乗松航、平田浩一郎、楠美智子、

日本物理学会第67回年次大会 (関西学院大学)

Presentation date： 2012.03
SiC上カーボンナノチューブ配向膜へのホウ素ドープ

小田晃司、乗松航、楠美智子、

第59回応用物理学関係連合講演会 (早稲田大学)

Presentation date： 2012.03
SiC表面分解法による数層グラフェンの面内構造解析

黒木淳、乗松航、楠美智子、

第59回応用物理学関係連合講演会 (早稲田大学)

Presentation date： 2012.03
n型Mn3Si4Al3系材料の熱電特性と元素置換効果

舟橋良次、松村葉子、田中秀明、竹内友成、鈴木亮輔、王一峰、乗松航、河本邦人、

第59回応用物理学関係連合講演会 (早稲田大学)

Presentation date： 2012.03
グラフェン研究の最新成果（依頼講演）

乗松航、楠美智子、 [Invited]

第6回材料フォーラム (ホテルサンルートプラザ名古屋)

Presentation date： 2012.01
Structural features of graphene layers on SiC (000-1) revealed by transmission electron microscopy

Wataru Norimatsu, Juji Takada, and Michiko Kusunoki,

International Symposium on Role of Electron Microscopy in Industry (Noyori Conference Hall, Nagoya Univ., Japan)

Presentation date： 2012.01
TEM Observations of B-doped Well-aligned Carbon Nanotube Films on SiC Substrate

Koji Oda, Wataru Norimatsu, and Michiko Kusunoki,

International Symposium on Role of Electron Microscopy in Industry (Noyori Conference Hall, Nagoya Univ., Japan)

Presentation date： 2012.01
Features of Epitaxial Graphene on SiC (Invited talk)

Wataru Norimatsu, Michiko Kusunoki, [Invited]

The 2nd Sino-Japan Energy Materials and Devices Joint Workshop (JST-MOST & CREST) (Univ. Electron. Sci. Tech. China, Chengdu, China)

Presentation date： 2011.12
Features of Epitaxial Graphene on SiC (Invited talk)

Wataru Norimatsu, Michiko Kusunoki, [Invited]

Nagoya Univ.-Tsinghua Univ.-Toyota Motor Corp.-Hokkaido Univ.-Univ. Electron. Sci. Tech. China Joint Symposium (NTTH2011) (Univ. Electron. Sci. Tech. China, Chengdu, China)

Presentation date： 2011.12
Diameter control of carbon nanotubes synthesized by SiC surface decomposition

Naoya Tomatsu, Wataru Norimatsu, Michiko Kusunoki,

Nagoya Univ.-Tsinghua Univ.-Toyota Motor Corp.-Hokkaido Univ.-Univ. Electron. Sci. Tech. China Joint Symposium (NTTH2011) (Univ. Electron. Sci. Tech. China, Chengdu, China)

Presentation date： 2011.12
First Principles Calculations of Close-packed and Doped Carbon Nanotubes

Noriyuki Ogasawara, Wataru Norimatsu, Michiko Kusunoki,

The 6th International Symposium on Surface Science (ISSS-6) (Tower Hall Funabori, Tokyo)

Presentation date： 2011.12
Plan-view of Few Layer Graphene on 6H-SiC by Transmission Electron Microscopy

Jun Kuroki, Wataru Norimatsu, Michiko Kusunoki,

The 6th International Symposium on Surface Science (ISSS-6) (Tower Hall Funabori, Tokyo)

Presentation date： 2011.12
Patterning of Aligned CNT Films using SiO2 Particles Monolayer as a Mask

Keita Matsuda, Wataru Norimatsu, Michiko Kusunoki,

The 6th International Symposium on Surface Science (ISSS-6) (Tower Hall Funabori, Tokyo)

Presentation date： 2011.12
Atomistic mechanism of graphene formation as predicted by nonequilibrium quantum chemical molecular dynamics simulations (Invited)

Stephan Irle, Ying Wang, Yoshio Nishimoto, Hu-Jun Qian, Masato Morita, Wataru Norimatsu, Michiko Kusunoki, Alister J. Page, Keiji Morokuma, [Invited]

International Symposium on EcoTopia Science 2011 (ISETS ‘11) (Nagoya Univ.)

Presentation date： 2011.12
Diameter control of carbon nanotubes synthesized by SiC surface decomposition

Naoya Tomatsu, Wataru Norimatsu, Michiko Kusunoki,

International Symposium on EcoTopia Science 2011 (ISETS ‘11) (Nagoya Univ.)

Presentation date： 2011.12
The size effect and the shape effect of ferroelectric domain structures in BaTiO3

Koichi Morita, Wataru Norimatsu, Michiko Kusunoki,

International Symposium on EcoTopia Science 2011 (ISETS ‘11) (Nagoya Univ.)

Presentation date： 2011.12
TEM Observations of B-doped Well-aligned Carbon Nanotube Films on SiC Substrate

Koji Oda, Wataru Norimatsu, Michiko Kusunoki,

International Symposium on EcoTopia Science 2011 (ISETS ‘11) (Nagoya Univ.)

Presentation date： 2011.12
Observations of Platinum Nanoparticles Supported on Well-aligned CNT Films at High Temperatures

Keita Matsuda, Wataru Norimatsu, Michiko Kusunoki,

International Symposium on EcoTopia Science 2011 (ISETS ‘11) (Nagoya Univ.)

