2022/05/18 更新

写真a

カワラダ ヒロシ
川原田 洋
所属
理工学術院 基幹理工学部
職名
教授
ホームページ

兼担

  • 理工学術院   大学院基幹理工学研究科

  • 理工学術院   大学院先進理工学研究科

学内研究所等

  • 2020年
    -
    2022年

    理工学術院総合研究所   兼任研究員

学歴

  •  
    -
    1985年

    早稲田大学   理工学研究科   電気工学  

  •  
    -
    1985年

    早稲田大学   理工学研究科   電気工学  

  •  
    -
    1978年

    早稲田大学   理工学部   電子通信学科  

学位

  • 早稲田大学   工学博士

  • doctor of engineering

経歴

  • 2017年04月
    -
     

    名古屋大学   未来材料・システム研究所   客員教授

  • 1995年08月
    -
    1996年09月

    ドイツ・フンボルト財団   フラウンホーファー研究所(応用固体物理部門)   研究員

  • 1995年04月
    -
     

    早稲田大学   理工学部   教授

  • 1990年04月
    -
    1995年03月

    早稲田大学   理工学部   助教授

  • 1986年04月
    -
    1990年03月

    大阪大学   工学部電気工学科   助手

  • 1983年04月
    -
    1985年03月

    早稲田大学   理工学部   助手

  • 1980年04月
    -
    1982年03月

    日立製作所   半導体事業部プロセス技術開発部

  • 1980年04月
    -
    1982年03月

    日立製作所   半導体事業部プロセス技術開発部

▼全件表示

所属学協会

  •  
     
     

    応用物理学会

 

研究分野

  • 電気電子材料工学

研究キーワード

  • 電子デバイス・機器工学、半導体工学、ナノテクノロジー

論文

  • Crystal analysis of grain boundaries in boron-doped diamond superconducting quantum interference devices operating above liquid helium temperature

    Aoi Morishita, Shotaro Amano, Ikuto Tsuyuzaki, Taisuke Kageura, Yasuhiro Takahashi, Minoru Tachiki, Shuuichi Ooi, Miwako Takano, Shunichi Arisawa, Yoshihiko Takano, Hiroshi Kawarada

    Carbon   181   379 - 388  2021年08月

    DOI

  • Low ON-Resistance (2.5 mΩ · cm2) Vertical-Type 2-D Hole Gas Diamond MOSFETs With Trench Gate Structure

    Jun Tsunoda, Masayuki Iwataki, Kiyotaka Horikawa, Shotaro Amano, Kosuke Ota, Atsushi Hiraiwa, Hiroshi Kawarada

    IEEE Transactions on Electron Devices    2021年07月

    DOI

  • Space-charge-controlled field emission analysis of current conduction in amorphous and crystallized atomic-layer-deposited Al2O3 on GaN

    Atsushi Hiraiwa, Kiyotaka Horikawa, Hiroshi Kawarada

    Journal of Applied Physics    2021年05月

    DOI

  • Drain Current Density Over 1.1 A/mm in 2D Hole Gas Diamond MOSFETs With Regrown p++-Diamond Ohmic Contacts

    Shoichiro Imanishi, Ken Kudara, Hitoshi Ishiwata, Kiyotaka Horikawa, Shotaro Amano, Masayuki Iwataki, Aoi Morishita, Atsushi Hiraiwa, Hiroshi Kawarada

    IEEE Electron Device Letters   42 ( 2 ) 204 - 207  2021年02月

    DOI

  • Microstructure, morphology and magnetic property of (001)-textured MnAlGe Films on Si/SiO<inf>2</inf> substrate

    Rie Y. Umetsu, Satoshi Semboshi, Yoshifuru Mitsui, Hirokazu Katsui, Yoshito Nozaki, Isamu Yuitoo, Teruaki Takeuchi, Mikiko Saito, Hiroshi Kawarada

    Materials Transactions   62 ( 5 ) 680 - 687  2021年

     概要を見る

    Substrate heating effects on the microstructure and magnetic properties of MnAlGe films grown on Si/SiO2 substrate by sputtering system were investigated. The MnAlGe film fabricated by low-temperature substrate heating demonstrated amorphous phase and paramagnetic property. The film of c-axis orientation associated with the Cu2Sb-type structure was obtained by sputtering at a substrate heating temperature of 270°C and it exhibited perpendicular magnetic anisotropy. From the magnetization curves measured at room temperature, the uniaxial magnetic anisotropy energy, Ku, was evaluated to be in the order of 106 erg/cm3, which is consistent with the literature, although the heating processing and temperature are slightly different. Microstructural observation indicated that the c-axis oriented grains were isolated in the matrix of the amorphous phase. The film lost the c-axis orientation at elevated substrate heating temperature, resulting in loss of the anisotropic magnetic property.

    DOI

  • Postdeposition annealing effect on the reliability of atomic-layer-deposited Al2O3 films on GaN

    Kiyotaka Horikawa, Satoshi Okubo, Hiroshi Kawarada, Atsushi Hiraiwa

    Journal of Vacuum Science & Technology B    2020年11月

    DOI

  • Application of 2DHG Diamond p-FET in Cascode With Normally-OFF Operation and a Breakdown Voltage of Over 1.7 kV

    Te Bi, Junxiong Niu, Nobutaka Oi, Masafumi Inaba, Toshio Sasaki, Hiroshi Kawarada

    IEEE Transactions on Electron Devices   67 ( 10 ) 4006 - 4009  2020年10月

    DOI

  • Local initial heteroepitaxial growth of diamond (111) on Ru (0001)/c-sapphire by antenna-edge-type microwave plasma chemical vapor deposition

    Wenxi Fei, Kongting Wei, Aoi Morishita, Hongxing Wang, Hiroshi Kawarada

    Applied Physics Letters    2020年09月

    DOI

  • Publisher's Note: “Oxidized Si terminated diamond and its MOSFET operation with SiO2 gate insulator” [Appl. Phys. Lett. 116, 212103 (2020)]

    Wenxi Fei, Te Bi, Masayuki Iwataki, Shoichiro Imanishi, Hiroshi Kawarada

    Applied Physics Letters   116 ( 26 ) 269901 - 269901  2020年06月

    DOI

  • Oxidized Si terminated diamond and its MOSFET operation with SiO2 gate insulator

    Wenxi Fei, Te Bi, Masayuki Iwataki, Shoichiro Imanishi, Hiroshi Kawarada

    Applied Physics Letters   116 ( 21 ) 212103 - 212103  2020年05月

    DOI

  • Over 12000 A/cm2 and 3.2 m$\Omega$ cm2 Miniaturized Vertical-Type Two-Dimensional Hole Gas Diamond MOSFET

    Masayuki Iwataki, Nobutaka Oi, Kiyotaka Horikawa, Shotaro Amano, Jun Nishimura, Taisuke Kageura, Masafumi Inaba, Atsushi Hiraiwa, Hiroshi Kawarada

    IEEE Electron Device Letters   41 ( 1 ) 111 - 114  2020年01月  [査読有り]

    DOI

  • Correlation between the Carbon Nanotube Growth Rate and Byproducts in Antenna‐Type Remote Plasma Chemical Vapor Deposition Observed by Vacuum Ultraviolet Absorption Spectroscopy

    Masafumi Inaba, Takumi Ochiai, Kazuyoshi Ohara, Ryogo Kato, Tasuku Maki, Toshiyuki Ohashi, Hiroshi Kawarada

    Small   15 ( 48 ) 1901504 - 1901504  2019年11月  [査読有り]

    DOI

  • Electrical property measurement of two-dimensional hole-gas layer on hydrogen-terminated diamond surface in vacuum-gap-gate structure

    Masafumi Inaba, Hiroshi Kawarada, Yutaka Ohno

    Applied Physics Letters   114 ( 25 ) 253504 - 253504  2019年06月  [査読有り]

    DOI

  • Triple nitrogen-vacancy centre fabrication by C5N4Hn ion implantation

    Haruyama Moriyoshi, Onoda Shinobu, Higuchi Taisei, Kada Wataru, Chiba Atsuya, Hirano Yoshimi, Teraji Tokuyuki, Igarashi Ryuji, Kawai Sora, Kawarada Hiroshi, Ishii Yu, Fukuda Ryosuke, Tanii Takashi, Isoya Junichi, Ohshima Takeshi, Hanaizumi Osamu

    NATURE COMMUNICATIONS   10  2019年06月  [査読有り]

    DOI

  • Point-Arc Remote Plasma Chemical Vapor Deposition for High-Quality Single Crystal Diamond Selective Growth

    Wenxi Fei, M. Inaba, H. Hoshino, I. Tsuyusaki, S. Kawai, M. Iwataki, Hiroshi Kawarada

    physica status solidi (a)    2019年06月  [査読有り]

    DOI

  • Normally-OFF Two-Dimensional Hole Gas Diamond MOSFETs Through Nitrogen-Ion Implantation

    Nobutaka Oi, Takuya Kudo, Masafumi Inaba, Satoshi Okubo, Shinobu Onoda, Atsushi Hiraiwa, Hiroshi Kawarada

    IEEE Electron Device Letters   40 ( 6 ) 933 - 936  2019年06月  [査読有り]

     概要を見る

    Diamond is a promising material for power applications owing to its excellent physical properties. Two-dimensional hole gas (2DHG) diamond metal-oxide-semiconductor field-effect transistors (MOSFETs) with hydrogen-terminated (C-H) channel have high current densities and high breakdown fields but often show normally-ON operation. From the viewpoint of safety, normally-OFF operation is required for power applications. In this letter, we used ion implantation to form a shallow and thin nitrogen-doped layer below the C-H channel region, which realized normally OFF operation. Nitrogen-ion implanted length is fixed at 5 or 10 mu m. Nitrogen is a deep donor (1.7 eV) and the nitrogen-doped layer prevents hole accumulation near the surface. The threshold voltage was as high as -2.5 V and no obvious dependence on the threshold voltage of nitrogenion implanted length is observed. The breakdown field was 2.7 MV/cm at room temperature. Of 64 devices with a common gate length, 75% showed normally-OFF operation. We confirmed the threshold voltage shift by a thin and shallow nitrogen-doped layer formed by ion implantation.

    DOI

  • Carbon 1s X-ray photoelectron spectra of realistic samples of hydrogen-terminated and oxygen-terminated CVD diamond (111) and (001)

    Shozo Kono, Taisuke Kageura, Yuya Hayashi, Sung-Gi Ri, Tokuyuki Teraji, Daisuke Takeuchi, Masahiko Ogura, Hideyuki Kodama, Atsuhito Sawabe, Masafumi Inaba, Atsushi Hiraiwa, Hiroshi Kawarada

    Diamond and Related Materials   93   105 - 130  2019年03月  [査読有り]

    DOI

  • Nitrogen-Terminated Diamond Surface for Nanoscale NMR by Shallow Nitrogen-Vacancy Centers

    Kawai Sora, Yamano Hayate, Sonoda Takahiro, Kato Kanami, Buendia Jorge J, Kageura Taisuke, Fukuda Ryosuke, Okada Takuma, Tanii Takashi, Higuchi Taisei, Haruyama Moriyoshi, Yamada Keisuke, Onoda Shinobu, Ohshima Takeshi, Kada Wataru, Hanaizumi Osamu, Stacey Alastair, Teraji Tokuyuki, Kono Shozo, Isoya Junichi, Kawarada Hiroshi

    JOURNAL OF PHYSICAL CHEMISTRY C   123 ( 6 ) 3594 - 3604  2019年02月  [査読有り]

    DOI

  • Carboxyl-functionalized graphene SGFET: pH sensing mechanism and reliability of anodization

    Falina, S., Syamsul, M., Iyama, Y., Hasegawa, M., Koga, Y., Kawarada, H.

    Diamond and Related Materials   91  2019年

    DOI

  • 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年  [査読有り]

    DOI

  • 3.8W/mm RF Power Density for ALD Al2O3-Based Two-Dimensional Hole Gas Diamond MOSFET Operating at Saturation Velocity

    Imanishi, Shoichiro, Horikawa, Kiyotaka, Oi, Nobutaka, Okubo, Satoshi, Kageura, Taisuke, Hiraiwa, Atsushi, Kawarada, Hiroshi

    Ieee Electron Device Letters   40 ( 2 ) 279 - 282  2019年  [査読有り]

    DOI

  • Deoxyribonucleic-acid-sensitive Polycrystalline Diamond Solution-gate 3 Field-effect Transistor with Carboxyl-terminated boron-doped 4 Channel

    Yukihiro Shintani, Shoji Ibori, Hiroshi Kawarada

    Analytical Sciences    2019年  [査読有り]

  • Irradiation-Induced Modification of the Superconducting Properties of Heavily-Boron-Doped Diamond

    Creedon, D. L., Jiang, Y., Ganesan, K., Stacey, A., Kageura, T., Kawarada, H., McCallum, J. C., Johnson, B. C., Prawer, S., Jarnieson, D. N.

    Physical Review Applied   10 ( 4 )  2018年

    DOI

  • Ionic-liquid-gating setup for stable measurements and reduced electronic inhomogeneity at low temperatures

    Takahide, Yamaguchi, Sasama, Yosuke, Takeya, Hiroyuki, Takano, Yoshihiko, Kageura, Taisuke, Kawarada, Hiroshi

    Review of Scientific Instruments   89 ( 10 )  2018年  [査読有り]

    DOI

  • Superconductivity in nano- and micro-patterned high quality single crystalline boron-doped diamond films

    Kageura, Taisuke, Hideko, Masakuni, Tsuyuzaki, Ikuto, Amano, Shotaro, Morishita, Aoi, Yamaguchi, Takahide, Takano, Yoshihiko, Kawarada, Hiroshi

    Diamond and Related Materials   90   181 - 187  2018年  [査読有り]

    DOI

  • Heteroepitaxial Diamond Field-Effect Transistor for High Voltage Applications

    Syamsul, Mohd, Oi, Nobutaka, Okubo, Satoshi, Kageura, Taisuke, Kawarada, Hiroshi

    Ieee Electron Device Letters   39 ( 1 ) 51 - 54  2018年  [査読有り]

     概要を見る

    The exceptional performance of diamond-based field-effect transistor technology is not restricted to devices that use single crystalline diamond alone. This letter explores the full potential of the heteroepitaxial diamond field-effect transistor (HED-FET). HED-FET devices were fabricated with a long gate-drain length ( LGD) configuration using C-H bonded channels, and a high maximum current density of 80 mA/mm and a high I ON/I OFF ratio of 109 were achieved. Additionally, the HED-FETs showed an average breakdown voltage of ≥500 V and comparatively high breakdown voltage of more than 1 kV. This letter represents a significant step toward the realization of the potential of widely available heteroepitaxial diamond for use in FET applications.

    DOI

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

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

    Journal of Applied Physics   123 ( 4 ) 145104/1 - 145104/7  2018年  [査読有り]

     概要を見る

    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.

    DOI

  • Time-dependent dielectric breakdown of atomic-layer-deposited Al2O3 films on GaN

    Hiraiwa, Atsushi, Sasaki, Toshio, Okubo, Satoshi, Horikawa, Kiyotaka, Kawarada, Hiroshi

    Journal of Applied Physics   123 ( 15 ) 155303/1 - 155303/9  2018年  [査読有り]

     概要を見る

    Atomic-layer-deposited (ALD) Al2O3 films are the most promising surface passivation and gate insulation layers in non-Si semiconductor devices. Here, we carried out an extensive study on the time-dependent dielectric breakdown characteristics of ALD-Al2O3 films formed on homo-epitaxial GaN substrates using two different oxidants at two different ALD temperatures. The breakdown times were approximated by Weibull distributions with average shape parameters of 8 or larger. These values are reasonably consistent with percolation theory predictions and are sufficiently large to neglect the wear-out lifetime distribution in assessing the long-term reliability of the Al2O3 films. The 63% lifetime of the Al2O3 films increases exponentially with a decreasing field, as observed in thermally grown SiO2 films at low fields. This exponential relationship disproves the correlation between the lifetime and the leakage current. Additionally, the lifetime decreases with measurement temperature with the most remarkable reduction observed in high-temperature (450 °C) O3-grown films. This result agrees with that from a previous study, thereby ruling out high-temperature O3 ALD as a gate insulation process. When compared at 200 °C under an equivalent SiO2 field of 4 MV/cm, which is a design guideline for thermal SiO2 on Si, high-temperature H2O-grown Al2O3 films have the longest lifetimes, uniquely achieving the reliability target of 20 years. However, this target is accomplished by a relatively narrow margin and, therefore, improvements in the lifetime are expected to be made, along with efforts to decrease the density of extrinsic Al2O3 defects, if any, to promote the practical use of ALD Al2O3 films.

    DOI

  • Electrical contact properties between carbon nanotube ends and a conductive atomic force microscope tip

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

    Journal of Applied Physics   123 ( 24 ) 244502/1 - 244502/8  2018年  [査読有り]

    DOI

  • Role of Carboxyl and Amine Termination on a Boron-Doped Diamond Solution Gate Field Effect Transistor (SGFET) for pH Sensing

    Falina, Shaili, Kawai, Sora, Oi, Nobutaka, Yamano, Hayate, Kageura, Taisuke, Suaebah, Evi, Inaba, Masafumi, Shintani, Yukihiro, Syamsul, Mohd, Kawarada, Hiroshi

    Sensors   18 ( 7 ) 2178/1 - 2178/10  2018年  [査読有り]

    DOI

  • Vertical-type two-dimensional hole gas diamond metal oxide semiconductor field-effect transistors

    Oi, Nobutaka, Inaba, Masafumi, Okubo, Satoshi, Tsuyuzaki, Ikuto, Kageura, Taisuke, Onoda, Shinobu, Hiraiwa, Atsushi, Kawarada, Hiroshi

    Scientific Reports   8   10660/1 - 10660/10  2018年  [査読有り]

    DOI

  • Lithographically engineered shallow nitrogen-vacancy centers in diamond for external nuclear spin sensing

    Fukuda, Ryosuke, Balasubramanian, Priyadharshini, Higashimata, Itaru, Koike, Godai, Okada, Takuma, Kagami, Risa, Teraji, Tokuyuki, Onoda, Shinobu, Haruyama, Moriyoshi, Yamada, Keisuke, Inaba, Masafumi, Yamano, Hayate, Stuerner, Felix M., Schmitt, Simon, McGuinness, Liam P., Jelezko, Fedor, Ohshima, Takeshi, Shinada, Takahiro, Kawarada, Hiroshi, Kada, Wataru, Hanaizumi, Osamu, Tanii, Takashi, Isoya, Junichi

    New Journal of Physics   20 ( 8 ) 083029 - 083029  2018年  [査読有り]

    DOI

  • Sheet resistance underneath the Au ohmic-electrode on hydrogen-terminated surface-conductive diamond (001)

    S. Kono, T. Sasaki, M. Inaba, A. Hiraiwa, H. Kawarada

    DIAMOND AND RELATED MATERIALS   80   93 - 98  2017年11月  [査読有り]

     概要を見る

    The sheet resistance (R-sk) underneath ohmic Au-electrodes on hydrogen-terminated surface-conductive diamond (001) surfaces was examined by a special current-voltage measurement. It has been found that R-sk is about similar to 200 times larger than the sheet resistance, R-sh, in the open areas without Au-electrodes. The specific contact resistance, R-c, of ohmic Au-electrodes on H-terminated surface-conductive diamonds as determined by linear transmission line models must be corrected accordingly. As the results of this, R-c is suggested to be of the order of 1 x 10(-3)-1 X 10(-4) Omega CM2.

    DOI

  • Fabrication of photo-electrochemical biosensors for ultrasensitive screening of mono-bioactive molecules: the effect of geometrical structures and crystal surfaces

    Naeem Akhtar, Mohammed Y. Emran, Mohamed A. Shenashen, Hesham Khalifa, Tetsuya Osaka, Ahmed Faheem, Takayuki Homma, Hiroshi Kawarada, Sherif A. El-Safty

    JOURNAL OF MATERIALS CHEMISTRY B   5 ( 39 ) 7985 - 7996  2017年10月  [査読有り]

     概要を見る

    The controlled design of biosensors based on the photo-electrochemical technique with high selectivity, sensitivity, and rapid response for monitoring of mono-bioactive molecules, particularly dopamine (DA) levels in neuronal cells is highly necessary for clinical diagnosis. Hierarchical carbon-, nitrogen-doped (CN) nickel oxide spear thistle (ST) flowers associated in single-heads (S), and symmetric and asymmetric-double heads (D and A, respectively) that are tightly connected through a micrometric dipole-like rod or trunk were fabricated by using a simple synthetic protocol. The CN-ST flower heads were decorated with dense nanotubular like hedgehog needle skins in vertical alignments. These designated architectures are key features for creating biosensor surface electrodes for photo-electrochemical, ultrasensitive screening of mono-bioactive molecules. The exceptional electrode designs produced numerous catalytically active sites, large surface area, and high electron-transfer mobility. The active coating of carbon-nitrogen nanospheres significantly enhanced the photo-electrocatalytic activity of the prepared biosensor electrodes and prevented leakage of photocatalytic activity under long-term exposure to irradiation. Among all photo-electrochemical assays, the biosensors showed significant sensitivity and selectivity for DA in the presence of interfering molecules such as ascorbic acid (AA), uric acid (UA), adrenaline (A), and noradrenaline (NA). The photo-electrochemical property of the CN-SST-{110} crystal surface electrode showed significant sensing performance for DA in terms of unimpeded diffusion pathways, a wide concentration-detection range, and a low detection limit, even in the presence of potentially interfering molecules compared with other electrode-modified CN-DST-{111} and CN-AST-{101} crystal surfaces. Furthermore, the CN-SST photo-biosensor electrode shows potential in the selective and sensitive determination of DA in real samples, such as human serum and secreted DA from living cells. This finding indicates that the hierarchical ST biosensor may enable analytical discrimination and monitoring of DA and can be employed for clinical diagnosis application.

    DOI

  • Polycrystalline Boron-doped diamond electrolyte-solution-gate field-effect transistor for an application to the measurement of water percentage in ethanol

    Y. Shintani, H. Kawarada

    Analytical Sciences   33 ( 10 ) 1193 - 1196  2017年10月  [査読有り]  [国内誌]

    DOI PubMed

  • フッ素終端ダイヤモンドを用いた全固体pHセンサ

    新谷幸弘, 川原田洋

    Chemical Sensors   33 ( Supplement B ) 112‐114  2017年09月

    J-GLOBAL

  • Vertical edge graphite layer on recovered diamond (001) after high-dose ion implantation and high-temperature annealing

    Masafumi Inaba, Akinori Seki, Kazuaki Sato, Tomoyoshi Kushida, Taisuke Kageura, Hayate Yamano, Atsushi Hiraiwa, Hiroshi Kawarada

    PHYSICA STATUS SOLIDI B-BASIC SOLID STATE PHYSICS   254 ( 9 ) 1700040 - 1700040  2017年09月  [査読有り]

     概要を見る

    A vertical edge graphite layer (VEG) fabricated on a diamond (001) substrate and the recovery of the crystallinity of the diamond substrate following high-dose ion implantation and high-temperature annealing (HTA) was investigated. The Al ions were implanted into the diamond (001) surface at 773K (500 degrees C), followed by HTA at 1973 K (1700 degrees C). The graphite edges were vertically oriented, but each domain was randomly rotated in the in-plane direction, which was confirmed via multiple cross-sectional transmission electron microscopy images obtained from different directions rotated 2, 5, 10, and 158 around the [001] axis. The Raman and photoluminescence exhibited no significant peaks. The initial sp(2) structure state of the VEG was nucleated in an early stage of the HTA and the surface diamond was subsequently reconstructed, which was confirmed using stopping-and-range-of-ions-in-matter calculations and Rutherford backscattering/channeling (RBS-C) measurements. The RBS-C spectra indicate that the crystal is maintained after hot implantation and is recovered by HTA. This VEG structure may be useful for ohmic contact with diamond electrical devices. (C) 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

    DOI

  • 全固体ガラスレスpHセンサの開発 (お客様と共創する研究開発 特集)

    新谷 幸弘, 小河 晃太朗, 猿谷 敏之, 川原田 洋

    横河技報 = Yokogawa technical report   60 ( 1 ) 31 - 34  2017年07月

    CiNii J-GLOBAL

  • Threshold voltage control of electrolyte solution gate field-effect transistor by electrochemical oxidation

    Takuro Naramura, Masafumi Inaba, Sho Mizuno, Keisuke Igarashi, Eriko Kida, Shaili Falina Mohd Sukri, Yukihiro Shintani, Hiroshi Kawarada

    APPLIED PHYSICS LETTERS   111 ( 1 ) 013505/1 - 013505/5  2017年07月  [査読有り]

     概要を見る

    Diamond electrolyte solution-gate-field effect transistors (SGFETs) are suitable for applications as chemical ion sensors because of their wide potential window and good physical and chemical stabilities. In this study, we fabricated an anodically oxidized diamond SGFET from a full hydrogen-terminated diamond SGFET and demonstrated control of the device threshold voltage by irreversible anodic oxidation. The applied anodic bias voltage (V-AO) was varied gradually from low to high (1.1-1.7 V). As the anodic oxidation proceeded, the threshold voltage shifted to more negative values with no degradation of hole mobility. Thus, anodic oxidation is a useful method for controlling the threshold voltage of diamond SGFETs. Published by AIP Publishing.

    DOI

  • Aptamer-Based Carboxyl-Terminated Nanocrystalline Diamond Sensing Arrays for Adenosine Triphosphate Detection

    Evi Suaebah, Takuro Naramura, Miho Myodo, Masataka Hasegawa, Shuichi Shoji, Jorge J. Buendia, Hiroshi Kawarada

    SENSORS   17 ( 7 ) 1686/1 - 1686/13  2017年07月  [査読有り]

     概要を見る

    Here, we propose simple diamond functionalization by carboxyl termination for adenosine triphosphate (ATP) detection by an aptamer. The high-sensitivity label-free aptamer sensor for ATP detection was fabricated on nanocrystalline diamond (NCD). Carboxyl termination of the NCD surface by vacuum ultraviolet excimer laser and fluorine termination of the background region as a passivated layer were investigated by X-ray photoelectron spectroscopy. Single strand DNA (amide modification) was used as the supporting biomolecule to immobilize into the diamond surface via carboxyl termination and become a double strand with aptamer. ATP detection by aptamer was observed as a 66% fluorescence signal intensity decrease of the hybridization intensity signal. The sensor operation was also investigated by the field-effect characteristics. The shift of the drain current-drain voltage characteristics was used as the indicator for detection of ATP. From the field-effect characteristics, the shift of the drain current-drain voltage was observed in the negative direction. The negative charge direction shows that the aptamer is capable of detecting ATP. The ability of the sensor to detect ATP was investigated by fabricating a field-effect transistor on the modified NCD surface.

    DOI

  • High Voltage Stress Induced in Transparent Polycrystalline Diamond Field-Effect Transistor and Enhanced Endurance Using Thick Al2O3 Passivation Layer

    Mohd Syamsul, Yuya Kitabayashi, Takuya Kudo, Daisuke Matsumura, Hiroshi Kawarada

    IEEE ELECTRON DEVICE LETTERS   38 ( 5 ) 607 - 610  2017年05月  [査読有り]

     概要を見る

    A transparent polycrystalline diamond field-effect transistor (FET) was fabricated and measured in room temperature measurements, which reveals comparatively high maximum current density and high breakdown voltage of more than 1000V. A harsh stress environment is proposed for simple and time-effective reliability stress measurement of the FET using a method of 50 continuous cycles of 500-V voltage stress. A 400-nm-thick Al2O3 counter-destructive passivation layer was implemented on the FET for the stress measurements. Devices with wide gate-drain length (L-GD) retain their FET characteristics after the harsh stress measurements by only 50% reductions maximum current density.

    DOI

  • Effect of a radical exposure nitridation surface on the charge stability of shallow nitrogen-vacancy centers in diamond

    Taisuke Kageura, Kanami Kato, Hayate Yamano, Evi Suaebah, Miki Kajiya, Sora Kawai, Masafumi Inaba, Takashi Tanii, Moriyoshi Haruyama, Keisuke Yamada, Shinobu Onoda, Wataru Kada, Osamu Hanaizumi, Tokuyuki Teraji, Junichi Isoya, Shozo Kono, Hiroshi Kawarada

    APPLIED PHYSICS EXPRESS   10 ( 5 ) 055503 /1 - 055503 /4  2017年05月  [査読有り]

     概要を見る

    A nitridation process of a diamond surface with nitrogen radical exposure far from the radio-frequency plasma for the stabilization of a negatively charged nitrogen-vacancy (NV%) centers near the surface is presented. At a nitrogen coverage of as high as 0.9 monolayers, high average Rabi contrasts of 0.40 +/- 0.06 and 0.46 +/- 0.03 have been obtained for single NV% centers formed by shallow nitrogen implantation with acceleration voltages of 1 and 2 keV, respectively. This indicates that nitrogen termination by a radical exposure process produces an electric charge state suitable for single NV- centers near the surface compared with the states obtained for alternatively terminated surfaces. (C) 2017 The Japan Society of Applied Physics

    DOI

  • An All-Solid-State pH Sensor Employing Fluorine-Terminated Polycrystalline Boron-Doped Diamond as a pH-Insensitive Solution-Gate Field-Effect Transistor

    Yukihiro Shintani, Mikinori Kobayashi, Hiroshi Kawarada

    SENSORS   17 ( 5 ) 1040/1 - 1040/7  2017年05月  [査読有り]

     概要を見る

    A fluorine-terminated polycrystalline boron-doped diamond surface is successfully employed as a pH-insensitive SGFET (solution-gate field-effect transistor) for an all-solid-state pH sensor. The fluorinated polycrystalline boron-doped diamond (BDD) channel possesses a pH-insensitivity of less than 3mV/pH compared with a pH-sensitive oxygenated channel. With differential FET (field-effect transistor) sensing, a sensitivity of 27 mv/pH was obtained in the pH range of 2-10; therefore, it demonstrated excellent performance for an all-solid-state pH sensor with a pH-sensitive oxygen-terminated polycrystalline BDD SGFET and a platinum quasi-reference electrode, respectively.

    DOI

  • Charge state stabilization of shallow nitrogen vacancy centers in diamond by oxygen surface modification

    Hayate Yamano, Sora Kawai, Kanami Kato, Taisuke Kageura, Masafumi Inaba, Takuma Okada, Itaru Higashimata, Moriyoshi Haruyama, Takashi Tanii, Keisuke Yamada, Shinobu Onoda, Wataru Kada, Osamu Hanaizumi, Tokuyuki Teraji, Junichi Isoya, Hiroshi Kawarada

    Japanese Journal of Applied Physics   56 ( 4 ) 04CK08/1 - 04CK08/7  2017年04月  [査読有り]

     概要を見る

    We investigated the charge state stability and coherence properties of near-surface single nitrogen vacancy (NV) centers in 12C-enriched diamond for potential use in nanoscale magnetic field sensing applications. The stability of charge states in negatively charged NV centers (NV-) was evaluated using one of the pulsed optically detected magnetic resonance measurements, Rabi oscillation measurements. During the accumulation of Rabi oscillations, an unstable shallow NV- was converted to a neutral state. As a result, the contrast of Rabi oscillations degraded, depending on charge state stability. We stabilized the NV- state of very shallow NV centers (∼2.6 ± 1.1nm from the surface) created by 1.2 keV nitrogen ion implantation by diamond surface modification, UV/ozone exposure, and oxygen annealing. This improvement indicates that we can suppress the upward surface band bending and surface potential fluctuations through Fermi level pinning originating from oxygen-terminated diamond surfaces.

    DOI

  • Normally-Off C-H Diamond MOSFETs With Partial C-O Channel Achieving 2-kV Breakdown Voltage

    Yuya Kitabayashi, Takuya Kudo, Hidetoshi Tsuboi, Tetsuya Yamada, Dechen Xu, Masanobu Shibata, Daisuke Matsumura, Yuya Hayashi, Mohd Syamsul, Masafumi Inaba, Atsushi Hiraiwa, Hiroshi Kawarada

    IEEE ELECTRON DEVICE LETTERS   38 ( 3 ) 363 - 366  2017年03月  [査読有り]

     概要を見る

    Diamond has unique physical properties, which show great promise for applications in the next generation power devices. Hydrogen-terminated (C-H) diamond metal-oxide-semiconductor field-effect transistors (MOSFETs) often have normally-on operation in devices, because the C-H channel features a p-type inversion layer; however, normally-off devices are preferable in power MOSFETs from the viewpoint of fail safety. We fabricated hydrogen-terminated (C-H) diamond MOSFETs using a partially oxidized ( partial C-O) channel. The fabricated MOSFETs showed a high breakdown voltage of over 2 kV at room temperature and normally-off characteristics with a gate threshold voltage V-th of -2.5-- 4 V.

    DOI

  • Smart Power Devices and ICs Using GaAs and Wide and Extreme Bandgap Semiconductors

    T. Paul Chow, Ichiro Omura, Masataka Higashiwaki, Hiroshi Kawarada, Vipindas Pala

    IEEE TRANSACTIONS ON ELECTRON DEVICES   64 ( 3 ) 856 - 873  2017年03月  [査読有り]

     概要を見る

    We evaluate and compare the performance and potential of GaAs and of wide and extreme bandgap semiconductors (SiC, GaN, Ga2O3, and diamond), relative to silicon, for power electronics applications. We examine their device structures and associated materials/process technologies and selectively reviewthe recent experimental demonstrations of high voltage power devices and IC structures of these semiconductors. We discuss the technical obstacles that still need to be addressed and overcome before large-scale commercialization commences.

    DOI

  • Post-deposition-annealing effect on current conduction in Al2O3 films formed by atomic layer deposition with H2O oxidant

    Atsushi Hiraiwa, Daisuke Matsumura, Satoshi Okubo, Hiroshi Kawarada

    JOURNAL OF APPLIED PHYSICS   121 ( 7 ) 074502/1 - 074502/8  2017年02月  [査読有り]

     概要を見る

    Atomic-layer-deposition (ALD) Al2O3 films are promising as gate insulators of non-Si semiconductor devices. Although they allow relatively small leakage currents just after deposition, ALD Al2O3 films formed at low temperatures are subject to high temperature during fabrication or operation of devices. Therefore, the effect of post-deposition annealing (PDA) on the properties of Al2O3 films is investigated in this study. ALD Al2O3 films formed using H2O oxidant at low temperatures are compacted by PDA, but their mass density and dielectric constant remain approximately unchanged or slightly decrease owing to the desorption of methyl groups contained in the films as impurities. In accordance with these results, the wet etching rate of Al2O3 films is not much reduced by PDA. The conduction current in ALD Al2O3 films formed on Si is reduced by PDA and becomes smaller than that in films formed at the same ALD temperatures as those of PDA. The conduction current for PDA temperatures above 250 degrees C, however, increases and, accordingly, spoils the merit of low-temperature ALD. Therefore, given that the dielectric constant of annealed films remains low, high-temperature ALD is practically more significant than applying PDA to low-temperature ALD Al2O3 films from the viewpoint of leakage current under the same thermal budget. Space-charge-controlled field emission analysis revealed that, at the aforementioned threshold temperature, PDA abruptly increases the Al2O3/SiO2 interfacial dipoles and simultaneously reduces the amount of the positive charge near the interface. The so-called negative-charge buildup by PDA might be caused by this decrease in the positive charge. Published by AIP Publishing.

    DOI

  • Durability-enhanced two-dimensional hole gas of C-H diamond surface for complementary power inverter applications

    Hiroshi Kawarada, Tetsuya Yamada, Dechen Xu, Hidetoshi Tsuboi, Yuya Kitabayashi, Daisuke Matsumura, Masanobu Shibata, Takuya Kudo, Masafumi Inaba, Atsushi Hiraiwa

    SCIENTIFIC REPORTS   7   42368/1 - 42368/8  2017年02月  [査読有り]

     概要を見る

    Complementary power field effect transistors (FETs) based on wide bandgap materials not only provide high-voltage switching capability with the reduction of on-resistance and switching losses, but also enable a smart inverter system by the dramatic simplification of external circuits. However, p-channel power FETs with equivalent performance to those of n-channel FETs are not obtained in any wide bandgap material other than diamond. Here we show that a breakdown voltage of more than 1600 V has been obtained in a diamond metal-oxide-semiconductor (MOS) FET with a p-channel based on a two-dimensional hole gas (2DHG). Atomic layer deposited (ALD) Al2O3 induces the 2DHG ubiquitously on a hydrogen-terminated (C-H) diamond surface and also acts as both gate insulator and passivation layer. The high voltage performance is equivalent to that of state-of-the-art SiC planar n-channel FETs and AlGaN/GaN FETs. The drain current density in the on-state is also comparable to that of these two FETs with similar device size and V-B.

    DOI

  • Aptamer strategy for ATP detection on nanocrystalline diamond functionalized by a nitrogen and hydrogen radical beam system

    E. Suaebah, Y. Seshimo, M. Shibata, S. Kono, M. Hasegawa, H. Kawarada

    JOURNAL OF APPLIED PHYSICS   121 ( 4 ) 044506/1 - 044506/6  2017年01月  [査読有り]

     概要を見る

    Here, we report a novel method for micropatterning oligonucleotides on the diamond surface via forming amine groups on the diamond surface by nitrogen/hydrogen radical treatment. The covalent bonding of the supporting oligonucleotide and characterization of an immobilized hybridized oligonucleotide with Cy5 modification were investigated by fluorescence microscopy. To investigate the effectiveness of nitrogen/hydrogen radical treatment for amine termination, two types of radical treatment were used: hydrogen/nitrogen radical treatment and pure nitrogen radical treatment. From the results, hydrogen/nitrogen radical treatment produces amine (NH2) termination on the diamond surface. The effect of amine termination was investigated by immobilization of single-stranded DNA via amide bonding between surface NH2 groups and COOH groups terminating the DNA. The immobilized single-stranded DNA (supporting DNA), which has a complementary relationship with the adenosine triphosphate (ATP) aptamer (DNA), hybridizes with the aptamer with attached fluorescence dye. When ATP molecules approach the double-stranded DNA, the aptamer forms a close relationship with the supporting DNA and combines with ATP. ATP detection was effectively carried out by reduction of fluorescence. Published by AIP Publishing.

    DOI

  • High voltage breakdown (1.8 kV) of hydrogenated black diamond field effect transistor

    M. Syamsul, Y. Kitabayashi, D. Matsumura, T. Saito, Y. Shintani, H. Kawarada

    Applied Physics Letters   109 ( 20 ) 203504/1 - 203504/4  2016年11月  [査読有り]

    DOI

  • Spin-induced anomalous magnetoresistance at the (100) surface of hydrogen-terminated diamond

    Yamaguchi Takahide, Yosuke Sasama, Masashi Tanaka, Hiroyuki Takeya, Yoshihiko Takano, Taisuke Kageura, Hiroshi Kawarada

    PHYSICAL REVIEW B   94 ( 16 ) 161301/1 - 161301/5  2016年10月  [査読有り]

     概要を見る

    We report magnetoresistance measurements of hydrogen-terminated (100)-oriented diamond surfaces wherein an ionic-liquid-gated field-effect-transistor technique was used to make hole carriers accumulate. Unexpectedly, the observed magnetoresistance is positive within the range of 2&lt;T&lt;10 K and -7&lt;B&lt;7 T, in striking contrast to the negative magnetoresistance previously detected for similar devices with (111)-oriented diamond surfaces. Furthermore, we find that (1) the magnetoresistance is orders of magnitude larger than that of the classical orbital magnetoresistance; (2) the magnetoresistance is nearly independent of the direction of the applied magnetic field; and (3) for the in-plane field, the magnetoresistance ratio, defined as [rho(B) - rho(0)]/rho(0), follows a universal function of B/T. These results indicate that the spin degree of freedom of hole carriers plays an important role in the surface conductivity of hydrogen-terminated (100) diamond.

    DOI

  • Polycrystalline boron-doped diamond with an oxygen-terminated surface channel as an electrolyte-solution-gate field-effect transistor for pH sensing

    Yukihiro Shintani, Shoji Ibori, Keisuke Igarashi, Takuro Naramura, Masafumi Inaba, Hiroshi Kawarada

    ELECTROCHIMICA ACTA   212   10 - 15  2016年09月  [査読有り]

     概要を見る

    A polycrystalline boron-doped diamond (BDD) electrolyte solution-gate field effect transistor (SGFET) for use as a pH sensorwas developed. The polycrystalline diamond films with a boron-doped layer possessed semiconducting properties that were comparable to hydrogen-terminated non-doped diamond. The hydrogen-terminated BDD surface was successfully transferred to a partially oxygen-terminated surface by ozone exposure, and its SGFET current-voltage (I-V) characteristics were evaluated with bias voltages within the potential window of diamond. The drain-source current(Ids)-drain-source voltage(Vds) characteristics showed pinch-off and saturation. In addition, they stably operated in electrolyte solutions with pH values from 2 to 12. The transfer characteristics exhibited a pH sensitivity of approximately 30 mV/ pH, which is comparable with the pH sensitivity of the conventional oxygen-terminated nondoped SGFET and the single-crystal BDD SGFET investigated in our previous work. Furthermore, the BDD SGFET exhibited improved long-term stability, and the coefficient of variation (CV) of Ids for 10 months was up to 10%. (C) 2016 Elsevier Ltd. All rights reserved.

    DOI

  • Effect of atomic layer deposition temperature on current conduction in Al2O3 films formed using H2O oxidant

    Atsushi Hiraiwa, Daisuke Matsumura, Hiroshi Kawarada

    JOURNAL OF APPLIED PHYSICS   120 ( 8 ) 084504/1 - 084504/10  2016年08月  [査読有り]

     概要を見る

    To develop high-performance, high-reliability gate insulation and surface passivation technologies for wide-bandgap semiconductor devices, the effect of atomic layer deposition (ALD) temperature on current conduction in Al2O3 films is investigated based on the recently proposed space-charge-controlled field emission model. Leakage current measurement shows that Al2O3 metal-insulator-semiconductor capacitors formed on the Si substrates underperform thermally grown SiO2 capacitors at the same average field. However, using equivalent oxide field as a more practical measure, the Al2O3 capacitors are found to outperform the SiO2 capacitors in the cases where the capacitors are negatively biased and the gate material is adequately selected to reduce virtual dipoles at the gate/Al2O3 interface. The Al2O3 electron affinity increases with the increasing ALD temperature, but the gate-side virtual dipoles are not affected. Therefore, the leakage current of negatively biased Al2O3 capacitors is approximately independent of the ALD temperature because of the compensation of the opposite effects of increased electron affinity and permittivity in Al2O3. By contrast, the substrate-side sheet of charge increases with increasing ALD temperature above 210 degrees C and hence enhances the current of positively biased Al2O3 capacitors more significantly at high temperatures. Additionally, an anomalous oscillatory shift of the current-voltage characteristics with ALD temperature was observed in positively biased capacitors formed by low-temperature (&lt;= 210 degrees C) ALD. This shift is caused by dipoles at the Al2O3/underlying SiO2 interface. Although they have a minimal positive-bias leakage current, the low-temperature-grown Al2O3 films cause the so-called blisters problem when heated above 400 degrees C. Therefore, because of the absence of blistering, a 450 degrees C ALD process is presently the most promising technology for growing high-reliability Al2O3 films. Published by AIP Publishing.

    DOI

  • Hydrogen-terminated diamond vertical-type metal oxide semiconductor field-effect transistors with a trench gate

    Masafumi Inaba, Tsubasa Muta, Mikinori Kobayashi, Toshiki Saito, Masanobu Shibata, Daisuke Matsumura, Takuya Kudo, Atsushi Hiraiwa, Hiroshi Kawarada

    APPLIED PHYSICS LETTERS   109 ( 3 ) 033503/1 - 033503/4  2016年07月  [査読有り]

     概要を見る

    The hydrogen-terminated diamond surface (C-H diamond) has a two-dimensional hole gas (2DHG) layer independent of the crystal orientation. A 2DHG layer is ubiquitously formed on the C-H diamond surface covered by atomic-layer-deposited-Al2O3. Using Al2O3 as a gate oxide, C-H diamond metal oxide semiconductor field-effect transistors (MOSFETs) operate in a trench gate structure where the diamond side-wall acts as a channel. MOSFETs with a side-wall channel exhibit equivalent performance to the lateral C-H diamond MOSFET without a side-wall channel. Here, a vertical-type MOSFET with a drain on the bottom is demonstrated in diamond with channel current modulation by the gate and pinch off. Published by AIP Publishing.

    DOI

  • 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年03月  [査読有り]

     概要を見る

    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.

    DOI

  • Radially oriented nanostrand electrodes to boost glucose sensing in mammalian blood

    Naeem Akhtar, Sherif A. El-Safty, Mamdouh E. Abdelsalam, Mohamed A. Shenashen, Hiroshi Kawarada

    BIOSENSORS & BIOELECTRONICS   77   656 - 665  2016年03月  [査読有り]

     概要を見る

    Architecture of nanoscale electrochemical sensors for ultra-trace detection of glucose in blood is important in real-life sampling and analysis. To broaden the application of electrochemical sensing of glucose, we fabricated, for the first time, a glucose sensor electrode based on radially oriented NiO nanostrands (NSTs) onto 3D porous Ni foam substrate for monitoring, as well as selective and sensitive sensing of glucose in mammalian blood. The simple, scalable one-pot fabrication of this NST-Ni sensor design enabled control of the pattern of radially oriented NSTs onto 3D porous Ni foam substrate. The radial orientation of NST-Ni electrode onto the interior of the 3D porous substrate with controlled crystal structure size and atomic arrangement along the axis of the strands, intrinsic surface defects, and superior surface properties, such as hydrophilicity, high surface energy, and high density led to highly exposed catalytic active sites. The hierarchical NST-Ni electrode was used to develop a sensitive and selective sensor over a wide range of glucose concentrations among actively competitive ions, chemical species and molecular agents, and multi-cyclic sensing assays. The NST-Ni electrode shows significant glucose sensing performance in terms of unimpeded diffusion pathways, a wide range of concentration detection, and lower limit of detection (0.186 mu M) than NiO nanosheet (NS)-Ni foam electrode pattern, indicating the effectiveness of the shape-dependent structural architecture of NST-Ni electrode. In this study, the NST-Ni electrode is fabricated to develop a simple, selective method for detecting glucose in physiological fluids (e.g., mammalian blood). (C) 2015 Elsevier B.V. All rights reserved.

    DOI

  • Space-charge-controlled field emission model of current conduction through Al2O3 films

    Atsushi Hiraiwa, Daisuke Matsumura, Hiroshi Kawarada

    JOURNAL OF APPLIED PHYSICS   119 ( 6 ) 064505/1 - 064505/13  2016年02月  [査読有り]

     概要を見る

    This study proposes a model for current conduction in metal-insulator-semiconductor (MIS) capacitors, assuming the presence of two sheets of charge in the insulator, and derives analytical formulae of field emission (FE) currents under both negative and positive bias. Since it is affected by the space charge in the insulator, this particular FE differs from the conventional FE and is accordingly named the space-charge-controlled (SCC) FE. The gate insulator of this study was a stack of atomic-layer-deposition Al2O3 and underlying chemical SiO2 formed on Si substrates. The current-voltage (I-V) characteristics simulated using the SCC-FE formulae quantitatively reproduced the experimental results obtained by measuring Au- and Al-gated Al2O3/SiO2 MIS capacitors under both biases. The two sheets of charge in the Al2O3 films were estimated to be positive and located at a depth of greater than 4 nm from the Al2O3/SiO2 interface and less than 2 nm from the gate. The density of the former is approximately 1 x 10(13) cm(-2) in units of electronic charge, regardless of the type of capacitor. The latter forms a sheet of dipoles together with image charges in the gate and hence causes potential jumps of 0.4V and 1.1V in the Au-and Al-gated capacitors, respectively. Within a margin of error, this sheet of dipoles is ideally located at the gate/Al2O3 interface and effectively reduces the work function of the gate by the magnitude of the potential jumps mentioned above. These facts indicate that the currents in the Al2O3/SiO2 MIS capacitors are enhanced as compared to those in ideal capacitors and that the currents in the Al-gated capacitors under negative bias (electron emission from the gate) are more markedly enhanced than those in the Au-gated capacitors. The larger number of gate-side dipoles in the Al-gated capacitors is possibly caused by the reaction between the Al and Al2O3, and therefore gate materials that do not react with underlying gate insulators should be chosen in order to achieve a low leakage current by suppressing the current enhancement. Although the current conduction in this study is essentially limited by FE, neither the Fowler-Nordheim (FN) nor Poole-Frenkel (PF) plots of the I-V characteristics are fitted by a linear function. The failures of the FN and PF plot methods alert us to the inaccuracies of basing the investigation of current conduction on these traditional plots. Hence, the methodology of a current conduction analysis and the knowledge of Al2O3 charging in this study provide a solid foundation for investigating the current conduction in MIS capacitors. (C) 2016 AIP Publishing LLC.

    DOI

  • 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年  [査読有り]

     概要を見る

    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.

    DOI

  • Diamond MOSFETs using 2D Hole Gas with 1700V Breakdown Voltage

    H. Kawarada, T. Yamada, D. Xu, Y. Kitabayashi, M. Shibata, D. Matsumura, M. Kobayashi, T. Saito, T. Kudo, M. Inaba, A. Hiraiwa

    2016 28TH INTERNATIONAL SYMPOSIUM ON POWER SEMICONDUCTOR DEVICES AND ICS (ISPSD)     483 - 486  2016年  [査読有り]

     概要を見る

    More than 1600V breakdown voltages have been obtained in hydrogen terminated (C-H) diamond planar p-channel MOSFETs with gate-drain distance of 16-22 mu m. The drain current density exceeds 100mA/mm in the FETs. The blocking voltage and drain current characteristics are comparable to those of n-channel AlGaN/GaN FETs and planar SiC MOSFETs in a similar device size. Atomic layer deposited Al2O3 works as gate insulator and passivation layer. It also induces the 2 dimensional hole gas ubiquitously on C-H diamond surface not only in planar, but in a trench gate structure. The first diamond vertical MOSFET has also operated using the trench structure.

    DOI

  • One-Pot Fabrication of Dendritic NiO@carbon-nitrogen Dot Electrodes for Screening Blood Glucose Level in Diabetes

    Naeem Akhtar, Sherif A. El-Safty, Mamdouh E. Abdelsalam, Hiroshi Kawarada

    ADVANCED HEALTHCARE MATERIALS   4 ( 14 ) 2110 - 2119  2015年10月  [査読有り]

     概要を見る

    Selective and sensitive glucose sensors with fast response for screening diabetic blood level are demanded. In this paper, the one-pot nanoarchitecture of dendritic NiO@carbon-nitrogen (C-N) dots (designated as NCD) sphere-wrapping Ni foam electrodes are reported as an effective and sensitive glucose sensor in blood samples. In this construction design, the NCD sphere electrode with excessive surface defects, large fractions of catalytic active sites, high surface area, and mobility of electron transfer through the actively surface NCD sphere can massively enhance the electrocatalytic activity for nonenzymatic glucose detection in diabetic blood. This portable sensor enables highly sensitive recognition of glucose detection (approximate to 0.01 x 10(-6) M) over a wider linear range (approximate to 0.005-12 x 10(-3) M) with rapid response time of a few seconds. The key result is that the engineered NCD sphere electrodes function as simple, easy-to-use electrochemical sensing assays of glucose levels in diabetic blood patients with a wide range of precision or linearity, recyclability, and excellent selectivity, even in the presence of potentially interfering organic (ascorbic acid, uric acid, dopamine, lactose, maltose, and sucrose) and inorganic (NaCl, Na2SO4, KCl, and K2SO4) species. The results demonstrate the potential for the electrochemical sensors to be used in preventing serious health problems associated with diabetes mismanagement.

    DOI

  • Electron transport dependence of nanoscale hemeprotein molecular structures for engineering electrochemical nanosensor

    Naeem Akhtar, Sherif A. El-Safty, Mamdouh E. Abdelsalam, Hiroshi Kawarada

    Nano-Structures and Nano-Objects   2   35 - 44  2015年08月  [査読有り]

     概要を見る

    Fast and simple methods with high sensitivity and selectivity for H2O2 assessment are important in biological and medical fields. In this study, we explored the effect of nano-object hemeproteins (denoted as N-HP) with various bio-functionalities on the electrochemical sensing performance of working electrodes toward H2O2 molecules by affecting interfacial electron transport and surface properties of N-HP. We successfully constructed three enzyme-free H2O2 sensors by coating a three-dimensional open-pore nickel (3D-Ni) foam electrode with similar concentrations of three different N-HP namely, hemoglobin (Hb
    68.000 kDa, 7.0 nm), myoglobin (Mb, 16,950 kDa, 4.0 nm), and cytochrome c (Cyt.c, 12,327 kDa, 3.0 nm). The N-HP-modified Ni foam can be directly used as electrodes, thereby simplifying the electrode fabrication process and offering advantages, such as enhanced electrode-electrolyte contact area and minimum diffusion resistance. N-HP can function as redox mediators for shuttling electrons on the electrode-electrolyte interface and for engaging sufficient electro-active species exposed on the surface of the Ni foam for Faradaic redox reactions. The electrocatalytic activities of the Ni foam electrodes modified with different N-HP (i.e., Hb, Mb, and Cyt.c) in the selective oxidation of H2O2 were investigated. Among the N-HP-modified Ni foam electrodes, Cyt.c modified Ni foam electrode showed the highest sensitivity with reduced hysteresis between cathodic and anodic sweep and low detection limit (0.20μM, with signal to noise ratio of 3). This diversity in sensing performance originates from the versatility of the heme group with different bio-functionalities, different sizes and interactions at the surface of the immobilized Ni foam substrate. In addition, the N-HP-modified Ni foam electrodes exhibited no effects on major interferences, such as ascorbic, uric acids, dopamine, L-Cysteine (L. Cyst), vitamin A, L-glutathione. Hence, these electrodes can be applied in analyzing biological systems, such as lemon juice. Immobilization of different N-HP with different bio-functionalities and sizes onto Ni foam electrodes may facilitate the design and fabrication of novel biosensors.

    DOI

  • Isotope analysis of diamond-surface passivation effect of high-temperature H2O-grown atomic layer deposition-Al2O3 films

    Atsushi Hiraiwa, Tatsuya Saito, Daisuke Matsumura, Hiroshi Kawarada

    JOURNAL OF APPLIED PHYSICS   117 ( 21 ) 215304/1 - 215304/10  2015年06月  [査読有り]

     概要を見る

    The Al2O3 film formed using an atomic layer deposition (ALD) method with trimethylaluminum as Al precursor and H2O as oxidant at a high temperature (450 degrees C) effectively passivates the p- type surface conduction (SC) layer specific to a hydrogen- terminated diamond surface, leading to a successful operation of diamond SC field- effect transistors at 400 degrees C. In order to investigate this excellent passivation effect, we carried out an isotope analysis using D2O instead of H2O in the ALD and found that the Al2O3 film formed at a conventional temperature (100 degrees C) incorporates 50 times more CH3 groups than the high- temperature film. This CH3 is supposed to dissociate from the film when heated afterwards at a higher temperature (550 degrees C) and causes peeling patterns on the H- terminated surface. The high- temperature film is free from this problem and has the largest mass density and dielectric constant among those investigated in this study. The isotope analysis also unveiled a relatively active H- exchange reaction between the diamond H- termination and H2O oxidant during the high- temperature ALD, the SC still being kept intact. This dynamic and yet steady H termination is realized by the suppressed oxidation due to the endothermic reaction with H2O. Additionally, we not only observed the kinetic isotope effect in the form of reduced growth rate of D2O-oxidant ALD but found that the mass density and dielectric constant of D2O-grown Al2O3 films are smaller than those of H2O-grown films. This is a new type of isotope effect, which is not caused by the presence of isotopes in the films unlike the traditional isotope effects that originate from the presence of isotopes itself. Hence, the high-temperature ALD is very effective in forming Al2O3 films as a passivation and/or gate-insulation layer of high-temperature-operation diamond SC devices, and the knowledge of the aforementioned new isotope effect will be a basis for further enhancing ALD technologies in general. (C) 2015 AIP Publishing LLC.

    DOI

  • Large-current-controllable carbon nanotube field-effect transistor in electrolyte solution

    Miho Myodo, Masafumi Inaba, Kazuyoshi Ohara, Ryogo Kato, Mikinori Kobayashi, Yu Hirano, Kazuma Suzuki, Hiroshi Kawarada

    APPLIED PHYSICS LETTERS   106 ( 21 ) 213503/1 - 213503/4  2015年05月  [査読有り]

     概要を見る

    Large-current-controllable carbon nanotube field-effect transistors (CNT-FETs) were fabricated with mm-long CNT sheets. The sheets, synthesized by remote-plasma-enhanced CVD, contained both single-and double-walled CNTs. Titanium was deposited on the sheet as source and drain electrodes, and an electrolyte solution was used as a gate electrode (solution gate) to apply a gate voltage to the CNTs through electric double layers formed around the CNTs. The drain current came to be well modulated as electrolyte solution penetrated into the sheets, and one of the solution gate CNT-FETs was able to control a large current of over 2.5 A. In addition, we determined the transconductance parameter per tube and compared it with values for other CNT-FETs. The potential of CNT sheets for applications requiring the control of large current is exhibited in this study. (C) 2015 AIP Publishing LLC.

    DOI

  • Blocking characteristics of diamond junctions with a punch-through design”, Journal of Applied Physics

    A. Hiraiwa, H. Kawarada

    Journal of Applied Physics   117 ( 12 ) 124503/1 - 124503/6  2015年03月  [査読有り]

    DOI

  • 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 ) 123501/1 - 123501/5  2015年03月  [査読有り]

     概要を見る

    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.

    DOI

  • Signature of high $T_c$ around 25K in higher quality heavily boron-doped diamond

    H. Okazaki, T. Wakita, T. Muro, T. Nakamura, Y. Muraoka, T. Yokoya, S. Kurihara, H. Kawarada, T. Oguchi, Y. Takano

    Appl. Phys. Lett.    2015年02月  [査読有り]

  • Repulsive effects of hydrophobic diamond thin films on biomolecule detection

    A. Rahim Ruslinda, Y. Ishiyama, V. Penmatsa, S. Ibori, H. Kawarada

    APPLIED SURFACE SCIENCE   328   314 - 318  2015年02月  [査読有り]

     概要を見る

    The repulsive effect of hydrophobic diamond thin film on biomolecule detection, such as single-nucleotide polymorphisms and human immunodeficiency virus type 1 trans-activator of transcription peptide protein detection, was investigated using a mixture of a fluorine-, amine-, and hydrogen-terminated diamond surfaces. These chemical modifications lead to the formation of a surface that effectively resists the nonspecific adsorption of proteins and other biomolecules. The effect of fluorine plasma treatment on elemental composition was also investigated via X-ray photoelectron spectroscopy (XPS). XPS results revealed a fluorocarbon layer on the diamond thin films. The contact angle measurement results indicated that the fluorine-treated diamond thin films were highly hydrophobic with a surface energy value of similar to 25 mN/m. (C) 2014 Elsevier B.V. All rights reserved.

    DOI

  • Room-temperature amorphous alloy field-effect transistor exhibiting particle and wave electronic transport

    M. Fukuhara, H. Kawarada

    JOURNAL OF APPLIED PHYSICS   117 ( 8 ) 084302/1 - 084302/5  2015年02月  [査読有り]

     概要を見る

    The realization of room-temperature macroscopic field effect transistors (FETs) will lead to new epoch-making possibilities for electronic applications. The I-d-V-g characteristics of the millimeter-sized aluminum-oxide amorphous alloy (Ni0.36Nb0.24Zr0.40)(90)H-10 FETs were measured at a gate-drain bias voltage of 0-60 mu V in nonmagnetic conditions and under a magnetic fields at room temperature. Application of dc voltages to the gate electrode resulted in the transistor exhibiting one-electron Coulomb oscillation with a period of 0.28 mV, Fabry-Perot interference with a period of 2.35 mu V under nonmagnetic conditions, and a Fano effect with a period of 0.26mV for Vg and 0.2 T under a magnetic field. The realization of a low-energy controllable device made from millimeter-sized Ni-Nb-Zr-H amorphous alloy throws new light on cluster electronics. (C) 2015 AIP Publishing LLC.

    DOI

  • Signature of high T c above 25 K in high quality superconducting diamond

    H. Okazaki, T. Wakita, T. Muro, T. Nakamura, Y. Muraoka, T. Yokoya, S. Kurihara, H. Kawarada, T. Oguchi, Y. Takano

    Applied Physics Letters   106 ( 5 ) 052601/1 - 052601/4  2015年02月  [査読有り]

    DOI

  • Functionalized carbon microarrays platform for high sensitive detection of HIV-Tat peptide

    Varun Penmatsa, Ruslinda A. Rahim, Hiroshi Kawarada, Chunlei Wang

    RSC ADVANCES   5 ( 80 ) 65042 - 65047  2015年  [査読有り]

     概要を見る

    The detection of HIV disease at an early stage has significant clinical implications. We report the detection of HIV-TAT peptide on a functionalized three-dimensional carbon micropillar array platform. The sensor showed a linear relationship between HIV-TAT concentration and fluorescence intensity in the sub-nanomolar range with a detection limit of 50 pmol.

    DOI

  • Direct Partial CH3 Termination into Carboxyl Terminated Diamond Surface for Biosensor

    Evi Suaebah, Takuro Naramura, Hiroshi Kawarada

    2015 IEEE SENSORS     1597 - 1600  2015年  [査読有り]

     概要を見る

    Immobilization is an important process of biosensor application. The simplest functionalize diamond surface was done by attached biomolecule on diamond surface with chemical linker compound modification. Carboxyl treatment is one choice for diamond functionalization. Methane gas was diluted with hydrogen gas for CH3 termination as an initial functionalization of diamond to transform to carboxyl termination. Diamond and biomolecule is a couple of highly functionally collaboration for biosensor even with low coverage for carboxyl terminated. This work shows that low coverage of carboxyl (similar to 1%) as the great data with high stability for biosensor applications.

    DOI

  • Depth Profiles of Absorbed Hydrogen in Ni-Nb-Zr Amorphous Alloy Ribbons by Glow Discharge Optical Emission Spectroscopy

    R. Y. Umetsu, M. Saito, T. Sasaki, T. Sekiguchi, J. Mizuno, H. Kawarada

    Open Journal of Metal   4 ( 4 ) 112 - 119  2014年12月  [査読有り]

    DOI

  • ダイヤモンド・トランジスタのバイオセンシングへの適用

    川原田 洋

    化学と工業   67 ( 11 ) 983 - 985  2014年11月  [査読有り]  [招待有り]

  • Substitution Effects of Cr or Fe on the Curie Temperature for Mn-Based Layered Compounds MnAlGe and MnGaGe With Cu2Sb-Type Structure

    Rie Y. Umetsu, Yoshifuru Mitsui, Isamu Yuito, Teruaki Takeuchi, Hiroshi Kawarada

    IEEE TRANSACTIONS ON MAGNETICS   50 ( 11 ) 1001904/1 - 1001904/4  2014年11月  [査読有り]

     概要を見る

    Structure, lattice parameters, spontaneous magnetization (I-s), and the Curie temperature (T-C) of MnAlGe and MnGaGe compounds with the Cu-2 Sb-type structure and their substituted compounds were investigated. Cr substitution for Mn enhanced I-s and T-C, whereas Fe substitution for Mn degraded them. These behaviors are in accord with the previously reported results, and are also common to the MnGaGe compound series. For MnAlGe, lattice parameter a increases by 0.2% and 0.4% for Cr and Fe substitution, while c changes by +0.1% and -1.3%, respectively. For MnGaGe, a decreases by 0.08% for Cr and increases by 0.2% for Fe substitution, while c changes by + 0.5% and -1.0%, respectively. T-C tended to increase with increasing length of c, suggesting that the interlayer distance between Mn layers is a key factor related to the height of T-C, i.e., the strength of the magnetic exchange interaction.

    DOI

  • 終端元素制御によるポリダイヤ電界効果トランジスタセンサの水素イオン感度制御

    新谷幸弘, 小河晃太朗, 猿谷敏之, 川原田洋

    Chem Sens   30 ( Supplement B ) 64 - 66  2014年09月

    CiNii J-GLOBAL

  • C-H surface diamond field effect transistors for high temperature (400°C) and high voltage (500V) operation

    H. Kawarada, H. Tsuboi, T. Naruo, T. Yamada, D. Xu, A. Daicho, T. Saito, A. Hiraiwa

    Appl. Phys. Lett .   105 ( 1 ) 013510/1 - 013510/4  2014年07月  [査読有り]

    DOI

  • High-reliability passivation of hydrogen-terminated diamond surface by atomic layer deposition of Al2O3

    Akira Daicho, Tatsuya Saito, Shinichiro Kurihara, Atsushi Hiraiwa, Hiroshi Kawarada

    JOURNAL OF APPLIED PHYSICS   115 ( 22 ) 223711/1 - 003711/4  2014年06月  [査読有り]

     概要を見る

    Although the two-dimensional hole gas (2DHG) of a hydrogen-terminated diamond surface provides a unique p-type conducting layer for high-performance transistors, the conductivity is highly sensitive to its environment. Therefore, the surface must be passivated to preserve the 2DHG, especially at high temperature. We passivated the surface at high temperature (450 degrees C) without the loss of C-H surface bonds by atomic layer deposition (ALD) and investigated the thermal reliability of the Al2O3 film. As a result, C-H bonds were preserved, and the hole accumulation effect appeared after the Al2O3 deposition by ALD with H2O as an oxidant. The sheet resistivity and hole density were almost constant between room temperature and 500 degrees C by the passivation with thick Al2O3 film thicker than 38 nm deposited by ALD at 450 degrees C. After the annealing at 550 degrees C in air The sheet resistivity and hole density were preserved. These results indicate the possibility of high-temperature application of the C-H surface diamond device in air. In the case of lower deposition temperatures, the sheet resistivity increased after air annealing, suggesting an insufficient protection capability of these films. Given the result of sheet resistivity after annealing, the increase in the sheet resistivity of these samples was not greatly significant. However, bubble like patterns were observed in the Al2O3 films formed from 200 to 400 degrees C by air annealing at 550 degrees C for 1 h. On the other hand, the patterns were no longer observed at 450 degrees C deposition. Thus, this 450 degrees C deposition is the sole solution to enabling power device application, which requires high reliability at high temperatures. (C) 2014 AIP Publishing LLC.

    DOI

  • Diamond surface conductivity: Properties, devices, and sensors

    Christopher I. Pakes, Jose A. Garrido, Hiroshi Kawarada

    MRS BULLETIN   39 ( 6 ) 542 - 548  2014年06月  [査読有り]

     概要を見る

    Hydrogen termination of diamond lowers its ionization energy, driving electron transfer from the valence band into an adsorbed water layer or to a strong molecular acceptor. This gives rise to p-type surface conductivity with holes confined to a subsurface layer of a few nanometers thickness. The transfer doping mechanism, the electronic behavior of the resulting hole accumulation layer, and the development of robust field-effect transistor (FED devices using this platform are reviewed. An alternative method of modulating the hole carrier density has been developed based upon an electrolyte-gate architecture. The operation of the resulting "solution-gated" FET architecture in two contemporary applications will be described: the charge state control of nitrogen-vacancy centers in diamond and biosensing. Despite 25 years of work in this area, our knowledge of surface conductivity of diamond continues to develop.

    DOI

  • Quantum oscillations of the two-dimensional hole gas at atomically flat diamond surfaces

    Yamaguchi Takahide, Hiroyuki Okazaki, Keita Deguchi, Shinya Uji, Hiroyuki Takeya, Yoshihiko Takano, Hidetoshi Tsuboi, Hiroshi Kawarada

    PHYSICAL REVIEW B   89 ( 23 ) 235304/1 - 235304/5  2014年06月  [査読有り]

     概要を見る

    Shubnikov-de Haas oscillations are observed in atomically flat hydrogen-terminated diamond surfaces with high-density hole carriers introduced by the electric field effect using an ionic liquid. The Shubnikov-de Haas oscillations depend only on the magnetic field component perpendicular to the diamond surface, thus providing evidence of two-dimensional Fermi surfaces. The effective masses estimated from the temperature dependence of the oscillations are close to the cyclotron effective masses of the valence band maxima in diamond. The estimated quantum scattering time is one order of magnitude longer than the transport scattering time and indicates that the carrier mobility is locally as high as several thousand cm(2)/V s at low temperature.

    DOI

  • Wide Temperature (10K-700K) and High Voltage (similar to 1000V) Operation of C-H Diamond MOSFETs for Power Electronics Application

    H. Kawarada, T. Yamada, D. Xu, H. Tsuboi, T. Saito, A. Hiraiwa

    2014 IEEE INTERNATIONAL ELECTRON DEVICES MEETING (IEDM)     11.2.1 - 11.2.4  2014年  [査読有り]

     概要を見る

    By forming a highly stable Al2O3 gate oxide on a C-H bonded channel of diamond, high-temperature and high-voltage metal-oxide-semiconductor field-effect transistor (MOSFET) has been realized. From -263 degrees C (10K) to 400 degrees C (673K), the variation of maximum drain-current is within 50% at a given gate bias. The maximum breakdown voltage (VB.,) of the MOSFET without a field plate is 996V at a gate-drain distance (LGD) of 9 mu m. We fabricated some MOSFETs satisfying VB,inaAGD &gt; 200V/[tm (2MV/cm). This value is superior to those of lateral SiC or GaN FETs.

    DOI

  • Synthesis and diffusion of MnBi in high magnetic fields

    M. Mitsui, R.Y. Umetsu, M. Saito, K. Koyama, H. Kawarada

    The International Symposium on Ecotopia Science 2013 and The 5th International Symposium on Advanced Materials Development and Integration of Novel Structural Metallic and Inorganic Materials (ISETS’13 and AMDI-4)     1317  2013年12月

  • Analyzing Hydrogen Charging pf Sputtered Ni-Nb-Zr Films Using Electrochemical Method

    M. Saito, R.Y. Umetsu, T. Sasaki, T. Sekiguch, J. Mizuno, H. Kawarada

    ovel Structural Metallic and Inorganic Materials (ISETS’13 and AMDI-4)     1229  2013年12月

  • Depth Profile Analysis of Hydrogen in Ni-Nb-Zr Amorphous Ribbon by Glow Discharge Optical Emission Spectrometry

    R.Y. Umetsu, M. Saito, T. Sasaki, T. Sekiguch, J. Mizuno, H. Kawarada

    The International Symposium on Ecotopia Science 2013 and The 5th International Symposium on Advanced Materials Development and Integration of Novel Structural Metallic and Inorganic Materials (ISETS’13 and AMDI-4)     1235  2013年12月

  • Magnetic properties and phase state of layered compound of (Mn,TM)XGe (TM = Fe and Cr, X = Al and Ga)

    R.Y. Umetsu, Y. Mitsui, I. Yuito, T. Takeuchi, H. Kawarada

    The International Symposium on Ecotopia Science 2013 and The 5th International Symposium on Advanced Materials Development and Integration of Novel Structural Metallic and Inorganic Materials (ISETS’13 and AMDI-4)     1250  2013年12月

  • Transport Properties of Ni-Nb-Zr Glassy Alloys and Hydrogen Absorbed Alloys

    Rie Y. Umetsu, Hajime Yoshida, Mikio Fukuhara, Shin-ichi Yamaura, Toshio Sasaki, Tetsushi Sekiguchi, Mikiko Saito, Jun Mizuno, Hiroshi Kawarada

    OJMetal   3 ( 3 ) 45 - 49  2013年09月  [査読有り]

    DOI

  • Low-Temperature Transport Properties of Holes Introduced by Ionic Liquid Gating in Hydrogen-Terminated Diamond Surfaces

    Takahide Yamaguchi, Eiichiro Watanabe, Hirotaka Osato, Daiju Tsuya, Keita Deguchi, Tohru Watanabe, Hiroyuki Takeya, Yoshihiko Takano, Shinichiro Kurihara, Hiroshi Kawarada

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   82 ( 7 ) 074718/1 - 074718/6  2013年07月  [査読有り]

     概要を見る

    The surface conductivity of (111)- and (100)-oriented hydrogen-terminated diamonds was investigated at low temperatures for different carrier densities. The carrier density was controlled in a wide range in an electric double-layer transistor configuration using ionic liquids. As the carrier density was increased, the temperature dependences of sheet resistance and mobility changed from semiconducting to metallic ones: the sheet resistance and mobility for the (111) surface were nearly independent of temperature for a sheet carrier density of approximate to 4 x 10(13) cm(-2), indicating metallic carrier transport. It was also found that the interface capacitance, determined from the gate voltage dependence of the Hall carrier density, depended significantly on the crystal orientation.

    DOI

  • Figure of merit of diamond power devices based on accurately estimated impact ionization processes

    Atsushi Hiraiwa, Hiroshi Kawarada

    J. Appl. Phys.   114 ( 3 ) 034506/1 - 034506/9  2013年07月

    DOI

  • Understanding the stability of a sputtered Al buffer layer for single-walled carbon nanotube forest synthesis

    Toshiyuki Ohashi, Ryogo Kato, Toshio Tokune, Hiroshi Kawarada

    CARBON   57   401 - 409  2013年06月  [査読有り]

     概要を見る

    We have clarified the reason that aluminum (Al) buffer layers prepared by sputtering on catalytic substrates are stable for single-walled carbon nanotube forest synthesis on chemical vapor deposition. We have focused on the difference between thermal evaporation and sputtering as the method for the preparation of the buffer layers and have analyzed the Al layers using X-ray photoelectron spectroscopy and transmission electron microscopy. Al layers produced by sputtering strongly suggest the formation of gamma-alumina by aluminum hydroxides while those from thermal evaporation contain metallic Al. As a result a drastic structural change occurs during thermal annealing, making the buffer layer unstable. (C) 2013 Elsevier Ltd. All rights reserved.

    DOI

  • Increasing the length of a single-wall carbon nanotube forest by adding titanium to a catalytic substrate

    Toshiyuki Ohashi, Takumi Ochiai, Toshio Tokune, Hiroshi Kawarada

    Carbon   57   79 - 87  2013年06月

     概要を見る

    The effect of titanium (Ti) added to the top layer of an aluminum (Al)/iron (Fe)/Al (bottom) sandwich catalytic substrate was studied. The Ti caused a significant lengthening in the single-wall carbon nanotube forest produced by chemical vapor deposition (CVD). In general, particles of iron oxide on the Al/Fe/Al catalytic substrate are formed by exposure to the atmosphere during deposition process of the substrate. The particles of iron oxide are metalized during pretreatment under a reductive gas before the growth of the nanotubes with nano-sized dispersion stabilized. On this process, the metallization and the stabilization of nano-sized iron oxide particles occur on the basis of the oxygen affinity in the top aluminum oxide layer, with the ionization tendency Al &gt
    Fe. It is thought that the addition of Ti increases the oxygen affinity of the catalytic substrate, since Ti has a stronger ionization tendency than Al. After optimizing the quantity of Ti added to the top layer, we successfully fabricated a millimeter-long, small-diameter, single-wall carbon nanotube forest. © 2013 Elsevier Ltd. All rights reserved.

    DOI

  • SPATIAL VARIATION OF TUNNELING SPECTRA IN (111)-ORIENTED FILMS OF BORON-DOPED DIAMOND PROBED BY STM/STS

    Terukazu Nishizaki, Takahiko Sasaki, Norio Kobayashi, Yoshihiko Takano, Masanori Nagao, Hiroshi Kawarada

    INTERNATIONAL JOURNAL OF MODERN PHYSICS B   27 ( 15 ) 1362014/1 - 1362014/7  2013年06月  [査読有り]

     概要を見る

    We report on scanning tunneling microscopy/spectroscopy (STM/STS) experiments on boron-doped diamond films. The tunneling conductance dI/dV spectra measured on the (111)-oriented surface show spatial variations which distribute irrespective of the surface morphology. The spatial variations are discussed in terms of characteristic features of the superconductivity under the condition of the considerable disorder by the boron doping.

    DOI

  • ボロンドープ多結晶ダイヤモンドトランジスタセンサのpH感応特性

    新谷幸弘, 明道三穗, 井堀翔志, 川原田洋

    Chem Sens   29 ( Supplement A ) 16 - 18  2013年03月

    CiNii J-GLOBAL

  • Effects of diamond-FET-based RNA aptamer sensing for detection of real sample of HIV-1 Tat protein

    A. Rahim Ruslinda, Kyosuke Tanabe, Shoji Ibori, Xianfen Wang, Hiroshi Kawarada

    BIOSENSORS & BIOELECTRONICS   40 ( 1 ) 277 - 282  2013年02月  [査読有り]

     概要を見る

    Diamond is a promising material for merging solid-state and biological systems owing to its chemical stability, low background current, wide potential window and biocompatibility. The effects of surface charge density on human immunodeficiency virus type 1 Trans-activator transcription (HIV-1 Tat) protein binding have been investigated on a diamond field-effect transistor (FET) using ribonucleic acid (RNA) aptamers as a sensing element on a solid surface. A change in the gate potential of 91.6 mV was observed, whereby a shift in the negative direction was observed at a source-drain current of -8 mu A in the presence of HIV-1 Tat protein bound to the RNA aptamers. Moreover, the reversible change in gate potential caused by the binding and regeneration cycles was very stable throughout cyclical detections. The stable immobilization is achieved via RNA aptamers covalently bonded to the carboxyl-terminated terephtalic acids on amine sites, thereby increasing the sensitivity of the HIV-1 Tat protein sensor. The reliable use of a real sample of HIV-1 Tat protein by an aptamer-FET was demonstrated for the first time, which showed the potential of diamond biointerfaces in clinical biosensor applications. (C) 2012 Elsevier B.V. All rights reserved.

    DOI

  • Effect of hydrogen and cluster morphology on the electronic behavior of Ni-Nb-Zr-H glassy alloys with subnanometer-sized icosahedral Zr5Ni5Nb5 clusters

    Mikio Fukuhara, Hajime Yoshida, Hiroshi Kawarada

    EUROPEAN PHYSICAL JOURNAL D   67 ( 2 ) 40/1 - 40/4  2013年02月  [査読有り]

     概要を見る

    The effects of hydrogen content and cluster morphology on the electronic transport behavior of (Ni0.36Nb0.24Zr0.40)(100-x)H-x (0 &lt; x &lt; 20) glassy alloys containing distorted nanostructural icosahedral Zr5Nb5Ni3 clusters have been studied. When the hydrogen content is less than 7 at%, the hydrogen atom is localized between Ni atoms of neighboring distorted icosahedral Zr5Ni5Nb3 clusters. The I-d-V-g-B characteristics of the (Ni0.36Nb0.4Zr0.40)(90)H-10 glassy alloy field-effect transistor (GAFET) showed room-temperature three-dimensional Coulomb oscillation and the Fano effect, which arises from interference of electrons traveling through two different cluster configurations, namely a localized discrete state inside the quantum dot and a continuum in the arm.