Presentation date： 2011.12
Doping of Boron into Well-aligned Carbon Nanotube Films on SiC Substrate

Koji Oda, Wataru Norimatsu, and Michiko Kusunoki,

15th International Conference on Thin Films (ICTF-15) (Kyoto TERRSA)

Presentation date： 2011.11
Nanocarbon thin films grown on silicon carbide

Wataru Norimatsu, and Michiko Kusunoki,

15th International Conference on Thin Films (ICTF-15) (Kyoto TERRSA)

Presentation date： 2011.11
Features of epitaxial graphene on silicon carbide {0001}

Wataru Norimatsu, and Michiko Kusunoki,

15th International Conference on Thin Films (ICTF-15) (Kyoto TERRSA)

Presentation date： 2011.11
Transmission electron microscope observations of epitaxial graphene on SiC (Invited talk)

Wataru Norimatsu, and Michiko Kusunoki, [Invited]

3rd International Symposium on the Science and Technology of Epitaxial Graphene (STEG 3) (St. Augustine, Florida, US)

Presentation date： 2011.10
Epitaxial graphene produced by thermal decomposition of TiC

Wataru Norimatsu, Keisuke Kimura, and Michiko Kusunoki,

2011 International Conference on Solid State Devices and Materials (SSDM 2011) (Aichi Industry & Labor Center (WINC AICHI))

Presentation date： 2011.09
SiC(0001)表面グラフェン形成の分子動力学シミュレーション

乗松航、盛田壮登、楠美智子、Irle Stephan、

日本物理学会 2011年秋季大会 (富山大学)

Presentation date： 2011.09
放射光X 線吸収分光によるSi ドープカーボンナノチューブの化学結合状態分析

泉雄大,室隆桂之,木下豊彦,乗松航,楠美智子,渡辺義夫、

応用物理学会第72回応用物理学会学術講演会 (山形大学)

Presentation date： 2011.09
SiC(000-1)表面上グラフェンの形成機構

乗松航、高田重治、楠美智子、

応用物理学会第72回応用物理学会学術講演会 (山形大学)

Presentation date： 2011.09
SiC上グラフェンの成長と構造選択性

楠美智子、乗松航、

応用物理学会第72回応用物理学会学術講演会 (山形大学)

Presentation date： 2011.08
Influence of Alkaline Earth Substitution on The Thermoelectric Properties of (BiS)1.2(TiS2)2 Misfit Layered Sulfides

Yulia Eka Putri, Chunlei Wan, Yifeng Wang, Wataru Norimatsu, Kunihito Koumoto,

第八回日本熱電学会学術講演会 (北海道大学)

Presentation date： 2011.08
Features of graphene layers on SiC (0001)

Wataru Norimatsu, and Michiko Kusunoki,

5th International Conference on Science and Technology for Advanced Ceramics and 2nd International Conference on Advanced Materials Development and Integration of Novel Structured Metallic and Inorganic Materials (STAC5-AMDI2) (Mielparque-Yokohama)

Presentation date： 2011.06
Tribological Properties of Vertically-Aligned Carbon Nano-Tube with Perfluoro-polyether Lubricant

H. Tani, K. Konishi, W. Norimatsu, M. Kusunoki, and N. Tagawa,

3rd European Conference on Tribology (ECOTRIB 2011) (Vienna & Wiener Neustadt, Austria)

Presentation date： 2011.06
白金担持カーボンナノチューブ膜の酸素ガス中高温その場観察

乗松航、松田敬太、浅井文崇、荒井重勇、楠美智子、

日本顕微鏡学会第67回学術講演会 (福岡国際会議場)

Presentation date： 2011.05
Features of graphene on SiC (000-1) revealed by transmission electron microscopy

Wataru Norimatsu, and Michiko Kusunoki,

Graphene 2011 (Bilbao Exhibition Center, Spain)

Presentation date： 2011.04
SiC(0001)表面上グラフェン形成の分子動力学シミュレーション

乗松航、盛田壮登、楠美智子、Stephan Irle

応用物理学会第58回応用物理学関係連合講演会 (神奈川工科大学)

Presentation date： 2011.03
SiC(0001)表面上グラフェンの結晶学的特徴

乗松航、楠美智子、

第40回フラーレン・ナノチューブ総合シンポジウム (名城大学)

Presentation date： 2011.03
カーボンナノチューブ

楠美智子、乗松航、

日本セラミックス協会東海支部講演会 (JFCC)

Presentation date： 2011.02
SiC上高密度CNT配向膜のパターニング

松田敬太、乗松航、楠美智子、

日本セラミックス協会第49回セラミックス基礎科学討論会 (岡山コンベンションセンター)

Presentation date： 2011.01
カーボンナノチューブ／SiC複合材料の放熱材料への応用

大森恒、乗松航、楠美智子、番場達也、南谷靖、市川琢也

日本セラミックス協会東海支部平成22年度学術研究発表会 (名城大学)

Presentation date： 2010.12
球状酸化物粒子を用いたCNT配向膜のパターニング

松田敬太、乗松航、楠美智子、

日本セラミックス協会東海支部平成22年度学術研究発表会 (名城大学)

Presentation date： 2010.12
QM/MDシミュレーションによるSiCステップ表面におけるグラフェン各形成過程の解明

盛田壮登、乗松航、楠美智子、Stephan Irle

日本表面科学会中部支部第10回学術講演会 (名古屋工業大学)

Presentation date： 2010.12
SiC表面分解法におけるカーボンナノチューブの直径制御

東松直哉、吉川奈保子、乗松航、楠美智子、

日本表面科学会中部支部第10回学術講演会 (名古屋工業大学)

Presentation date： 2010.12
SiC表面分解からの高密度ナノカーボンの直接合成とその応用（招待講演）

楠美智子、乗松航、 [Invited]

第19回ポリマー材料フォーラム (名古屋国際会議場)

Presentation date： 2010.12
Structure Control of Carbon Nanotube Films and Graphene on SiC (Invited talk)

Michiko Kusunoki, and Wataru Norimatsu, [Invited]

2010 Materials Research Society Fall Meeting (Hynes Convention Center, Boston, US)

Presentation date： 2010.12
SiC表面分解法によるカーボンナノチューブ・グラフェン構造制御

楠美智子、乗松航、

日本顕微鏡学会受賞講演 (金沢グランドホテル)

Presentation date： 2010.11
Nano-Carbon Structures on SiC

Wataru Norimatsu, and Michiko Kusunoki,

The International Symposium on Visualization in Joining & Welding Science through Advanced Measurements and Simulation (Visual JW2010) (Hotel Hankyu Expo Park, Osaka, Japan)