    DOI

  • Platelet-derived growth factor oncoprotein detection using three-dimensional carbon microarrays

    Varun Penmatsa, A. Rahim Ruslinda, Majid Beidaghi, Hiroshi Kawarada, Chunlei Wang

    BIOSENSORS & BIOELECTRONICS   39 ( 1 ) 118 - 123  2013年01月  [査読有り]

     概要を見る

    The potential of aptamers as ligand binding molecule has opened new avenues in the development of biosensors for cancer oncoproteins. In this paper, a label-free detection strategy using signaling aptamer/protein binding complex for platelet-derived growth factor (PDGF-BB) oncoprotein detection is reported. The detection mechanism is based on the release of fluorophore (TOTO intercalating dye) from the target binding aptamer's stem structure when it captures PDGF. Amino-terminated three-dimensional carbon microarrays fabricated by pyrolyzing patterned photoresist were used as a detection platform. The sensor showed near linear relationship between the relative fluorescence difference and protein concentration even in the sub-nanomolar range with an excellent detection limit of 5 pmol. This detection strategy is promising in a wide range of applications in the detection of cancer biomarkers and other proteins. (C) 2012 Elsevier B.V. All rights reserved.

    DOI

  • Functionalized three-dimensional carbon microarrays for cancer biomarker detection

    V. Penmatsa, A. R. Ruslinda, M. Beidaghi, H. Kawarada, C. Wang

    ECS Transactions   45 ( 15 ) 7 - 14  2013年

     概要を見る

    A label-free detection strategy for the detection of platelet-derived growth factor (PDGF-BB) oncoprotein detection using signaling aptamer/protein binding complex is reported. The 3D carbon microarrays detection platform was fabricated by pyrolyzing patterned photoresist and surface functionalized using directamination technique. The detection strategy is based on the release of TOTO intercalating dye from the target binding aptamer's stem structure when it captures PDGF. The sensor showed near linear relationship between the relative fluorescence difference and protein concentration with a very good detection limit of 5 pmol. This detection strategy is promising for the potential detection of different cancer biomarkers and proteins.

    DOI

  • Effect of hydrogen absorption on electrical transport properties for Ni36Nb24Zr40 amorphous alloy ribbons

    Rie Y. Umetsu, Hajime Yoshida, Mikio Fukuhara, Shin-Ichi Yamaura, Makoto Matsuura, Toshio Sasaki, Tetsushi Sekiguchi, Mikiko Saito, Jun Mizuno, Hiroshi Kawarada

    Materials Transactions   54 ( 8 ) 1339 - 1342  2013年

     概要を見る

    Electrical resistivity measurements in the temperature range from 6 to 300K were carried out in order to investigate the effects of the hydrogen absorption on the transport properties of Ni36Nb24Zr40 amorphous alloy ribbon. The electrical resistivity basically behaved negative temperature dependence in all prepared specimens of (Ni0.36Nb 0.24Zr0.40)100-xHx with 0 ≤ x &lt
    15. The absolute value of temperature coefficient of the resistivity, TCR, increased with increasing the amount of the absorbed hydrogen. In addition, it was also clear that the electrical resistivity gradually increased with the time just after electrochemically charging, and tended to saturate after about 800 ks at 300 K. The behavior of the gradual increase in the electrical resistivity with the time was explained by the model including two kinds of the relaxation times, being associated with the migration of the hydrogen from the sample surface. © 2013 The Japan Institute of Metals and Materials.

    DOI

  • Accuracy assessment of sheet-charge approximation for Fowler-Nordheim tunneling into charged insulators

    Atsushi Hiraiwa, Tatsuya Saito, Akira Daicho, Hiroshi Kawarada

    Journal of Applied Physics   114 ( 13 ) 134501/1 - 134501/9  2013年

     概要を見る

    Various insulators are used as gate dielectrics and passivation layers in wide-bandgap (WBG) semiconductor devices as well as in advanced Si devices, and the understanding of their current conduction mechanism is essential to achieve their high performance and high reliability. Because these insulators are more or less charged, the conduction current is mostly caused by the Fowler-Nordheim (FN) tunneling into charged insulators, ruling out the conventional analytic FN formula. In order to facilitate the analysis of these currents, we focused on the method, named sheet-charge approximation (SCA), of approximating the charge distribution in the insulators by a charge sheet that has the same areal density and centroid as those of the original. Using, as references, the results obtained exactly calculating the tunneling current in the framework of the Wentzel-Kramers-Brillouin approximation, we confirmed the advantage of SCA over the previous method using a tunneling-endpoint field, the error of SCA-estimated areal charge densities being at most 30% for rectangular charge distributions of which charge centroids are known as in stacked films. In a more general case where the centroid is unknown, the SCA usually provides only a charge moment with reference to the insulator/anode interface, being unable to decompose the moment into the areal charge density and centroid. However, this demerit of SCA can be overcome through a reverse-biased current-voltage measurement using a capacitor formed on a heavily doped substrate or a capacitor with a diffusion layer attached, which measurement provides a charge moment with reference to the original cathode/insulator interface. Using these two kinds of charge moments, we can separately extract the areal charge density and centroid. Hence, the SCA has practical significance as a tool for analyzing conduction currents through charged insulators, especially through stacked films, and accordingly will play an important role in improving the performance and reliability of gate dielectrics and passivation layers for various WBG semiconductor devices as well as of high-k gate stacks for advanced Si devices. © 2013 AIP Publishing LLC.

    DOI

  • Refractory two-dimensional hole gas on hydrogenated diamond surface

    Atsushi Hiraiwa, Akira Daicho, Shinichiro Kurihara, Yuki Yokoyama, Hiroshi Kawarada

    JOURNAL OF APPLIED PHYSICS   112 ( 12 ) 124504  2012年12月  [査読有り]

     概要を見る

    Use of two-dimensional hole gas (2DHG), induced on a hydrogenated diamond surface, is a solution to overcoming one of demerits of diamond, i.e., deep energy levels of impurities. This 2DHG is affected by its environment and accordingly needs a passivation film to get a stable device operation especially at high temperature. In response to this requirement, we achieved the high-reliability passivation forming an Al2O3 film on the diamond surface using an atomic-layer-deposition (ALD) method with an H2O oxidant at 450 degrees C. The 2DHG thus protected survived air annealing at 550 degrees C for an hour, establishing a stable high-temperature operation of 2DHG devices in air. In part, this achievement is based on high stability of C-H bonds up to 870 degrees C in vacuum and above 450 degrees C in an H2O-containing environment as in the ALD. Chemically, this stability is supported by the fact that both the thermal decomposition of C-H bonds and reaction between C-H bonds and H2O are endothermic processes. It makes a stark contrast to the instability of Si-H bonds, which decompose even at room temperature being exposed to atomic hydrogen. In this respect, the diamond 2DHG devices are also promising as power devices expectedly being free from many instability phenomena, such as hot carrier effect and negative-bias temperature instability, associated with Si devices. As to adsorbate, which is the other prerequisite for 2DHG, it desorbed in vacuum below 250 degrees C, and accordingly some new adsorbates should have adsorbed during the ALD at 450 degrees C. As a clue to this question, we certainly confirmed that some adsorbates, other than those at room temperature, adsorbed in air above 100 degrees C and remained at least up to 290 degrees C. The identification of these adsorbates is open for further investigation. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4769404]

    DOI

  • Mesoporous NiO nanomagnets as catalysts and separators of chemical agents

    Mohamed Khairy, Sherif A. El-Safty, Mohamed Ismael, Hiroshi Kawarada

    APPLIED CATALYSIS B-ENVIRONMENTAL   127 ( 1-10 ) 1 - 10  2012年10月  [査読有り]

     概要を見る

    The development of a sustainable catalyst could potentially provide a long-term solution to industrial processes, especial those in the chemical industry, that require the production of a large quantity of raw materials manufactured from renewable resources. Therefore, establishing a proper design for a highly efficient and long-term reusable catalyst is one of the crucial environmental issues facing humanity. In this study, we developed a simple control for hierarchal mesoporous nickel oxide (NiO) nanomagnets (NMs) with flower- and sphere-like morphology and large mesocage cavities. In the fabrication of super-nanostructure NiO, features that were affected by the shape, surface, and size of particles exhibit high catalytic activities of chemical agents, such as o-aminophenol. Our findings shows that the NiO NM with flower-like morphology NFs has higher catalytic activity toward the oxidation of organic contaminates than that of nanospheres NSs or even other magnetic nanoparticles (NPs) such as Fe3O4 NPs. Furthermore, the NiO NMs are capable of the high-gradient magnetic separation of organic contaminants from aquatic life with excellent reusability even after several cycles, which may help in wastewater management and supply. To understand the effectiveness of NiO NM functionalities in terms of hierarchical mesocage parameters, as well as in terms of shape- and size-morphologies in such chemical reactions, surface interaction and magnetic separation with chemical agents and theoretical calculations were performed. (C) 2012 Elsevier B.V. All rights reserved.

    DOI

  • High Priority of Nanocrystalline Diamond as a Biosensing Platform

    Xianfen Wang, Shinichiro Kurihara, Masataka Hasegawa, A. Rahim Ruslinda, Hiroshi Kawarada

    JAPANESE JOURNAL OF APPLIED PHYSICS   51 ( 9 ) 090125  2012年09月  [査読有り]

     概要を見る

    Here we report the performance of surface functionalized diamond surfaces as biosensing platform for human immunodeficiency virus transactivator of transcription (HIV-Tat) peptide detection. Comparative investigations were conducted on nanocrystalline diamond (NCD) and polycrystalline diamond (PCD) films. Scanning electron microscopy (SEM) images revealed the morphology differences between NCD and PCD films. X-ray photoelectron spectroscopy (XPS) data showed that functional components and corresponding coverages, demonstrating denser carboxyl acid groups and fluorinated groups on NCD than that PCD films after UV/ozone and fluorine plasma treatment respectively. Contact angle results showed the differences in surface wettability and free energy between functionalized NCD and PCD biosensors. Fluorescence observations confirmed that higher biosensing performance can be obtained on NCD biosensors with high sensitivity selectivity, and stability. The NCD films with denser surface coverages of functionalizations made NCD films much more priority as an effective biosensing candidate than PCD films. (C) 2012 The Japan Society of Applied Physics

    DOI

  • Multidirectional porous NiO nanoplatelet-like mosaics as catalysts for green chemical transformations

    Sherif A. El-Safty, Mohamed Khairy, Mohamd Ismael, Hiroshi Kawarada

    APPLIED CATALYSIS B-ENVIRONMENTAL   123   162 - 173  2012年07月

     概要を見る

    The design of multidirectional porous metal oxide catalysts has attracted extensive attention because such materials have potential for environmental applications. To satisfy the requirements of these applications, large-scale production, low-cost manufacturing, and efficient transformation reactions are needed. The present paper reports the fabrication of hierarchical nickel oxide nanocrystals (NiO NCs) with hexagonal nanoplatelets and micro-, meso-, and macropore cavities through an eco-friendly method. The controlled size and shape of the NiO platelets in condensed orientation sequence "tesserae blocks" led to the formation of a hexagonal mosaic-like morphology. The NiO NCs could be recovered and reused without lost of activity over a number of batch reactions. In addition, theoretical models to predict the molecular structures of both the intermediate and transition states within the chemical transformation reactions were developed. The theoretical findings in the current study provide insight into the key factors that control the changes in the molecular structure throughout the transformation mechanism of the phenolic pollutants using NiO platelet nanocatalysts. (C) 2012 Elsevier B.V. All rights reserved.

    DOI

  • Multidirectional porous NiO nanoplatelet-like mosaics as catalysts for green chemical transformations

    Sherif A. El-Safty, Mohamed Khairy, Mohamd Ismael, Hiroshi Kawarada

    APPLIED CATALYSIS B-ENVIRONMENTAL   123   162 - 173  2012年07月  [査読有り]

     概要を見る

    The design of multidirectional porous metal oxide catalysts has attracted extensive attention because such materials have potential for environmental applications. To satisfy the requirements of these applications, large-scale production, low-cost manufacturing, and efficient transformation reactions are needed. The present paper reports the fabrication of hierarchical nickel oxide nanocrystals (NiO NCs) with hexagonal nanoplatelets and micro-, meso-, and macropore cavities through an eco-friendly method. The controlled size and shape of the NiO platelets in condensed orientation sequence "tesserae blocks" led to the formation of a hexagonal mosaic-like morphology. The NiO NCs could be recovered and reused without lost of activity over a number of batch reactions. In addition, theoretical models to predict the molecular structures of both the intermediate and transition states within the chemical transformation reactions were developed. The theoretical findings in the current study provide insight into the key factors that control the changes in the molecular structure throughout the transformation mechanism of the phenolic pollutants using NiO platelet nanocatalysts. (C) 2012 Elsevier B.V. All rights reserved.

    DOI

  • Effective Surface Functionalization of Nanocrystalline Diamond Films by Direct Carboxylation for PDGF Detection via Aptasensor

    Xianfen Wang, Yoko Ishii, A. Rahim Ruslinda, Masataka Hasegawa, Hiroshi Kawarada

    ACS APPLIED MATERIALS & INTERFACES   4 ( 7 ) 3526 - 3534  2012年07月  [査読有り]

     概要を見る

    An aptasensor was designed on a nanocrystalline diamond (NCD) surface that combined with biological recognition elements, PDGF-binding aptamers, which inherently possess high affinity to PDGF-BB proteins. Functional components such as carboxylic acids (-COOH) and amines (-NH2) were directly introduced onto the NCD surface and used as probing units for immobilization of PDGF-binding aptamers. The surface coverage of different components on the NCD was analyzed by X-ray photoelectron spectroscopy (XPS) measurements, and the effects of various functionalizations on the NCD biosensor performance were investigated via fluorescence observations. The coverages of carboxyl and amine groups achieved were 12 and 23%, respectively, for the directly aminated and carboxylated NCD; however, the lower density of carboxyl groups on the functionalized surface did not deteriorate the performance of the COOH-NCD biosensor. Fluorescence investigations demonstrated comparable performance in sensitivity and selectivity for PDGF protein detection on COOH-NCD and NH2-NCD biosensors. Multiple regeneration tests clearly showed that the COOH-NCD biosensor as well as the NH2-NCD biosensor retained a high performance without exhibiting any noticeable degradation.

    DOI

  • Vertical SNS weak-link Josephson junction fabricated from only boron-doped diamond

    M. Watanabe, R. Kanomata, S. Kurihara, A. Kawano, S. Kitagoh, T. Yamaguchi, Y. Takano, H. Kawarada

    PHYSICAL REVIEW B   85 ( 18 ) 184516  2012年05月  [査読有り]

     概要を見る

    A vertical superconductor/normal conductor/superconductor (SNS) weak-link Josephson junction has been successfully fabricated from only homoepitaxial diamond films. Superconducting diamond, normal-state diamond, and superconducting diamond are homoepitaxially grown in a sequence. The temperature dependence of the critical superconducting current was fitted using Likharev's theory of SNS weak-link junctions. When the normal-state-diamond thickness L is much larger than the coherent length in the normal-state-diamond xi(n), an exponential temperature dependence of normalized critical current was observed, indicating a proximity effect. Shapiro steps in the current-voltage characteristics under microwave irradiation were observed in the junction with L &gt;&gt;xi(n).

    DOI

  • Capacitance Distribution of Ni-Nb-Zr-H Glassy Alloys

    Mikio Fukuhara, Hajime Yoshida, Nobuhisa Fujima, Hiroshi Kawarada

    JOURNAL OF NANOSCIENCE AND NANOTECHNOLOGY   12 ( 5 ) 3848 - 3852  2012年05月  [査読有り]

     概要を見る

    Capacitance distribution of {(Ni0.6Nb0.4)(1-x)Zr-x}(100-y)-H-y (x = 0.30, 0.35, 0.40, 0.45 and 0.50, 0 &lt;= y &lt;= 20) glassy alloy ribbons was carried out by ac impedance analysis at frequency of 1 kHz, in terms of a distributed constant equivalent circuit. The capacitance can be represented by oblique contour lines. The highest capacitance (1-11 mu F) could be found near the point when x = 0.40, y = 10, which is a composition occurring room-temperature Coulomb oscillation, while capacitance of the composition (x = 0.35, y = 4) occurring ballistic transport was around 0.8 mu F. The capacitance difference would be explained by an effect of hydrogen localization derived from morphology of distorted Zr-centered icosahedral Zr5Ni5Nb3 clusters and ideal Ni-centered clusters. The electrocapillarity equation showed that the specific capacitance between two electrodes increases parabolic with decreasing the distance, as a polarized glutinous liquid.

    DOI

  • High quality single-walled carbon nanotube synthesis using remote plasma CVD

    Toshiyuki Ohashi, Ryogo Kato, Takumi Ochiai, Toshio Tokune, Hiroshi Kawarada

    DIAMOND AND RELATED MATERIALS   24   184 - 187  2012年04月  [査読有り]

     概要を見る

    Single-walled carbon nanotube (SWNT) forest synthesis using antenna-type remote plasma chemical vapor deposition (ARPCVD) is presented. A series of synthesis using carbon monoxide gas as carbon feedstock reveals that the remote conditions, in other words, distance between an antenna and a substrate affects the quality of nanotube significantly. That is, far distance geometry on ARPCVD creates high-quality SWNTs. It motivates us to use same methodology for the synthesis using CH4/H-2 previously proven to make long SWNT forests. Finally, along the methodology, we achieve to make SWNT forest with high-quality and small diameter successfully. This study offers an important suggestion to embody SWNT forests with both length and quality using remote plasma CVD. (C) 2012 Elsevier B.V. All rights reserved.

    DOI

  • Controllable oxidization of boron doped nanodiamond covered with different solution via UV/ozone treatment

    X. F. Wang, M. Hasegawa, K. Tsugawa, A. R. Ruslinda, H. Kawarada

    DIAMOND AND RELATED MATERIALS   24   146 - 152  2012年04月  [査読有り]

     概要を見る

    UV/ozone irradiation was designed for controllable oxidation of nanodiamond films with distinctive chemical species. XPS investigation revealed that various kinds of oxygen-related chemical components would be functionalized onto nanodiamond surface covered by selective liquids for UV/ozone treatment. And the results of contact angle tests were in good accordance with the oxygen contents revealed from the deconvoluted C 1 s peaks. The covered solution on the nanodiamond film was found to be one significant factor besides Uv/ozone illumination. Surface chemical components and the wettability were proved to be closely dependent on the covered liquids on the UV/ozone treated nanodiamond surface. Without any cover solution, heavy defects would be induced on nanodiamond via direct UV/ozone irradiation. However, basic solution rich with OH anions would be taken as an effective way for controllable oxidation, achieving high percentage of COOH but less defects on the nanocrystalline diamond surface. This controllable oxidation strategy would be widely applied for controllable surface modification of nanodiamond films in the device field. (C) 2011 Elsevier B.V. All rights reserved.

    DOI

  • Boron δ-doped (111) diamond solution gate field effect transistors

    R.Edgington, A.R.Ruslinda, S.Sato, Y.Ishiyama, K.Tsuge, T.Ono, H.Kawarada

    Biosensors and Bioelectronics   33 ( 1 ) 152 - 157  2012年03月  [査読有り]

    DOI

  • Growth and electrical characterisation of δ-doped boron layers on (111) diamond surfaces

    R. Edgington, S. Sato, Y. Ishiyama, R. Morris, R. B. Jackman, Hiroshi Kawarada

    J. Appl. Phys.   111 ( 3 ) 033710 - 033710  2012年02月  [査読有り]

    DOI

  • Highly sensitive detection of platelet-derived growth factor on a functionalized diamond surface using aptamer sandwich design

    A. Rahim Ruslinda, Varun Penmatsa, Yoko Ishii, Shinya Tajima, Hiroshi Kawarada

    ANALYST   137 ( 7 ) 1692 - 1697  2012年  [査読有り]

     概要を見る

    Aptamer-based fluorescence detection of platelet-derived growth factor (PDGF) on a functionalized diamond surface was demonstrated. In this work, a sandwich design based on the ability of PDGF to bind with aptamers at its two available binding sites was employed. It was found that this sandwich design approach significantly increases the fluorescence signal intensity, and thereby a very low detection limit of 4 pM was achieved. The effect of the ionic strength of MgCl2 buffer solution was also investigated, and the most favourable binding for PDGF-BB occurred at a Mg2+ concentration of 5.5 mM. Since the aptamers bind to the target PDGF with high affinity, fluorescence detection exhibited high selectivity towards different biomolecules. The high reproducibility of detection was confirmed by performing three cycles of measurements over a period of three days.

    DOI

  • High Frequency Operation of H-terminated Diamond FETs

    H.Kawarada

    Jpn. J. Appl. Phys.   51 ( 9 ) 090111  2012年

    DOI

  • Fluorescence-Signaling Aptasensor for ATP and PDGF Detection on Functionalized Diamond Surface

    A. Rahim Ruslinda, Y. Ishiyama, X. Wang, T. Kobayashi, H. Kawarada

    JOURNAL OF THE ELECTROCHEMICAL SOCIETY   159 ( 5 ) J182 - J187  2012年  [査読有り]

     概要を見る

    An aminated diamond-based aptasensor is presented for adenosine triphosphate (ATP) and platelet-derived growth factor (PDGF) detection. In this work, a signal-off detection method was employed to provide a sensitive, selective and reusable platform for the simple detection of PDGF and ATP. The detection limit of 0.2 nM and 0.2 mu M of PDGF and ATP were achieved, respectively. It was also demonstrated in this study that the aptasensor is selective for PDGF and ATP over other biomolecules. In addition, the reusability of the aptasensor was confirmed by performing multiple cycles, which shows that diamond is a promising candidate as a material for biosensor applications. Moreover, this detection system does not require a target label and it is unaffected by non-specific binding. (C) 2012 The Electrochemical Society. [DOI: 10.1149/2.083205jes]

    DOI

  • Higher coverage of carboxylic acid groups on oxidized single crystal diamond (001)

    Xianfen Wang, A. Rahim Ruslinda, Yuichiro Ishiyama, Yoko Ishii, Hiroshi Kawarada

    DIAMOND AND RELATED MATERIALS   20 ( 10 ) 1319 - 1324  2011年11月  [査読有り]

     概要を見る

    The effects of crystal orientation to the surface chemistry of single crystal diamond (001) and (111) were investigated after wet chemical oxidation. Direct carboxylation has been successfully achieved via wet chemical oxidation on native diamond (001) and (111) surface with distinguished portions of carboxylic acid groups (-COOH). High resolution X-ray photoelectron spectroscopy (XPS) analysis revealed that various kinds of chemical groups including both single and double oxygen-related components were covalently functionalized onto the single crystal diamond. The percentages of -COOH are approximately 9.2% and 4.7% on (001) and (111) surface respectively, showing evidently that the density of -COOH groups on (001) surface is surprisingly higher than that of (111) surface. Comprehensive comparison revealed that oxygen-related groups is higher on (001) compared with that of (111) surface. The conversion mechanism was supposed to explain the evolution from hydrogenated to oxygenated functionalizations on diamond with differently oriented crystal facets, and the crystal orientation was the significant factor in controlling the surface reactivity and hence the oxidization process. (C) 2011 Elsevier B.V. All rights reserved.

    DOI

  • Human immunodeficiency virus trans-activator of transcription peptide detection via ribonucleic acid aptamer on aminated diamond biosensor

    A. Rahim Ruslinda, Xianfen Wang, Yoko Ishii, Yuichiro Ishiyama, Kyosuke Tanabe, Hiroshi Kawarada

    APPLIED PHYSICS LETTERS   99 ( 12 ) 123702  2011年09月  [査読有り]

     概要を見る

    The potential of ribonucleic acid (RNA) as both informational and ligand binding molecule have opened a scenario in the development of biosensors. An aminated diamond-based RNA aptasensor is presented for human immunodeficiency virus (HIV) trans-activator of transcription (Tat) peptide protein detection that not only gives a labeled or label-free detection method but also provides a reusable platform for a simple, sensitive, and selective detection of proteins. The immobilized procedure was based on the binding interaction between positively charged amine terminated diamond and the RNA aptamer probe molecules with the negatively charged surface carboxylic compound linker molecule such as terephthalic acid. (C) 2011 American Institute of Physics. [doi:10.1063/1.3643067]

    DOI

  • Diamond electrolyte solution gate FETs for DNA and protein sensors using DNA/RNA aptamers

    H. Kawarada, A. R. Ruslinda

    PHYSICA STATUS SOLIDI A-APPLICATIONS AND MATERIALS SCIENCE   208 ( 9 ) 2005 - 2016  2011年09月  [査読有り]

     概要を見る

    For DNA and protein detection, we have analyzed DNA/RNA immobilized biosensors based on diamond field effect transistors (FETs), where several types of atomic or molecule termination have been realized on their surfaces. Amine termination and carboxyl termination necessary for biomolecule immobilization can be formed directly on the diamond surfaces resulting in the immobilization of short DNA/RNA within 5 nm from the surface. Owing to the high areal capacitance of a liquid electric double layer capacitor and a solid channel capacitor, the change in the surface charge caused by the hybridization of DNA/RNA and the protein binding to DNA/RNA aptamers can be efficiently detected. The charge of surface termination groups such as NH3+, O-, COO- affects the suppression of nonspecific binding. The detection of biomolecules such as one-base mismatch of DNA and proteins that is unaffected by nonspecific binding can be realized as a result. (C) 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

    DOI

  • Photoemission study of electronic structure evolution across the metal-insulator transition of heavily B-doped diamond

    H. Okazaki, T. Arakane, K. Sugawara, T. Sato, T. Takahashi, T. Wakita, M. Hirai, Y. Muraoka, Y. Takano, S. Ishii, S. Iriyama, H. Kawarada, T. Yokoya

    JOURNAL OF PHYSICS AND CHEMISTRY OF SOLIDS   72 ( 5 ) 582 - 584  2011年05月  [査読有り]

     概要を見る

    We studied the electronic structure evolution of heavily B-doped diamond films across the metal-insulator transition (MIT) using ultraviolet photoemission spectroscopy (UPS). From high-temperature UPS, through which electronic states near the Fermi level (E(F)) up to similar to 5k(B)T can be observed (k(B) is the Boltzmann constant and T the temperature), we observed the carrier concentration dependence of spectral shapes near E(F). Using another carrier concentration dependent UPS, we found that the change in energy position of sp-band of the diamond valence band, which corresponds to the shift of E(F), can be explained by the degenerate semiconductor model, indicating that the diamond valence band is responsible for the metallic states for samples with concentrations above MIT. We discuss a possible electronic structure evolution across MIT. (C) 2010 Elsevier Ltd. All rights reserved.

    DOI

  • Fabrication of Metal-Oxide-Diamond Field-Effect Transistors with Submicron-Sized Gate Length on Boron-Doped (111) H-Terminated Surfaces Using Electron Beam Evaporated SiO2 and Al2O3

    Takeyasu Saito, Kyung-Ho Park, Kazuyuki Hirama, Hitoshi Umezawa, Mitsuya Satoh, Hiroshi Kawarada, Zhi-Quan Liu, Kazutaka Mitsuishi, Kazuo Furuya, Hideyo Okushi

    JOURNAL OF ELECTRONIC MATERIALS   40 ( 3 ) 247 - 252  2011年03月  [査読有り]

     概要を見る

    A H-terminated surface conductive layer of B-doped diamond on a (111) surface was used to fabricate a metal-oxide-semiconductor field-effect transistor (MOSFET) using an electron beam evaporated SiO2 or Al2O3 gate insulator and a Cu-metal stacked gate. When the bulk carrier concentration was approximately 10(15)/cm(3) and the B-doped diamond layer was 1.5 mu m thick, the surface carrier mobility of the H-terminated surface on the (111) diamond before FET processing was 35 cm(2)/Vs and the surface carrier concentration was 1.5 9 10(13)/cm(2). For the SiO2 gate (0.76 mu m long and 50 mu m wide), the maximum measured drain current at a gate voltage of -3.0 V was -75 mA/mm and the maximum transconductance was 24 mS/mm, and for the Al2O3 gate (0.64 mu m long and 50 mu m wide), these features were -86 mA/mm and 15 mS/mm, respectively. These values are among the highest reported direct-current (DC) characteristics for a diamond homoepitaxial (111) MOSFET.

    DOI

  • Aptasensor for Oncoprotein Platelet-Derived Growth Factor Detection on Functionalized Diamond Surface by Signal-Off Optical Method

    Yoko Ishii, Shinya Tajima, Hiroshi Kawarada

    APPLIED PHYSICS EXPRESS   4 ( 2 ) 027001 - 027001  2011年02月  [査読有り]

     概要を見る

    The highly sensitive detection of platelet-derived growth factor (PDGF) has been realized using aptamers immobilized on a diamond surface. The detection mechanism of PDGF is based on the release of an intercalating dye from the aptamer&apos;s stem structure during deformation when the aptamer captures PDGF. The detection by fluorescence reduction (signal-off method) does not require a target label and is unaffected by nonspecific binding. The high reproducibility of detection was confirmed. Since aptamers bind to their target PDGF with high affinity, the sensor exhibited high selectivity and sensitivity. The quantitation limit was determined to be 1 pM. (C) 2011 The Japan Society of Applied Physics

    DOI

  • Electronic structures of B 2p levels in homo-epitaxial growth boron-doped diamond by soft X-rays absorption spectroscopy

    Jin Nakamura, Eiki Kabasawa, Yoshihisa Harada, Shingo Iriyama, Akihiro Kawano, Tamio Oguchi, Kazuhiko Kuroki, Yoshihiko Takano, Hiroshi Kawarada

    PHYSICA C-SUPERCONDUCTIVITY AND ITS APPLICATIONS   470   S671 - S672  2010年12月

     概要を見る

    Four B-2p in-gap components are observed in B-K XAS spectra using single crystalline boron-doped diamond (BDD) sample. From the polarization dependence of the spectra, the weak peak labeled 1 near the Fermi level is assigned to the hybridized state with C-2p hole state. For the BDD sample grown along < 111 > direction, B-2 dimer is easily created along the growth direction and compensate carriers. A considerable amount of B-H complex and/or B-n cluster is also present. A growth of the peak-1 area intensity is most important to rise the superconducting transition temperature of BDD. (C) 2010 Elsevier B.V. All rights reserved.

    DOI

  • Stacked SNS Josephson junction of all boron doped diamond

    M. Watanabe, A. Kawano, S. Kitagoh, T. Yamaguchi, Y. Takano, H. Kawarada

    PHYSICA C-SUPERCONDUCTIVITY AND ITS APPLICATIONS   470 ( SUPPL.1 ) S613 - S615  2010年12月  [査読有り]

     概要を見る

    It is important for a new superconducting device application to demonstrate Josephson effect by homoepitaxial all diamond junction. Using only CVD diamond, we have fabricated stacked SNS (superconductor-normal conductor superconductor) Josephson junction where normal state diamond film is sandwiched by superconducting diamond films. The current-voltage (I-V) characteristics of the junction showed clear Josephson properties at 2K. (C) 2009 Elsevier B.V. All rights reserved.

    DOI

  • Cross-sectional TEM study and film thickness dependence of Tc in heavily boron-doped superconducting diamond

    S. Kitagoh, R. Okada, A. Kawano, M. Watanabe, Y. Takano, T. Yamaguchi, T. Chikyow, H. Kawarada

    PHYSICA C-SUPERCONDUCTIVITY AND ITS APPLICATIONS   470 ( SUPP.1 ) S610 - S612  2010年12月  [査読有り]

     概要を見る

    The film thickness dependence of Tc in heavily B-doped diamond (1 1 1) and (0 0 1) films was investigated and cross-sectional transmission electron microscope observation was employed to investigate the crystalline structure of heavily B-doped diamond. (1 1 1) films with 5 nm or more and (0 0 1) films with 40 nm or more show superconducting transition. Few dislocations are observed in 500 nm from the interface between the substrate and B-doped homoepitaxial layer in (1 1 1) film and defective structure observed in (0 0 1) film. (C) 2010 Elsevier B.V. All rights reserved.

    DOI

  • Critical concentrations of superconductor to insulator transition in (111) and (001) CVD boron-doped diamond

    A. Kawano, H. Ishiwata, S. Iriyama, R. Okada, S. Kitagoh, M. Watanabe, Y. Takano, T. Yamaguchi, H. Kawarada

    PHYSICA C-SUPERCONDUCTIVITY AND ITS APPLICATIONS   470 ( 1 ) S604 - S607  2010年12月  [査読有り]

     概要を見る

    The superconducting transition temperatures (T(C)) of (1 1 1) and (0 0 1) boron-doped diamond films deposited by microwave plasma assisted chemical vapor deposition (MPCVD) are investigated in the wide boron concentration range of 1 x 10(20) - 1 x 10(22) cm(-3). The critical boron concentrations of superconductor to insulator transition in (1 1 1) and (0 0 1) films are 3 x 10(20) cm(-3). T(C) in (1 1 1) films does not have the tendency to saturate up to 1 x 10(22) cm(-3), while T(C) in (0 0 1) films saturates. (C) 2010 Elsevier B.V. All rights reserved.

    DOI

  • Aptamer-based biosensor for sensitive PDGF detection using diamond transistor

    A. Rahim Ruslinda, Shinya Tajima, Yoko Ishii, Yuichiro Ishiyama, Robert Edgington, Hiroshi Kawarada

    BIOSENSORS & BIOELECTRONICS   26 ( 4 ) 1599 - 1604  2010年12月  [査読有り]

     概要を見る

    The detection of platelet-derived growth factor (PDGF) via a solution-gate field-effect transistor (SGFET) has been demonstrated for the first time using aptamers immobilized on a diamond surface. Upon introduction of PDGF to the immobilized aptamer, a shift of 31.7 mV in the negative direction is observed at a source-drain current of -50 mu A. A shift of 32.3 mV in the positive direction is detected after regeneration by SDS solution, indicating that the static measurement returns to its original value. These SGFETs operate stably within the large potential window of diamond (&gt;3.0 V), and hence the surface channel does not need passivating with a thick insulating layer. Thereof, the immobilized aptamer channels have been exposed directly to the electrolyte solution without a gate insulator. Immobilization is achieved via aptamers covalently bonding to amine sites, thereby increasing the sensitivity of the biosensors. Diamond SGFETs have potential for the detection of PDGF and show durability against biological degradation after repeated usage and regeneration. (C) 2010 Elsevier B.V. All rights reserved.

    DOI

  • Fabrication of calcium ion sensitive diamond field effect transistors (FETs) based on immobilized calmodulin

    Jung-Hoon Yang, Munenori Degawa, Kwang-Soup Song, Chunlei Wang, Hiroshi Kawarada

    MATERIALS LETTERS   64 ( 21 ) 2321 - 2324  2010年11月  [査読有り]

     概要を見る

    We have developed calcium (Ca(2+)) ion sensitive solution-gate field effect transistors (SGFETs) on polycrystalline diamond by using partial amination and immobilization of calmodulin (CaM), a specific protein to calcium ions. The CaM is covalently immobilized on functionalized diamond surface, and the functionalized surface was analyzed by X-ray photoelectron spectroscopy, respectively. Also, the high performance of the CaM-immobilized diamond SGFET for detecting Ca(2+) were studied with respect to high selectivity and sensitivity in various concentrations and pH. (C) 2010 Elsevier B.V. All rights reserved.

    DOI

  • Low drift and small hysteresis characteristics of diamond electrolyte-solution-gate FET

    Yoshinori Sasaki, Hiroshi Kawarada

    JOURNAL OF PHYSICS D-APPLIED PHYSICS   43 ( 37 ) 374020  2010年09月  [査読有り]

     概要を見る

    We have investigated drift and hysteresis characteristics on an electrolyte-solution-gate field-effect transistor (SGFET) with a unique structure using polycrystalline diamond and verified the possibility as chemical sensors and biosensors. Silicon-based ion-sensitive field effect transistors (ISFETs) have not yet solved such time-related issues due to the chemical instability of the passivation layer covering on SiO2 and that is why the Si-ISFET is not wide spread. First of all, we have confirmed that the pH sensitivities of oxygen-and amine-terminated diamond surfaces are 20 mV/pH and 48 mV/pH, respectively, whereas that of hydrogen-terminated surface is only 7 mV/pH. Drift characteristics measurement on diamond SGFET reveals that diamond SGFETs with any surface termination are more stable in electrolyte solution than Si-ISFETs with typical passivation membranes. Hysteresis width, which is known to be a more serious cause of measurement error than drift, proves to be 0.39 mV on amine-terminated SGFET. This is less than 1/10 compared with common Si3N4-ISFET. These results can be explained by high tolerance of diamond against ions in solution due to intrinsic chemical stability and densely packed structure of diamond itself. In this work, we bear out that diamond SGFET is a promising platform for highly sensitive biosensor application owing to the superiority in terms of time response and resulting measurement accuracy.

    DOI

  • Superconductor-to-insulator transition in boron-doped diamond films grown using chemical vapor deposition

    Akihiro Kawano, Hitoshi Ishiwata, Shingo Iriyama, Ryosuke Okada, Takahide Yamaguchi, Yoshihiko Takano, Hiroshi Kawarada

    PHYSICAL REVIEW B   82 ( 8 ) 085318  2010年08月  [査読有り]

     概要を見る

    The critical concentration of superconductor-to-insulator transition in boron-doped diamond is determined in two ways, namely, the actual doping concentration of boron and the Hall carrier concentration. Hall carrier concentrations in (111) and (001) films exceed the actual doping concentration owing to the distortion of the Fermi surface. The high critical boron concentration in (110) films is owing to the effect of the high concentration of interstitial boron atoms. A boron concentration of 3 X 10(20) cm(-3) in substitutional site is required for inducing superconductivity in diamond.

    DOI

  • Ultrashallow TiC Source/Drain Contacts in Diamond MOSFETs Formed by Hydrogenation-Last Approach

    Yoshikatsu Jingu, Kazuyuki Hirama, Hiroshi Kawarada

    IEEE TRANSACTIONS ON ELECTRON DEVICES   57 ( 5 ) 966 - 972  2010年05月  [査読有り]

     概要を見る

    Applying the hydrogen (H) radical exposure at the last step of MOSFET fabrication process, an oxygen (O)-terminated channel was converted to a H-terminated one to obtain subsurface hole accumulation for field-effect transistor operation. Low-resistive titanium carbide (TiC) source/drain and alumina gate oxide were resistant to the hydrogenation process. The shallow TiC side contacts (similar to 3 nm in depth) to the hole accumulation layer (channel) showed good ohmic contacts with a specific contact resistance of 2 x 10(-7) -7 x 10(-7) Omega.cm(2). For diamond MOSFETs with the TiC ohmic layer, the saturated maximum drain current and maximum transconductance reached 160 mA/mm and 45 mS/mm, respectively. An f(T) of 6.2 GHz and an f(max) of 12.6 GHz were obtained. The hydrogenation-last approach is a nondestructive method for the fabrication of diamond MOSFET with high production yield.

    DOI

  • Low-temperature synthesis of multiwalled carbon nanotubes by graphite antenna CVD in a hydrogen-free atmosphere

    Daisuke Yokoyama, Takayuki Iwasaki, Kentaro Ishimaru, Shintaro Sato, Mizuhisa Nihei, Yuji Awano, Hiroshi Kawarada

    CARBON   48 ( 3 ) 825 - 831  2010年03月  [査読有り]

     概要を見る

    Multiwalled carbon nanotubes (MWCNTs) were synthesized at 390 degrees C in a hydrogen-free atmosphere by graphite antenna chemical vapor deposition, which provides carbon radicals by the etching of the antenna itself in a He- or Ar-based noble gas plasma. An increase in the number of defects in the graphite layers of the CNTs was observed with increasing hydrogen partial pressure. The results of X-ray photoelectron spectroscopy analysis suggested that these defects were caused by the transformation from an sp(2) to an sp(3) structure in the graphite layers of CNTs due to hydrogen radicals. (C) 2009 Elsevier Ltd. All rights reserved.

    DOI

  • Schottky barrier heights, carrier density, and negative electron affinity of hydrogen-terminated diamond

    K. Tsugawa, H. Noda, K. Hirose, H. Kawarada

    PHYSICAL REVIEW B   81 ( 4 ) 045303  2010年01月  [査読有り]

     概要を見る

    Chemical trends of Schottky barrier heights of ten kinds of metal contacts on hydrogen-terminated diamond (001) surfaces are estimated from the temperature dependence of their current-voltage characteristics. In addition to the measurements, the interface of the metal/hydrogen-terminated diamond is theoretically modeled including the carrier density of the surface conductive layer and the electron-affinity variation from the clean surface of the hydrogen-terminated diamond. Based on the model, a relation among the carrier density, the electron affinity variation, and the barrier heights are derived. The relation explains well experimental results of and other than the present work.

    DOI

  • High-Performance P-Channel Diamond Metal-Oxide-Semiconductor Field-Effect Transistors on H-Terminated (111) Surface

    Kazuyuki Hirama, Kyosuke Tsuge, Syunsuke Sato, Tetsuya Tsuno, Yoshikatsu Jingu, Shintaro Yamauchi, Hiroshi Kawarada

    APPLIED PHYSICS EXPRESS   3 ( 4 ) 044001  2010年  [査読有り]

     概要を見る

    Through the enhancement of hole accumulated density near hydrogen-terminated (111) diamond surfaces, low sheet resistance (similar to 5 k Omega/sq) has been obtained compared with widely used (001) diamond surfaces (similar to 10 k Omega/sq). Using the hole accumulation layer channel, a high drain current density of -850 mA/mm was obtained in p-channel metal-oxide-semiconductor field-effect transistors (MOSFETs). This drain current density is the highest value for diamond FETs. The high drain current on the (111) surface is attributed to two factors: The low source and drain resistances owing to the high hole carrier density and the high channel mobility at a high gate-source voltage on the (111) surface. (C) 2010 The Japan Society of Applied Physics

    DOI

  • Soft X-ray Core-Level Photoemission Study of Boron Sites in Heavily Boron-Doped Diamond Films

    Hiroyuki Okazaki, Rikiya Yoshida, Takayuki Muro, Takanori Wakita, Masaaki Hirai, Yuji Muraoka, Yoshihiko Takano, Shingo Iriyama, Hiroshi Kawarada, Tamio Oguchi, Takayoshi Yokoya

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   78 ( 3 ) 034703  2009年03月  [査読有り]

     概要を見る

    We have performed high-resolution soft x-ray B 1s core-level photoemission spectroscopy of heavily boron-doped diamond films in order to study the chemical sites of doped-boron atoms and their relation to the superconducting transition temperature (T-c). We find that B 1s core-level spectra exhibit several fine structures and three bulk components can he resolved from photon energy dependent studies and spectral fittings. These results indicate existence of several chemical environments of doped-boron atoms. One of the bulk components having the lowest binding energy can be assigned to a signal from substitutionally doped-boron atoms. Comparisons of bulk components with T-c suggest spectroscopic evidence for the importance of substitutionally doped-boron atoms for effective carrier and superconductivity.

    DOI

  • DC and RF Performance of Diamond MISFETs with Alumina Gate Insulator

    Hirama K, Jingu Y, Ichikawa M, Umezawa H, Kawarada H

    Silicon Carbide and Related Materials 2007, Pts 1 and 2   600-603   1349 - 1351  2009年  [査読有り]

    DOI

  • ワイドギャップ半導体ダイヤモンドを用いた高周波高出力MOSFETの開発

    平間 一行, 川原田 洋

    科学と工業   83 ( 4 ) 149 - 156  2009年

  • Low-temperature STM/STS studies on boron-doped (111) diamond films

    Terukazu Nishizaki, Yoshihiko Takano, Masanori Nagao, Tomohiro Takenouchi, Hiroshi Kawarada, Norio Kobayashi

    JOURNAL OF PHYSICS AND CHEMISTRY OF SOLIDS   69 ( 12 ) 3027 - 3030  2008年12月  [査読有り]

     概要を見る

    We have performed scanning tunneling microscopy/spectroscopy (STM/STS) experiments on (111)oriented epitaxial films of heavily boron-doped diamond (T-c similar to 5.4 K). We present that tunneling conductance spectra show temperature-dependent spatial variations. In the low-temperature region (T = 0.47K), the tunneling spectra do not show strong spatial dependence and a superconducting energy gap is observed independent of the surface morphology. In the high-temperature region (T = 4.2 K), on the other hand, the tunneling conductance spectra show significant spatial dependence, indicating the inhomogeneous distribution of the superconducting property due to the distribution of boron atoms. (C) 2008 Elsevier Ltd. All rights reserved.

    DOI

  • Characterization of boron-doped diamonds using B-11 high-resolution NMR at high magnetic fields

    M. Murakami, T. Shimizu, M. Tansho, Y. Takano, S. Ishii, E. A. Ekimov, V. A. Sidorov, H. Sumiya, H. Kawarada, K. Takegoshi

    DIAMOND AND RELATED MATERIALS   17 ( 11 ) 1835 - 1839  2008年11月

     概要を見る

    B-11 static/magic-angle spinning (MAS) NMR experiments are applied to four different B-doped diamond samples prepared by either high-pressure and high-temperature (HPHT) or CVD methods with various starting materials. Application of MAS enhances the spectral resolution appreciably and differences of the four B-doped diamond samples are well reflected in the corresponding MAS spectra. From the comparison among the MAS spectra, and also their dependences on the magnetic-field and the pulse-flip angle. it is suggested that at least four kinds of boron including two kinds of impurities exist in B-doped diamond. We further examine B-11 spin-lattice relaxation times (T-1) for the four components and find that one of them is extremely short (ca. 500 ms) while others are in the range of several seconds. Relation between the component having the short T, and the super conducting transition temperature (T-c) value is suggested. (C) 2008 Elsevier B.V. All rights reserved.

    DOI

  • Characterization of Hybridization on Diamond Solution-Gate Field-Effect Transistors for Detecting Single Mismatched Oligonucleotides

    Jung-Hoon Yang, Shouma Kuga, Kwang-Soup Song, Hiroshi Kawarada

    APPLIED PHYSICS EXPRESS   1 ( 11 ) 11801  2008年11月

     概要を見る

    Using diamond field-effect transistors (FETs) operated in electrolyte solution (solution-gate FETs; SGFETs), a label-free charge detection method between complementary and single mismatched target oligonucleotides is proposed. The probe oligonucleotides immobilized at the activated carboxyl groups of carboxylic aromatic compounds (CACs) on the previously formed amino groups of the diamond surface. The high performance of the diamond surface for oligonucleotides detection was studied with respect to selectivity, sensitivity, and reproducibility of the diamond SGFETs. (C) 2008 The Japan Society of Applied Physics

    DOI

  • Detection of mismatched DNA on partially negatively charged diamond surfaces by optical and potentiometric methods

    Shoma Kuga, Jung-Hoon Yang, Hironori Takahashi, Kazuyuki Hiirama, Takayuki Iwasaki, Hiroshi Kawarada

    JOURNAL OF THE AMERICAN CHEMICAL SOCIETY   130 ( 40 ) 13251 - 13263  2008年10月  [査読有り]

     概要を見る

    The effects of surface charge density on DNA hybridization have been investigated on a mixture of hydrogen-, oxygen-, and amine-terminated diamond surfaces. A difference in the hybridization efficiencies of complementary and mismatched DNA was clearly observed by fluorescence and potentiometric observations at a particular coverage of oxygen. In the fluorescence observation, singly mismatched DNA was detected with high contrast after appropriate hybridization on the surface with 10-20% oxygen coverage. The amount of oxygen in the form of C-O- (deprotonated C-OH) producing the surface negative-charge density was estimated by X-ray photoelectron spectroscopy. Electrolyte solution gate field-effect transistors (SGFETs) were used for potentiometric observations. The signal difference (change in gate potential) on the SGFET, which was as large as similar to 20 mV, was caused by the difference in the hybridization efficiencies of complementary target DNA (cDNA) and singly mismatched (1 MM) target DNA with a common probe DNA immobilized on the same SGFET. The reversible change in gate potential caused by the hybridization and denaturation cycles and discriminating between the complementary and 1 MM DNA targets was very stable throughout the cyclical detections. Moreover, the ratio of signals caused by hybridization of the cDNA and 1 MM DNA targets with the probe DNA immobilized on the SGFET was determined to be 3:1 when hybridization had occurred (after 15 min on SGFET), as determined by real-time measurements. From the viewpoint of hybridization kinetics, the rate constant for hybridization of singly mismatched DNA was a factor of similar to 3 smaller than that of cDNA on this functionalized (oxidized and arninated) diamond surface.

    DOI

  • Vertically aligned carbon nanotube growth from Ni nanoparticles prepared by ion implantation

    T. Iwasaki, S. Mejima, T. Koide, R. Morikane, H. Nakayama, T. Shinada, I. Ohdomari, H. Kawarada

    DIAMOND AND RELATED MATERIALS   17 ( 7-10 ) 1443 - 1446  2008年07月  [査読有り]

     概要を見る

    Vertically aligned carbon nanotubes (CNTs) were synthesized from Ni nanoparticles prepared by ion implantation. Ni ions were implanted at 30 keV into thermally grown SiO2 Substrates using a focused-ion-beam. High-density nanoparticle formation was investigated with high doses up to 5.0 x 10(17) ions/cm(2). Dense Ni nanoparticles in the order of 10(11)-10(12) cm(-2) were obtained on a SiO2 substrate, and the particle density and diameter were controlled by post-implantation annealing. Particles annealed at 700 degrees C led to vertically aligned CNTs. Interestingly, catalysts were longer along the vertical axis and the lower half of the Ni particle was buried in SiO2. (c) 2008 Elsevier B.V. All rights reserved.

    DOI

  • Channel mobility evaluation for diamond MOSFETs using gate-to-channel capacitance measurement

    K. Hirama, H. Takayanagi, S. Yamauchi, J. H. Yang, H. Umezawa, H. Kawarada

    DIAMOND AND RELATED MATERIALS   17 ( 7-10 ) 1256 - 1258  2008年07月  [査読有り]

     概要を見る

    In this work, the channel mobility (mu(ch)) of diamond metal-oxide-semiconductor field-effect transistors (MOSFETs) with hole accumulation layer channels was evaluated from the gate-to-channel capacitance and drain conductance for the first time. The FET structure was utilized for the capacitance-voltage (C-V) measurement, and the gate-to-channel capacitance (C-GC) under the forward bias condition was proportional to the gate area, as in the case of Si MOSFETs. For the accurate evaluation of the drain conductance, diamond MOSFETs were fabricated on IIa-type diamond films with low boron concentrations (&lt; 10(14) cm(-3)). In a 60-mu m gate-length diamond MOSFET, a mu(ch) of 145cm(2)/Vs was obtained, which is comparable to that of a SiC inversion layer. (C) 2008 Elsevier B.V. All rights reserved.

    DOI

  • Temperature-dependent localized excitations of doped carriers in superconducting diamond

    K. Ishizaka, R. Eguchi, S. Tsuda, A. Chainani, T. Yokoya, T. Kiss, T. Shimojima, T. Togashi, S. Watanabe, C.-T. Chen, Y. Takano, M. Nagao, I. Sakaguchi, T. Takenouchi, H. Kawarada, S. Shin

      100 ( 16 ) 166402  2008年04月  [査読有り]

    DOI

  • Electrical properties of carbon nanotubes grown at a low temperature for use as interconnects

    Daisuke Yokoyama, Takayuki Iwasaki, Kentaro Ishimaru, Shintaro Sato, Takashi Hyakushima, Mizuhisa Nihei, Yuji Awano, Hiroshi Kawarada

    JAPANESE JOURNAL OF APPLIED PHYSICS   47 ( 4 ) 1985 - 1990  2008年04月  [査読有り]

     概要を見る

    We measured the electrical properties of vertically aligned carbon nanotubes (CNTs) synthesized from via holes by radical chemical vapor deposition at a low temperature of 390 degrees C, which meets the requirements of the Si large scale integration (LSI) process. To use the CNTs could be used for LSI wiring, we applied chemical mechanical polishing (CMP) to the CNTs and successfully reduced the via resistance by a factor of ten. In addition, the resistance of the CNTs was reduced further to 0.6 Omega for 2-mu m-diameter vias by annealing at 400 degrees C. Although the temperature dependence of the resistance of the CNTs grown in vias (CNT-vias) did not indicate ballistic transport, which is one of the expected properties of CNTs, we found that CMP and annealing are effective for reducing the via resistance of CNTs.

    DOI

  • Spontaneous polarization model for surface orientation dependence of diamond hole accumulation layer and its transistor performance

    K. Hirama, H. Takayanagi, S. Yamauchi, J. H. Yang, H. Kawarada, H. Umezawa

    APPLIED PHYSICS LETTERS   92 ( 11 ) 112107  2008年03月  [査読有り]

     概要を見る

    Diamond metal-oxide-semiconductor field-effect transistors (FETs) have been fabricated on IIa-type large-grain diamond substrates with a (110) preferential surface. The drain current and cutoff frequency are -790 mA/mm and 45 GHz, respectively, which are higher than those of single-crystal diamond FETs fabricated on (001) homoepitaxial diamond films. The hole carrier density of the hole accumulation layer depends on the orientation of the hydrogen-terminated diamond surface, for which (110) preferentially oriented films show 50%-70% lower sheet resistance than a (001) substrate. We propose that the hole density of the surface accumulation layer is proportional to the C-H bond density on the surface. (c) 2008 American Institute of Physics.

    DOI

  • Mechanism analysis of interrupted growth of single-walled carbon nanotube arrays

    Takayuki Iwasaki, John Robertson, Hiroshi Kawarada

    NANO LETTERS   8 ( 3 ) 886 - 890  2008年03月  [査読有り]

     概要を見る

    We investigated the growth mechanism of layered single-walled carbon nanotube (SWNT) mats by a cutting method. Transmission electron microscope observations revealed that new SWNTs grown below first grown SWNTs also have caps at their tips. Raman spectroscopy suggests that the SWNTs in each layer have the same chirality distribution. This growth method might be a way to prove a factor of chirality selection of SWNTs.

    DOI

  • Highly selective growth of vertically aligned double-walled carbon nanotubes by a controlled heating method and their electric double-layer capacitor properties

    Takayuki Iwasaki, Tasuku Maki, Daisuke Yokoyama, Hironori Kumagai, Yasuhiro Hashimoto, Takuma Asari, Hiroshi Kawarada

    PHYSICA STATUS SOLIDI-RAPID RESEARCH LETTERS   2 ( 2 ) 53 - 55  2008年03月  [査読有り]

     概要を見る

    Vertically aligned double-walled carbon nanotubes (DWCNTs) with the highest selectivity of 90% were synthesized by a controlled heating method and their electric double-layer capacitor characteristics were evaluated. DWCNT arrays had a specific capacitance of 83 F/g, which is one of the highest values among CNT arrays in a nonaqueous solution and is almost equivalent to that for single-walled CNT (SWCNT) arrays reported previously. At the same specific capacitance, DWCNTs with superior structural properties are more promising for practical capacitors than SWCNTs. (c) 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

    DOI

  • Pressure effect of superconducting transition temperature for boron-doped diamond films

    F. Tomioka, S. Tsuda, T. Yamaguchi, H. Kawarada, Y. Takano

    PHYSICA C-SUPERCONDUCTIVITY AND ITS APPLICATIONS   468 ( 15-20 ) 1228 - 1230  2008年  [査読有り]

    DOI

  • Near E-F electronic structure of heavily boron-doped superconducting diamond

    Okazaki H, Yokoya T, Nakamura J, Yamada N, Nakamura T, Muro T, Tamenori Y, Matsushita T, Takata Y, Tokushima T, Shin S, Takano Y, Nagao M, Takenouchi T, Kawarada H, Oguchi T

    Journal of Physics and Chemistry of Solids   69 ( 12 ) 2978 - 2981  2008年  [査読有り]

    DOI

  • 電解質溶液ゲートFETを利用したDNAセンサー

    川原田 洋

    応用物理   77 ( 10 ) 1229 - 1234  2008年

  • 水素終端ダイヤモンド表面近傍に存在するp型表面蓄積層

    川原田 洋, 平間 一行, 荻原 大輔

    表面科学   29 ( 3 ) 144 - 155  2008年

  • ホール蓄積層チャネルを用いた高周波ダイヤモンドFET

    平間 一行, 川原田 洋

    ニューダイヤモンド   90   2 - 9  2008年

  • Functionalization of ultradispersed diamond for DNA detection

    Jung-Hoon Yang, Yoshikazu Nakano, Yasunori Murakami, Kwang-Soup Song, Hiroshi Kawarada

    JOURNAL OF NANOPARTICLE RESEARCH   10   69 - 75  2008年  [査読有り]

     概要を見る

    Functionalization of nanoparticles and immobilization of biomolecules on nanoparticles are important techniques for various applications in biotechnology. For application in the biomedical field, the surface of ultradispersed diamond (UDD) is immobilized with amino-terminated DNA after functionalizing carboxylic or amino group on the UDD surface. The characterized surface of UDD, carboxylated UDD, and aminated UDD were analyzed by DRIFT spectroscopy. In addition, hybridization with Cy-5 labeled target DNA was clearly observed on functionalized UDD by fluorescence microscopy.

    DOI

  • B-11 nuclear magnetic resonance study on existence of boron-hydrogen complex in boron-doped diamond

    Miwa Murakami, Tadashi Shimizu, Masataka Tansho, Yoshihiko Takano, Satoshi Ishii, Evaueni Ekimov, Vladimir Sidorov, Hiroshi Kawarada, Kiyonori Takegoshi

    JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS & EXPRESS LETTERS   46 ( 45-49 ) L1138 - L1140  2007年12月

     概要を見る

    The assignment of boron not contributing to conductivity in boron-doped diamond to boron-hydrogen complex is reexamined using a new B-11 two-dimensional NMR technique, which is developed to detect H-1-B-11 dipolar broadening. It is shown that the amount of boron-hydrogen complex is not substantial and the previous assignment is thus less plausible. Possible mechanisms of linebroadening are discussed.

    DOI

  • Low temperature grown carbon nanotube interconnects using inner shells by chemical mechanical polishing

    Daisuke Yokoyama, Takayuki Iwasaki, Tsuyoshi Yoshida, Hiroshi Kawarada, Shintaro Sato, Takashi Hyakushima, Mizuhisa Nihei, Yuji Awano

    APPLIED PHYSICS LETTERS   91 ( 26 ) 263101  2007年12月  [査読有り]

     概要を見る

    Vertically aligned multiwalled carbon nanotubes (MWCNTs) were synthesized by remote plasma chemical vapor deposition at a low temperature of 390 degrees C, which meets the requirement of the large scale integration (LSI) process. For wiring application, we measured the electrical properties of MWCNT-via structures with and without chemical mechanical polishing (CMP). The via resistances were reduced using inner shells of MWCNTs whose caps were opened due to CMP. The improved resistance after annealing at 400 degrees C was 0.6 Omega for 2 mu m vias. Our process is suitable for LSI because the temperature never exceeds the allowable temperature of 400 degrees C in the Si LSI process. (c) 2007 American Institute of Physics.

    DOI

  • Core-level electronic structure evolution of heavily boron-doped superconducting diamond studied with hard x-ray photoemission spectroscopy

    T. Yokoya, E. Ikenaga, M. Kobata, H. Okazaki, K. Kobayashi, A. Takeuchi, A. Awaji, Y. Takano, M. Nagao, I. Sakaguchi, T. Takenouchi, K. Kobayashi, H. Kawarada, T. Oguchi

    PHYSICAL REVIEW B   75 ( 20 ) 205117  2007年05月  [査読有り]

     概要を見る

    Hard x-ray photoemission spectroscopy has been used to study intrinsic core-level electronic structure evolution of heavily boron-doped superconducting diamond films made with a microwave plasma-assisted chemical-vapor deposition method. The boron concentration dependent C 1s core-level spectra show systematic changes in the shift of the main peak and in the evolution of an additional feature at 1.1-1.3 eV lower binding energy than the main peak. In comparison to a low boron concentration nonsuperconducting diamond, the higher boron concentration doped diamond films show formation of several additional features in the B 1s core levels. Based on the present results, the local chemical environments around the doped boron atoms, the efficiency of hole doping by boron doping, and the implications for a recent x-ray absorption study are discussed.

    DOI

  • Superconducting properties of homoepitaxial CVD diamond

    Y. Takano, T. Takenouchi, S. Ishii, S. Ueda, T. Okutsu, I. Sakaguchi, H. Umezawa, H. Kawarada, M. Tachiki

    DIAMOND AND RELATED MATERIALS   16 ( 4-7 ) 911 - 914  2007年04月  [査読有り]

     概要を見る

    Superconductivity was achieved above 10 K in heavily boron-doped diamond thin films deposited by the microwave plasma-assisted chemical vapor deposition (CVD) method. Advantages of the CVD method are the controllability of boron concentration in a wide range, and a high boron concentration, compared to those obtained using the high-pressure high-temperature method. The superconducting transition temperatures of homoepitaxial (111) films are determined to be 11.4 K for Tc onset and 8.4 K for zero resistance from transport measurements. In contrast, the superconducting transition temperatures of (100) films T-C onset=6.3 K and T-C zero=3.2 K were significantly suppressed. (C) 2007 Elsevier B.V. All rights reserved.

    DOI

  • Phonon softening in superconducting diamond

    M. Hoesch, T. Fukuda, J. Mizuki, T. Takenouchi, H. Kawarada, J. P. Sutter, S. Tsutsui, A. Q. R. Baron, M. Nagao, Y. Takano

    PHYSICAL REVIEW B   75 ( 14 ) 140508  2007年04月  [査読有り]

     概要を見る

    We observe strong softening of optical-phonon modes in superconducting (T-c=4.2 K) boron-doped diamond near the Brillouin-zone center using inelastic x-ray scattering from a chemical vapor deposition grown highly oriented sample. The magnitude of the softening, and our observation that it becomes stronger approaching zone center, supports theoretical models suggesting a phonon-mediated pairing mechanism via coupling of optical-phonon modes to Fermi surfaces around the zone center. The electron-phonon coupling parameter is determined as approximately lambda=0.33.

    DOI

  • Growth kinetics of 0.5 cm vertically aligned single-walled carbon nanotubes

    Guofang Zhong, Takayuki Iwasaki, John Robertson, Hiroshi Kawarada

    JOURNAL OF PHYSICAL CHEMISTRY B   111 ( 8 ) 1907 - 1910  2007年03月  [査読有り]

     概要を見る

    Half-centimeter-high mats of vertically aligned single-walled carbon nanotubes were grown at 600 degrees C by point-arc microwave plasma chemical vapor deposition. The mats were produced from 0.5 nm of an Fe catalyst layer, thus showing one of the highest catalytic yields of similar to 10(5) times. The growth process shows a lack of poisoning of the catalyst, in contrast to other reports. The experimental results confirm that the growth rate is ultimately limited by the gas phase diffusion of hydrocarbon radicals.

    DOI

  • Miniaturized diamond field-effect transistors for application in biosensors in electrolyte solution

    Kwang-Soup Song, Takahiro Hiraki, Hitoshi Umezawa, Hiroshi Kawarada

    APPLIED PHYSICS LETTERS   90 ( 6 ) 63901  2007年02月  [査読有り]

     概要を見る

    The authors fabricated diamond solution-gate field-effect transistors (SGFETs) with miniaturization of the channel length to 5 mu m by photolithography. The channel surface was directly functionalized with amine by ultraviolet irradiation in an ammonia gas for 4 h and aminated diamond SGFETs were sensitive to pH by 40 mV/pH. Urease was immobilized on the amine-modified channel surface, which was sensitive to urea by 27 mu A/decade from 10(-5)M to 10(-2)M. The authors fabricated submicron-sized (500 nm) diamond SGFETs using electron-beam lithography. The transconductance (g(m)) was 56 mS/mm, which was 930-fold greater than that of the 500 mu m channel length. (c) 2007 American Institute of Physics.

    DOI

  • 24pXA-1 高濃度ホウ素ドープダイヤモンドの軟X線光電子分光(ダイヤモンド・Si超伝導,領域8,強相関係:高温超伝導,強相関f電子系など)

    岡崎 宏之, 石井 聡, 入山 慎吾, 川原田 洋, 横谷 尚睦, 室 隆桂之, 中村 哲也, 松下 智裕, 脇田 高徳, 村岡 祐治, 平井 正明, 高野 義彦

    日本物理学会講演概要集   62 ( 0 ) 665 - 665  2007年  [査読有り]

    DOI CiNii

  • Detection of single-mismatch DNA on hydrogen-terminated diamond surface

    J. -H. Yang, S. Kuga, H. Kawarada

    PROCEEDINGS OF THE 5TH JOINT MEETING ON MEDICINAL CHEMISTRY     77 - 80  2007年  [査読有り]

  • High-performance p-channel diamond MOSFETs with alumina gate insulator

    Hirama K, Takayanagi H, Yamauchi S, Jingu Y, Umezawa H, Kawarada H

    2007 IEEE International Electron Devices Meeting, Vols 1 and 2     873 - 876  2007年  [査読有り]

    DOI

  • Microwave operation of diamond metal-insulator-semiconductor field-effect transistors fabricated on single-crystal chemical vapor deposition substrate

    Hirama K, Takayanagi H, Yamauchi S, Umezawa H, Kawarada H

    New Diamond and Frontier Carbon Technology   17 ( 4 ) 201 - 209  2007年  [査読有り]

  • Growth of heavily boron-doped polycrystalline superconducting diamond

    Umezawa H, Takenouchi T, Kobayashi K, Takano Y, Nagao M, Tachiki M, Hatano T, Kawarada H

    New Diamond and Frontier Carbon Technology   17 ( 1 ) 1 - 9  2007年  [査読有り]

  • Diamond MISFETs fabricated on high quality polycrystalline CVD diamond

    Hirama K, Takayanagi H, Yamauchi S, Jingu Y, Umezawa H, Kawarada H, Ieee

    Proceedings of the 19th International Symposium on Power Semiconductor Devices and Ics     269 - 272  2007年  [査読有り]

    DOI

  • Valence band electronic structures of heavily boron-doped superconducting diamond studied by synchrotron photoemission spectroscopy

    Yokoya T, Nakamura T, Matsushita T, Muro T, Ikenaga E, Kobata M, Kobayashi K, Takano Y, Nagao M, Takenouchi T, Kawarada H, Oguchi T

    New Diamond and Frontier Carbon Technology   17 ( 1 ) 11 - 20  2007年  [査読有り]

  • Electronic structures of heavily boron-doped superconducting diamond films

    Yokoya T, Okazaki H, Nakamura T, Matsushita T, Muro T, Ikenaga E, Kobata M, Kobayashi K, Takeuchi A, Awaji A, Takano Y, Nagao M, Takenouchi T, Kawarada H, Oguchi T

    Materials Research Society Symposium Proceedings   956   39 - 46  2007年  [査読有り]

  • Electronic devices

    Hironobu Miyamoto, Manabu Arai, Hiroshi Kawarada, Naoharu Fujimori, Sadafumi Yoshida, Takashi Shinohe, Akio Hiraki, Hirohisa Hiraki, Hideomi Koinuma, Masao Katayama

    Wide Bandgap Semiconductors: Fundamental Properties and Modern Photonic and Electronic Devices     231 - 280  2007年

    DOI

  • Observation of a superconducting gap in boron-doped diamond by laser-excited photoemission spectroscopy

    K. Ishizaka, R. Eguchi, S. Tsuda, T. Yokoya, A. Chainani, T. Kiss, T. Shimojima, T. Togashi, S. Watanabe, C. -T. Chen, C. Q. Zhang, Y. Takano, M. Nagao, I. Sakaguchi, T. Takenouchi, H. Kawarada, S. Shin

    PHYSICAL REVIEW LETTERS   98 ( 4 ) 47003  2007年01月  [査読有り]

     概要を見る

    We investigate the temperature (T)-dependent low-energy electronic structure of a boron-doped diamond thin film using ultrahigh resolution laser-excited photoemission spectroscopy. We observe a clear shift of the leading edge below T=11 K, indicative of a superconducting gap opening (Delta similar to 0.78 meV at T=4.5 K). The gap feature is significantly broad and a well-defined quasiparticle peak is lacking even at the lowest temperature of measurement (=4.5 K). We discuss our results in terms of disorder effects on the normal state transport and superconductivity in this system.

    DOI

  • Microscopic evidence for evolution of superconductivity by effective carrier doping in boron-doped diamond: B-11-NMR study

    H. Mukuda, T. Tsuchida, A. Harada, Y. Kitaoka, T. Takenouchi, Y. Takano, M. Nagao, I. Sakaguchi, T. Oguchi, H. Kawarada

    PHYSICAL REVIEW B   75 ( 3 ) 33301  2007年01月  [査読有り]

     概要を見る

    We have investigated the superconductivity discovered in boron-doped diamonds by means of B-11-NMR on heteroepitaxially grown (111) and (100) films. B-11-NMR spectra for all of the films are identified to arise from the substitutional B(1) site as single occupation and lower symmetric B(2) site substituted as boron+hydrogen (B+H) complex, respectively. Clear evidence is presented that the effective carriers introduced by B(1) substitution are responsible for the superconductivity, whereas the charge neutral B(2) sites does not offer the carriers effectively. The result is also corroborated by the density of states deduced by 1/T1T measurement, indicating that the evolution of superconductivity is driven by the effective carrier introduced by substitution at B(1) site.

    DOI

  • Characterization of DNA hybridization on partially aminated diamond by aromatic compounds

    Jung-Hoon Yang, Kwang-Soup Song, Guo-Jun Zhang, Munenori Degawa, Yoshinori Sasaki, Iwao Ohdomari, Hiroshi Kawarada

    LANGMUIR   22 ( 26 ) 11245 - 11250  2006年12月  [査読有り]

     概要を見る

    Here, we report a novel method of micropatterning oligonucleotides via aromatic groups as linkers on partially amino-terminated diamond and the inherence on subsequent hybridization. The covalent immobilization of probe oligonucleotides and characterization of immobilized probe oligonucleotides with carboxylic compounds were investigated by X-ray photoelectron spectroscopy (XPS). To confirm the effects of linker flexibility in a low amino group on diamond for probe oligonucleotides, three kinds of dicarboxylic compounds-adipic acid, terephthalic acid, and trimesic acidswere used for immobilization of probe oligonucleotides, like linkers; and these oligonucleotides were hybridized with target oligonucleotides labeled with Cy 5 on the micropatterned diamond surface. The hybridization intensities determined by epifluorescence microscopy were compared and analyzed.

    DOI

  • Characterization of DNA hybridization on partially aminated diamond by aromatic compounds

    Jung-Hoon Yang, Kwang-Soup Song, Guo-Jun Zhang, Munenori Degawa, Yoshinori Sasaki, Iwao Ohdomari, Hiroshi Kawarada

    LANGMUIR   22 ( 26 ) 11245 - 11250  2006年12月

     概要を見る

    Here, we report a novel method of micropatterning oligonucleotides via aromatic groups as linkers on partially amino-terminated diamond and the inherence on subsequent hybridization. The covalent immobilization of probe oligonucleotides and characterization of immobilized probe oligonucleotides with carboxylic compounds were investigated by X-ray photoelectron spectroscopy (XPS). To confirm the effects of linker flexibility in a low amino group on diamond for probe oligonucleotides, three kinds of dicarboxylic compounds-adipic acid, terephthalic acid, and trimesic acidswere used for immobilization of probe oligonucleotides, like linkers; and these oligonucleotides were hybridized with target oligonucleotides labeled with Cy 5 on the micropatterned diamond surface. The hybridization intensities determined by epifluorescence microscopy were compared and analyzed.

    DOI

  • Trapping mechanism on oxygen-terminated diamond surfaces

    Yutaka Itoh, Yu Sumikawa, Hitoshi Umezawa, Hiroshi Kawarada

    APPLIED PHYSICS LETTERS   89 ( 20 ) 203503  2006年11月  [査読有り]

     概要を見る

    Mechanisms of the hole trap and detrap on the oxygen-terminated diamond surfaces measured by diamond in-plane-gated field-effect transistors (FETs) have been investigated. Reproducible hysteresis characteristics are observed in the I-DS-V-GS characteristics of the diamond in-plane-gated FETs. They are caused by carrier trapping in the oxidized diamond surface and detrapping under a light irradiation, the wavelength of which affects the hysteresis width. Carriers are trapped by continuous surface states deeper than 2.0 eV from the valence band maximum in the oxidized diamond surface, where the position of the highest occupied level (Fermi level) is located between 2.0 and 2.4 eV. (c) 2006 American Institute of Physics.

    DOI

  • Characterization of direct immobilized probe DNA on partially functionalized diamond solution-gate field-effect transistors

    Jung-Hoon Yang, Kwang-Soup Song, Shouma Kuga, Hiroshi Kawarada

    JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS & EXPRESS LETTERS   45 ( 42-45 ) L1114 - L1117  2006年11月  [査読有り]

     概要を見る

    Amino groups were functionalized directly on the diamond surface after treating 0.5 monolayer of oxidation for detection of DNAs. Also, immobilization of probe DNAs was carried out directly on the partially aminated diamond without linker molecules. Specific hybridization with 21-mer DNA at a concentration of 100 nM could be clearly detected by two methods, fluorescence microscopy and diamond solution-gate field-effect transistors (SGFETs). DNA hybridization was confirmed using Cy-5-labeled target DNA on a micropatterned diamond surface. The changes in gate potential by the negative charge of immobilized or hybridized DNA were measured on SGFETs and hybridization efficiency on the functionalized diamond surface was estimated as about 40%.

    DOI

  • Label-free DNA sensors using ultrasensitive diamond field-effect transistors in solution

    Kwang-Soup Song, Gou-Jun Zhang, Yusuke Nakamura, Kei Furukawa, Takahiro Hiraki, Jung-Hoon Yang, Takashi Funatsu, Iwao Ohdomari, Hiroshi Kawarada

    PHYSICAL REVIEW E   74 ( 4 ) 41919  2006年10月  [査読有り]

     概要を見る

    Charge detection biosensors have recently become the focal point of biosensor research, especially field-effect-transistors (FETs) that combine compactness, low cost, high input, and low output impedances, to realize simple and stable in vivo diagnostic systems. However, critical evaluation of the possibility and limitations of charge detection of label-free DNA hybridization using silicon-based ion-sensitive FETs (ISFETs) has been introduced recently. The channel surface of these devices must be covered by relatively thick insulating layers (SiO2, Si3N4, Al2O3, or Ta2O5) to protect against the invasion of ions from solution. These thick insulating layers are not suitable for charge detection of DNA and miniaturization, as the small capacitance of thick insulating layers restricts translation of the negative DNA charge from the electrolyte to the channel surface. To overcome these difficulties, thin-gate-insulator FET sensors should be developed. Here, we report diamond solution-gate FETs (SGFETs), where the DNA-immobilized channels are exposed directly to the electrolyte solution without gate insulator. These SGFETs operate stably within the large potential window of diamond (&gt; 3.0 V). Thus, the channel surface does not need to be covered by thick insulating layers, and DNA is immobilized directly through amine sites, which is a factor of 30 more sensitive than existing Si-ISFET DNA sensors. Diamond SGFETs can rapidly detect complementary, 3-mer mismatched (10 pM) and has a potential for the detection of single-base mismatched oligonucleotide DNA, without biological degradation by cyclically repeated hybridization and denature.

    DOI

  • Low-energy electrodynamics of superconducting diamond

    M. Ortolani, S. Lupi, L. Baldassarre, U. Schade, P. Calvani, Y. Takano, M. Nagao, T. Takenouchi, H. Kawarada

    PHYSICAL REVIEW LETTERS   97 ( 9 ) 97002  2006年09月  [査読有り]

     概要を見る

    Heavily boron-doped, diamond films can become superconducting with critical temperatures T-c well above 4 K. Here we first measure the reflectivity of such a film down to 5 cm(-1), by also using coherent synchrotron radiation. We thus determine the optical gap 2 Delta, the field penetration depth lambda, the range of action of the Ferrell-Glover-Tinkham sum rule, and the electron-phonon spectral function alpha F-2(omega). We conclude that diamond behaves as a dirty BCS superconductor.

    DOI

  • Semi-quantitative study on the fabrication of densely packed and vertically aligned single-walled carbon nanotubes

    GF Zhong, T Iwasaki, H Kawarada

    CARBON   44 ( 10 ) 2009 - 2014  2006年08月  [査読有り]

     概要を見る

    This paper presents, for the first time, a semi-quantitative study on the production of densely packed and vertically aligned (DPVA) single-walled carbon nanotubes (SWNTs) from ultra-thin catalytic films. An up-to-date highest volume density (60-70 kg m(-3)) and the corresponding high surface density on the order of 10(16) m(-2) of DPVA-SWNTs have been achieved by point-arc microwave plasma chemical vapor deposition. The precise thickness control of the sandwich-like catalytic nanostructure of 0.5 nm Al2O3/0.5 nm Fell &gt; 5 nm Al2O3, developed by the authors, and a short-time (5 min) heat pretreatment of substrates at a temperature as low as 600 degrees C play the very key role in the process of fabricating DPVA-SWNTs. (c) 2006 Elsevier Ltd. All rights reserved.

    DOI

  • pH-sensitive diamond field-effect transistors (FETs) with directly aminated channel surface

    Kwang-Soup Song, Yusuke Nakamura, Yuichi Sasaki, Munenori Degawa, Jung-Hoon Yang, Hiroshi Kawarada

    ANALYTICA CHIMICA ACTA   573   3 - 8  2006年07月  [査読有り]

     概要を見る

    We have introduced pH sensors fabricated on diamond thin films through modification of the surface-terminated atom. We directly modified the diamond surface from hydrogen to amine or oxygen with ultraviolet (UV) irradiation under ammonia gas. The quantified amine site based on the spectra obtained by X-ray photoelectron spectroscopy (XPS) is 26% (2.6 x 10(14) cm(-2)) with UV irradiation for 8 h and its coverage is dependent on the UV irradiation time. This directly aminated diamond surface is stable with long-term exposure in air and electrolyte solution. We fabricated diamond solution-gate field-effect transistors (SGFETs) without insulating layers on the channel surface. These diamond SGFETs with amine modified by direct amination are sensitive to pH (45 mV/pH) over a wide range from pH 2 to 12 and their sensitivity is dependent on the density of binding sites corresponding to UV irradiation time on the channel surface. (c) 2006 Elsevier B.V. All rights reserved.