Presentation date： 2010.11
グラフェン/SiCの結晶成長と構造評価

楠美智子、乗松航、

(財)科学技術戦略推進機構 (JCII戦略推進部)

Presentation date： 2010.10
Transmission electron microscope observations of nano-structured materials (Invited talk)

Wataru Norimatsu, Michiko Kusunoki, Chunlei Wan, Ning Wang, and Kunihito Koumoto [Invited]

JST-MOST Project and CREST-Koumoto Team Joint Workshop (Jozankei, Hokkaido)

Presentation date： 2010.10
SiC表面分解によるCNT/グラフェンの構造制御

楠美智子、乗松航、

第4回CPC研究会講演会 (新御茶ノ水総評会館)

Presentation date： 2010.10
SiCからのCNT/グラフェンの合成と電子顕微鏡による構造評価

楠美智子、乗松航、

電子情報技術産業協会JEITA「ナノカーボンエレクトロニクス技術分科会」 (福岡)

Presentation date： 2010.09
Siドープカーボンナノチューブ配向膜の電気的および結晶学的特徴

乗松航、丸山雄大、笹井亮、高瀬浩一、楠美智子、

日本物理学会 2010年秋季大会 (大阪府立大学)

Presentation date： 2010.09
SiC表面分解によるナノチューブ・グラフェンの合成と評価

楠美智子、乗松航、

科学技術交流会ナノ粒子研究会 (名大シンポジオンホール)

Presentation date： 2010.09
Siを注入したCNT配向膜／SiCの硬X線光電子分光法による化学状態分析

町田雅武、孫珍永、陰地宏、広沢一郎、丸山雄大、乗松航、楠美智子、渡辺義夫、

応用物理学会第71回学術講演会 (長崎大学)

Presentation date： 2010.09
Formation of ABC-stacked graphene layers on SiC (0001)

Wataru Norimatsu, and Michiko Kusunoki,

2nd International Symposium on the Science and Technology of Epitaxial Graphene (STEG2) (Amelia Island, Florida, USA)

Presentation date： 2010.09
SiC-C面上グラフェン膜の作製と透過型電子顕微鏡観察

高田重治、乗松航、楠美智子、

応用物理学会第71回学術講演会 (長崎大学)

Presentation date： 2010.09
SiC表面分解法により作製した配向性カーボンナノチューブの直径制御

乗松航、吉川奈保子、楠美智子、

日本顕微鏡学会第66回学術講演会 (名古屋国際会議場)

Presentation date： 2010.05
SiC(0001)表面上グラフェンの結晶学的特徴

乗松航、楠美智子、

日本顕微鏡学会第66回学術講演会 (名古屋国際会議場)

Presentation date： 2010.05
垂直高配向カーボンナノチューブのバーニッシュヘッドへの応用

小西圭祐、谷弘詞、楠美智子、乗松航、多川則男、

トライボロジー会議 2010春東京 (国立オリンピック記念青少年総合センター)

Presentation date： 2010.05
Formation mechanism of graphene on SiC (0001)

Wataru Norimatsu, and Michiko Kusunoki,

Graphene Week 2010 (University of Maryland, USA)

Presentation date： 2010.04
SiC上グラフェンの結晶学的特徴

乗松航、楠美智子、

日本物理学会第65回年次大会 (岡山大学)

Presentation date： 2010.03
SiドープCNT配向膜の電気特性評価と高分解能TEMによる構造解析

丸山雄大、乗松航、楠美智子、

応用物理学会第57回関係連合講演会 (東海大学)

Presentation date： 2010.03
SiC表面分解法により作製したグラフェンの結晶学的特徴

乗松航、楠美智子、

応用物理学会第57回関係連合講演会 (東海大学)

Presentation date： 2010.03
High Thermal Conductivity of Carbon Nanotube and SiC Composites Synthesized by Surface Decomposition

Michiko Kusunoki, Wataru Norimatsu, and Chihiro Kawai,

34th International Conference and Exposition on Advanced Ceramics and Composites (Hilton Daytona Beach Resort & Ocean Center, Florida, USA)

Presentation date： 2010.01
Application of Carbon Nanotube and SiC composites for a thermal interface material

Michiko Kusunoki, Wataru Norimatsu, and Chihiro Kawai,

34th International Conference and Exposition on Advanced Ceramics and Composites (Hilton Daytona Beach Resort & Ocean Center, Florida, USA)

Presentation date： 2010.01
SiC(0001)上グラフェンの形成過程

乗松航、楠美智子、

第9回日本表面科学会中部支部学術講演会 (名古屋工業大学)

Presentation date： 2009.12
TiC表面分解による波状グラフェンの形成

木村佳祐、乗松航、楠美智子、

第9回日本表面科学会中部支部学術講演会 (名古屋工業大学)

Presentation date： 2009.12
Wavy graphene formed by surface decomposition of TiC

Keisuke Kimura, Wataru Norimatsu, and Michiko Kusunoki,

2009 Tsinghua Univ. –Nagoya Univ. –Hainan Univ. – Toyota Motor Corp. Joint Symposium on Advanced Materials Science (Hainan University, Haikou, Hainan, China)

Presentation date： 2009.12
Design of High-functional Nano-Carbon Structures on SiC Surface

Michiko Kusunoki, and Wataru Norimatsu,

2009 Tsinghua Univ. –Nagoya Univ. –Hainan Univ. – Toyota Motor Corp. Joint Symposium on Advanced Materials Science (Hainan University, Haikou, Hainan, China)

Presentation date： 2009.12
SiC表面分解法による高配向カーボンナノチューブの直径制御

吉川奈保子、乗松航、楠美智子、

日本セラミックス協会東海支部学術研究発表会 (名古屋大学)

Presentation date： 2009.11
Application of close-packed-carbon-nanotube films on SiC for heat-release devices