    DOI

  • pH-sensitive diamond field-effect transistors (FETs) with directly aminated channel surface

    Kwang-Soup Song, Yusuke Nakamura, Yuichi Sasaki, Munenori Degawa, Jung-Hoon Yang, Hiroshi Kawarada

    ANALYTICA CHIMICA ACTA   573 ( Sp. Iss ) 3 - 8  2006年07月  [査読有り]

     概要を見る

    We have introduced pH sensors fabricated on diamond thin films through modification of the surface-terminated atom. We directly modified the diamond surface from hydrogen to amine or oxygen with ultraviolet (UV) irradiation under ammonia gas. The quantified amine site based on the spectra obtained by X-ray photoelectron spectroscopy (XPS) is 26% (2.6 x 10(14) cm(-2)) with UV irradiation for 8 h and its coverage is dependent on the UV irradiation time. This directly aminated diamond surface is stable with long-term exposure in air and electrolyte solution. We fabricated diamond solution-gate field-effect transistors (SGFETs) without insulating layers on the channel surface. These diamond SGFETs with amine modified by direct amination are sensitive to pH (45 mV/pH) over a wide range from pH 2 to 12 and their sensitivity is dependent on the density of binding sites corresponding to UV irradiation time on the channel surface. (c) 2006 Elsevier B.V. All rights reserved.

    DOI

  • Fabrication of T-shaped gate diamond metal-insulator-semiconductor field-effect transistors

    Kazuyuki Hirama, Shingo Miyamoto, Hiroki Matsudaira, Hitoshi Umezawa, Hiroshi Kawarada

    JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS BRIEF COMMUNICATIONS & REVIEW PAPERS   45 ( 7 ) 5681 - 5684  2006年07月  [査読有り]

     概要を見る

    Diamond metal-insulator-semiconductor field effect transistors (MISFETs) with gates of 0.2-0.9 mu m length and T-shape were realized by trilayer resist electron-beam lithography. FETs show a cut-off frequency (f(T)) of 11 GHz and maximum oscillation frequency (f(max)) of 22 GHz. The f(max)/f(T) ratio of this FET was more than double that of FETs with a conventional gate structure and the same gate length. The f(T) of 11 GHz was half the maximum for diamond FETs due to parasitic capacitance at the gate-drain and gate-source electrodes. The T-shaped gate structure and the source-to-drain spacing must be optimized to reduce parasitic capacitance between each electrode.

    DOI

  • DNA micropatterning on polycrystalline diamond via one-step direct amination

    GJ Zhang, KS Song, Y Nakamura, T Ueno, T Funatsu, Ohdomari, I, H Kawarada

    LANGMUIR   22 ( 8 ) 3728 - 3734  2006年04月  [査読有り]

     概要を見る

    We report a novel method of one-step direct amination oil polycrystalline diamond to produce functionalized surfaces for DNA micropatterning by photolithography. Polycrystalline diamond was exposed to UV irradiation in ammonia gas to generate amine groups directly. After patterning, optical microscopy confirmed that micropatterns covered with an Au mask were regular in size and shape. The regions outside the micropatterns were passivated with fluorine termination by C3F8 plasma, and the chemical changes on the two different surfaces-the amine groups inside the patterned regions by one-step direct amination and fluorine termination outside the patterned regions-were characterized by spatially resolved X-ray photoelectron spectroscopy (XPS). The patterned areas terminated with active amine groups were then immobilized with probe DNA via a bifunctional molecule. The sequence specificity was conducted by hybridizing fluorescently labeled target DNA to both complementary and noncomplementary probe DNA attached inside the micropatterns. The fluorescence micropatterns observed by epifluorescence microscopy corresponded to those imaged by optical microscopy. DNA hybridization and denaturation experiments on a DNA-modified diamond show that the diamond surfaces reveal superior stability. The influence of a different amination time oil fluorescence intensity was compared. Different terminations as passivated layers were investigated, and as a result, fluorine termination points to the greatest signal-to-noise ratio.

    DOI

  • Characterization of diamond metal-insulator-semiconductor field-effect transistors with aluminum oxide gate insulator

    K Hirama, S Miyamoto, H Matsudaira, K Yamada, H Kawarada, T Chikyo, H Koinuma, K Hasegawa, H Umezawa

    APPLIED PHYSICS LETTERS   88 ( 11 ) 112117  2006年03月  [査読有り]

     概要を見る

    Metal-insulator-semiconductor field-effect transistors (MISFETs) with aluminum oxide as a gate insulator have been fabricated on a hydrogen-terminated diamond surface using its surface conductive layer. The aluminum oxide gate insulator was deposited on the diamond surface by the pulsed laser deposition method. The on-off ratio measured by dc was greater than five orders of magnitude, one of the best results reported for diamond FETs. The gate leak current of aluminum oxide MISFETs is three orders of magnitude less than that of conventional CaF2 MISFETs. These characteristics indicate that aluminum oxide gate insulators are suitable for high reliability power device applications of diamond MISFETs. (c) 2006 American Institute of Physics.

    DOI

  • Electrical properties of diamond MISFETs with submicron-sized gate on boron-doped (111) surface

    Takeyasu Saito, Kyung-ho Park, Kazuyuki Hirama, Hitoshi Umezawa, Mitsuya Satoh, Hiroshi Kawarada, Zhi-Quan Liu, Kazutaka Mitsuishi, Hideyo Okushi

    PROGRESS IN SEMICONDUCTOR MATERIALS V-NOVEL MATERIALS AND ELECTRONIC AND OPTOELECTRONIC APPLICATIONS   891   485 - +  2006年

     概要を見る

    An H-terminated-surface conductive layer of B-doped diamond on a (I 11) surface was used to fabricate a metal insulator semiconductor field effect transistor (MISFET) using CaF2, SiO2 or Al2O3 gate insulators and a Cu-metal stacked gate. For a CaF2 gate, the maximum measured drain current (I-dmax) was 240 mA/mm and the maximum transconductance (g(m)) was 70 mS/mm, and the cut-off frequency of 4 GHz was obtained. For a SiO2 gate, I-dmax and g(m) were 75 mA/mm and 24 mS/mm, respectively, and for an Al2O3 gate, these characteristics were 86 mA/mm and 15 mS/mm, respectively. These values are among the highest reported DC and RF characteristics for a diamond homoepitaxial (I 11) MISFET.

  • 気相成長ダイヤモンドの超伝導

    高野 義彦, 川原田洋

    セラミックス   41 ( 1 ) 47 - 49  2006年  [査読有り]

  • ホウ素ドープ・ダイヤモンドの超伝導

    高野 義彦, 川原田洋

    固体物理   41 ( 7 ) 457 - 466  2006年  [査読有り]

    DOI

  • Soft X-ray angle-resolved photoemission spectroscopy of heavily boron-doped superconducting diamond films

    T. Yokoya, T. Nakamura, T. Matushita, T. Muro, H. Okazaki, M. Arita, K. Shimada, H. Namatame, M. Taniguchi, Y. Takano, M. Nagao, T. Takenouchi, H. Kawarada, T. Oguchi

    SCIENCE AND TECHNOLOGY OF ADVANCED MATERIALS   7   S12 - S16  2006年  [査読有り]

     概要を見る

    We have performed soft X-ray angle-resolved photoemission spectroscopy (SXARPES) of microwave plasma-assisted chemical vapor deposition diamond films with different B concentrations in order to study the origin of the metallic behavior of superconducting diamond. SXARPES results clearly show valence band dispersions with a bandwidth of similar to 23 eV and with a top of the valence band at gamma point in the Brillouin zone, which are consistent with the calculated valence band dispersions of pure diamond. Boron concentration-dependent band dispersions near the Fermi level (E-F) exhibit a systematic shift of E-F, indicating depopulation of electrons due to hole doping. These SXARPES results indicate that diamond bands retain for heavy boron doping and holes in the diamond band are responsible for the metallic states leading to superconductivity at low temperature. A high-resolution photoemission spectroscopy spectrum near E-F of a heavily boron-doped diamond superconductor is also presented. (c) 2006 NIMS and Elsevier Ltd. All rights reserved.

    DOI

  • Scanning tunneling microscopy and spectroscopy studies of superconducting boron-doped diamond films

    Terukazu Nishizaki, Yoshihiko Takano, Masanori Nagao, Tomohiro Takenouchi, Hiroshi Kawarada, Norio Kobayashi

    SCIENCE AND TECHNOLOGY OF ADVANCED MATERIALS   7   S22 - S26  2006年  [査読有り]

     概要を見る

    We report on scanning tunneling microscopy/spectroscopy (STM/STS) experiments on (111)-oriented epitaxial films of heavily boron-doped diamond grown by using the microwave plasma-assisted chemical vapor deposition method. STM/STS measurements were performed by He-3-refrigerator based STM under ultra-high vacuum. The STM topography on the film surface shows a corrugation (with a typical size of similar to 1 mu m) and grain-like microstructures (similar to 5-20 nm). The tunneling conductance spectra do not show large spatial dependence and superconductivity is observed independent of the surface structures. The tunneling spectra are analyzed by the Dynes function and the superconducting energy gap is estimated to be Delta = 0.87 meV at T = 0.47 K, corresponding to 2 Delta/k(B)T(c) = 3.7. The relatively large value of the broadening parameter Gamma = 0.38 meV is discussed in terms of the inelastic electron scattering processes. (c) 2006 NIMS and Elsevier Ltd. All rights reserved.

    DOI

  • Laser-excited photoemission spectroscopy study of superconducting boron-doped diamond

    K. Ishizaka, R. Eguchi, S. Tsuda, T. Kiss, T. Shimojima, T. Yokoya, S. Shin, T. Togashi, S. Watanabe, C. -T. Chen, C. Q. Zhang, Y. Takano, M. Nagao, I. Sakaguchi, T. Takenouchi, H. Kawarada

    SCIENCE AND TECHNOLOGY OF ADVANCED MATERIALS   7   S17 - S21  2006年  [査読有り]

     概要を見る

    We have investigated the low-energy electronic state of boron-doped diamond thin film by the laser-excited photoemission spectroscopy. A clear Fermi-edge is observed for samples doped above the semiconductor-metal boundary, together with the characteristic structures at 150 x n meV possibly due to the strong electron-lattice coupling effect. In addition, for the superconducting sample, we observed a shift of the leading edge below T-c indicative of a superconducting gap opening. We discuss the electron-lattice coupling and the superconductivity in doped diamond. (c) 2006 NIMS and Elsevier Ltd. All rights reserved.

    DOI

  • B-11-NMR study in boron-doped diamond films

    H. Mukuda, T. Tsuchida, A. Harada, Y. Kitaoka, T. Takenouchi, Y. Takano, M. Nagao, I. Sakaguchi, H. Kawarada

    SCIENCE AND TECHNOLOGY OF ADVANCED MATERIALS   7   S37 - S40  2006年  [査読有り]

     概要を見る

    We have investigated an origin of the superconductivity discovered in boron (B)-doped diamonds by means of B-11-NMR on heteroepitaxially grown (111) and (100) films and polycrystalline film. The characteristic difference of B-NMR spectral shape for the (111) and (100) thin films is demonstrated as arising from the difference in the concentration (n(B(1))) of boron substituted for carbon. It is revealed from a scaling between a superconducting transition temperature T-c and n(B(1)) that the holes doped into diamond via the substitution of boron for carbon are responsible for the onset of superconductivity. The result suggests that the superconductivity in boron-doped diamond is mediated by the electron-phonon interaction brought about a high Debye temperature similar to 1860 K characteristic for the diamond structure. (c) 2006 NIMS and Elsevier Ltd. All rights reserved.

    DOI

  • Acoustic and optical phonons in metallic diamond

    M. Hoesch, T. Fukuda, T. Takenouchi, J. P. Sutter, S. Tsutsui, A. Q. R. Baron, M. Nagao, Y. Takano, H. Kawarada, J. Mizuki

    SCIENCE AND TECHNOLOGY OF ADVANCED MATERIALS   7   S31 - S36  2006年  [査読有り]

     概要を見る

    The dispersion of acoustic and optical phonons in highly boron-doped diamond has been measured by inelastic X-ray scattering at an energy resolution of 6.4 meV. The sample is doped in the metallic regime and shows superconductivity below 4.2 K (midpoint). The data are compared to pure and nitrogen-doped diamond that represent the non-metallic state. No difference is found for the acoustic phonons in the three samples, while the optical phonons show a shift of the dispersion (softening) in qualitative agreement with earlier results from Raman spectroscopy. The presence of boron and nitrogen incorporated into the diamond lattice leads to structural disorder. Evidence for this is found both in the observation of otherwise symmetry-forbidded Bragg intensity at (002) and intensity from acoustic phonon modes in the vicinity of (002). (c) 2006 NIMS and Elsevier Ltd. All rights reserved.

    DOI

  • Low-temperature growth of vertically aligned single-walled carbon nanotubes by radical CVD

    Takayuki Iwasaki, Goufang Zhong, Hiroshi Kawarada

    NEW DIAMOND AND FRONTIER CARBON TECHNOLOGY   16 ( 3 ) 177 - 184  2006年  [査読有り]

     概要を見る

    Very dense and vertically aligned single-walled carbon nanotubes (SWNTs) were synthesized using a radical CVD apparatus at a low temperature of 600 degrees C. A high density of catalytic particles, which is necessary for the growth of vertically aligned SWNTs, was prepared by heat treatment of a sandwich-like catalyst structure of Al2O3/Fe/Al2O3. In our CVD apparatus, a sphere-shaped microwave plasma ball was fixed at the antenna in the chamber and was 50 mm away from the substrate, which indicates that ions cannot contribute to the growth of SWNTs. The radical CVD system produced a very long catalyst lifetime of over 30 h, because catalysts were not damaged and etched by ions. Using the catalysts with the long lifetime, lengths of SWNTs increased to millimeter order. Root growth mode of SWNTs was clarified by marker growth, which synthesized two vertically aligned SWNT layers on a substrate at different growth times.

  • Enhancement of field emission characteristics of tungsten emitters by single-walled carbon nanotube modification

    D Ferrer, T Tanii, Matsuya, I, G Zhong, S Okamoto, H Kawarada, T Shinada, Ohdomari, I

    APPLIED PHYSICS LETTERS   88 ( 3 ) 33116  2006年01月  [査読有り]

     概要を見る

    We present a simple method for improving the field emission performance of tungsten-tip electron sources based on single-walled carbon nanotube (SWCNT) modification. By coating a sandwich-like thin film of Al-Fe-Al (with Fe as a catalyst) on a tungsten tip, SWCNTs were synthesized at 600 degrees C in a chemical vapor deposition (CVD) reactor. The influence of CNT modification on the electron emission characteristics of the emitters was investigated by means of a triode structure. We have found that CNT-modified tungsten tips exhibit low threshold-voltage for electron emission, and improved emission-current stability, compared with nonmodified and Al-Fe-Al-coated needles. (c) 2006 American Institute of Physics.

    DOI

  • Origin of the metallic properties of heavily boron-doped superconducting diamond

    T Yokoya, T Nakamura, T Matsushita, T Muro, Y Takano, M Nagao, T Takenouchi, H Kawarada, T Oguchi

    NATURE   438 ( 7068 ) 647 - 650  2005年12月  [査読有り]

     概要を見る

    The physical properties of lightly doped semiconductors are well described by electronic band- structure calculations and impurity energy levels(1). Such properties form the basis of present- day semiconductor technology. If the doping concentration n exceeds a critical value n(c), the system passes through an insulator- to- metal transition and exhibits metallic behaviour; this is widely accepted to occur as a consequence of the impurity levels merging to form energy bands(2). However, the electronic structure of semiconductors doped beyond nc have not been explored in detail. Therefore, the recent observation of superconductivity emerging near the insulator- to- metal transition(3) in heavily boron- doped diamond(4,5) has stimulated a discussion on the fundamental origin of the metallic states responsible for the superconductivity. Two approaches have been adopted for describing this metallic state: the introduction of charge carriers into either the impurity bands(6) or the intrinsic diamond bands(7-9). Here we show experimentally that the doping- dependent occupied electronic structures are consistent with the diamond bands, indicating that holes in the diamond bands play an essential part in determining the metallic nature of the heavily boron- doped diamond superconductor. This supports the diamond band approach and related predictions, including the possibility of achieving dopant- induced superconductivity in silicon and germanium(7). It should also provide a foundation for the possible development of diamond- based devices(10).

    DOI

  • Characterization of locally modified diamond surface using Kelvin probe force microscope

    M Tachiki, Y Kaibara, Y Sumikawa, M Shigeno, H Kanazawa, T Banno, KS Song, H Umezawa, H Kawarada

    SURFACE SCIENCE   581 ( 2-3 ) 207 - 212  2005年05月  [査読有り]

     概要を見る

    The surface potential difference between an H-terminated surface and a locally oxidized diamond surface produced by an atomic force microprobe was investigated using a Kelvin probe force microscope. The potential of the H-terminated diamond surface was observed to be similar to 0.1 V higher than that of the oxidized diamond surface. The surface potential difference can be interpreted in terms of the positions of the vacuum level, the Fermi level, and the conduction and valence band edges, when negative electron affinity and p-type surface conduction are assumed on the H-terminated diamond surface. The surface dipole induced by the electronegativity differences between the surface atoms of the diamond affects the difference in the surface potential between the two surfaces. (c) 2005 Elsevier B.V. All rights reserved.

    DOI

  • Low temperature synthesis of extremely dense, and vertically aligned single-walled carbon nanotubes

    GF Zhong, T Iwasaki, K Honda, Y Furukawa, Ohdomari, I, H Kawarada

    JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS BRIEF COMMUNICATIONS & REVIEW PAPERS   44 ( 4A ) 1558 - 1561  2005年04月  [査読有り]

     概要を見る

    A novel point-arc microwave plasma chemical vapor deposition (CVD) apparatus was employed to grow single-walled carbon nanotubes (SWNTs) on Si substrates coated with a sandwich-like nano-layer structure of 0.7 nm Al2O3 (top)/0.5 nm Fe/ 5-70nm Al2O3 by conventional high frequency sputtering. The growth of extremely dense and vertically aligned SWNTs with an almost constant growth rate of 270 mu m/h within 40 min at a temperature as low as 600 degrees C was demonstrated for the first time. The volume density of the as-grown SWNT films is as higher as 66 kg/m(3).

    DOI

  • Very high yield growth of vertically aligned single-walled carbon nanotubes by point-arc microwave plasma CVD

    GF Zhong, T Iwasaki, K Honda, Y Furukawa, Ohdomari, I, H Kawarada

    CHEMICAL VAPOR DEPOSITION   11 ( 3 ) 127 - 130  2005年03月  [査読有り]

    DOI

  • Evaluations of electrical properties for ZnTe thin films electrodeposited from a citric acid bath with a Hall effect measurement

    T Ohtomo, T Ishizaki, D Ogiwara, H Kawarada, A Fuwa

    JOURNAL OF THE JAPAN INSTITUTE OF METALS   69 ( 3 ) 298 - 302  2005年03月  [査読有り]

     概要を見る

    ZnTe thin films were electrochemically deposited onto Au-coated Cu substrates from an electrolytic solution containing ZnSO4, TeO2, citric acid and sodium citrate. Effects of deposition potentials and solution's Zn concentrations on the structure, chemical composition and electrical property were investigated. The resistivity, conduction type, carrier density, and carrier mobility were evaluated with a Hall effect measurement apparatus. A film with nearly stoichiometric composition was deposited at -0.80 V vs. Ag/AgCl at 353 K from a solution containing 2.0 x 10(-2) kmol m(-3)-ZnSO4, 1.0 X 10(-4) kmol m(-3)-TeO2, 9.0 X 10(-2) kmol m(-3)-Citric acid and 2.1 x 10(-1) kmol m(-3)-Sodium citrate and was well crystallized with cubic preferential orientation along the (111) plane. A resistivity, the carrier density and the carrier mobility were 4.1 X 10(2) Omega m, 2.9 x 10(19) m(-3) and 5.3 x 10(-4) m(2) V-1 s(-1), respectively.

  • RF diamond transistors: Current status and future prospects

    Umezawa H, Hirama K, Arai T, Hata H, Takayanagi H, Koshiba T, Yohara K, Mejima S, Satoh M, Song K. S, Kawarada H

    Japanese Journal of Applied Physics Part 1-Regular Papers Brief Communications & Review Papers   44 ( 11 ) 7789 - 7794  2005年  [査読有り]

    DOI DOI2

  • Fabrication of diamond MISFET with micron-sized gate length on boron-doped (111) surface

    Saito T, Park K. H, Hirama K, Umezawa H, Satoh M, Kawarada H, Okushi H

    Diamond and Related Materials   14 ( 11-12 ) 2043 - 2046  2005年  [査読有り]

    DOI

  • Superconductivity in polycrystalline diamond thin films

    Yoshihiko Takano, Masanori Nagao, Tomohiro Takenouchi, Hitoshi Umezawa, Isao Sakaguchi, Masashi Tachiki, Hiroshi Kawarada

    DIAMOND AND RELATED MATERIALS   14   1936 - 1938  2005年  [査読有り]

    DOI

  • ダイヤモンドの超伝導

    高野 義彦, 川原田洋

    FSST NEWS   ( 104 ) 2 - 5  2005年  [査読有り]

  • 表面修飾ダイヤモンドトランジスタによるDNA及びバイオセンシング応用

    川原田 洋, 宋 光燮

    化学と工業   58 ( 4 ) 473 - 476  2005年

  • 多結晶ダイヤモンドを用いた電解質溶液FETsのバイオセンサへの応用

    宋 光燮, 中村 雄介, 出川 宗里, 佐々木 順紀, 梅沢 仁, 川原田 洋

    日本結晶成長学会誌   31   4  2005年

  • Micropatterning oligonucleotides on single-crystal diamond surface by photolithography

    GJ Zhang, H Umezawa, H Hata, T Zako, T Funatsu, L Ohdomari, H Kawarada

    JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS & EXPRESS LETTERS   44 ( 8-11 ) L295 - L298  2005年  [査読有り]

     概要を見る

    DNA micropatterns have been for the first time fabricated on a single-crystal diamond surface in conjunction with the photolithography technique. A new chemical modification process for producing amine groups inside patterned regions and a passivation layer terminated with fluorine outside patterned regions is demonstrated. The resulting amine groups within patterned areas and fluorine termination outside patterned areas on the single-crystal diamond surface were characterized by spatially resolved X-ray photoelectron spectroscopy. Amine-terminated oligonucleotides were then linked to the amine patterned regions using a crosslinker. It was revealed that hybridization on DNA-patterned diamond is specific and selective, with a low background outside the patterns and strong binding to complementary probe DNA immobilized inside the patterns but no binding to noncomplementary probe DNA similarly immobilized inside the patterns. These results suggest that DNA micropatteming on a single-crystal diamond may serve as an ideal platform for future biochips and biosensors.

    DOI

  • Characteristics of diamond electrolyte solution-gate FETs (SGFETs) and applications to biosensor

    KS Song, H Kawarada

    NEW DIAMOND AND FRONTIER CARBON TECHNOLOGY   15 ( 6 ) 325 - 335  2005年  [査読有り]

     概要を見る

    A diamond electrolyte solution-gate FET (SGFET) for use in electrolyte solutions has been fabricated for the first time. Perfect device characteristics (pinch-off and saturation in I(DS)-V(DS)) have been obtained with bias voltages within the potential window of diamond. The hydrogen-terminated (H-terminated) diamond surface was sensitive to halogen ions at approximately 30 mV/decade. We modified the H-terminated diamond surface with oxygen by treatment with ozone. Partially oxygen-terminated sites were insulating and insensitive to halogen ions. The H-terminated channel surface was modified to be partially amine-oxygen-terminated (H-A-O-terminated) to achieve pH sensitivity when irradiated with UV light in an ammonia solution. The pH sensitivity of a diamond surface modified was about 50 mV/pH unit from pH 2 to 10. We immobilized specific enzymes (urease and glucose oxidase) on the modified channel surface. The sensitivities to urea and glucose were approximately 30 mV/decade and 20 mV/decade, respectively.

  • Characteristics of diamond electrolyte solution-gate FETs (SGFETs) and applications to biosensor

    KS Song, H Kawarada

    NEW DIAMOND AND FRONTIER CARBON TECHNOLOGY   15 ( 6 ) 325 - 335  2005年  [査読有り]

     概要を見る

    A diamond electrolyte solution-gate FET (SGFET) for use in electrolyte solutions has been fabricated for the first time. Perfect device characteristics (pinch-off and saturation in I(DS)-V(DS)) have been obtained with bias voltages within the potential window of diamond. The hydrogen-terminated (H-terminated) diamond surface was sensitive to halogen ions at approximately 30 mV/decade. We modified the H-terminated diamond surface with oxygen by treatment with ozone. Partially oxygen-terminated sites were insulating and insensitive to halogen ions. The H-terminated channel surface was modified to be partially amine-oxygen-terminated (H-A-O-terminated) to achieve pH sensitivity when irradiated with UV light in an ammonia solution. The pH sensitivity of a diamond surface modified was about 50 mV/pH unit from pH 2 to 10. We immobilized specific enzymes (urease and glucose oxidase) on the modified channel surface. The sensitivities to urea and glucose were approximately 30 mV/decade and 20 mV/decade, respectively.

  • Synthesis of highly oriented and dense conical carbon nanofibers by a DC bias-enhanced microwave plasma CVD method

    GF Zhong, T Iwasaki, H Kawarada, Ohdomari, I

    THIN SOLID FILMS   464 ( 65 ) 315 - 318  2004年10月  [査読有り]

     概要を見る

    Conical carbon nanofibers (CCNFs) have been synthesized on Si substrates coated with a Fe thin film of a few nanometers in thickness by a DC bias-enhanced microwave plasma chemical vapor deposition (CVD) method using H-2 and CH4 as reactant gases under a chamber pressure of about 230 Pa. Without DC bias, only catalytic nanoparticles could be observed by field emission scanning electron microscopy (FE-SEM) on substrate surface after growth. Highly oriented and dense CCNFs could be deposited when a negative DC bias in the range of 150-230 V was applied to the substrate holder during growth. The average density of CCNFs was measured as being of the order of 10(10) cm(-2), while the average length was of the order of 10(2) nm, and the conical angle was in the range of 10-15degrees. The relationships between the density, the root diameter and the length of CCNFs are discussed. (C) 2004 Elsevier B.V. All rights reserved.

    DOI

  • Superconductivity in diamond thin films well above liquid helium temperature

    Y Takano, M Nagao, Sakaguchi, I, M Tachiki, T Hatano, K Kobayashi, H Umezawa, H Kawarada

    APPLIED PHYSICS LETTERS   85 ( 14 ) 2851 - 2853  2004年10月  [査読有り]

     概要を見る

    We report unambiguous evidence for superconductivity in a heavily boron-doped diamond thin film grown by microwave plasma-assisted chemical vapor deposition (MPCVD). An advantage of the MPCVD-deposited diamond is that it can contain boron at high concentration, especially in (111)-oriented films. Superconducting transition temperatures are determined by transport measurements to be 7.4 K for T-C onset and 4.2 K for zero resistance. The upper critical field is estimated to be 7 T. Magnetization as a function of magnetic fields shows typical type-II superconducting properties. (C) 2004 American Institute of Physics.

    DOI

  • Over 20-GHz cutoff frequency submicrometer-gate diamond MISFETs

    H Matsudaira, S Miyamoto, H Ishizaka, H Umezawa, H Kawarada

    IEEE ELECTRON DEVICE LETTERS   25 ( 7 ) 480 - 482  2004年07月  [査読有り]

     概要を見る

    Submicrometer-gate (0.2-0.5-mum) diamond metal-insulator-semiconductor field-effect transistors (MISFETs) were fabricated on an H-terminated diamond surface. The maximum transconductance in dc mode reaches 165 mS/mm, while the average transconductance is 70 mS/mm in submicrometer-gate diamond MISFETs. The highest cutoff frequency of 23 GHz and the maximum frequency of oscillation of 25 GHz are realized in the 0.2-mum-gate diamond MISFET. From the intrinsic transconductances or the cutoff frequencies, the saturation velocities are estimated to be 4 x 10(6) cm/s in the submicrometer-gate FETs. They are reduced by gate-drain capacitance and source resistance.

    DOI

  • Memory effect of diamond in-plane-gated field-effect transistors

    Y Sumikawa, T Banno, K Kobayashi, Y Itoh, H Umezawa, H Kawarada

    APPLIED PHYSICS LETTERS   85 ( 1 ) 139 - 141  2004年07月  [査読有り]

     概要を見る

    A memory effect of in-plane-gated field-effect transistors (IPGFETs) has been observed on hydrogen-terminated and oxygen-terminated diamond surfaces. The hysteresis characteristics are achieved by the hole traps in the oxygen-terminated surface of the IPGFETs where the threshold voltage shift by the gate voltage sweep is confirmed in the I-d-V-g characteristics. This feature is observed under light illumination, and depends on the radiant flux density. The hysteresis characteristics become very small under the condition of no light irradiation at room temperature. It is assumed that carrier trap sites on the insulating part of IPGFET cause the hysteresis characteristics. Radiant flux enhances carrier migration. (C) 2004 American Institute of Physics.

    DOI

  • Large-area synthesis of carbon nanofibers by low-power microwave plasma-assisted CVD

    GF Zhong, M Tachiki, H Umezawa, T Fujisaki, H Kawarada, Ohdomari, I

    CHEMICAL VAPOR DEPOSITION   10 ( 3 ) 125 - +  2004年06月  [査読有り]

     概要を見る

    Communication: Novel antenna edge microwave plasma CVD (AE-MPCVD) is used for the first time to grow CNFs (carbon nanofibers). The synthesis of CNFs on large-area substrates with high growth reproducibility is reported at low microwave power input and with remote deposition. A Growth area ten times as large as the plasma size generated is achieved by AE-MPCVD. Because of its structural simplicity, AE-MPCVD systems can easily be scaled up by applying multi-antenna edge arrays without considering complex microwave geometry or cavity and the total growth area and quality of CNFs are thus expected to be greatly improved.

    DOI

  • Surface-modified diamond field-effect transistors for enzyme-immobilized biosensors

    KS Song, M Degawa, Y Nakamura, H Kanazawa, H Umezawa, H Kawarada

    JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS & EXPRESS LETTERS   43 ( 6B ) L814 - L817  2004年06月  [査読有り]

     概要を見る

    The enzyme sensors using electrolyte-solution-gate diamond field effect transistors (SGFETs) have been developed for the first time. The hydrogen-terminated surface channel of the FETs was modified into partially aminated and oxygen-terminated (H-A-O-terminated) with irradiation of ultraviolet in an ammonia environment. The pH response of that is obtained about 50 mV/pH at pH 2-10. The concentration of substrates (urea or glucose) in the electrolyte solution has been detected by the pH change due to the bio-catalyzed effect of enzyme (urease or glucose oxidase), which is immobilized on the channel of SGFETs. The sensitivity of urea and glucose is approximately 30 mV/decade and 20 mV/decade respectively.

    DOI

  • 多結晶ダイヤモンド表面を用いた電解質溶液FETsのバイオセンサへの応用

    宋 光燮, 中村 雄介, 出川 宗則, 佐々木 順紀, 梅沢 仁, 川原田 洋

    日本結晶成長学会論文誌   31 ( 4 ) 335 - 340  2004年

  • ダイヤモンドにおけるキャリア輸送特性とFETへの応用

    川原田 洋, 梅沢 仁

    応用物理   73 ( 3 ) 339 - 345  2004年

  • Diamond field effect transistors using H-terminated surfaces

    H Kawarada

    THIN-FILM DIAMOND II   77   311 - 338  2004年  [査読有り]

  • Cl- sensitive biosensor used electrolyte-solution-gate diamond FETs

    KS Song, T Sakai, H Kanazawa, Y Araki, H Umezawa, M Tachiki, H Kawarada

    BIOSENSORS & BIOELECTRONICS   19 ( 2 ) 137 - 140  2003年11月  [査読有り]

     概要を見る

    We have investigated the electrolyte-solution-gate field effect transisitors (SGFETs) used hydrogen terminated (H-terminated) or partially oxygen terminated (O-terminated) polycrystalline diamond surface in the Cl- and Br- ionic solutions. The H-terminated channel SGFETs are insensitive to pH values in electrolyte solutions. The threshold voltages of the diamond SGFETs shift according to the density of Cl(-)and Br- ions about 30 mV/decade. One of the attractive biomedical applications for the Cl- sensitive SGFETs is the detection of chloride density in blood or in sweat especially in the case of cystic fibrosis. The sensitivities of Cl- and Br- ions have been lost on the partially O-terminated diamond surface. These phenomena can be explained by the polarity of surface change on the H-terminated and the O-terminated surface. (C) 2003 Elsevier B.V. All rights reserved.

    DOI

  • RF performance of diamond surface-channel field-effect transistors

    H Umezawa, S Miyamoto, H Matsudaira, H Ishizaka, KS Song, M Tachiki, H Kawarada

    IEICE TRANSACTIONS ON ELECTRONICS   E86C ( 10 ) 1949 - 1954  2003年10月  [査読有り]

     概要を見る

    RF diamond FETs have been realized on a hydrogen-terminated diamond surface conductive layer. By utilizing the self-aligned gate fabrication process which is effective for the reduction of the parasitic resistance, the transconductance of diamond FETs has been greatly improved. Consequently, the high frequency operation of 22 GHz has been realized in 0.2 mum gate diamond MISFETs with a CaF2 gate insulator. This value is the highest in diamond FETs and is comparable to the maximum value of SiC MESFETs at present.

  • Ozone-treated channel diamond field-effect transistors

    T Sakai, KS Song, H Kanazawa, Y Nakamura, H Umezawa, M Tachiki, H Kawarada

    DIAMOND AND RELATED MATERIALS   12 ( 10-11 ) 1971 - 1975  2003年10月  [査読有り]

     概要を見る

    Diamond field-effect transistors (FETs) whose channel is partially oxidized and highly resistive are fabricated by ozone treatment. These FETs are operated in electrolyte solutions. From XPS analyses, it is evident that hydrogen-terminated (H-terminated) diamond is partially oxygen-terminated (O-terminated) by ozone treatment. The quantification of surface oxygen in ozone-treated diamond is carried out. The quantification shows that the surface oxygen increases with an increase in ozone treatment time indicating the control of oxygen coverage. The partially O-terminated diamond surface channel is much less conductive compared with the H-terminated diamond. The ozone-treated FETs were operated stably even though the channel of the FETs becomes highly resistive. For the sensing of particular ions or molecules by the immobilization of sensing components, the control of surface termination is necessary. (C) 2003 Elsevier Science B.V. All rights reserved.

    DOI

  • Non-linear increases in excitonic emission in synthetic type-IIa diamond

    K Nakazawa, H Umezawa, M Tachiki, H Kawarada

    DIAMOND AND RELATED MATERIALS   12 ( 10-11 ) 1995 - 1998  2003年10月  [査読有り]

     概要を見る

    Free-exciton emissions increase non-linearly by cathodoluminescence (CL) above the threshold probe current of 30 muA in high-pressure high-temperature synthetic type-IIa diamond. A droplet of electron-hole liquid (EHL) is also observed by CL for the first time. Furthermore, boron acceptor bound-exciton emission as well as free-exciton emission also increases super-linearly in an unintentionally boron-contaminated area. The threshold probe current of non-linear increase of excitonic emission is in accordance with the emergence of the EHL peak. It is considered that the non-linear increase of excitonic emissions is due to the increase in the radiative recombination rate of free excitons under high exciton density. (C) 2003 Elsevier Science B.V. All rights reserved.

    DOI

  • Deep sub-micron gate diamond MISFETs

    H Matsudaira, A Takuya, H Umezawa, S Miyamoto, H Ishizaka, M Tachiki, H Kawarada

    DIAMOND AND RELATED MATERIALS   12 ( 10-11 ) 1814 - 1818  2003年10月  [査読有り]

     概要を見る

    The basic characteristics of the short channel FETs have been investigated for the high-frequency performance of the diamond MISFETs. The deep sub-micron gate (0.23-0.5 mum) diamond MISFETs were fabricated on an H-terminated diamond surface. The short channel effect is well suppressed utilizing thin gate insulator. Accordingly, the transconductance is improved by reduction of gate length down to 0.2 mum. This tendency is observed in diamond MISFETs for the first time. Maximum transconductance reaches 71 mS/mm in DC mode and 51 mS/mm in AC mode. The f(T) of 40 GHz is expected in 0.2 mum gate MISFETs as a result. (C) 2003 Elsevier B.V. All rights reserved.

    DOI

  • Cryogenic operation of surface-channel diamond field-effect transistors

    H Ishizaka, M Tachiki, KS Song, H Umezawa, H Kawarada

    DIAMOND AND RELATED MATERIALS   12 ( 10-11 ) 1800 - 1803  2003年10月  [査読有り]

     概要を見る

    Cryogenic operation of field-effect transistors (FETs) fabricated on hydrogen-terminated (H-terminated) diamond surface conductive layers is investigated. 5-mum gate-length metal-insulator-semiconductor FETs (MISFETs) is fabricated using CaF2 film as a gate insulator. The MISFETs operate successfully even at 4.4 K. At low temperature, the contact between source/drain electrode and H-terminated diamond surface cannot maintain ohmic characteristics, because the thermal activation energy of the carriers is not high enough to overcome the barrier height at the interfaces between the source electrode and the H-terminated diamond. Estimated channel mobility increases from 63 cm(2)/V-s to 137 cm(2)/V-s and the maximum transconductance increases from 10.5 mS/mm to 14.5 mS/mm, as the temperature decreases from 300 K to 4.4 K, indicating reduced phonon scattering of the channel. (C) 2003 Elsevier Science B.V. All rights reserved.

    DOI

  • Diamond nanofabrication and characterization for biosensing application

    M Tachiki, Y Kaibara, Y Sumikawa, M Shigeno, T Banno, KS Song, H Umezawa, H Kawarada

    PHYSICA STATUS SOLIDI A-APPLIED RESEARCH   199 ( 1 ) 39 - 43  2003年09月  [査読有り]

     概要を見る

    Surface potential of the H-terminated and locally oxidized diamond surfaces is investigated by Kelvin probe force microscope. Potential of H-terminated diamond surface is observed to be similar to0.1 V higher than that of oxidized diamond surface. Surface potential difference is attributed to the surface charge induced by the electronegativity differences of the terminated atoms. The difference of DNA physisorption on the H- and O-terminated diamond surfaces due to the surface charging effect is also observed. (C) 2003 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

    DOI

  • Electron-spectroscopy and -diffraction study of the conductivity of CVD diamond (001)2 x 1 surface

    S Kono, T Takano, M Shimomura, T Goto, K Sato, T Abukawa, M Tachiki, H Kawarada

    SURFACE SCIENCE   529 ( 1-2 ) 180 - 188  2003年04月  [査読有り]

     概要を見る

    A chemical vapor deposition as-grown diamond (0 0 1) single-domain 2 x 1 surface was studied by electron-spectroscopy and electron-diffraction in ultrahigh vacuum (UHV). In order to change the surface conductivity (SC) of the diamond in UHV, three annealing stages were used; without annealing, annealing at 300 degreesC and annealing at 550 degreesC. From low energy electron diffraction and X-ray photoelectron spectroscopic (XPS) studies, an existence of SC was suggested for the first two stages of annealing and an absence of SC was suggested for the last stage of annealing. Changes in C KVV Auger electron spectroscopic spectra, C KVV Auger electron diffraction (AED) patterns and C 1s XPS peak positions were noticed between the annealing stages at 300 and 550 degreesC. These changes are interpreted as such that the state of hydrogen involvement in a subsurface of diamond (001)2 x 1 changes as SC changes. In particular, the presence of local disorder in diamond configuration in SC subsurface is pointed out from C KVV AED. From C Is XPS peak shifts, a lower bound for the Fermi-level for SC layers from the valence band top is presented to be similar to0.5 eV. (C) 2003 Elsevier Science B.V. All rights reserved.