Wataru Norimatsu, and Michiko Kusunoki,

The International Conference on Carbon Nanostructured Materials (Cnano ‘09) (Rocabella Resorts & Spa Hotel, Santorini, Greece)

Presentation date： 2009.10
SiC上グラフェンの高分解能透過型電子顕微鏡観察

乗松航、楠美智子、

日本物理学会秋季大会 (熊本大学)

Presentation date： 2009.09
Si Doping into Densely-Aligned Carbon Nanotube Films on SiC

Takehiro Maruyama, Kenta Yoshida, Wataru Norimatsu, and Michiko Kusunoki,

R’09 Twin World Congress (Nagoya University)

Presentation date： 2009.09
Upgrade Conversion of Spent SiC Abrasive Powder to CNT particles

Ryo Sasai, Takayuki Morishita, Ichikawa Akihiro, Motohiro Yamamoto, Wataru Norimatsu, and Michiko Kusunoki,

R’09 Twin World Congress (Nagoya University)

Presentation date： 2009.09
Heat-release Application of the Carbon-nanotube/silicon-carbide Composite Materials Made From Used-SiC Abrasive Powders

Wataru Norimatsu, and Michiko Kusunoki,

R’09 Twin World Congress (Nagoya University)

Presentation date： 2009.09
SiC表面分解法によるグラフェンの高分解能透過型電子顕微鏡観察

乗松航、楠美智子、

応用物理学会第70回学術講演会 (富山大学)

Presentation date： 2009.09
Siドープカーボンナノチューブ配向膜の作製

丸山雄大、乗松航、楠美智子、

応用物理学会第70回学術講演会 (富山大学)

Presentation date： 2009.09
高配向CNT／SiC複合体の高効率放熱材料への応用

乗松航、楠美智子、

第4回3大学3研究所連携プロジェクト公開討論会 (東京工業大学田町キャンパス内キャンパス・イノベーションセンター)

Presentation date： 2009.08
Doping of Si into Aligned Carbon Nanotube Films on SiC

Takahiro Maruyama, Kenta Yoshida, Wataru Norimatsu, and Michiko Kusunoki,

The 18th International Conference on Electronic Properties of Two-Dimensional Systems (EP2DS) (Kobe International Conference Center, Japan)

Presentation date： 2009.07
Atomic structures of the interface between homogeneous graphene and 6H-SiC (0001)

Wataru Norimatsu, and Michiko Kusunoki,

The 18th International Conference on Electronic Properties of Two-Dimensional Systems (EP2DS) (Kobe International Conference Center, Japan)

Presentation date： 2009.07
TiC表面分解法による波状グラフェンの形成過程

木村佳祐、乗松航、楠美智子、

第38回東海若手セラミスト懇話会 (鳥羽シーサイドホテル)

Presentation date： 2009.07
炭化アルミニウム表面分解過程の透過型電子顕微鏡による観察

高田重治、乗松航、楠美智子、

第38回東海若手セラミスト懇話会 (鳥羽シーサイドホテル)

Presentation date： 2009.07
SiC表面分解法を用いたCNT膜の合成と電気的特性評価

盛田壮登、乗松航、楠美智子、

第38回東海若手セラミスト懇話会 (鳥羽シーサイドホテル)

Presentation date： 2009.07
SiC表面分解法により作製したグラフェン/SiC界面の透過型電子顕微鏡観察

乗松航、楠美智子、

日本顕微鏡学会第65回学術講演会 (仙台国際センター)

Presentation date： 2009.05
TiC表面分解法によるグラフェンの形成過程

木村佳祐、乗松航、楠美智子、

日本顕微鏡学会第65回学術講演会 (仙台国際センター)

Presentation date： 2009.05
グラフェン／SiC界面の透過型電子顕微鏡観察

乗松航、楠美智子、

応用物理学会第56回関係連合講演会 (筑波大学)

Presentation date： 2009.03
SiC表面分解グラフェンにおける界面の構造

乗松航、楠美智子、

日本物理学会第64回年次大会 (立教大学)

Presentation date： 2009.03
Transmission electron microscope observation of the interface between graphene and 6H-SiC (0001)

Wataru Norimatsu, and Michiko Kusunoki,

Graphene Week 2009 (Universitätszentrum Obergurgl, Ötz Valley , Austria)

Presentation date： 2009.03
高密度・高配向CNT膜へのSiドープ

丸山雄大、吉田健太、乗松航、楠美智子、

第36回フラーレン・ナノチューブ総合シンポジウム (名城大学)

Presentation date： 2009.03
SiドープCNT配向膜の作製とTEMによる構造・組成評価

丸山雄大、吉田健太、乗松航、楠美智子、

第8回日本表面科学会中部支部学術講演会若手講演会 (名古屋大学)

Presentation date： 2008.12
SiC表面グラフェンにおける界面の構造

乗松航、楠美智子、

第8回日本表面科学会中部支部学術講演会若手講演会 (名古屋大学)

Presentation date： 2008.12
Application of carbon-nanotube/silicon-carbide composite materials for heat-release devices

Wataru Norimatsu, Chihiro Kawai, and Michiko Kusunoki,

The IUMRS International Conference in Asia 2008 (IUMRS-ICA 2008) (Nagoya Congress Center, Japan)

Presentation date： 2008.12
Formation of uniform carbon nanotube films and graphene on SiC

Michiko Kusunoki, Wataru Norimatsu,

The 5th International Symposium on Surface Science and Nanotechnology (ISSSN) (Waseda Univ.)

Presentation date： 2008.11
Interface Structure Of Graphene On Silicon Carbide

Wataru Norimatsu, Michiko Kusunoki,

Nagoya Univ.-Tshinghua Univ.-Toyota Joint Symposium (N-T-T) (Nagoya Univ.)

Presentation date： 2008.09
SiC表面分解法によるカーボンナノチューブの放熱応用

乗松航、楠美智子、河合千尋、

応用物理学会 2008年第69回学術講演会 (中部大学)

Presentation date： 2008.09
SiC上グラフェンにおける界面の構造

乗松航、楠美智子、

応用物理学会 2008年第69回学術講演会 (中部大学)

Presentation date： 2008.09
SiC表面分解法により作製したカーボンナノチューブの放熱応用

乗松航、河合千尋、楠美智子、

第35回記念フラーレン・ナノチューブ総合シンポジウム (東京工業大学)

Presentation date： 2008.08
SiドープCNT配向膜の作製とTEMによる構造・組成評価

丸山雄大、吉田健太、乗松航、楠美智子、

第36回東海若手セラミスト懇話会 (岐阜ホテルパーク)

Presentation date： 2008.07
SiドープCNT配向膜の作製とTEMによる構造・組成評価

丸山雄大、吉田健太、乗松航、楠美智子、

日本顕微鏡学会 2008年第64回学術講演会 (国立京都国際会館)

Presentation date： 2008.05
Sr1.5La0.5MnO4における軌道変調・電荷密度波状態の結晶学的特徴

乗松航、小山泰正、

日本物理学会 2008年第63回年次大会 (近畿大学)

Presentation date： 2008.03
Mechanical Characteristics of Closed-Packed Carbon Nanotubes on SiC

W. Norimatsu, H. Usami, K. Miyake, and M. Kusunoki,

International Carbon nanotube conference in NU (ICNTC) (Nagoya)

Presentation date： 2008.02
Sr2-xNdxMnO4における軌道・電荷変調状態の結晶学的特徴

乗松航、小山泰正、

日本物理学会 2007年第62回年次大会 (北海道大学)

Presentation date： 2007.09
Crystallographic features of the orbital-ordered state in the layered perovskite manganite Sr2-xPrxMnO4

W. Norimatsu, G. Shindo and Y. Koyama,

The International Conference on Strongly Correlated Electron Systems (SCES’07) (Houston, USA)

Presentation date： 2007.05
層状ペロブスカイトSr2-xNdxMnO4における軌道整列状態の特徴

乗松航、小山泰正、

日本物理学会 2007年春季大会 (鹿児島大学)

Presentation date： 2007.03
Stability of electronic states in the layered perovskite Sr2-xNdxMnO4

Wataru Norimatsu and Yasumasa Koyama,

19th International Symposium on Superconductivity (ISS2006) (Nagoya Congress Center)

Presentation date： 2006.11
Sr2-xNdxMnO4における軌道整列および電荷・軌道整列状態の安定性

乗松航、小山泰正、

日本物理学会 2006年秋季大会 (千葉大学)

Presentation date： 2006.09
層状ペロブスカイト型酸化物(Sr,La)2MnO4における低温斜方晶相の透過型電子顕微鏡観察

乗松航、小山泰正、

日本金属学会 2005年秋期大会 (広島大学)

Presentation date： 2005.09
層状ペロブスカイト(Sr,La)2MnO4における低温斜方晶相の透過型電子顕微鏡観察

乗松航、小山泰正、

日本物理学会 2005年秋季大会 (同志社大学京田辺キャンパス)

Presentation date： 2005.09
Crystallographic features of the low-temperature orthorhombic state in Sr2-xLaxMnO4 around x=0.15

W. Norimatsu and Y. Koyama,

The International Conference on Strongly Correlated Electron Systems 2005 (SCES05) (Vienna, Austria)

Presentation date： 2005.06
層状ペロブスカイト(Sr,La)2MnO4における低温斜方晶相の結晶学的特徴

乗松航、小山泰正、

日本物理学会第60回年次大会 (東京理科大学)

Presentation date： 2005.03
層状ペロブスカイト型Mn酸化物(Sr,La)2MnO4における強誘電相転移の特徴

乗松航、小山泰正、

日本金属学会 2004年秋期大会 (秋田大学)

Presentation date： 2004.09
(Sr,La)2MnO4における強誘電相転移の結晶学的特徴

乗松航、小山泰正、

日本物理学会 2004年秋季大会 (青森大学)

Presentation date： 2004.09
Dielectric and crystallographic features of the orthorhombic phase in Sr2-xLaxMnO4 around x=0.15

W. Norimatsu and Y. Koyama,

The 5th Korea-Japan Conference on Ferroelectricity (KJCFE2004) (Seoul, Korea)

Presentation date： 2004.08
Sr2-xLaxMnO4における強誘電相の特徴

乗松航、小山泰正、

日本物理学会第59回年次大会 (九州大学)

Presentation date： 2004.03

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Research Projects

固体電解質/ナノカーボン界面でのLi挿入脱離機構解明と新機能創出

日本学術振興会科学研究費助成事業

Project Year :

2022.04

-

2024.03

乗松航
固体電解質/高品質単一方位グラフェンによるリチウム挿入脱離現象の解明

日本学術振興会科学研究費助成事業

Project Year :

2020.04

-

2022.03

乗松航

　View Summary

本研究では、SiC基板上大面積高品質単一方位グラフェンを、固体電解質との界面における電気化学反応研究のモデル試料として用いることで、その詳細を明らかにすることを目標としている。具体的には、固体電解質としてはリン酸リチウムオキシナイトライドガラス（LiPON）を用い、グラフェン層間およびグラフェン/基板界面へのLiイオンの挿入と拡散についてのメカニズムを明らかにすることを目指した。
今年度は、昨年度の実験結果により示唆された単層グラフェンでのLi挿入脱離機構について、より詳細を明らかにするために、グラフェン層数が2層程度の試料についても同様に実験を行った。その結果、層数が増加しても酸化ピークが2本観察されることがわかった。層数増加に伴うその変化は、低電位側のピークの高電流値化と高電位側へのシフトであった。この結果は、低電位側がグラフェン層間、高電位側がグラフェン/基板界面でのLi挿入脱離であるとする考えを補強するものである。また、多層グラファイトにおけるステージ構造変化との対応に関しては、複数の酸化ピークの電流値とピーク位置が、ステージ構造変化に対応する酸化ピークへと系統的に変化していることもわかった。電気化学インピーダンス測定、充放電測定からは、層数増加に伴って、Li挿入サイトが増加したことを示唆する結果が得られた。これらの成果について、新学術領域会議に加えて、2022年3月の応用物理学会において発表した。また、多層グラファイトにおける結果は2021年10月に出版され、1～2層グラフェンの結果については新学術領域代表である入山・本山グループと共同研究論文を投稿中である。
Is wafer-scale graphene on the semi-insulating SiC the most appropriate for electronics applications?