    DOI

  • 水素終端表面伝導層を用いた高周波ダイヤモンドFET

    梅沢 仁, 石坂 博明, 宮本 真吾, 宋 光燮, 立木 実, 川原田 洋

    電子情報通信学会論文誌C   J86-C  2003年04月

  • Electron-spectroscopy and-diffraction study of the conductivity of CVD diamond(001)2×1 surface

    S. Kono, T. Takano, M. Shimomura, T. Goto, K. Sato, T. Abukawa, M. Tachiki, H. Kawarada

    Surface Science   529 ( 1-2 ) 180 - 188  2003年04月  [査読有り]

    DOI

  • Initial growth of heteroepitaxial diamond on Ir(001)/MgO(001) substrates using antenna-edge-type microwave plasma assisted chemical vapor deposition

    T Fujisaki, M Tachiki, N Taniyama, M Kudo, H Kawarada

    DIAMOND AND RELATED MATERIALS   12 ( 3-7 ) 246 - 250  2003年03月  [査読有り]

     概要を見る

    Initial growth of heteroepitaxial diamond on Ir (0 0 1)/MgO (0 0 1) was investigated by scanning electron microscopy, reflection high-energy electron diffraction (RHEED) and atornic force microscopy. Bias-enhanced nucleation (BEN) was performed by antenna-edge-type microwave plasma assisted chemical vapor deposition. In BEN, diamond crystallites nucleated and grew along the [ - I 10] and [1 10] directions of iridium. Diamond was likely to nucleate on protruded iridium areas. After BEN, in addition to the diamond diffraction spots, iridium bulk diffraction spots, which were not observed before BEN, were observed by RHEED. The iridium. surface appeared to be protruded and changed by the high ion current density in BEN. Under [0 0 1] selective growth conditions, diamond crystallites, which were less than 10 run in diameter, were etched by H-2 plasma. Diamond nucleated areas corresponded to the surface ridges of iridium along the 1 101 and [ 1 10] directions at 10-40 run intervals before BEN. (C) 2003 Elsevier Science B.V. All rights reserved.

    DOI

  • High performance diamond MISFETs using CaF2 gate insulator

    S Miyamoto, H Matsudaira, H Ishizaka, K Nakazawa, H Taniuchi, H Umezawa, M Tachiki, H Kawarada

    DIAMOND AND RELATED MATERIALS   12 ( 3-7 ) 399 - 402  2003年03月  [査読有り]

     概要を見る

    A cut-off frequency of 15 GHz and a maximum frequency of oscillation of 20 GHz are realized in a 0.4-mum gate diamond metal-insulator-semiconductor field-effect transistor (MISFET). The cut-off frequency is the highest value for diamond FETs ever reported. The RF characteristics of the MISFETs are higher than those of metal-semiconductor FETs at the same gate lengths. The CaF2 gate insulator improves the carrier mobility according to the Hall measurement system. The mobility increases in the surface conductive layer result in high RF performance. The source-gate passivation of CaF2 results in the high DC transconductance because of the reduction of series resistances. A cut-off frequency of more than 30 GHz is expected with the gate minimization and the CaF2 passivation of source-gate and gate-drain spacings. (C) 2003 Elsevier Science B.V. All rights reserved.

    DOI

  • Fabrication of diamond in-plane-gated field effect transistors using oxygen plasma etching

    T Banno, M Tachiki, K Nakazawa, Y Sumikawa, H Umezawa, H Kawarada

    DIAMOND AND RELATED MATERIALS   12 ( 3-7 ) 408 - 412  2003年03月  [査読有り]

     概要を見る

    Diamond dual in-plane-gated field effect transistors with very low gate leakage current have been fabricated on an undoped hydrogen-terminated diamond p-type surface using oxygen plasma etching. Adjusting the threshold voltage optimally by one side gate, lateral electric field from the other side gate modulates the channel conductance. The oxygen plasma etching of 60 nm in depth fully isolated the channel of the hydrogen-terminated diamond surface conductive layer from the side gates resulting very low gate leakage current (&lt; 1 pA at -60 V) at room temperature. This feature provides a necessary condition for the fabrication of diamond single-hole transistors operated at room temperature. (C) 2003 Elsevier Science B.V. All rights reserved.

  • Effect of iodide ions on the hydrogen-terminated and partially oxygen-terminated diamond surface

    H Kanazawa, KS Song, T Sakai, Y Nakamura, H Umezawa, M Tachiki, H Kawarada

    DIAMOND AND RELATED MATERIALS   12 ( 3-7 ) 618 - 622  2003年03月  [査読有り]

     概要を見る

    The effect of I- ions on the threshold voltages of the electrolyte-solution-gate diamond field-effect transistors (SGFETs) in KI solution is investigated. The threshold voltages of hydrogen-terminated (H-terminated) diamond SGFETs shift in the KI concentration range of 10(-6)-10(-1) M in aqueous solutions. The sensitivity of the H-ten-ninated diamond surface to I- ions is higher than that to Cl- or Br- ions. However, the sensitivity to I- ions of the partially oxygen-terminated (O-terminated) diamond surface drastically decreases with ozone treatment. The mechanisms of these phenomena can be explained by the surface charge and the adsorbability of I- ions on the H-terminated and O-terminated diamond surfaces. (C) 2003 Elsevier Science B.V. All rights reserved.

  • Control wettability of the hydrogen-terminated diamond surface and the oxidized diamond surface using an atomic force microscope

    Y Kaibara, K Sugata, M Tachiki, H Umezawa, H Kawarada

    DIAMOND AND RELATED MATERIALS   12 ( 3-7 ) 560 - 564  2003年03月  [査読有り]

     概要を見る

    The force-distance curve indicates the difference in wettability between the hydrogen-terininated (H-terminated) diamond surface and the AYM-field-assisted local oxidized (O-terminated) area. Using a hydrophilic (silicon with native oxide) tip and a hydrophobic (coated with gold) tip as AFM tips, the adhesion force mapping measurement shows that the H-terminated surface is hydrophobic and that the O-terminated surface is hydrophilic. After heating in vacuum, the difference in the adhesion force between two surfaces decreased. This means that water adsorbed on the tip and sample surfaces affects the adhesion force. As an alternative measurement, the contact angle measurement of the H-terminated surface and the chemically oxidized surface was performed. It is proved that the oxidized surface is more hydrophilic than the H-terminated surface and that its surface energy is derived from surface polarity such as that involved in hydrogen bonding and electric dipole which is twofold that the H-terminated surface. (C) 2003 Elsevier Science B.V All rights reserved.

  • Cathodoluminescence and Hall-effect measurements in sulfur-doped chemical-vapor-deposited diamond

    K Nakazawa, M Tachiki, H Kawarada, A Kawamura, K Horiuchi, T Ishikura

    APPLIED PHYSICS LETTERS   82 ( 13 ) 2074 - 2076  2003年03月  [査読有り]

     概要を見る

    Dominant n-type conductivity in sulfur-doped chemical-vapor-deposited diamond is observed by Hall-effect measurement. The activation energy is estimated at 0.5-0.75 eV above 600 K. Below 600 K, the carrier concentration deviates from the activation energy, and Hall mobility decreases in comparison with that above 600 K. It is considered that hopping conduction takes place. By cathodoluminescence measurement, free-exciton recombination radiation is observed in spite of a very high sulfur doping level of 2.5% during deposition, where boron is not detected by secondary ion mass spectroscopy. Therefore, the n-type conductivity of sulfur-doped diamond is caused by a sulfur-related mechanism. (C) 2003 American Institute of Physics.

    DOI

  • Electron spectroscopy and diffraction study of the origin of CVD diamond surface conductivity

    S Kono, T Takano, M Shimomura, T Goto, K Sato, T Abukawa, M Tachiki, H Kawarada

    NEW DIAMOND AND FRONTIER CARBON TECHNOLOGY   13 ( 5 ) 247 - 255  2003年  [査読有り]

     概要を見る

    The origin of surface conductivity (SC) of a CVD diamond (001) single-domain 2x1 surface was studied by electron spectroscopy and electron diffraction in UHV. In order to change SC of the diamond in UHV, two annealing stages were used: annealing at 300 degreesC and annealing at 550 degreesC. From the results of LEED and XPS, the existence of SC was suggested for the first stage of annealing and the absence of SC was suggested for the last stage of annealing. Changes in C KVV AES spectra, C KVV AED patterns and C 1s XPS peak positions were noted between the annealing stages at 300 and 550 degreesC. These changes are interpreted in that the state of hydrogen involvement on a subsurface of diamond (001)2x1 changes as SC changes. From C 1s XPS peak shifts, a lower bound for the Fermi level for SC layers from the valence band top is presented to be similar to0.5 eV.

  • 水素終端表面伝導層を用いた高周波ダイヤモンドFET

    梅沢 仁, 石坂 博明, 宮本 真吾, 宋 光燮, 立木 実, 川原田 洋

    電子情報通信学会論文誌C   J86-C   419 - 425  2003年

  • Fabrication of single-hole transistors on hydrogenated diamond surface using atomic force microscope

    M Tachiki, H Seo, T Banno, Y Sumikawa, H Umezawa, H Kawarada

    APPLIED PHYSICS LETTERS   81 ( 15 ) 2854 - 2856  2002年10月  [査読有り]

     概要を見る

    Nanofabrication of electron devices based on the stability of hydrogen- and oxygen-terminated diamond surfaces is performed using an atomic force microscope modification technology. A nanotechnology involving the separation of C-H and C-O bonded surfaces has been applied to realize the single-hole transistors. The single-hole transistors operate at liquid-nitrogen temperature (77 K), where the Coulomb oscillation characteristics are clearly observed. (C) 2002 American Institute of Physics.

    DOI

  • Nanoscale modification of the hydrogen-terminated diamond surface using atomic force microscope

    K Sugata, M Tachiki, T Fukuda, H Seo, H Kawarada

    JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS   41 ( 7B ) 4983 - 4986  2002年07月  [査読有り]

     概要を見る

    Local insulation on the hydrogen-terminated homoepitaxial diamond (001) surface was performed using an atomic force microscope (AFM). The mechanism is analogous to electrochemical anodic oxidation in which the sample acts as an anode while the AFM tip acts as a cathode and the water layer from the atmosphere between the tip and the sample surface works as the electrolyte. The current measured during insulation indicates the anodization characteristics of the process. The surface modification has been found to be strongly dependent on the electric field between the sample and the tip. We also demonstrate the modification with the alternating current (AC) voltage bias. This method prevents buildup of space charge during modification and leads to the increase of the modified line width compared with the static voltage bias. Under proper conditions, such as suitable writing speed and bias voltage, the minimum line width reaches 35 nm in the case of AC bias.

    DOI

  • Investigation of current-voltage characteristics of oxide region induced by atomic force microscope on hydrogen-terminated diamond surface

    H Seo, M Tachiki, T Banno, Y Sumikawa, H Umezawa, H Kawarada

    JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS   41 ( 7B ) 4980 - 4982  2002年07月  [査読有り]

     概要を見る

    The current-voltage characteristic of the atomic force microscope (AFM) field-assisted local oxidized region on an undoped hydrogen-terminated (H-terminated) diamond surface is investigated. The barrier height on the top of the valence band between the undoped H-terminated diamond surface and the AFM oxidized surface is estimated by Fowler-Nordheim (F-N) tunneling current analysis. By fitting the parameter of the slope in the F-N plot, the barrier height is estimated to be 61 meV in the electrically isolated conductive island structure. On the other hand, the barrier height is also estimated to be 72 meV in the lateral tunneling diode.

    DOI

  • Microwave performance of diamond field-effect transistors

    H Taniuchi, H Umezawa, H Ishizaka, H Kawarada

    JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS   41 ( 4B ) 2591 - 2594  2002年04月  [査読有り]

     概要を見る

    The microwave performance of diamond metal semiconductor field-effect transistors (MESFET) and metal insulator semiconductor field-effect transistors (MISFET) fabricated on hydrogen-terminated diamond surface is investigated. A cut-off frequency of 2.2 GHz is obtained on a 2 mum Cu gate MESFET with a transconductance of 70 mS/mm. A cut-off frequency of 11 GHz is obtained on a 0.7 mum gate MISFET with a transconductance of 40 mS/mm. Despite the lower transconductance, the cut-off frequency of MISFET is higher than that of MESFET due to not only gate minimization but also increased carrier mobility due to the use of CaF2 as the gate insulator, High-frequency equivalent circuits are derived from S-parameters for MISFET with various gate lengths, Reduction of gate-source parasitic resistance and capacitance in MISFET by the improvement of device structure yield high frequency performance.

    DOI

  • Heteroepitaxial diamond thin film growth on Ir(001)/MgO(001) substrate by antenna-edge plasma assisted chemical vapor deposition

    M Tachiki, T Fujisaki, N Taniyama, M Kudo, H Kawarada

    JOURNAL OF CRYSTAL GROWTH   237   1277 - 1280  2002年04月  [査読有り]

     概要を見る

    Heteroepitaxial (0 0 1) diamond films are successfully grown on high-quality (0 0 1)Ir/(0 0 1)MgO substrates. To enhance the epitaxial nucleation and growth of the diamond, antenna-edge microwave plasma chemical vapor deposition (MPCVD) has been used as a bias enhanced nucleation step. Subsequently, the diamond growth step is performed using conventional MPCVD in a &lt;0 0 1&gt; fast growth mode. Scanning electron microscope (SEM) observation and reflection high-energy electron diffraction (RHEED) reveals the epitaxial ordering of deposited film in several millimeters square area. (C) 2002 Elsevier Science B.V. All rights reserved.

  • RF performance of high transconductance and high-channel-mobility surface-channel polycrystalline diamond metal-insulator-semiconductor field-effect transistors

    H Umezawa, T Arima, N Fujihara, H Taniuchi, H Ishizaka, M Tachiki, C Wild, P Koidl, H Kawarada

    JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS   41 ( 4B ) 2611 - 2614  2002年04月  [査読有り]

     概要を見る

    The RF device potential of surface-channel polycrystalline diamond metal-insulator-semiconductor field-effect transistors (MISFETs) is demonstrated for the first time, Utilizing a self-aligned gate field-effect transistor (FET) fabrication process, effective transconductance of 70 mS/mm is realized at 0.7 mum gate length. This FET also shows high f(T) and f(max) of 2.7 and 3.8 GHz, respectively. However, the breakdown voltage and f(max)/f(T) ratio are lower than those for the homoepitaxial layer because of the parasitic capacitance at the grain boundaries in the drain region. Because of the fluctuation of channel mobility, the fluctuation of g(m) and f(T) is observed. In order to realize high-power operation at high frequency, the fabrication of the FET on a single grain to reduce the parasitic capacitance is required.

  • High frequency performance of diamond field-effect transistor

    Jpn.J.Appl.Phys.   41   2591 - 2594  2002年04月

  • Effect of Cl- ionic solutions on electrolyte-solution-gate diamond field-effect transistors

    T Sakai, Y Araki, H Kanazawa, H Umezawa, M Tachiki, H Kawarada

    JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS BRIEF COMMUNICATIONS & REVIEW PAPERS   41 ( 4B ) 2595 - 2597  2002年04月  [査読有り]

     概要を見る

    Diamond field-effect transistors (FETs) operate in electrolyte solutions having a wide pH range of 1-13. The FETs have been fabricated using a p-type surface conductive layer, where the diamond surface is exposed directly to the electrolyte solutions. From the drain current-gate voltage (I-ds-V-gs) characteristics of the FETs, it appears that the threshold voltages of the FETs are independent of the pH value of the solution. In Cl- ionic solutions, however, the threshold voltages shift approximately 30mV with a one-order-of-magnitude change of molar concentration of Cl- ions. This sensitivity of the FET to Cl- ion's concrentration is observed in the 10(-1)-10(-6) M range of potassium chloride (KCI) solutions.

  • RF performance of diamond MISFETs

    H Umezawa, H Taniuchi, H Ishizaka, T Arima, N Fujihara, M Tachiki, H Kawarada

    IEEE ELECTRON DEVICE LETTERS   23 ( 3 ) 121 - 123  2002年03月  [査読有り]

     概要を見る

    A cutoff frequency (f(T)) of 11 GHz is realized in the hydrogen-terminated surface channel diamond metal-insulator-semiconductor field-effect transistor (MISFET) with 0.7 mum gate length. This value is five times higher than that of 2 mum gate metal-semiconductor (MES) FETs and the maximum value in diamond FETs at present. Utilizing CaF2 as an insulator in the MIS structure, the gate-source capacitance is reduced to half that of diamond MESFET because of the gate insulator capacitance being in series to the surface-channel capacitance. This FET also exhibits the highest f(max) of 18 GHz and 15 dB of power gain at 2 GHz. The high-frequency equivalent circuits of diamond MISFET are deduced from the S-parameters obtained from RF measurement.

  • Fabrication of heteroepitaxial diamond thin films on Ir(001)/MgO(001) substrates using antenna-edge-type microwave plasma-assisted chemical vapor deposition

    T Fujisaki, M Tachiki, N Taniyama, M Kudo, H Kawarada

    DIAMOND AND RELATED MATERIALS   11 ( 3-6 ) 478 - 481  2002年03月  [査読有り]

     概要を見る

    enhanced nucleation, antenna-edge-type microwave plasma-assisted chemical vapor deposition (MPCVD) was used. Subsequently, the &lt;001&gt; selective and smoothing growth processes were conducted by conventional MPCVD. Reconstructed (2 X I) structure patterns have been observed by reflection high-energy electron diffraction (RHEED), which indicated that the surface of the diamond film is very smooth. The mean roughness is less than 2 nm in a 10-mum(2) area, as revealed by atomic force microscopy observations. (C) 2002 Elsevier Science B.V. All rights reserved.

  • Fabrication of diamond single-hole transistors using AFM anodization process

    T Banno, M Tachiki, H Seo, H Umezawa, H Kawarada

    DIAMOND AND RELATED MATERIALS   11 ( 3-6 ) 387 - 391  2002年03月  [査読有り]

     概要を見る

    By the field-assisted local anodization technique using an atomic force microscope (AFM), a single-hole transistor has been fabricated on an undoped hydrogen-terniinated diamond surface where p-type conduction occurs on the subsurface region. A dual side-gated FET structure has been applied to modulate the island potential in the single-hole transistor. The island size is 230 nmx230 nm, and the width of the barrier is approximately 100 nm. Measurements of the current-gate voltage characteristic at a temperature of 4.6 K show significant non-linearities including a current oscillation suggestive of single-hole transistor behavior. The oscillation that is significantly affected by the application of the side gate potential is explained by the shrinkage of the conductive island with the expansion of the depletion region. (C) 2002 Elsevier Science B.V. All rights reserved.

  • DC and RF characterisitics of 0.7-μm-gate length diamond metal-insulater-semiconductor field-effect transistor

    H. Ishizaka, H. Umezawa, H. Taniuchi, T. Arima, N. Fujihara, M. Tachiki, H. Kawarada

    Diamond Relat.Mater.   11 ( 3-6 ) 378 - 381  2002年03月  [査読有り]

  • ダイヤモンド表面のエレクトロニクス・バイオ応用

    表面科学   23 ( -7 ) 411 - 416  2002年

  • Low-temperature operation of diamond surface-channel field-effect transistors

    M Tachiki, H Ishizaka, T Banno, T Sakai, KS Song, H Umezawa, H Kawarada

    DEFECT AND IMPURITY ENGINEERED SEMICONDUCTORS AND DEVICES III   719   139 - 143  2002年  [査読有り]

     概要を見る

    Cryogenic operation of the diamond surface-channel field-effect transistors (FETs) is investigated. Metal-insulator-semiconductor FETs (MISFETs) are fabricated using CaF2 as a gate insulator. MISFETs operate successfully even at 4.4 K. At low temperature, field-effect enhances the drain current, even if the surface holes become almost frozen-out. Channel mobility increases as temperature decreases to 4.4 K, which indicates the reduced phonon scattering.

  • Heteroepitaxial diamond thin film growth on Ir(001)/MgO(001) substrate by antenna-edge plasma assisted chemical vapor deposition (St. Elmo CVD)

    M Tachiki, T Fujisaki, N Taniyama, M Kudo, H Kawarada

    NEW DIAMOND AND FRONTIER CARBON TECHNOLOGY   12 ( 6 ) 333 - 341  2002年  [査読有り]

  • Heteroepitaxial diamond thin film growth on Ir(001)/MgO(001) substrate by antenna-edge plasma assisted chemical vapor deposition (St. Elmo CVD)

    M Tachiki, T Fujisaki, N Taniyama, M Kudo, H Kawarada

    NEW DIAMOND AND FRONTIER CARBON TECHNOLOGY   12 ( 6 ) 333 - 341  2002年  [査読有り]

  • HIgh Performance Diamond Field-Effect Transistors on Hydrogen-Terminated Surface-Channel

    H. Umezawa, H. Taniuchi, T. Arima, H. Ishizaka, N. Fujihara, Y. Ohba, M. Tachiki, H. Kawarada

    IEEJ   C-122   10 - 16  2002年

  • Excitonic recombination radiation in phosphorus-doped CVD diamonds

    K Nakazawa, K Tanabe, M Tachiki, H Kawarada, S Koizumi

    PHYSICAL REVIEW B   64 ( 23 ) 235203  2001年12月  [査読有り]

     概要を見る

    Free-exciton and bound-exciton recombination radiations are observed reproducibly at different doping levels using cathodoluminescence in phosphorus-doped chemical-vapor-deposited (CVD) diamond thin films. The films are grown by microwave-plasma-assisted CVD, and are doped with phosphine during deposition. From the energy difference between free- and bound-exciton recombination radiation,, the binding energy of free excitons to neutral donors is found to be 90 meV. The intensity of bound-exciton recombination radiation decreases as the temperature increases. On the other hand. the intensity of free-exciton recombination radiation increases apparently from 80 to 150 K in samples with phosphorus-carbon concentration ratios of 200, 500, and 1000 ppm. Using the rate equation for transfer processes among free and bound excitons, the radiative process with increasing temperature is explained. The dissociated bound excitons are directly transferred to free excitons with increasing temperature.

    DOI

  • Nanodevice Fabrication on Hydrogenated Diamond Surface using Atomic Force Microscope

    Mat.Res.Soc.Sympo.Proc/Materials Research Society    2001年09月

  • Fabrication of Sub-0.1 &#181;m Channel Diamond MISFET

    H. Umezawa, H. Kawarada

    Mat.Res.Soc.Sympo.Proc/Materials Research Society    2001年09月

  • High-frequency performance of diamond field-effect transistor

    H Taniuchi, H Umezawa, T Arima, M Tachiki, H Kawarada

    IEEE ELECTRON DEVICE LETTERS   22 ( 8 ) 390 - 392  2001年08月  [査読有り]

     概要を見る

    The microwave performance of a diamond metal-semiconductor held-effect transistor (MESFET) is reported for the first time. MESFETs with a gate length of 2-3 mum and a source-gate spacing of 0.1 mum were fabricated on the hydrogen-terminated surface of an undoped diamond film grown by microwave plasma chemical vapor deposition (CVD) utilizing a self-aligned gate fabrication process, A maximum transconductance of 70 mS/mm was obtained on a 2 mum gate MESFET at V-GS = -1.5 V and V-DS = -5 V for which a cutoff frequency f(T) and a maximum oscillating frequency f(max) of 2.2 GHz and 7 GHz were obtained, respectively.

  • Potential Applications of Surface Channel Diamond Field Effect Transistors

    H. Umezawa, H. Taniuchi, T. Arima, M. Tachiki, H. Kawarada

    Diamond Relat. Mater/Elsevier   10  2001年08月

  • High-Frequency Applications of diamond MESFETs

    H. Taniuchi, H. Umezawa, T. Arima, M. Tachiki, H. Kawarada

    IEEE Electron Device Lett./IEEE   EDL-22 ( 8 )  2001年08月

  • Diamond deposition on a large-area substrate by plasma-assisted chemical vapor deposition using an antenna-type coaxial microwave plasma generator

    N Taniyama, M Kudo, O Matsumoto, H Kawarada

    JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS   40 ( 7A ) L698 - L700  2001年07月  [査読有り]

     概要を見る

    Diamond deposition on a large area silicon wafer substrate (phi 100 mm) is achieved with a methane/hydrogen plasma induced by an antenna-type coaxial microwave plasma generator. Deposition of diamond is observed over the entire substrate. Diamond precursors arc emitted radially onto a silicon substrate from the plasma sphere generated at the tip of the antenna. The possibility of diamond deposition outside the plasma sphere is discussed using a semi-empirical equation.

  • 表面伝導層を用いたダイヤモンド電子デバイス

    川原田 洋, 立木 実, 梅沢 仁

    応用物理/応用物理学会   70 ( 5 ) 536 - 541  2001年05月

  • Electrolyte-solution-gate FETs using diamond surface for biocompatible ion sensors

    H Kawarada, Y Araki, T Sakai, T Ogawa, H Umezawa

    PHYSICA STATUS SOLIDI A-APPLIED RESEARCH   185 ( 1 ) 79 - 83  2001年05月  [査読有り]

     概要を見る

    Diamond field effect transistors have operated in electrolyte solution for the first time. Since the hydrogen-terminated diamond surfaces are stable enough for the use as an electrochemical electrode, the diamond surface channels are exposed to the electrolyte in the transistor structure. A perfect pinch-off and saturated current-voltage characteristics have been obtained for bias voltages within the potential window. The threshold voltages are almost constant in electrolytes with different pH values of 7-13, indicating pH insensitiveness of the hydrogen-terminated diamond surface. Based on this pH insensitive: surface, ion selective regions can be fabricated to form transistor-based biosensors.

  • Characterization of diamond surface-channel metal-semiconductor field-effect transistor with device simulation

    K Tsugawa, H Umezawa, H Kawarada

    JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS   40 ( 5A ) 3101 - 3107  2001年05月  [査読有り]

     概要を見る

    The DC operation of surface-channel metal-semiconductor field-effect transistors (MESFETs) using p-type conductive layers on hydrogen-terminated diamond surfaces is investigated by two-dimensional device simulation. As a result, a model to describe the surface semiconducting layer, in which acceptors are distributed two-dimensionally on the surface, is found to reproduce actual device characteristics well. Based on the model, the carrier (hole) concentration at a depth of 10 nm is determined to be three orders less than that at the surface. This thin channel realizes complete channel pinch-off and drain-current saturation with high transconductance, observed in the actual diamond surface-channel MESFETs. In the simulation, the transconductance of diamond surface-channel MESFETs with a self-aligned I mum gate exceeds 100 mS/mm. This result agrees well with a recent experimental result. The transconductance over 100 mS/mm can compete with that of Si metal-oxide-semiconductor field-effect transistors (MOSFETs) of the same gate length. The hydrogen-terminated diaomond surface is naturally equipped with the silicon-on-insulator-like (SOI-like) thin channel and shallow junction depth required for a nanoscale FET, such as one with a gate length of less than 50 nm.

  • ダイヤモンド・ナノテクノロジー

    川原田洋

    NTTサイエンスフォーラム   第12回  2001年04月

  • ダイヤモンドナノ加工技術

    マテリアルインテグレーション 14   47-51  2001年

  • High frequency application of high transconductance surface-channel diamond field-effect transistors

    H Umezawa, H Taniuchi, T Arima, H Ishizaka, N Fujihara, Yoshikazu, Ohba, M Tachiki, H Kawarada

    ISPSD'01: PROCEEDINGS OF THE 13TH INTERNATIONAL SYMPOSIUM ON POWER SEMICONDUCTOR DEVICES & ICS     195 - 198  2001年  [査読有り]

     概要を見る

    High frequency operations of diamond field-effect transistors (FETs) on the hydrogen-terminated surface channel are realized for the first time. The cut-off frequency (f(T)) and maximum oscillation frequency (f(max)) of surface-channel diamond metal-sen-ii conductor (MES) FET with 2 mum gate length are 2.2 and 7 GHz respectively. Due to the effect of gate insulator insertion, the source-gate capacitance (C-GS) of surface-channel diamond (MIS) FET is reduced as half as that of diamond MESFETs. The 1 mum gate MISFET shows higher f(T) of 4.8 GHz and f(max) of 11 GHz in spite of comparatively low transconductance. The f(T) Of More than 20 GHz is expected at 0.5 mum gate MISFET, because transconductance of 90 mS/mm diamond MISFET with 1 mum gate length has been already demonstrated.

  • High-Performance Surface-Channel Diamond Field-Effect Transistors”,

    Proc.SiC &amp; Relat.Mater.(ECSCRM2000),Mater.Sci.Forum/Trans Tech   353-356   815 - 818  2001年  [査読有り]

  • Cu/CaF2/diamond metal-insulator-semiconductor field-effect transistor utilizing self-aligned gate fabrication process

    H Umezawa, H Taniuchi, T Arima, M Tachiki, K Tsugawa, S Yamanaka, D Takeuchi, H Okushi, H Kawarada

    JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS   39 ( 9AB ) L908 - L910  2000年09月  [査読有り]

     概要を見る

    High-performance metal-insulator-semiconductor field-effect transistors (MIS FET) on hydrogen-terminated homoepitaxial diamond films are demonstrated. The gate insulator is evaporated CaF2 which does not cause interface stales. This is the first study of a CaF2/diamond MISFET fabricated by a self-aligned gate fabrication process by which the gate length and the source gate spacing are effectively reduced. The maximum transconductance is 86 mS/mm, which is the highest value in diamond MISFETs at present.

  • Surface Order Evaluation of the Heteroepitaxial Diamond Film Growth on an Inclined β-SiC(001)39

    S. Kono, T. Goto, T. Abukawa, C. Wild, P. Koidl, H. Kawarada

    Jpn. J. Appl. Phys./The Institute of Pure and Applied Physics   39 ( 7B ) 4372 - 4373  2000年07月  [査読有り]

  • Nanofabrication on hydrogen-terminated diamond surfaces by atomic force microscope probe-induced oxidation

    M Tachiki, T Fukuda, K Sugata, H Seo, H Umezawa, H Kawarada

    JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS   39 ( 7B ) 4631 - 4632  2000年07月  [査読有り]

     概要を見る

    Field-assisted local oxidation on a hydrogen-terminated (001) diamond surface was performed using an atomic force microscope (AFM). Anodic oxidation by a surface water meniscus layer is suggested to account for this oxidation process. Through the oxygenated al ca, Fowler-Nordheim (F-N) tunneling current was observed. The difference in electron affinity between the hydrogen-terminated surface and the oxygenated area was confirmed by scanning electron microscopic (SEM) observations.

  • Control of adsorbates and conduction on CVD-grown diamond surface, using scanning probe microscope

    M Tachiki, T Fukuda, K Sugata, H Seo, H Umezawa, H Kawarada

    APPLIED SURFACE SCIENCE   159   578 - 582  2000年06月  [査読有り]

     概要を見る

    Nanofabrication on a hydrogen-terminated diamond surface is performed by controlling surface adsorbates, using a scanning probe microscope (SPM) technique. Insulated areas are successfully obtained by changing hydrogen termination to oxygen termination. The Auger electron spectrum (AES) indicated the presence of oxygen adsorbed on the modified surface area. A small isolated conductive area is fabricated. and using this structure, a metal-insulator-metal (MIM) diode-like I-V characteristic is observed. Anodic oxidation using the surface water is also suggested for our experimental results. (C) 2000 Elsevier Science B.V. All rights reserved.

  • Surface Channel Diamond Field Effect Transistors and Their Applications(invited paper)

    Proc 1st Int. Workshop on Ultra-Low-Loss Pow. Dev. Tech.     112 - 115  2000年05月

  • The reduction of parasitic resistance by improving the diamond FET fabrication process

    T Arima, H Taniuchi, H Umezawa, M Tachiki, K Tsugawa, S Yamanaka, D Takeuchi, H Okushi, H Kawarada

    NEW DIAMOND AND FRONTIER CARBON TECHNOLOGY   10 ( 1 ) 56 - 56  2000年  [査読有り]

  • Oxygen plasma etching of polycrystalline diamond

    K Tanabe, H Umezawa, M Tachiki, H Kawarada

    NEW DIAMOND AND FRONTIER CARBON TECHNOLOGY   10 ( 1 ) 54 - 54  2000年  [査読有り]

  • Nanofabrication on the surface of the hydrogen-terminated diamond with the scanning probe microscope and I-V characteristics of the surface conductive layer

    K Sugata, M Tachiki, H Umezawa, T Fukuda, H Seo, T Arima, H Taniuchi, H Kawarada

    NEW DIAMOND AND FRONTIER CARBON TECHNOLOGY   10 ( 1 ) 44 - 44  2000年  [査読有り]

  • High-performance surface-channel diamond field-effect transistors

    H. Umezawa, H. Taniuchi, T. Arima, M. Tachiki, H. Okushi, H. Kawarada

    SILICON CARBIDE AND RELATED MATERIALS, ECSCRM2000 MATERIALS SCIENCE FORUM   353 ( 3 ) 815 - 818  2000年

  • High-Performance Surface-Channel Diamond Field-Effect Transistors

    Proc.Silicon Carbide and Related Materials,ECSCRM2000 Mater.Sci.Forum   353-356   815 - 818  2000年

  • Diamond ISFET in alkaline solution

    T Ogawa, Y Araki, M Tachiki, H Kawarada

    NEW DIAMOND AND FRONTIER CARBON TECHNOLOGY   10 ( 1 ) 58 - 58  2000年  [査読有り]

  • Device simulations of diamond surface-channel FETs with quantum transport model

    Y Ohba, S Sen, K Tsugawa, H Taniuchi, H Kawarada

    NEW DIAMOND AND FRONTIER CARBON TECHNOLOGY   10 ( 1 ) 57 - 57  2000年  [査読有り]

  • Cu/CaF2/diamond MISFET utilizing self-aligned gate process

    H Taniuchi, T Arima, H Umezawa, M Tachiki, K Tugawa, S Yamanaka, D Takeuchi, H Okushi, H Kawarada

    NEW DIAMOND AND FRONTIER CARBON TECHNOLOGY   10 ( 1 ) 55 - 55  2000年  [査読有り]

  • Control of diamond surface properties by AFM

    H Seo, M Tachiki, T Fukuda, K Sugata, H Kawarada

    NEW DIAMOND AND FRONTIER CARBON TECHNOLOGY   10 ( 1 ) 43 - 43  2000年  [査読有り]

  • Cluster calculations of diamond-SiC and -Si interface structures

    K Morita, K Hine, K Tsugawa, H Kawarada

    NEW DIAMOND AND FRONTIER CARBON TECHNOLOGY   10 ( 1 ) 31 - 31  2000年  [査読有り]

  • High-Performance Diamond Metal-Semiconductor Field-Effect Transistor with 1 μm Gate Length

    H. Umezawa, K. Tsugawa, S. Yamanaka, D. Takeuchi, H. Okushi, H. Kawarada

    Jpn. J. Appl. Phys /応用物理学会   38 ( 11A ) L1222 - L1224  1999年11月  [査読有り]

  • High Performance Diamond Field Effect Transistors Using Hydrogen-Terminated Surfaces for Electron Device and Sensor Applications

    Proc ADC/FCT'99/NEDO,JFCC     134 - 137  1999年09月

  • High-Performance Diamond Surface-Channel Field-Effect Transistors and Their Operation Mechanism

    K. Tsugawa, K. Kitatani, H. Noda, A. Hokazono, K. Hirose, M. Tajima, H. Kawarada

    Diamond and Related Materials/Elsevie   8   927 - 933  1999年07月

  • Fabrication of 1 mu m gate diamond FET using self-aligned gate process

    H Umezawa, K Kitatani, K Kinumura, N Seto, K Tsugawa, H Kawarada

    NEW DIAMOND AND FRONTIER CARBON TECHNOLOGY   9 ( 2 ) 151 - 153  1999年  [査読有り]

  • Device simulations of diamond surface-channel MESFETs

    K Tsugawa, H Kawarada

    NEW DIAMOND AND FRONTIER CARBON TECHNOLOGY   9 ( 2 ) 154 - 155  1999年  [査読有り]

  • Cluster calculations of diamond-SiC interface structures

    K Morita, K Tsugawa, Y Yamamoto, H Kawarada

    NEW DIAMOND AND FRONTIER CARBON TECHNOLOGY   9 ( 2 ) 157 - 157  1999年  [査読有り]

  • Cathodoluminescence of phosphorus-doped {111} homoepitaxial diamond thin films

    A Sato, K Tanabe, S Egawa, T Tsubota, S Morooka, J Hojyo, H Maeda, H Kawarada

    NEW DIAMOND AND FRONTIER CARBON TECHNOLOGY   9 ( 2 ) 123 - 125  1999年  [査読有り]

  • Surface p-channel metal-oxide-semiconductor field effect transistors fabricated on hydrogen terminated (001) surfaces of diamond

    A. Hokazono, K. Tsugawa, H. Umezana, K. Kitatani, H. Kawarada

    Solid-State Electronics   43 ( 8 ) 1465 - 1471  1999年

     概要を見る

    Metal-oxide-semiconductor field effect transistors (MOSFETs) with a surface p-channel have been fabricated on hydrogen-terminated diamond (001) surfaces without doping. The maximum transconductance of the device with the gate length of 6 μm is 16 mS/mm, which is the highest in diamond MOSFETs and comparable to that of silicon n-channel MOSFET with the same gate length. The relatively high transconductance is due to the low density of surface states on hydrogen-terminated diamond. The diamond MOSFETs operate at the temperatures of up to 330°C in air without any passivation of the device surfaces.

    DOI

  • MOSFETs on polished surfaces of polycrystalline diamond

    K. Kitatani, H. Umezawa, K. Tsugawa, K. Ueyama, T. Ishikura, S. Yamashita, H. Kawarada

    Diamond and Related Materials   8 ( 10 ) 1831 - 1833  1999年

     概要を見る

    MOSFETs on polished polycrystalline diamond surfaces have been fabricated. The best transconductance is 1.0mS/mm. The breakdown voltages of these FETs are over 200V, comparable to those reported in homoepitaxial diamond MESFETs. A polycrystalline diamond FET is a candidate for sensors in hard environment, due to its feasibility in large-area wafers. © 1999 Elsevier Science S.A.

    DOI

  • Cathodoluminescence of phosphorus-doped {111} homoepitaxial diamond thin films

    A Sato, K Tanabe, S Egawa, T Tsubota, S Morooka, J Hojyo, H Maeda, H Kawarada

    NEW DIAMOND AND FRONTIER CARBON TECHNOLOGY   9 ( 2 ) 123 - 125  1999年  [査読有り]

  • Application and device modeling of diamond FET using surface semiconductive layers

    K Tsugawa, H Noda, A Hokazono, K Kitatani, K Morita, H Kawarada

    ELECTRONICS AND COMMUNICATIONS IN JAPAN PART II-ELECTRONICS   81 ( 7 ) 19 - 27  1998年07月  [査読有り]

     概要を見る

    Hydrogen-terminated diamond surfaces exhibit p-type conduction without doping impurities. The surface conductive layers possess a suitable thickness of similar to 10 nm for FET channels. The present work describes the fabrication of high-performance MESFETs and MOSFETs using the surface conductive layers on hydrogen-terminated homoepitaxial CVD diamond films. In the case of MESFETs, both enhancement-mode (normally off) and depletion-mode (normally on) operations are realized by selecting the gate metals. In the case of MOSFETs, depletion-mode operation is realized at present. The best transconductances in diamond are obtained in both MESFETs and MOSFETs. In addition, the de operation of the diamond surface-channel FETs has been evaluated with device simulations using several models for the surface conductive layer. Consequently, a model with accepters distributed two-dimensionally on the surface reproduces the actual I-V characteristics. Moreover, based on the model, the de performance of self-aligned 1-mu m-gate MESFETs not realized in diamond has been simulated. As a result, their transconductances exceed 100 mS-mm(-1). (C) 1998 Scripta Technica.