Japan Society for the Promotion of Science Grants-in-Aid for Scientific Research

Project Year :

2018.04

-

2021.03

Norimatsu Wataru

　View Summary

In this study, we performed experiments in order to understand the factors and their contributions which affect the carrier mobility in graphene grown by thermal decomposition of SiC. From the experimental results, we found that the quality of graphene on SiC have no significant difference with the other graphene growth techniques, while the defects of the SiC surface seemed to degrade the mobility. On the effect of the graphene/SiC interface, we performed the hydrogen intercalation experiments under high-pressure H_2 condition, and revealed the microscopic mechanism in the initial stage of the intercation. Based on the large-area graphene transfer technique, we also succeeded in the fabrication of the millimeter-scale twisted bilayer graphene and the observation of their electronic structure.
Experimental and theoretical study on the two-dimensional Al-C material AlCene

Japan Society for the Promotion of Science Grants-in-Aid for Scientific Research

Project Year :

2016.04

-

2018.03

Norimatsu Wataru, KUSUNOKI Michiko, TERASAWA Tomo-o, MATSUDA Keita, FUKUI Mai

　View Summary

In this study, growth of two-dimensional aluminum carbide was demonstrated. As a result of the first-principles calculation, two-dimensional aluminum carbide (AlCene) was a semiconductor with a indirect gap of about 2.18 eV. On the other hand, highly crystalline and extremely thin aluminum carbide was successfully grown on the SiC (000-1) substrate by the pulsed laser deposition technique. At the interface, the carbon atoms of the topmost SiC surface and the aluminum atoms of the aluminum carbide made bonds, which was revealed by high-resolution transmission electron microscope observations.
Development of new graphene production method based on SiC

Japan Society for the Promotion of Science Grants-in-Aid for Scientific Research

Project Year :

2014.04

-

2017.03

Norimatsu Wataru, KUSUNOKI Michiko, BAO Jianfeng, MATSUDA Keita, MASUMORI Atsushi, MIYAMOTO Genki, TSURUTA Haruka, FUKUI Mai, TAKATA Nao

　View Summary

In this research project, I aimed to grow graphene with various properties by thermal decomposition of the carbide thin film grown on the SiC substrate. For example, graphene grown from the aluminum carbide on SiC was suggested to be aluminum-doped. As another example, graphene grown from the boron carbide on SiC was characterized by heavy boron-doping and the spin glass behavior was observed. Thus, graphene grown by thermal decomposition of the carbide film is a promising technique to obtain graphene with the novel structures and properties.
Investigation of carbon nanotube materials with ultra-high specific sureface aria by surface decomposition of SiC nano particles

Japan Society for the Promotion of Science Grants-in-Aid for Scientific Research

Project Year :

2014.04

-

2017.03

Kusunoki Michiko

　View Summary

To develop low-cost carbon nanotubes with high specific surface area and without catalytic metals, we investigated the synthetic condition of aligned and dense carbon nanotubes by the surface decomposition of SiC particles. First, it was revealed that the carbon nanotubes were synthesized in a simple and easy alumina tubular furnace. It was also confirmed that flowing adequate amount of oxygen gas into the furnace for some amounts of SiC particles and rotating the tubular carbon case supporting SiC samples to mixing them with an adequate rotation rate increased effectively the formation rate of the carbon nanotubes.
Clarification of Layer-Anion Interaction of Layered Double Hydroxide for Realizing Highly Selective Anion Exchange

Japan Society for the Promotion of Science Grants-in-Aid for Scientific Research

Project Year :

2010

-

2012

SASAI Ryo, MORIYOSHI Chikako, IYI Nobuo, KAMESHIMA Yoshikazu, NORIMATSU Wataru

　View Summary

For applying layered double hydroxide (LDH) with anion-exchangeable ability to water purification process, both anion exchange reaction experiments and crystal structure analysis of LDH consisting of Mg and Al (Mg/Al = 2), and Ni and Al (Ni/Al =2, 3, 4)synthesized by hydrothermal method were investigated. It could be found that Ni/Al ratio had remarkable influence on nitrate selectivity of Ni/Al-LDH. Moreover, it could be found that his remarkable nitrate selectivity could be caused by the difference of movability of incorporated anions in interlayer spaece.

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Misc

High-resolution transmission electron microscopy of graphene/superconducting-carbide

榊原涼太郎, 乗松航

名古屋大学電子光学研究のあゆみ ( 34 ) 2023

J-GLOBAL
Step unbunching phenomenon on 4H-SiC substrate surface

榊原涼太郎, 乗松航

応用物理学会春季学術講演会講演予稿集(CD-ROM) 70th 2023

J-GLOBAL
Fe intercalation in graphene/SiC (0001) and its interface structure

榊原涼太郎, 寺澤知潮, 寺澤知潮, 乗松航

応用物理学会秋季学術講演会講演予稿集(CD-ROM) 84th 2023

J-GLOBAL
Fabrication and evaluation of graphene/WC/SiC heterostructure

大塚康平, 伊藤孝寛, 遠藤彰, 乗松航

応用物理学会秋季学術講演会講演予稿集(CD-ROM) 84th 2023

J-GLOBAL
Superconducting transition temperature enhancement of TaC thin film induced by graphene growth and its mechanism

近藤大斗, 榊原涼太郎, 林直輝, 伊藤孝寛, 遠藤彰, 鈴木舞奈佳, 石井祐太, 若林裕助, 乗松航

応用物理学会秋季学術講演会講演予稿集(CD-ROM) 83rd 2022

J-GLOBAL
Li⁺ Insertion/Extraction Reactions at LiPON/Graphene Interface on SiC

山本智士, 榊原涼太郎, 石垣範和, 本山宗主, 乗松航, 入山恭寿

電気化学秋季大会講演要旨集(CD-ROM) 2021 2021

J-GLOBAL
Li⁺ Insertion/Extraction Reactions at LiPON/Single-Layer Graphene Interface on SiC

山本智士, 榊原涼太郎, 石垣範和, 本山宗主, 乗松航, 入山恭寿

電池討論会PDF要旨集(CD-ROM) 62nd 2021

J-GLOBAL
Mechanism of the formation of graphene on SiC by hydrogen intercalation

榊原涼太郎, 乗松航

応用物理学会春季学術講演会講演予稿集(CD-ROM) 68th 2021

J-GLOBAL
SiC上グラフェンの電子状態に対する界面の影響

佐藤京樹, 榊原涼太郎, 河原憲治, 吾郷浩樹, 林直輝, 伊藤孝寛, 乗松航

応用物理学会春季学術講演会講演予稿集(CD-ROM) 66th 2019

J-GLOBAL
SiC上グラフェンの移動度に及ぼす界面の影響

榊原涼太郎, 河原憲治, 吾郷浩樹, 乗松航

応用物理学会秋季学術講演会講演予稿集(CD-ROM) 79th 2018

J-GLOBAL
Physical properties of highly boron-doped graphene on SiC

Norimatsu Wataru, Masumori Atsushi, Funahashi Ryoji, Endo Akira, Kusunoki Michiko

JSAP Annual Meetings Extended Abstracts 2016.2 3529 - 3529 2016.09

DOI J-GLOBAL
23pPSB-64 Crystallographic and electronic features of Si-doped CNT film

Norimatsu W., Maruyama T., Sasai R., Takase K., Kusunoki M.

Meeting Abstracts of the Physical Society of Japan 65 ( 0 ) 644 - 644 2010

DOI CiNii J-GLOBAL

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Syllabus

Physical Electronics Laboratory B

School of Fundamental Science and Engineering

2024 spring quarter
Physical Electronics Seminar B

School of Fundamental Science and Engineering

2024 spring quarter
Physical Electronics Laboratory A

School of Fundamental Science and Engineering

2024 winter quarter
Physical Electronics Seminar A

School of Fundamental Science and Engineering

2024 winter quarter
Introduction to Materials Science

School of Fundamental Science and Engineering

2024 winter quarter
Bachelor Thesis B [S Grade]

School of Fundamental Science and Engineering

2024 fall semester
Bachelor Thesis B

School of Fundamental Science and Engineering

2024 spring semester
Bachelor Thesis B

School of Fundamental Science and Engineering

2024 fall semester
Statistical Physics

School of Fundamental Science and Engineering

2024 spring semester
Bachelor Thesis A [S Grade]

School of Fundamental Science and Engineering

2024 fall semester
Bachelor Thesis A [S Grade]

School of Fundamental Science and Engineering

2024 spring semester
Introduction to Electronic and physical systems [S Grade]

School of Fundamental Science and Engineering

2024 spring semester
Introduction to Electronic and physical systems

School of Fundamental Science and Engineering

2024 spring semester
Electronic and Physical Systems Laboratory C [S Grade]

School of Fundamental Science and Engineering

2024 fall semester
Electronic and Physical Systems Laboratory C

School of Fundamental Science and Engineering

2024 fall semester
Electronic and Physical Systems Laboratory B [S Grade]

School of Fundamental Science and Engineering

2024 spring semester
Electronic and Physical Systems Laboratory B

School of Fundamental Science and Engineering

2024 spring semester
Electronic and Physical Systems Laboratory A [S Grade]

School of Fundamental Science and Engineering

2024 fall semester
Electronic and Physical Systems Laboratory A

School of Fundamental Science and Engineering

2024 fall semester
Bachelor Thesis A

School of Fundamental Science and Engineering

2024 fall semester
Bachelor Thesis A

School of Fundamental Science and Engineering

2024 spring semester
Electronic and Physical Systems Practice C [S Grade]

School of Fundamental Science and Engineering

2024 spring semester
Electronic and Physical Systems Practice C

School of Fundamental Science and Engineering

2024 spring semester
Special Seminar on Electronic and Physical Systems

School of Fundamental Science and Engineering

2024 fall semester
Solid State Physics

School of Fundamental Science and Engineering

2024 fall semester
Introduction of Group Theory to Solid-state Physics [S Grade]

School of Fundamental Science and Engineering

2024 spring semester
Introduction of Group Theory to Solid-state Physics

School of Fundamental Science and Engineering

2024 spring semester
Introduction to Electronic and Physical Systems [S Grade]

School of Fundamental Science and Engineering

2024 an intensive course(spring)
Introduction to Electronic and Physical Systems

School of Fundamental Science and Engineering

2024 an intensive course(spring)
Master's Thesis (Department of Electronic and Physical Systems)

Graduate School of Fundamental Science and Engineering

2024 full year
Master's Thesis (Department of Electronic and Physical Systems)

Graduate School of Fundamental Science and Engineering

2024 full year
Master's Thesis (Department of Materials Science)