  • Application and device modeling of diamond FET using surface semiconductive layers

    K Tsugawa, H Noda, A Hokazono, K Kitatani, K Morita, H Kawarada

    ELECTRONICS AND COMMUNICATIONS IN JAPAN PART II-ELECTRONICS   81 ( 7 ) 19 - 27  1998年07月  [査読有り]

     概要を見る

    Hydrogen-terminated diamond surfaces exhibit p-type conduction without doping impurities. The surface conductive layers possess a suitable thickness of similar to 10 nm for FET channels. The present work describes the fabrication of high-performance MESFETs and MOSFETs using the surface conductive layers on hydrogen-terminated homoepitaxial CVD diamond films. In the case of MESFETs, both enhancement-mode (normally off) and depletion-mode (normally on) operations are realized by selecting the gate metals. In the case of MOSFETs, depletion-mode operation is realized at present. The best transconductances in diamond are obtained in both MESFETs and MOSFETs. In addition, the de operation of the diamond surface-channel FETs has been evaluated with device simulations using several models for the surface conductive layer. Consequently, a model with accepters distributed two-dimensionally on the surface reproduces the actual I-V characteristics. Moreover, based on the model, the de performance of self-aligned 1-mu m-gate MESFETs not realized in diamond has been simulated. As a result, their transconductances exceed 100 mS-mm(-1). (C) 1998 Scripta Technica.

  • Surface morphology and surface p-channel field effect transistor on the heteroepitaxial diamond deposited on inclined beta-SiC(001) surfaces

    H Kawarada, C Wild, N Herres, P Koidl, Y Mizuochi, A Hokazono, H Nagasawa

    APPLIED PHYSICS LETTERS   72 ( 15 ) 1878 - 1880  1998年04月  [査読有り]

     概要を見る

    The effect of an inclined substrate on heteroepitaxial diamond has been investigated on 4 degrees off beta-SiC(001) tilted around the [&lt;(1)over bar10&gt;] axis. Homogeneous macro steps with (001) terraces are observed in the [&lt;(1)over bar10&gt;] direction forming, a vicinal angle of 3 degrees-4 degrees from the (001) surface reflecting the substrate inclination. The selective growth is effective even if the dominant orientation is inclined by several degrees from the surface normal, The tilt deviation is less than 1 degrees in the heteroepitaxial film. p-channel field effect transistors have been fabricated on these heteroepitaxial films. The device performance is as good as that on homoepitaxial films. (C) 1998 American Institute of Physics.

  • p型半導体ダイヤモンドとその応用

    ニューセラミックス&エレクトロニクセラミクス/ティー・アイ・シー   11 ( 3 )  1998年03月

  • ダイヤモンド電界効果トランジスタの現状と将来

    川原田洋

    応用物理(総合報告)/応用物理学会   67 ( 2 ) 128 - 138  1998年02月

  • Metal-semiconductor field-effect transistors on hydrogen-terminated diamond surfaces

    K Tsugawa, K Kitatani, H Kawarada

    DIAMOND FILMS AND TECHNOLOGY   8 ( 4 ) 289 - 297  1998年  [査読有り]

     概要を見る

    High-performance metal-semiconductor field-effect transistors (MESFETs) have been fabricated using p-type surface semiconductive layers on hydrogen-terminated surfaces of homoepitaxial CVD diamond films. In addition, their de operation has been evaluated by device simulations to investigate the device operation mechanism. The fabricated MESFETs have been operated in both enhancement and depletion modes by selecting the electronegativity of the gate metal. The MESFETs exhibit complete channel pinch-off and drain-current saturation. The best transconductance for each mode of MESFETs exceeds 10 mS/mm with a gate length of 3-7 mu m. In the device simulations, a model of the surface semiconductive layer in which accepters are distributed two-dimensionally on the surface reproduces well the actual de characteristics. Based on this model, the simulations for a gate length of 1 mu m have also been carried out to predict the operation of smaller devices. It was found that their transconductances exceed 100 mS/mm.

  • ダイヤモンド表面チャネル型FET −その動作機構と応用−

    電子情報通信学会論文誌/電子情報通信学会   J81 ( C-II ) 172 - 179  1998年01月

  • MESFETs and MOSFETs on hydrogen-terminated diamond surfaces

    K Tsugawa, A Hokazono, H Noda, K Kitatani, K Morita, H Kawarada

    SILICON CARBIDE, III-NITRIDES AND RELATED MATERIALS, PTS 1 AND 2   264-2   977 - 980  1998年  [査読有り]

     概要を見る

    High-performance MESFETs and MOSFETs have been fabricated on hydrogen-terminated surfaces of homoepitaxial diamond films prepared by chemical vapor deposition (CVD). Both enhancement and depletion-mode MESFETs have been obtained with the best transconductances of 10mS/mm in enhancement mode and 12mS/mm in depletion mode. Depletion-mode MOSFETs have been also realized with the best transconductance of 16mS/mm utilizing evaporated SiOx as gate insulator. The de performance of the devices using the hydrogen-terminated diamond surfaces has been evaluated by two-dimensional drift-diffusion device simulations using several models of surface channels on the hydrogen-terminated surfaces. Consequently, a realistic surface-channel model has been obtained. Based on the model, the simulations for self-aligned-1 mu m-gate devices have been also carried out to predict the operation of smaller diamond devices not realized in diamond at present. Their transconductances exceed 100mS/mm.

  • Metal-semiconductor field-effect transistors on hydrogen-terminated diamond surfaces

    K Tsugawa, K Kitatani, H Kawarada

    DIAMOND FILMS AND TECHNOLOGY   8 ( 4 ) 289 - 297  1998年  [査読有り]

     概要を見る

    High-performance metal-semiconductor field-effect transistors (MESFETs) have been fabricated using p-type surface semiconductive layers on hydrogen-terminated surfaces of homoepitaxial CVD diamond films. In addition, their de operation has been evaluated by device simulations to investigate the device operation mechanism. The fabricated MESFETs have been operated in both enhancement and depletion modes by selecting the electronegativity of the gate metal. The MESFETs exhibit complete channel pinch-off and drain-current saturation. The best transconductance for each mode of MESFETs exceeds 10 mS/mm with a gate length of 3-7 mu m. In the device simulations, a model of the surface semiconductive layer in which accepters are distributed two-dimensionally on the surface reproduces well the actual de characteristics. Based on this model, the simulations for a gate length of 1 mu m have also been carried out to predict the operation of smaller devices. It was found that their transconductances exceed 100 mS/mm.

  • Enhancement/depletion surface channel field effect transistors of diamond and their logic circuits

    A Hokazono, H Kawarada

    JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS   36 ( 12A ) 7133 - 7139  1997年12月  [査読有り]

     概要を見る

    Using the p-type surface-conductive layer of diamond film, enhancement mode and depletion mode metal-semiconductor field effect transistors were fabricated on the same surface by changing the metals of the gate electrode. The threshold voltages of p-type metal semiconductor field effect transistors (MESFETs) can be controlled from negative (enhancement mode) to positive (depletion mode) as the electronegativities of gate metals increase. By the realization of high transconductance and the fabrication of enhancement and depletion mode MESFETs; the E/D-type logic circuits such as inverter; NAND and NOR circuits were fabricated for the first time.

  • Comparative Study of Excitonic Recombination Radiation From Diamonds Grown by CVD and HP/HT Methods

    T. Murakami, K. Nakamura, S. Yamashita, S. Takeuchi, M. Murakawa, H.Kawarada

    Diam. Rel. Mat./Elsevier   6   1668 - 1673  1997年05月

  • Heteroepitaxial growth of highly oriented diamond on cubic silicon carbide

    H Kawarada, C Wild, N Herres, R Locher, P Koidl, H Nagasawa

    JOURNAL OF APPLIED PHYSICS   81 ( 8 ) 3490 - 3493  1997年04月  [査読有り]

     概要を見る

    We have deposited epitaxial diamond films with very low angular spread on epitaxial beta-phase silicon carbide layers on silicon (001) substrates. From x-ray rocking curve measurements, half-widths of the angular spread of the crystal orientation as low as 0.6 degrees have been determined, which is the smallest value ever reported in heteroepitaxial diamond films and appears to be smaller than those of the beta-phase silicon carbide underlayers. The him surface exhibits a roughness of about 100 nm with very few discernible boundaries due to misorientation. The optimization of the bias-enhanced nucleation process and the control of selective growth are the main factors for the improvement of the crystallinity. (C) 1997 American Institute of Physics.

  • Device modeling of high performance diamond MESFETs using p-type surface semiconductive layers

    H Noda, A Hokazono, H Kawarada

    DIAMOND AND RELATED MATERIALS   6 ( 5-7 ) 865 - 868  1997年04月  [査読有り]

     概要を見る

    The operation of high-performance diamond MESFETs using thin p-type surface semiconductive layers of undoped hydrogent-erminated CVD diamond films has been simulated. We have used diffusion profiles of shallow accepters to describe the surface conductive layer. In order to describe metal/hydrogen/diamond interfaces, we have assumed an incomplete contact model where an atomic scale gap (similar to 0.5 nm) is inserted between the metal and the diamond. The results of this model have been compared with those obtained from direct metal/diamond contact model. The experimental I-V characteristics have been realized with acceptor density of 1 x 10(13) cm(-2), and the transconductance per unit gate width of diamond MESFETs with 1 mu m gate length is predicted to be nearly 50 mS mm(-1) by using both complete and incomplete contact models. (C) 1997 Elsevier Science S.A.

  • Heteroepitaxial growth of highly oriented diamond on cubic silicon carbide

    H Kawarada, C Wild, N Herres, R Locher, P Koidl, H Nagasawa

    JOURNAL OF APPLIED PHYSICS   81 ( 8 ) 3490 - 3493  1997年04月  [査読有り]

     概要を見る

    We have deposited epitaxial diamond films with very low angular spread on epitaxial beta-phase silicon carbide layers on silicon (001) substrates. From x-ray rocking curve measurements, half-widths of the angular spread of the crystal orientation as low as 0.6 degrees have been determined, which is the smallest value ever reported in heteroepitaxial diamond films and appears to be smaller than those of the beta-phase silicon carbide underlayers. The him surface exhibits a roughness of about 100 nm with very few discernible boundaries due to misorientation. The optimization of the bias-enhanced nucleation process and the control of selective growth are the main factors for the improvement of the crystallinity. (C) 1997 American Institute of Physics.

  • Surface characterization of smooth heteroepitaxial diamond layers on beta-SiC (001)

    Y Mizuochi, H Nagasawa, H Kawarada

    DIAMOND AND RELATED MATERIALS   6 ( 2-4 ) 277 - 281  1997年03月  [査読有り]

     概要を見る

    Surface morphology of continuous heteroepitaxial diamond layers on beta-SiC (001) has been characterized by various methods. From surface normal SEM images, the surface was so smooth that crystal boundaries were not clearly observed, but in AFM and Normarski optical microscope images, shallow gaps supposed to be remnant boundaries and wrinkles on the surfaces were observed. On the other hand, isolated (001) surfaces before coalescence had no wrinkles and were smoother than the surface of continuous heteroepitaxial films. The wrinkles observed only on the continuous heteroepitaxial film are considered to be formed by strain caused by coalescence, and raise the new problem of heteroepitaxy when the degree of orientation is improved. (C) 1997 Elsevier Science S.A.

  • Enhancement/depletion MESFETs of diamond and their logic circuits

    A Hokazono, T Ishikura, K Nakamura, S Yamashita, H Kawarada

    DIAMOND AND RELATED MATERIALS   6 ( 2-4 ) 339 - 343  1997年03月  [査読有り]

     概要を見る

    Using the p-type surface-conductive layer of diamond film, enhancement mode and depletion mode MESFETs have been fabricated by changing the metals of the gate electrode. The threshold voltages of MESFETs depend on the electronegativity of the metals. A MESFET with a Cr gate was operated in depletion mode and exhibited a peak transconductance of 12.3 mS mm(-1), which is the highest in diamond FETs. This high performance can be obtained by a self-aligned gate fabrication process, which minimizes the spacing between the ohmic contacts and the Schottky contact. By utilizing an E-MESFET for the driver and a D-MESFET for the active load, E/D-type logic circuits such as NOT, NAND and NOR circuits have been fabricated for the first time. (C) 1997 Elsevier Science S.A.

  • Surface properties of hydrogen-terminated diamonds and their applications to electron devices.

    H Kawarada

    PHYSICS OF DIAMOND   135   505 - 535  1997年  [査読有り]

  • ダイヤモンドヘテロエピタキシャル成長の現状

    フロンティア・カーボン・テクノロジー・シンポジウム/NEDO    1996年10月

  • Electron affinity and surface re-ordering of homoepitaxial diamond (100)

    KW Wong, ST Lee, RWM Kwok, YW Lam, H Kawarada

    JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS   35 ( 10 ) 5444 - 5447  1996年10月  [査読有り]

     概要を見る

    The change in electron affinity and the se-ordering of the diamond surface upon annealing of a homoepitaxially grown diamond (100) thin film were investigated by ultraviolet photoemission spectroscopy, low energy electron diffraction (LEED), and Auger electron spectroscopy. When the sample was heated to similar to 1250 degrees C, the electron affinity of the sample changed from negative to positive and the LEED pattern changed from (2 x 1/1 x 2) to (1 x 1). When the sample was further annealed at similar to 900 degrees C, the electron affinity and the LEED pattern reverted to negative and (2 x 1/1 x 2) respectively. The sample was then heated to similar to 1100 degrees C, followed by annealing at similar to 900 degrees C again, and the same phenomenon was observed. These observations were considered to be associated with the disordering/re-ordering behavior of the diamond surface upon annealing.

  • Electrically isolated metal-semiconductor field effect transistors and logic circuits on homoepitaxial diamonds

    H Kawarada, M Itoh, A Hokazono

    JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS & EXPRESS LETTERS   35 ( 9B ) L1165 - L1168  1996年09月  [査読有り]

     概要を見る

    Isolated metal-semiconductor field effect transistors (MESFETs) have been fabricated on homoepitaxial diamonds grown by microwave plasma chemical vapor deposition. Source, drain and channel regions are fabricated using the surface p-type semiconductive layer unique to hydrogen-terminated diamond surfaces. Other areas are irradiated by an argon beam to obtain highly resistive regions. The maximum transconductance of the isolated MESFETs with 7 mu m gate length is 4.5 mS/mm, which is comparable to that of silicon MOSFET with the same gate length. NOT, NAND, NOR, and R-S flip-flop circuits have been fabricated for the first time on diamond using enhancement-mode active loads.

  • Scanning tunneling microscopy and spectroscopy for studying hydrogen-terminated homoepitaxial diamond surfaces

    A Sato, S Yamashita, H Kawarada

    SILICON CARBIDE AND RELATED MATERIALS 1995   142   1099 - 1102  1996年  [査読有り]

     概要を見る

    STM with STS has been employed to acquire the information on the electronic structure of H-terminated homoepitaxial diamond (001) and (111) surfaces. The STS spectra for (001) and (111) surfaces reveal the existence of surface state near the top of valence-band states. It is suggested that this surface state is responsible for the formation of p-type surface semiconductive layers.

  • Observation of dominant free exciton recombination from synthesized diamond by cathodoluminescence measurement

    J Imamura, T Tsutsumi, T Murakami, H Kawarada, S Takeuchi, M Murakawa

    SILICON CARBIDE AND RELATED MATERIALS 1995   142   1087 - 1090  1996年  [査読有り]

     概要を見る

    In this study, we have observed dominant free-exciton (FE) recombination radiation from chamber frame (CF) diamond. Since CF diamond is extremely purr, in the Ct. spectra of the edge emission we have observed the FELO emission rarely observed in diamond grown by means of a conventional microwave plasma-assisted CVD method. The intensity ratio of the FETO over the band A is 58.5. This high crystallinity of CF diamond is hardly destroyed by the electron beam. In the CF method, when the reaction pressure is a little larger than atmospheric pressure. pure crystals can be obtained.

  • Fabrication of logic circuits using diamond metal-semiconductor field-effect transistor

    M Itoh, A Hokazono, H Noda, H Kawarada

    SILICON CARBIDE AND RELATED MATERIALS 1995   142   1095 - 1098  1996年  [査読有り]

     概要を見る

    Metal-semiconductor field-effect transistors (MESFETs) have been fabricated using the p-type surface-conductive layer of diamond film. The surface-conductive layers have been employed as the channel of MESFETs. Since that surface-conductive layer is ultrathin, these MESFETs exhibit the enhancement mode in the gate metal with high Schottky barrier hight. These MESFETs exhibit channel pinch-off, complete current saturation, and the highest transconductance in diamond FETs. The device isolation has been carried out by insulating surface-conductive layer except for channel with exporsure of Ar+. With this technique, the fabrications of diamond logic circuits and memories (NAND, NOR, NOT, and RS flipflop) are demonstrated for the first time.

  • Device modeling of enhancement-mode diamond MESFET utilizing p-type surface semiconductive layers

    N Jin, H Sakai, K Tsugawa, H Kawarada

    SILICON CARBIDE AND RELATED MATERIALS 1995   142   1091 - 1094  1996年  [査読有り]

     概要を見る

    Undoped hydrogen-terminated CVD diamond films are known to have thin p-type surface semiconductive layers. Enhancement mode MESFETs were fabricated utilizing these layers. In this simulation, we estimated the hole concentration and the channel depth of the surface layer We have evaluated that the channel depth of the surface semiconductive layer is approximately 22nm (the diffusion length, 11nm), and the surface acceptor concentration is 1.0 x 10(10)/cm(3). By evaluating the more accurate hole concentration of the thin p-type semiconductive layer, we may predict the performance of diamond electronic devices having submicron-gate.

  • Hydrogen-terminated diamond surfaces and interfaces

    H Kawarada

    SURFACE SCIENCE REPORTS   26 ( 7 ) 205 - 259  1996年  [査読有り]

     概要を見る

    Surfaces and interfaces of hydrogen-terminated diamonds are reviewed. The control and preparation of diamond surfaces have been greatly advanced by the recent progress in epitaxial growth, which is discussed in Section 2. In Section 3, the hydrogen-terminated surfaces of (111) and (001) are explained in terms of types of hydrides, surface reconstructions, stability of surface C-H bonds, and surface p-type conduction. In Section 4, metal/diamond contacts are reviewed. Schottky and ohmic properties are discussed on the basis of hydrogen termination, surface treatment, metal electronegativity, interfacial reaction, and surface states. The first application of hydrogen-terminated surfaces as electron devices is presented for the metal-semiconductor field effect transistor.

  • β-SiC(001)基板上のダイヤモンドヘテロエピタキシャル成長

    SiCおよび関連ワイドギャップ半導体研究会/応用物理学会    1995年12月

  • ダイヤモンドMESFETを用いた集積回路作製のための基礎技術とフリップフロップICメモリーの作製

    SiCおよび関連ワイドギャップ半導体研究会/応用物理学会    1995年12月

  • 表面伝導層ダイヤモンドMESFETを用いたフリップフロップICメモリーの作製

    第9回ダイヤモンドシンポジウム    1995年11月

  • 素子分離されたデプレッションモードダイヤモンドMESFETの作製と評価II

    第9回ダイヤモンドシンポジウム    1995年11月

  • β-SiCをバッファ層としたSi(001)基板上でのダイヤモンドヘテロエピタキシャル成長

    日本結晶成長学会誌/アグネ   22 ( 4 )  1995年10月

  • SCANNING-TUNNELING-MICROSCOPE OBSERVATION OF THE HOMOEPITAXIAL DIAMOND(001) 2X1 RECONSTRUCTION OBSERVED UNDER ATMOSPHERIC-PRESSURE

    H KAWARADA, H SASAKI, A SATO

    PHYSICAL REVIEW B   52 ( 15 ) 11351 - 11358  1995年10月  [査読有り]

     概要を見る

    The 2X1/1X2 surface reconstruction of a homoepitaxial diamond (001) surface has been examined using a scanning tunneling microscope at an atomic scale and reflection electron microscopy at a macroscopic scale. The monohydride dimer, which is a unit of the surface reconstruction, has a symmetric structure. These monohydride structures contribute to the surface p-type conduction in undoped films. The surface is composed of elongated dimer rows. Antiphase boundaries have been observed, which is indicative of low-temperature epitaxy where surface migration is limited. Macroscopic surface flatness has been improved during the growth stage in the presence of oxygen and boron which enhance migration.

  • initial growth of heteroepitaxial diamond on Si(001) Substrates via β-SiC buffer

    Jpn. J. Appl. Phys. /応用物理学会   34 ( 9A ) 4898 - 4904  1995年09月  [査読有り]

  • FABRICATION AND CHARACTERIZATION OF METAL-SEMICONDUCTOR FIELD-EFFECT TRANSISTOR UTILIZING DIAMOND SURFACE-CONDUCTIVE LAYER

    M ITOH, H KAWARADA

    JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS   34 ( 9A ) 4677 - 4681  1995年09月  [査読有り]

     概要を見る

    Metal-semiconductor field-effect transistors (MESFETs) have been fabricated using the p-type surface-conductive layer of undoped homoepitaxial diamond film on the surface. The layers have been employed as tile channel of MESFETs. Since the surface-conductive layer is ultrathin, the depletion region has already closed the surface-conductive channel at the gate voltage of 0 V i.e., these MESFETs exhibit the enhancement mode (normally off-mode). The threshold voltages are -1.6V and -0.7V in the case of Al and Pb gate respectively. These MESFETs also exhibit channel pinch-off and complete saturation of drain current, and high transconductance of 2.5 mS/mm at room temperature. This value is the highest of all diamond FETs at present. enhancement/resistor (E/R) inverters with the enhancement mode transistor and resistor, and direct coupled enhancement/enhancement (E/E) inverters with the two enhancement mode transistors have been also fabricated. This E/R inverter exhibits high voltage gain. For a E/E inverter, the voltage gain has also been measured as a function of frequency. The high 3-dB frequency (f(H)) is above 2 MHz. The voltage gain at frequency =f(H) (Hz) is equal to 1/root 2 the voltage gain at freyuency=0(Hz).

  • HETEROEPITAXIAL GROWTH OF TUNGSTEN CARBIDE FILMS ON W(110) BY PLASMA-ENHANCED CHEMICAL-VAPOR-DEPOSITION

    M KATOH, H KAWARADA

    JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS   34 ( 7A ) 3628 - 3630  1995年07月  [査読有り]

     概要を見る

    Tungsten carbide (WC) layers have been grown epitaxially on tungsten single crystals for the first time by using microwave plasma and electron cyclotron resonance plasma carburization of single-crystalline tungsten. WC on tungsten is grown epitaxially as (0001)WC//(110)W in the alignment [1 (2) over bar 10]WC//[(1) over bar 11]W.

  • Si基板上でのダイヤモンドヘテロエピタキシャル膜の作製

    NEW DIAMOND/Japan New Diamond Forum    1995年04月

  • ダイヤモンド状薄膜

    平木 昭夫, 川原田 洋

    炭素   1987 ( 128 ) 41 - 49  1987年

     概要を見る

    The properties of diamond are ascribed to C-C sp3 bondings from the point of chemical bonding. Diamond-like carbon (DLC) thin film is defined as a carbon film which is composed of chiefly C-C sp3 bondings. The characteristics of DLC films are approaching those of diamond crystals. DLC films have been formed in non-equilibrium states such as plasma processes, because sp2 bondings are stable under atomospheric pressure and ordinary temperature.<BR>Among plasma processes, we have concentrated on reactive sputtering which is distinguished from usual physical sputtering. In reactive sputtering deposition, H radicals are thought to sputter graphite target chemically and deposit sp3 rich thin films selectively on substrates. We have also discussed characterization techniques which are applied to distinguish the chemical bondings and the micro structures in DLC thin films.

    DOI CiNii

  • Effectofaradicalexposurenitridationsurfaceonthechargestabilityofshallownitrogen-vacancycentersindiamond

    T.Kageura, K.Kato, H.Yamano, E.Suaebah, M.Kajiya, S.Kawai, M.Inaba, T.Tanii, M.Haruyama, K.Yamada, S.Onoda, W.Kada, O.Hanaizumi, T.Teraji, J.Isoya, S.Kono, H.Kawarada

    Phys.Express10(2017)055503  

  • Selective Growth of Carbon Nanostructures on Nickel Implanted Nanopyramid Array, Appl. Surf. Sci. 234, 2004, 72.

    D.Ferrer, T.Shinada, T.Tanii, J.Kurosawa, G.Zhong, Y.Kubo, S.Okamoto, H.Kawarada, I.Ohdomari

     

  • Label-free DNA sensors using diamond FETs

    K. S. Song, G. J. Zhang, Y. Nakamura, K. Furukawa, T. Hiraki, J. H. Yang, I.Ohdomari, H. Kawarada

    Phys. Rev. E   74 ( 4 ) 41919

  • Growth of Dense Single-walled Carbon Nanotubes in Nano-sized Silicon Dioxide Holes for Future Microelectronics

    T. Iwasaki, R. Morikane, T. Edura, M. Tokuda, K. Tsutsui, Y. Wada, H. Kawarada

    Carbon   submitted

  • Characterization of immobilized DNA on functionalized ultradispersed diamond

    J. H. Yang, Y. Nakano, Y. Murakami, K. S. Song, H. Kawarada

    Chem. Phys.Lett.   submitted

  • Characterization of hybridization kinetics on functionalized diamond SGFETs for detecting single-mismatch oligonucleotides

    J. H. Yang, K. S. Song, Y. Sasaki, M. Degawa, K. Furukawa, T. Hiraki, H. Kawarada

    advanced functional materials   submitted

▼全件表示

書籍等出版物

  • Power Electronics Device Applications of Diamond Semiconductors

    Satoshi Koizumi, Hitoshi Umezawa, Julien Pernot, Mariko Suzuki( 担当: 共著)

    Woodhead Publishing  2018年06月 ISBN: 9780081021835

  • ポストシリコン半導体 −ナノ成膜ダイナミクスと基板・界面効果−

    財満 鎭明, 川原田 洋 ほか

    株式会社 エヌ・ティー・エス  2013年06月 ISBN: 9784864690591

  • ダイヤモンドエレクトロニクスの最前線

    久我 翔馬, 梁 正勲, 川原田 洋

    シーエムシー出版  2008年 ISBN: 9784781300498

  • マイクロアレイ・バイオチップの最新技術

    川原田 洋

    シーエムシー出版  2008年 ISBN: 9784882319863

  • Low-Pressure Synthetic Diamond

    Bernhard Dischler, Christoph Wil

    Springer-Verlag  1998年08月

Misc

▼全件表示

産業財産権

  • 積層体、単結晶ダイヤモンド基盤及びその製造方法

    川原田 洋, 費 文茜, 森下 葵

    特許権

  • ダイヤモンド電界効果トランジスタ及びその製造方法

    川原田 洋, 矢部 太一

    特許権

  • 半導体装置及びその製造方法、電界効果トランジスタ

    平岩 篤, 堀川 清貴, 河野 省三, 川原田 洋

    特許権

  • ダイヤモンド半導体基板の製造方法

    川原田 洋, 平岩 篤, 蔭浦 泰資

    特許権

  • ノーマリオフ動作ダイヤモンド電力素子及びこれを用いたインバータ

    川原田 洋, 稲葉 優文, 牛 俊雄, 畢 特, 大井 信敬

    特許権

  • 水中通信装置及び水中通信方法

    川原田 洋, 井山 裕太郎, 梶家 美貴, 蓼沼 佳斗, 新谷 幸弘

    特許権

  • トランジスタの製造方法及びセンサ素子

    6205017

    川原田 洋

    特許権

  • カーボンナノチューブの製造方法

    6037287

    川原田 洋, 落合 拓海, 大原 一慶

    特許権

  • ダイヤモンド薄膜の表面処理方法、電界効果トランジスタの製造方法、及びセンサ素子

    川原田 洋

    特許権

  • 透明導電体及び透明導電体の製造方法

    6099260

    川原田 洋

    特許権

  • 半導体装置に好適なカーボンナノチューブ束群を用いた半導体装置の製造方法、及び半導体装置

    6215537

    稲葉 優文, 渋谷 恵, 川原田 洋, 大原 一慶, 落合 拓海

    特許権

  • キャリア輸送方向に対して直交する方向にCNTチャネルを有する電界効果トランジスタ

    6215536

    稲葉 優文, 川原田 洋, 大原 一慶, 落合 拓海, 渋谷 恵

    特許権

  • 電界効果トランジスタ

    6215535

    川原田 洋, 大原 一慶, 落合 拓海, 稲葉 優文, 渋谷 恵

    特許権

  • 電力素子、電力制御機器、電力素子の製造方法

    6218062

    川原田 洋, 平岩 篤, 大長 央, 齋藤 達也

    特許権

  • カーボンナノチューブ合成装置

    6037281

    川原田 洋

    特許権

  • カーボンナノチューブ成長用基板、その製造方法及び配向カーボンナノチューブの製造方法

    5610298

    川原田 洋, 落合 拓海

    特許権

  • 電界効果型トランジスター

    5713431

    川原田 洋

    特許権

  • カーボンナノチューブの製造方法

    5555944

    大原 一慶, 川原田 洋, 落合 拓海, 飯塚 正知

    特許権

  • カーボンナノチューブの製造方法

    5572874

    川原田 洋, 落合 拓海, 飯塚 正知, 大原 一慶

    特許権

  • 電界効果トランジスタ、その製造方法及びバイオセンサ

    5366215

    川原田 洋, 田島 慎也

    特許権

  • ジョセフソン素子

    5496585

    川原田 洋, 河野 明大, 渡邊 惠

    特許権

  • ダイヤモンド薄膜およびダイヤモンド電界効果トランジスター

    5483168

    川原田 洋, 平間 一行

    特許権

  • 電界効果型トランジスタおよび集積回路

    5648812

    川原田 洋, 水野 潤, 関口 哲志, 齋藤 美紀子

    特許権

  • 配向カーボンナノチューブの製造方法

    5732636

    川原田 洋, 加藤 良吾

    特許権

  • 単層カーボンナノチューブ製造方法、半導体配線構造の製造方法、フィールドエミッションディスプレイ用電子部品の製造方法及び探針製造方法

    5269352

    川原田 洋, 岩崎 孝之

    特許権

  • 単層カーボンナノチューブの製造方法およびその製造装置

    川原田 洋, 大泊 巌, ジョン ゴウファン

    特許権

▼全件表示

その他

  • 科学技術振興事業団 ...

     概要を見る

    科学技術振興事業団 戦略的基礎研究推進事業 研究領域「電子・光子等の機能制御」 研究課題「表面吸着原子制御による極微細ダイヤモンドデバイス」雇用研究員(k2001.10)

  • 科学技術振興事業団 戦略的基礎研究推進事業 研究領域「電子・光子等の機能制御」 研究課題「表面吸着原子制御による極微細ダイヤモンドデバイス」雇用研究員(k2001.10)

受賞

  • 文部科学大臣表彰 科学技術賞(研究部門)

    2016年04月   ダイヤモンドパワートランジス タおよびバイオセンサの研究  

  • 応用物理学会フェロー表彰

    2010年  

  • 超伝導科学技術賞

    2007年  

共同研究・競争的資金等の研究課題

  • 電子スピンの量子状態変化を検出原理に持つカロリーメータの開発

    研究期間:

    2017年04月
    -
    2020年03月
     

     概要を見る

    ダイヤモンド中の窒素・空孔(NV)センターが持つ電子スピンの磁場・温度依存性をX線検出器の一種であるカロリーメータに適用するための研究を行った。既存のカロリーメータは、吸収体、遷移端温度計(TES)と超伝導量子干渉計(SQUID)、熱浴等から成る。吸収体の極微小な温度変化をTES・SQUIDで計測する。本研究では、NVセンターの電子スピンの磁場・温度特性を利用して微小な温度変化を捉えることのできる「電子スピン型カロリーメータ」の開発を目指した。電子スピンを利用する研究と並行し、硼素添加の単結晶ダイヤモンドが数K領域で超伝導を示す特徴を利用し、数K動作のダイヤモンドTESやSQUIDをカロリーメータに適用するための研究も実施した。NVセンターは室温において利用されることが多いが、カロリーメータでは極低温における磁場・温度計測が求められる。NVセンターは100 Kを下回ると温度計測の感度が鈍化するため、従来よりも高感度な計測が必要とされる。そこで、NVセンター間の量子もつれを利用して高感度計測する方法に着目した。本研究では、量子もつれを生成し得るNVセンターの3量子ビット化に世界で初めて成功し、超高感度計測に向けて前進した。開発した手法はさらなる多量子ビット化の可能性を秘めており、カロリーメータだけでなく他の超高感度計測へも貢献し得る。一方、単結晶超伝導ダイヤモンドSQUID動作を世界で初めて実現した。動作温度は2.6 Kであり、動作温度を10 Kまで向上させる道筋も示した。このように数Kで動作するダイヤモンドSQUIDが開発できたことにより、数K動作のダイヤモンドカロリーメータ開発が大きく進展した。令和元年度が最終年度であるため、記入しない。令和元年度が最終年度であるため、記入しない

  • ダイヤモンド表面キャリアによる電子スピン制御とその生体分子核スピン観測への応用

    研究期間:

    2014年05月
    -
    2019年03月
     

     概要を見る

    ダイヤモンド中の窒素と空孔なる中心(NV)が負に帯電した状態(NV-)を表面近傍でも安定となる表面処理技術や表面デバイス技術を構築した。特にラビ振動コントラストを利用したNV-の安定性評価法と窒素終端表面でのNV-の安定化方法を開発した。窒素終端表面のNH2基により生体分子を直接共有結合固定した際の浅いNV-の安定化を見出した。デッカップリング法(XY-8法)によるコヒーレンス時間T2のさらなる上昇により、にてダイヤモンド表面の1Hおよび31Pの局所的な核磁気共鳴(NMR)観測を可能とした。近年、10-20塩基(3-8nm)の短いDNAやRNAの挙動が注目され、メッセンジャーRNAとの結合によるRNA干渉を利用した医薬品やDNA/RNAによるアプタマセンサ等に利用されている。これらの短いDNAやRNAの2次構造変化、つまりコンフォメーション変化、例えばタンパク質とカップルする際の構造の動的変化は、分子生物学の重要テーマである。通常のNMRは集団的な生体分子の挙動で、個々分子の2次構造変化の測定手段はない。本研究の局所的なNMR観測の分解能がさらに向上すれば、分子生物学における貢献は大きい

  • ダイヤモンド中のNVセンターのナノ配列作製による数量子ビット量子レジスタの実現

    研究期間:

    2014年04月
    -
    2017年03月
     

     概要を見る

    室温量子スピンとして優れたNVセンダ同士の相互作用に着目した。量子レジスタの多量子ビット化をめざして、短い距離(~13 nm)のNVセンダ配列を規則的なナノホール配列をもつマスク注入により作製する技術を開発した。平均距離~5nmの高濃度NVセンタを作製し、離散的時間結晶の生成を室温で実証した。単一NVセンタにもナノホール注入を応用し、量子センサー・アレイを作製した。量子アルゴリズムを高磁場測定と組み合わせたナノNMRにおいて超微量の試料のケミカルシフトを観測する高分解能を達成した。高品質結晶合成により、結晶中の離れた位置のSiV-センタから識別できない単一光子を発生することに成功した

  • クローニングによるSiC上のジグザグ型カーボンナノチューブ・フォレストの長尺化

    研究期間:

    2014年04月
    -
    2016年03月
     

     概要を見る

    ジグザグ型にカイラリティのそろった、炭化ケイ素(SiC)基板上に成長させたカーボンナノチューブ(CNT)フォレストを基板として用いて、そのカイラリティを引き継ぐCNTフォレストを、CVDの手法を応用して無触媒で成長させた。その研究内容として、①酸化亜鉛とカーボンをSiC基板上に堆積し、この2層マスクが1600℃の高温でマスクの機能を果たし、選択成長を実現した。②高温過酸化水素水処理により曲率の大きいCNTのキャップ部分を選択的に除去することに成功した。③メタン・水素系ガス雰囲気において、900℃以上でCNTの再成長を確認した。今後、CNTフォレストのSiCオーミック電極応用などが期待される

  • ダイヤモンド表面近傍の電子スピン制御による単一核スピンの観測

    研究期間:

    2014年04月
    -
    2015年03月
     

     概要を見る

    ダイヤモンド表面で、n型反転層形成により、表面側のNVセンターを100%NV-にすることで、高感度で局所NMRを行うことが本研究の目的である。反転層形成には、正の電子親和力(χ=+1.5-2.0eV)を有する酸素終端ダイヤモンド表面を利用する。それよりも小さな電子親和力をもつSiO2(χ=+0.95eV)をこれらの酸素終端ダイヤモンド表面に形成することで伝導帯のバンドオフセットΔEC>0.5eVを形成し、ダイヤモンド側に伝導電子の蓄積で100%NV-にする。オフセットΔEC>0.5eVとなる絶縁膜はSiO2が最も優れている。反転層形成用ゲート絶縁膜としてはSi熱酸化膜が最もよい。Si熱酸化膜をダイヤモンド上に形成するために、Siでダイヤモンド表面を被覆し、熱酸化を行った。Siの被覆がなければ、ダイヤモンド表面が酸化エッチングされる条件でも、ダイヤモンド表面は安定であった。この結果、熱酸化SiO2/ダイヤモンド界面を形成することに、初めて成功した。この構造に透明電極を形成した金属-酸化物(SiO2の場合)-半導体(MOS)構造を形成し、電子・正孔対を形成し、電子を表面側に捕集して、容量-電圧法(C-V法)にて電子がMOS界面に蓄積しているのを観測する予定である。いまだ報告例のない10nm以下の浅いNV-センターの形成に最も重要な技術であり、熱酸化SiO2/ダイヤモンド界面を形成の意義は大きい。局所NMRでは、DNAおよびRNAのコンフォメーション等のダイナミックな運動の観察が将来の目的であるが、まずはこれら核酸の基本構造となる31P核スピンのNMRをダイヤモンド表面近傍のNV-で観測する技術を、ダイヤモンド上のSiO2中の31P(原子密度で約1%)で測定する試料作製を行った。ダイヤモンド外の31Pの検出として、SiO2中の31P の単一核スピンとNV-電子スピンのエンタングルメント状態でNMR観測を行った。明確な31Pでピークの確認を今後行う。この結果は、生体分子の局所NMR観測の第一歩として意味がある。26年度が最終年度であるため、記入しない。26年度が最終年度であるため、記入しない

  • アプタマー固定ダイヤモンド表面による高感度プロテインチップ

    研究期間:

    2011年04月
    -
    2014年03月
     

     概要を見る

    ダイヤモンドに共有結合固定したDNA、RNAをアプタマーとして特定標的の検出を行った。1)アプタマー固定のダイヤモンド表面でアプタマーと標的としてHIV-TATタンパク質と血小板成長由来因子(PDGF)の結合過程を蛍光標識による光学検出と電界効果トランジスタ(FET)による電荷検出の双方から検討した。2)標的のアデノシン三リン(ATP)に蛍光標識をつけず、ATPのアプタマー(DNA)側に蛍光標識をつけ、アプタマーの挙動からATPを高感度検出した。3)流路の底部での異なるアプタマーが固定される複数のFETからなるFETアレーで特定タンパク質検出を実施し、集積センサの基礎技術を開発した