Graduate School of Fundamental Science and Engineering

2024 full year
Seminar on Solid State Physics D

Graduate School of Fundamental Science and Engineering

2024 fall semester
Seminar on Solid State Physics C

Graduate School of Fundamental Science and Engineering

2024 spring semester
Seminar on Solid State Physics B

Graduate School of Fundamental Science and Engineering

2024 fall semester
Seminar on Solid State Physics A

Graduate School of Fundamental Science and Engineering

2024 spring semester
Seminar on Solid State Physics D

Graduate School of Fundamental Science and Engineering

2024 fall semester
Seminar on Solid State Physics C

Graduate School of Fundamental Science and Engineering

2024 spring semester
Seminar on Solid State Physics B

Graduate School of Fundamental Science and Engineering

2024 fall semester
Seminar on Solid State Physics A

Graduate School of Fundamental Science and Engineering

2024 spring semester
Advanced Solid State Physics

Graduate School of Fundamental Science and Engineering

2024 fall semester
Research on Solid State Physics

Graduate School of Fundamental Science and Engineering

2024 full year
Research on Solid State Physics

Graduate School of Fundamental Science and Engineering

2024 full year
Research on Physics of Low-dimensional Materials

Graduate School of Fundamental Science and Engineering

2024 full year
Research on Solid State Physics

Graduate School of Fundamental Science and Engineering

2024 full year
Seminar on Physics of Low-dimensional Materials B

Graduate School of Fundamental Science and Engineering

2024 fall semester
Seminar on Physics of Low-dimensional Materials D

Graduate School of Fundamental Science and Engineering

2024 fall semester
Seminar on Physics of Low-dimensional Materials A

Graduate School of Fundamental Science and Engineering

2024 spring semester
Seminar on Physics of Low-dimensional Materials C

Graduate School of Fundamental Science and Engineering

2024 spring semester
Physics of Low-dimensional Materials

Graduate School of Fundamental Science and Engineering

2024 fall semester
Mathematical Modeling for Materials B

Graduate School of Fundamental Science and Engineering

2024 summer quarter
Mathematical Modeling for Materials A

Graduate School of Fundamental Science and Engineering

2024 spring quarter
Research on Physics of Low-dimensional Materials

Graduate School of Fundamental Science and Engineering

2024 full year
Advanced Solid State Physics

Graduate School of Advanced Science and Engineering

2024 fall semester

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Sub-affiliation

Faculty of Science and Engineering Graduate School of Fundamental Science and Engineering

Research Institute

2023

-

2024

Waseda Research Institute for Science and Engineering Concurrent Researcher
2023

-

2024

Kagami Memorial Research Institute for Materials Science and Technology Concurrent Researcher

Internal Special Research Projects

遷移金属炭化物を用いた2次元物質の結晶成長と新機能開拓

2023

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　2次元材料である遷移金属ダイカルコゲナイド（TMD）は、次世代半導体材料として期待されている。本研究では、TMDの結晶成長における新技術として、遷移金属炭化物（TMC）を原料とする手法の開拓を目指している。具体的には、SiC単結晶基板上にTMCをエピタキシャル成長させ、そのTMC薄膜にカルコゲンを添加することにより、TMD/TMCヘテロ構造を作製する。近年、TMC自体もトポロジカル半金属やトポロジカル超伝導体の候補として注目されている。すなわち、2次元TMD/3次元TMCヘテロ構造によって、両者の持つ特異な電子状態や物性を掛け合わせることで、新機能の探索を目指す。2023年度には、SiC単結晶基板上に炭化タングステン（WC）薄膜を形成し、カルコゲンとしてSeを添加することで、高品質なWSe2の結晶成長を目指して実験を行った。具体的にはまず、パルスレーザー堆積法を用いてWC薄膜を形成した。基板温度1100℃、1x10^-5Pa程度において、比較的結晶性が良く、表面も平坦なWC薄膜が得られることがわかった。続いて、このWC薄膜に対してSe化処理を行うための装置を作製した。ロータリーポンプにより真空引きのできる管状炉を用いて、窒素ガスを流しながら、WC/SiC試料とSe粉末を同時に加熱した。加熱温度は500℃以上とし、昇華したSeがWC/SiC基板上に堆積してWSe2形成反応を起こすことを期待した。得られた試料に対してX線光電子分光測定およびラマン分光測定を行ったところ、基板表面上にSeは検出されたものの、WSe2由来のラマンピークは検出されなかった。すなわち、今回の条件ではWSe2は形成されないことが示唆される。今後は、窒素ガスの代わりにAr/H2ガスもしくは真空中での加熱を行うことで、WSe2形成を試みるとともに、NbSe2/NbCヘテロ構造の作製も目指して実験を行う。
強相関電子系マンガン酸化物における相転移の結晶学的研究

2005

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　強相関電子系として特徴づけられるマンガン酸化物の中で、層状ペロブスカイトSr2-xLaxMnO4では、その結晶構造の2次元性を反映した電子状態および物性の出現が予想される。我々は、これまでにSr2-xLaxMnO4の結晶学的特徴を調べ、eg電子濃度に対応するLa置換量xの増加に伴い、その基底状態が正方晶相からx=0.15付近で斜方晶相、0.2≦x≦0.5では電荷・軌道整列相へと変化することを報告している。このことは、電荷・軌道整列の無秩序相と秩序相の間に中間相が存在することを示している。そこで本研究では、中間相としての斜方晶相における電荷・軌道状態を明らかにするため、その格子系の応答である結晶学的特徴について主に透過型電子顕微鏡を用いた低温その場観察により調べた。　本研究では、固相法およびクエン酸共沈法を用いて0.08≦x≦0.25のSr2-xLaxMnO4試料を作製した。得られた試料の結晶学的特徴については、室温から12Kの各温度における電子回折図形および明・暗視野像を透過型電子顕微鏡で撮影することにより明らかにした。　本観察から、x=0.15試料の250K付近において高温正方晶相から斜方晶相への構造相転移、および斜方晶相の分域構造が斜方晶度の異なる2つのバリアントOIとOIIの交互配列からなることを確認した。そこで分域構造の形成過程を調べたところ、まず高温正方晶領域内に大きさ10nm程度の斜方晶バリアントOI斑点状領域が出現、一方向に配列することにより斜方晶バリアントOIと正方晶領域の交互配列した2相共存状態を生むことが分った。さらにこの正方晶領域は斜方晶バリアントOIIへと変化し、2つの斜方晶バリアントから成る分域構造が出現した。このことは、斜方晶相出現での主秩序パラメータが、自発歪みではなく、軌道自由度に関係したヤーン・テラー変位であることを示唆している。