  • ナノ構造配列を基盤とする分子ナノ工学の構築とマイクロシステムへの展開

    科学研究費助成事業(早稲田大学)  科学研究費助成事業(COE形成基礎研究費)

    研究期間:

    2001年
    -
    2005年
     

     概要を見る

    拠点の整備状況
    本拠点を中核として、ナノテクファウンドリ、21世紀COEに係る2拠点などを統合した「ナノ理工学研究機構」の設立(平成15年12月)に加え、平成16年度には、文科省科学技術振興調整費「戦略的研究拠点形成プログラム」にかかわる「早稲田大学先端科学・健康医療融合研究機構」が発足、本拠点との連携によって、ナノバイオテクノロジー研究推進体制が強化された。
    研究成果
    各個研究に加え、チーム内外の共同研究を督励し、13件の研究を推進。また、プロトタイプ(PT)研究として、平成15年度に5件、16年度に更に2件の研究課題を選定。以下、グループ(G)毎に主要な研究成果をまとめる。
    <ナノ物性G>
    大泊研
    ・ドーパント原子の規則配列をもつ新規半導体を創製、特性揺らぎ減少を確認。本成果はNature誌に掲載。
    ・有機シラン単分子膜をレジストとする電子線リソグラフィを開発、分解能10nmの高精細パターン形成に成功。
    ・スライドガラスにナノ加工を施し、従来不可能な高濃度蛍光色素条件下での蛋白質間相互作用の1分子観察技術を実現。(共同-船津研)
    ・Si酸化過程を原子スケールで再現する大規模シミュレータの開発(PT研究)により、従来理論を覆す新理論の発見、酸化種拡散に関する理論予測の放射光X線回折実験による実証、に成功。(共同-阪大グループ)
    ・ナノ改質の原子的素過程の解明のために、独自開発した「イオン銃/超高真空高温STM複合装置」を用い、イオン照射誘起欠陥の動態、スパッタリング素過程のリアルタイム観察に成功。
    川原田研
    ・ボロン(アクセプタ)を大量にドープした気相合成ダイヤモンドでの超伝導を発現。本成果はNature誌に掲載。
    ・100nmゲートダイヤモンドバイオセンサ開発に成功、MEMS技術を併用して、zept(10^<-19>〜10^<-21>)molの高感度検出を可能とした。
    ・表面修飾ダイヤモンドトランジスタ試作により、50GHzの動作周波数確認。1GHzでの出力密度2.1W/mmを実現。
    ・表面修飾ダイヤモンドによりDNAの局所固定およびDNAアクティブセンサ開発に成功。(共同-大泊研)
    星野研
    ・蛋白質とナノ構造基板間の相互作用を理論的に計算し、基板の疎/親水性による水溶性蛋白質の小さな選択吸着性を発見、ナノ構造配列による蛋白質の結晶成長装置を試作。(共同-大泊研)
    <ケミカルナノプロセスG>
    逢坂研
    ・新電析浴により実用的に十分な腐食耐性を有する軟磁性CoFe薄膜の作製に成功。記録媒体薄膜の作製では、磁壁やラフネスの制御により低雑音化を実現。(PT研究)
    ・超小型燃料電池の試作セルにて、0.81mW/cm^2の出力密度と安定動作を実現。(共同-庄子研)
    黒田研
    ・メソポーラス金属層の形成に成功。それを応用した新規デバイスの開発を開始。(共同-逢坂研)
    ・センチメートルスケールで単結晶様の細孔構造の配向性3次元メソポーラスシリカ薄膜作製に成功。
    西出研
    ・高分子配列固定の研究において、電気化学的に有機ラジカル公文氏のスピン密度を可逆変化させることに成功。(共同-大泊研)
    ・Coポルフィリンに替る安価な材料としてCoフタロシアニンにおいて酸素促進輸送を確認。Coポルフィリンを多孔ガラスに担持させることによりマスクとしての使用に必要な高流量を達成。(PT研究)
    <バイオマイクロシステムG>
    松本研
    ・生体関連物質の超高感度検出のために新規希土類蛍光錯体の開発、DNA分析への応用、白金ナノワイヤ合成のための多核錯体の合成を行った。
    ・MEMS技術を活用した細胞破砕の基礎実験を行い、破砕時間200msを確認。(共同-庄子研)
    庄子研
    ・バイオマイクロシステム構築のため、インジェクタ、フィルタ、バルブなどのマイクロ流体素子の試作、評価を行った。
    ・燃料電池および高感度酵素検出システムのマイクロ化。(共同-逢坂研)
    船津研
    ・細胞内情報伝達の可視化のために、イントロンとエキソンを異なる蛍光色素で標識し、スプライシングを1分子レベルで検出する技術を開発。
    ・ガラス基板へのナノ開口配列形成により1分子レベルの生体分子間相互作用の検出技術を開発。(共同-大泊研、庄子研)
    <ナノ理工学基礎G>
    堀越研
    ・希薄磁性半導体GaMnAsにおいて世界最高のキュリー温度(250K)を達成。
    ・シングルイオン注入法による半導体中強磁性体クラスタ配列形成(共同-大泊研)、ペロブスカイト系強磁性体を用いる極微小不揮発性メモリなそ、半導体内スピンに関する研究を開始。
    大場研
    ・ナノ実験系の基礎理論からの指導原理の提示を目的に、ナノ構造体と環境系との相互作用のモデル化、半導体中の励起子のトンネル現象(共同-堀越研)、半導体中の不純物原子配列が固体物性に及ぼす効果(共同-大泊研)の評価、などを進めた。

  • 高機能性新半導体デバイス開発

    文部科学省 

    研究期間:

    1998年
    -
    2002年
     

  • 多孔質Si上へのGaAs分子線エピタキシャル成長

    科学研究費助成事業(大阪大学)  科学研究費助成事業(一般研究(B))

    研究期間:

    1989年
    -
    1991年
     

     概要を見る

    Si上へのGaAsエピタキシャル成長は格子定数及び熱膨張係数の差により、転位等の多数の欠陥が導入される。本研究ではこの欠陥を低減するために、多孔質Si上へのGaAs分子線エピタキシャル成長を試みた。得られた成果は以下の通りである。
    (1)多孔質Si上に直接GaAsを成長させ、その初期過程の解明及び欠陥の評価を、反射高速電子線回折法、X線及び紫外線光電子分光法、高速イオン散乱法を用いて行った。その結果、成長時に多孔質Siは形態変化し、多くのファセットが形成され、このため欠陥が導入されることが判明した。
    (2)この形態変化を防ぐために、多孔質Siを酸化し、孔の側面を酸化膜で保護した上に薄いSiを成長し、さらにGaAsを成長した。これにより、ウェ-ハの湾曲の大きさが従来より減少し、熱膨張係数の差による熱的歪が緩和されていることが分かったが、透過電子顕微鏡による観察から、まだ欠陥が多数存在することが明らかになった。これは多孔質Siの清浄化とその上への薄いSi膜の成長に起因することが分かった。
    (3)この為、p^+ Si上にあらかじめ薄いnSiを成長させ、部分的にnSiを除去し、p^+ Siのみ選択的に多孔質化し、その上にGaAsを成長させることを試みた。また、多孔質Siのみを酸化し、SOI構造とし、その上にGaAs層を成長させることも試みた。いずれの方法でも、GaAsエピタキシャル成長ができることは確認したが、まだ欠陥の評価までには至っていない。今後の残された課題である。また、この研究の過程で1μm位の非常に薄いSi上にGaAs層を成長させると、表面は鏡面となり、良好な成長層が得られる可能性が高いことが分かった。以上より、多孔質Si上へのGaAsエピタキシャル成長の基礎が得られた。

  • 気相合成ダイヤモンド薄膜による高効率青色発光デバイスの試作

    科学研究費助成事業(大阪大学)  科学研究費助成事業(試験研究)

    研究期間:

    1988年
    -
    1990年
     

     概要を見る

    この研究では、大阪大学工学部・平木研究所で開発された有磁場マイクロ波プラズマCVD法および通常型マイクロ波プラズマCVD波で良質の結晶ダイヤモンド薄膜(以下CVDダイヤモンドと省略)を合成し、不純物(B、Nなど)の導入、電子線および中性子線の照射、アニ-リングなどによりCVDダイヤモンドの発光センタ-、発光機構など光特性に関する研究を行ない、青色および短波長のエレクトロルミネッセンス・デバイス(ELD)の試作および実用化を検討した。
    アンド-プのCVDダイヤモンドからのカソ-ドルミネッセンスは青色領域にピ-ク(2.8ー2.9eV)を持ち、天然IIa型が示すのものと同一である。また、バンド端間還移に起因する自由励起子発光が観測された。硼素、窒素をそれぞれド-プした膜から特徴的な発光が見られ、その発光強度、スペクトルの形はド-プ量、励起密度、温度に依存する。硼素および窒素を同時にド-プした場合、それぞれの特徴的な発光が現われるが、硼素の方が支配的である。ダイヤモンドの発光センタ-は結晶の成長セクタ-に大きく依存することがわかった。アンド-プおよび硼素ド-プによる発光領域は{100}で、窒素によるのは{111}である。これらは、不純物あるいは格子欠陥の分布を反映している。または、高エネルギ-電子線照射によって、窒素を含有するダイヤモンドに点欠陥が導入され、アニ-ルによって様々な強度の高い発光センタ-が形成されている。さらに、CVDダイヤモンド薄膜を用いて、作製したショットキ-・ダイオ-ドから、エレクトルミネッセンスを初めて観測した。この研究によって、気相合成ダイヤモンドの光学特性を深く理解でき、さらに、ダイヤモンド薄膜は青色発光デバイスに非常に適切な材料であることを示している。

  • ビーム照射とECRプラズマとの併用法による良質ダイヤモンドの成膜

    科学研究費助成事業(大阪大学)  科学研究費助成事業(一般研究(B))

    研究期間:

    1987年
    -
    1988年
     

     概要を見る

    本研究は、ECRプラズマCVD法を使用し、低圧、低温でダイヤモンド薄膜を合成し、その際、ビーム照射により活性化された表面を使用することにより良質結晶薄膜を形成することを目的として行われた。以下に研究成果をまとめる。
    1)低圧でのダイヤモンドの合成と成長機構:電子サイクロトロン共鳴(ECR)条件およびそれよりも高い磁場条件(非共鳴条件)をはじめて成膜領域に応用し、低圧でもプラズマ密度を低下させないでダイヤモンドの成膜を行った。従来法よりも2桁近い低圧である10^<-1>Torr以下でもダイヤモンドの形成が可能であり、この低圧化は成膜温度の低下(従来法よりも200℃以上低下)に結びついた。さらに、低圧下では基板バイアスの効果が顕著となり、負の基板バイアスではダイヤモンドが成長せず、正の基板バイアスでは成長することがわかった。これより、運動エネルギをある程度(〜20eV)もったイオンはダイヤモンドの形成に有害となり、形成に必要なのは10eV以下のエネルギーをもった中性粒子(ラディカル)であることが判明した。
    2)均一な粒径をもつ多結晶膜の形成:基板へのArイオン照射により、Si上のSiO_2ドットのエッジに核形成サイトを形成した。ダイヤモンドの核はこれ以外の所に発生せず、単一核から発生した粒子は10μmの大きさまで成長し、粒径のそろった多結晶ダイヤモンドが得られる。この技術は、任意の基板上に単結晶に近い薄膜を形成する上で極めて発展性の高いものである。
    3)単結晶に匹敵する物性:気相合成法により得られたダイヤモンド薄膜は、カリードルミネッセンス法により青色および緑色の発光をし、不純物導入により半導体化が可能である。この半導体膜ではショットキー・ダイオードが作製でき、接合面からエレクトロルミネッセンスが観測され、半導体材料としての有望性が認められた。

  • エピタクシャル成長の基礎過程

     概要を見る

    本総合研究の分担研究者は、エピタクシ-解析手法の研究者、超伝導体薄膜研究者、高温超伝導体薄膜研究者、ダイヤモンド薄膜研究者等から構成されているが、互いに有機的に協力して研究を遂行してきた。先ずRHEED(反射高速電子回折)、TRAXS(全反射角X線分光)電子顕微鏡などを用いて、Si(100)表面において、Insbの吸着・成長の素過程の詳しい研究、エピタクシ-法により、1原子層のGeやSnを表面から数原子層の所に埋め込む(ド-プ)実験、UHVーSEMによるSi(111)上のAu、Agの吸着構造の研究などを行った。酸化物高温超伝導体については、マグネトロンスパッタリング法等により、エピタクシャル成長薄膜の研究を行い、高品質の薄膜の形成法、エピタクシャル成長の制御法、トンネル接合の形成法などの研究を行った。ダイヤモンド薄膜については、様々なCVD法により薄膜を作成し、その構造や成長方位、核の発生場所やその分布等の研究を行った平成2年11月19〜21日に、「ホテル伊豆高原」において、研究会を開催し、研究成果の発表、討論、情報の交換等を行った。またエピタクシ-の研究の歴史、現状、将来性等に付いて、国内的、国際的な立場から分析、討論した。その結果、これに関する日本の研究の実績は高く、これを重点領域研究としてさらに飛躍的に発展させることは、基礎科学的な観点からしても極めて重要であるばかりでなく、産業界に与えるインパントも莫大であり、社会的な要請も極めて大きいと考える意見が圧倒的であり、これを緊急に取り上げて推進させる必要があるという結論に至った。その後8人の世話人が選出され、小会合、アンケ-トによる調査、意見の交換等を重ね、重点領域研究の申請書を作成した

  • 超LSIの微小部位毎の放射線耐性評価技術に関する研究

     概要を見る

    本年度は、放射線耐性評価システムの開発とデバイスに対する照射実験を並行して行った。1.放射線耐性評価システムの開発高精度照準のため平成3年度に6軸ゴニオメータの導入を行い、現在0.1μmの移動精度、1μmの絶対位置決め精度を確認している。また、ゴニオメータを動かすことによる、シングルイベント耐性のマッピング実験に成功した。また、イオン入射角を変化させた際のシングルイベント耐性の評価にも成功した。また、これまでにI-V,C-V測定装置として使用されてきた測定器を、本システムの制御に使用しているコンピュータに統合した。これに併せ、イオンを照射しつつ電気的特性を評価するための試料ホルダーを製作し、トータルドーズ耐性評価実験に利用している。さらに、デバイスの放射線耐性の温度依存性を評価する為の試料温度制御機構を導入し、現在立ち上げのための試運転を行っている。2.デバイスに対する照射実験シングルイベント耐性評価実験としては、市販64kbit SRAMに対しシングルイオン照射実験を行い、ソフトエラー耐性の照射部位依存性の評価した。また、宇宙空間での使用のために開発された64kbit SRAMに対して照射実験を開始した。デバイスの電源電圧を下げることで等価的に高LET、高エネルギーの重イオンを照射したのと同様の効果が得られることを利用して、ソフトエラー発生部位の電源電圧依存性からソフトエラー耐性の定量的な評価を行った。トータルドーズ耐性評価実験としては、テストデバイス上の20×20μmのゲート領域を持つMOSFETに対し、任意個のイオンを照射し、FETの電気的特性の変化を評価した

  • 界面反応の物理・化学

     概要を見る

    「界面反応の物理・化学」という視点から、「コンタクト抵抗の低減」および「コンタクト構造の安定性」という問題に対処するべく、ショットキ-障壁高さ(SBH)の低減、界面介在物の除去、熱力学的ならびに速度論的安定性、界面構造のダイナミクスというより具体的なテ-マについて各分担者が研究を進めてきた。SBHに関しては、弾道電子放射顕微鏡(BEEM)による測定を国内で初めて実現した。またエレクトロマイグレ-ションによる半導体界面の形成法を提案し、実際に電子ビ-ムによる原子層の描画を可能にした。さらに量子化学的理論計算を用いて、界面の局所的な電荷分布がSBHに与える影響について検討した。界面介在物の除去の限界に対する考察に関連して、Si(111)ー7X7構造の形成は酸素原子の存在が本質的な要因であるという仮説を提案した。コンタクト構造の熱力学的安定性に関して、応力や電界が拡散や界面反応を促進させるか否かは、反応物質に依存することを明確にした。またCu/Si界面組成がSi基板の面方位によって異なることが判った。Si基板の面方位について、A1をエピ成長させた時のSBHや界面の熱的安定性について調べた。GaAs用オ-ミックコンタクト材に含まれるAuは構造不安定化の主因ではないことを示した。また化学量論的な金属間化合物膜を用いて平衡界面を達成したコンタクト構造は極めて高安定であることを実証した。さらにIn/αーSn系においてInの蒸着量に伴う不整合相の特異的な生成・消滅を観察した。速度論的安定性に関して、AuおよびSi基板上に単原子吸着したTMGの熱または光による分解過程をUPSを用いて調べた。また弾性歪エネルギ-、界面エネルギ-が薄膜の構造組成に与える影響を定量的に評価し、その緩和機構を検討した。界面構造のダイナミクスに関しては、拡散と弾性場が相互作用する場合について、非平衡熱力学の一般的関係から現象論的発展方程式を導くことに成功した

  • 高融点金属単結晶上のNiをバッファ層としたダイヤモンドのエピタキシャル成長

     概要を見る

    単結晶Wの表面制御技術の開発二次再結晶法にて得られた単結晶Wロフドからラウエ法を用いて方位選択カフトを行い(110)表面をだし、機械研磨および電界研磨を行い破砕層を除去した。その後、表面の無秩序層を除去するために必要であった高温(2300℃)熱処理の代りに、水素プラズマ処理(900℃)を行い、より低温で平坦な単結晶W表面を得る技術を開発した。メタン・水素混合プラズマによるダイヤモンド核形成制御電子サイクロトロン共鳴(ECR)によるメタン・水素混合プラズマを利用したイオン照射を行い,従来ドライプロセスでは困難であった異種基板上でのダイヤモンド核形成制御を可能とした。このイオン照射により単結晶W(110)表面にはWC(001)がエピタキシャル成長し,引きつづく照射によりダイヤモンド層が形成するのを確認した。この結果は,バッファ層としてNiよりも熱的安定性の高いWCをバッファ層としてダイヤモンドがヘラロエピタキシャル成長する可能性を示すものである。エピタキシャルNi薄膜上でのダイヤモンド粒子の部分的なエピタキシャル成長Niのエピタキシャル層を形成した表面上にダイヤモンドを形成した。表面の清浄化を水素プラズマにて行い,表面に存在するNiO層を除去した基板を使用した。ダイヤモンドの核形成密度の上昇および20%程度の粒子がC(111)11Ni(111),C<110>11Ni<110>の方位関係でエピタキシャル成長しているのが確認された。Ni表面のポランシャルが共有結合物質のエピタキシャル成長にとって有効であることが示された。しかし,Ni層が薄いとプラズマによりNiが除去されてしまう問題も指摘されている。最適なNi層の厚みの検討と核形成密度の向上が最重要課題である

  • シングルイオン注入法の実現と固体物性制御への応用

     概要を見る

    0.1μm以下の寸法を持つ極微半導体構造に、ドーパントイオンを1個づつ任意個数だけ打ち込むためのシングルイオン注入装置(SII)の開発を行った。注入イオンの計数、イオン入射の検出効率の調査を行い、注入イオン数の揺らぎをランダムな場合の半分以下に押さえる見通しを得た。シングルイオンマイクロプローブを利用し、超LSIのメモリデバイス中でのソフトエラー耐性の弱い部位の特定、エラーの発生条件、および発生機構を明らかにした。従来のFIBを用いた極微構造加工法における加工損傷、加工精度の問題点を、FIBによる熱酸化膜の表面改質と異方性エッチングを組み合わせることにより克服し、ナノスケールSi極微構造を実現した。SIIによりナノサイズの表面改質を行ったシリコン表面に、メッキが選択成長することを確認した。I-V特性の温度依存性等の調査により、金属/半導体界面近傍のイオン照射欠陥による界面整流性の変化の原因がフェルミレベルピニングの変化に起因したショットキー障壁高さの変化であることを明らかにした。注入イオンによって生成される欠陥を陽電子消滅法によって評価し、欠陥の深さ方向分布と注入イオン種の関係を明らかにした。陽電子ビーム強度の向上のため、高効率の陽電子減速材の開発、^<60>Coから放出されるγ線の利用を試み、従来の方法に比べて1000倍の効率を予想させる基礎的実験結果を得た。分子軌道法を用いて、シリコンの表面構造、反応の理論解析を行い、酸化、水素原子の脱離、アルカリ金属吸着過程およびその安定構造を明らかにした。7×7構造形成過程のエネルギー計算を行い、酸素原子との相関を議論した。Si表面に形成されるDAS構造の成長過程をSTMを用いた高温その場観察で詳細に研究した。また、この構造の核の形成、消滅を高温でその場観察し、核の臨界サイズを明らかにした

  • ダイヤモンド・ヘラロエピタキシャル成長層による耐環境電子テバイスの基礎検討

     概要を見る

    1)同軸マイクロ波プラズマ発生源の開発:同軸マイクロ波プラズマ発生源を開発し、プラズマ発生モードを従来の矩形導波管のTE01モードから同軸管のTEMモードに変更した。この結果、計画どおり、a)プラズマ発生領域が拡大し、b)ヘテロエピタキシャル核形成に必要なイオンの運動エネルギー(20-30eV)の制御性が向上した。c)また、結晶性の向上が期待される200Torr付近でのプラズマ安定性が極めて向上した。2)ヘテロエピタキシャル成長の初期過程の観察:ヘテロエピタキシャル核形成に必要なSiC表面の構造に関する重要な知見を、初期成長過程の高分解能SEM観察から得ることが出来た。これにより目的とする高い核形成密度による平坦なヘテロエピタキシャル成長が可能となった。3)ヘテロエピタキシャル成長層でのMESFET作製:ゲート長5μm程度の金属-半導体FET(MESFET)を作製した。p型半導体領域としては水素終端表面を使用した。ソースおよびドレインのためのオーミック電極にはAuを、ゲートにはAlを使用した。相互コンダクタンスでヘテロエピタキシャル成長層では現在最も高い7-8mS/mmを得ている。この値はホモエピタキシャル成長層の最高値の1/2-2/3に匹敵し、ヘテロエピタキシャル成長層での高い正孔移動度を反映したものである。4)NAND回路,NOR回路、R-Sフルップフロップ回路の動作確認:NAND回路、NOR回路、R-Sフリップフロップ回路の動作が確認された。また、相互コンダクタンス15mS/mm以上のMOSFET動作がダイヤモンドで初めて確認され(酸化膜にはSiO_2を使用)、室温から350℃まで同一特性を示した。これらは世界で最も進んだ結果であり、ヘテロエピタキシャル成長層でのデバイス特性向上において重要な指針となった

  • ヘテロエピタキシャルダイヤモンド電界効果トランジスタを利用した耐環境バイオセンサ

     概要を見る

    本研究では,電気化学的に耐久性のある水素終端ダイヤモンド表面上に,イオン感応性FET(ISFET)を形成し,これをバイオセンサーのトランスデューサとして機能させ,従来のSi MOSFETと比較し,より堅牢なセンサーの試作検討を3ヵ年にて行った.1.解質溶液をゲートとしたFETを水素終端ダイヤモンド表面上に作製した.このFETのゲート部は,ダイヤモンド水素終端表面を直接電解質水溶液にさらしたもので,溶液とソースの電位差がゲートバイアスとなる.半導体表面を直接液体電解質にさらした構造のFETとしては世界ではじめてのもので,従来のISFETよりも高い電流駆動能力が得られる.2.作製された電解質ゲートFETは,ホモエピタキシャルダイヤモンドやヘテロエピタキシャルダイヤモンドのみならず,成膜が容易な多結晶ダイヤモンドでも,理想的な静特性をしめした.3.作製されたFETは,完全なピンチオフとドレイン電流の飽和を示し,オフ時の漏れ電流が極めて少なく,オンオフの電流比が4桁以上ある.さらに、pH1からpH14まで上記の特性で安定に動作した.4.閾値電圧の溶液pH依存性を調査した結果,閾値電圧は電解質のpHに対してネルンスト応答せず,一定の閾値電圧をとることがわかった.これにより、pHに依存しない表面の上に所望の感応基を設けることが出来る.5.一方,Cl^-イオン濃度に関しては,濃度が1桁変化するごとにしきい値電圧が30-60mV変化することがわかった.1Mol/Lから10^<-6>Mol/Lの範囲でCl^-イオン濃度の検出が行えることがわかり,Cl^-感応性FETとしての応用が期待される.以上,耐環境バイオセンサーの基礎デバイスであるダイヤモンド電解質溶液ゲートFETを世界で最初に開発し,過酷な環境での動作確認,さらに微量塩素イオンの検出に成功した

  • ダイヤモンド・ヘテロエピタキシャル層による高耐圧、高周波電界効果トランジスタ

     概要を見る

    本研究では、研究代表者らが開発したダイヤモンド表面チャネル型FETの特性向上を行い、高耐圧、高周波でのデバイス動作を検討することを目的とし、従来のSi、GaAsもしくはワイドギャップ半導体であるSiC、GaNと比較し、より高い電力駆動能力を示すトランジスタの試作検討を3ヶ年にて行った。これにより、(1)ダイヤモンド水素終端構造にダメージを与えずに自己整合的にゲートを作製するプロセスを独自に開発し、ゲート長の微細化とともに寄生抵抗成分となるソース・ゲート、ゲート・ドレイン間隔を狭めることに成功した。このプロセスの実現により、ゲート長1μm、ソース・ゲート間隔0.1μm程度のCuゲートMESFETにおいて110mS/mmの相互コンダクタンスが実現した。(2)CaF 2をゲート絶縁膜に用いたダイヤモンドMIS構造を形成し、同様のプロセスを用いてMISFETを作製した。このMISFETは最大で90mS/mmの相互コンダクタンスが実現している(ゲート長1.2μm)。また、このMISFETにおいてはSiC-MOSFETの特性の二倍以上にあたる250cm^2/Vsの高い実効移動度が得られた。(3)ダイヤモンドトランジスタでは初めてめっきプロセスを利用し、オンウェハにてダイヤモンドMESFETにおける高周波散乱パラメータ測定を行った。これにより世界に先駆けてダイヤモンドトランジスタの高周波動作を確認した。2μmクラスのMESFETにおいては、遮断周波数2.2GHz、最大発振周波数7GHzと比較的高い値であったが、これは研究代表者らが開発したダイヤモンドFETの高い相互コンダクタンスを反映している結果である。(4)MIS構造のCaF 2パッシベート効果による高い移動度、およびゲート絶縁膜の挿入による低いゲート容量を反映させることにより、MISFETはMESFETよりも高周波特性に有利であると考え、MISFETにおける高周波動作を確認した。作製したMISFETはゲート長0.6μmで11GHzの遮断周波数と18GHzの最大発振周波数を実現しており、今後ゲート長の微細化によって他のワィドギャップ半導体の特性を凌ぐ特性が得られると考えられる。(5)ダイヤモンドの高い破壊電界を反映して、5μmのゲート長において200Vを超える破壊電界を有するMESFETの作製に成功した。また、二次元デバイスシミュレーションを用いて、ゲート・ドレイン間隔を広げることにより破壊電圧が得られることが示され、ゲート長0.5μmにおいて、ゲート・ドレイン間隔を0.8μmにすることにより、遮断周波数11GHzを得つつも破壊電圧150Vが同時に得られることが示された。以上、水素終端ダイヤモンドFET作製プロセスを独自に開発することによりダイヤモンドの持つポテンシャルを引き出すことを可能とし、高周波動作および高出力動作に成功した

  • アダマント薄膜表面のナノ機能デザイン

     概要を見る

    アダマント材料は,高い硬度とヤング率などのさまざまな魅力ある特性を備えた共有結合性軽元素材料である.これには,ダイヤモンドを代表的とするホモアダマント,立方晶窒化ホウ素をはじめとするヘテロダイヤモンド,ダイヤモンド状非晶質炭素膜のようなアモルファスアダマントなどがある.本科学研究費では,アダマント薄膜の機械的応用,化学的・バイオ応用,電子デバイス応用などの観点から,これまで個々に行われてきたアダマント薄膜研究を整理統合して,課題解決の方策を探るとともに,特異な表面物性を利用した新機能への展開を図ることを目的とする.特に,これらの成果を基にして本研究を特定領域研究に発展させることを期待している.このため,アダマント薄膜表面のナノ機能デザインに関して,表面ナノ構造,表面ナノ加工,表面の電子機能,表面の化学機能の四つの観点から,国際会議や国内学会講演会等の発表状況を中心に調査研究を行った.同じアダマント材料であっても,材料ごとに応用展開を図ろうとする分野が異なっていることが明らかとなった.特に,ホモアダマントであるダイヤモンドについては,表面を終端するH原子の官能基への置換操作を利用したバイオ応用展開が世界的に精力的に進められている現状が判明した.また,個々の研究を比較検討する場としてアダマント薄膜研究会「アダマント材料の将来を考える」を主催し,アダマント薄膜の表面構造操作によるFETセンサーをはじめとする各種応用について議論を行い,今後の研究の展開方向に関する質疑を行った

  • ダイヤモンド薄膜表面の導電性制御によるハイパワー高周波トランジスタの開発

     概要を見る

    ダイヤモンドトランジスタの性能向上および安定性向上を目的とした要素技術として、(1)FIB装置を用いたシート抵抗IkΩ/sq.以下の局所低抵抗層の形成技術、(2)2×10^<-4>[Ωcm]の熱的安定性のある超高濃度ボロンドープダイヤモンド(ボロン濃度:1.42×10^<22>[cm^<-3>])の成膜技術、(3)従来のCaF_2絶縁膜よりも3桁以上のゲートリーク電流低減を達成した、高品質なAl_2O_3ゲート絶縁膜形成技術、(4)低消費電力化を目的とした、オゾン処理によるダイヤモンドFETの閾値制御技術、を開発した。デバイス評価手法としては、De-embedding手法を導入することで、寄生成分の影響を除去し、ダイヤモンドMISFETの真性特性評価が可能となった。また、水素終端ダイヤモンド中に形成されるホール蓄積層のキャリア走行メカニズム解明を念頭に、移動度の実行垂直電界依存性を明らかにした。デバイス作製のプロセス技術としては、ゲート長0.2μm以下の微細ゲート構造作製のためのセルフアラインプロセスと、ゲート抵抗の低減を目的としたT型ゲート電極構造の作製プロセスを確立した。ダイヤモンドMISFET作製と特性評価としては、前述の微細プロセス技術を用いて、ゲート長0.15μmのダイヤモンドMISFETの作製に成功し、遮断周波数30GHz、最高発振周波数48GHzを達成した。また、Al_2O_3ゲート絶縁膜を用いたダイヤモンドMISFETの作製に成功し、絶縁膜厚3nm、ゲート長0.3μmにて遮断周波数30GHz、最高発振周波数60GHzを達成した。更に、世界で初めてダイヤモンドMISFETにおいてロードプル測定を行い、ゲート幅100μm,ゲート長0.3μmのデバイスにおいて、1GHzの高周波大信号入力時に電力密度2.14W/mmが得られた。この値は報告されているGaAsFETやSi LDMOSの電力密度の最高値よりも優れたものであり、ハイパワー高周波トランジスタとしてのダイヤモンドFETの優位性を確認できた

  • 超長寿命触媒微粒子によるセンチメートル長垂直配向単層カーボンナノチューブ合成

     概要を見る

    我々の触媒は30時間以上活性を保ち、単層カーボンナノチューブが成長し続けるが、単層カーボンナノチューブが長くなるほどカーボンラジカルの拡散距離が長くなるために、成長速度は時間とともに減少する。そこで、隙間をあけて拡散距離を短くするためにパターン成長を行った。円柱状にパターン成長した場合は、パターンなしに比べて、同じ10時間成長にも関わらず600um長く伸びた。これは、単層カーボンナノチューブの根元にある触媒微粒子に、パターン成長の側壁から多量の前駆体が進入可能になったからである。ハニカム構造のパターン成長を用い30時間成長を行った結果、5.2mmの垂直配向単層カーボンナノチューブが得られた。これは、現時点で垂直配向単層カーボンナノチューブにおいて世界で最も高い値である。しかし、この成長においても時間とともに成長速度が減少した。これはハニカム中の600umの隙間においてもラジカルの拡散が抑制されてしまうことを示している。より大きな隙間ならば単層カーボンナノチューブの成長速度が減少しないと考え、ライン状のパターン(4mm x 0.3mm)を用いたところ、20時間の成長でも成長速度は時間に比例し、線形な成長が得られた。また、さらなる高速成長の達成のためにCVD条件の最適化を行った。その結果、成長速度に大きな影響を与えるパラメータは温度であることが分かった。これまで用いていた600℃での成長に比べ、690℃では約3倍の850um/hという高い成長速度が得られた。これは、高い温度によってラジカルの拡散係数が上昇したことと、触媒の活性が高まったことによると考えられる。この温度において20時間の成長において5.3mmまでカーボンナノチューブを伸長することに成功した。今後、この最適CVD条件とパターン成長を組み合わせることによりさらに長尺な単層カーボンナノチューブの合成が期待できる

  • 高密度正孔ガスを利用したダイヤモンド高出力ミリ波トランジスタ

     概要を見る

    ダイヤモンドは降伏電界が半導体中最も高く、物質中最高の熱伝導率をもち、従来の半導体で不可能であった高出力高周波デバイスや低損失電力素子が期待される。本研究では、ダイヤモンド電界効果トランジスタ(FET)の性能を表面やバルクでの異種原子制御より向上させ、ミリ波帯で動作する高周波デバイスや超伝導ダイヤモンドを利用した新機能デバイスの開発を行った。この結果、現在の半導体でのFETの最大級の電流密度1A/mmを達成し、ミリ波帯に入る50GHz近くでの動作およびSiおよびGaAs等の従来の半導体を越えるGHz帯での高い電力制御を可能とした。400℃での高温動作も可能とした。また、ダイヤモンド超伝導を利用したジョセフソン接合でテラヘルツ帯の特性振動数を得た

  • 一塩基遺伝子変異および特定タンパク質検出用ダイヤモンドトランジスタ

     概要を見る

    1.ダイヤモンド表面での電解質溶液ゲートトランジスタ(SGFET)による高感度センサ化学修飾ダイヤモンド表面の電気化学的耐久性を見出し、溶液中での安定なFET動作を三確認し、従来のSiISFETよりも堅牢なセンサとなることを見出した(論文2)。ボロンデルタドーピングチャネル(厚み1-3nm)を(111)面で作製し、浅いTiC接合(学会1)でデルタドーピング層へのオーミック接合を可能とし、高性能FETセンサを作製した(学会9)。作製されたFETは、ホモエピタキシャルやヘテロエピタキシャルダイヤモンドのみならず、成膜が容易な多結晶ダイヤモンドでも、センサとしては十分な電気特性を示した(論文1,2,学会9)。2.微細化SGFETによる高感度一塩基遺伝子変異検出上記SGFETをナノサイズまで微細化して分子認識素子に発展させるため電子ビーム露光装置にてリソグラフィーの高精度化を図り、200nmサイズSGFETのチャネル(検出部)にDNAを固定し、一塩基違いによる電位変化を高精度で検出するのに成功した(学会1,4)。ソース、ドレイン、ゲート構造を有するダイヤモンド表面上に、局所酸化・フッ素化(局所絶縁化)によってサイドゲート絶縁領域を形成し、極細の導電性チャネル(水素終端)を残し、サイドゲートによる横方向からのドレイン電流制御を可能として参照電極がないin vivoセンサに発展させた。3.ダイヤモンド表面上のアプタマーによる血小板由来成長因子(platelet derived growth factor,PDGF)の検出ダイヤモンド表面上に固定されたDNAアプタマーにてPDGFの検出を蛍光法(論文3)およびSGFETによる電荷検出法(論文1)の両者で可能とし、FETによるタンパク質の再現性よい電荷検出に初めて成功した。ATPについても同様の結果を得ている

▼全件表示

講演・口頭発表等

  • Exploring the potential of heteroepitaxial diamond as field effect transistor

    M. Syamsul, H. Kawarada  [招待有り]

    2018 E-MRS Fall Meeting & Exhibit   (Warsaw, Poland) 

    発表年月: 2018年09月

  • RF Performance of ALD-Al2O3 2DHG Diamond MOSFETs at High Voltage Operation for High Output Power

    S. Imanishi, N. Oi, S. Okubo, K. Horikawa, T. Kageura, A. Hiraiwa, H. Kawarada

    2018 International Conference on Solid State Devices and Materials(SSDM2018)   (Tokyo, Japan) 

    発表年月: 2018年09月

  • Superconducting Boron-doped Diamond Josephson Junction Operating above Liquid He Temperature, 4.2K

    S. Amano, T. Kageura, I. Tsuyuzaki, M. Tachiki, S. Ooi, K. Hirata, S. Arisawa, H. Osato, D. Tsuya, Y. Takano, H. Kawarada

    2018 International Conference on Solid State Devices and Materials(SSDM2018)   (Tokyo, Japan) 

    発表年月: 2018年09月

  • Properties of Shallow Nitrogen Vacancy Centers in Nitrogen Terminated Diamond and Detection of Nuclear Magnetic Resonance

    T. Sonoda, S. Kawai, H. Yamano, K. Kato, J. J. Buendia, T. Kageura, Y. Ishii, K. Nagaoka, R. Fukuda, T. Okada, M. Haruyama, T. Tanii, K. Yamada, S. Onoda, W. Kada, O. Hanaizumi, A. Stacey, T. Teraji, S. Kono, J. Isoya, H. Kawarada

    2018 International Conference on Solid State Devices and Materials(SSDM2018)   (Tokyo, Japan) 

    発表年月: 2018年09月

  • New Glass-less pH Sensing System Using Diamond Electrolyte Solution Gate FETs (SGFETs) and Vessel Gate

    Y. Iyama, S. Falina, Y. Shintani, H. Kawarada

    2018 International Conference on Solid State Devices and Materials(SSDM2018)   (Tokyo, Japan) 

    発表年月: 2018年09月

  • High-bias-instability Al2O3 films formed by high-temperature annealing after atomic layer deposition

    K. Horikawa, A. Hiraiwa, S. Okubo, T. Kageura, H. Kawarada

    2018 International Conference on Solid State Devices and Materials(SSDM2018)   (Tokyo, Japan) 

    発表年月: 2018年09月

  • Normally-Off 2DHG Diamond Al2O3/SiO2 MOSFETs without deteriorating Drain Current Density

    T. Yabe, N. Oi, J. J. Buendia, S. Okubo, K. Horikawa, T. Kageura, S. Kono, A. Hiraiwa, H. Kawarada

    2018 International Conference on Solid State Devices and Materials(SSDM2018)   (Tokyo, Japan) 

    発表年月: 2018年09月

  • Vertical-Type 2DHG Diamond MOSFETs with a Few Micro Meter Length Trench Structure

    M. Iwataki, N. Oi, K. Horikawa, S. Amano, T. Kageura, M. Inaba, A. Hiraiwa, H. Kawarada

    2018 International Conference on Solid State Devices and Materials(SSDM2018)   (Tokyo, Japan) 

    発表年月: 2018年09月

  • Superconductivity in high quality single crystal boron-doped diamond films with Tc above 10K

    T. Kageura, I. Tsuyuzaki, T.Yamaguchi, Y. Takano, H.Kawarada

    29th International Conference on Diamond and Carbon Materials   (Dubrovnik, Croatia) 

    発表年月: 2018年09月

  • 相補型パワーインバータに向けたダイヤモンド2次元正孔ガス高耐圧電界効果トランジスタ

    川原田 洋  [招待有り]

    第46回 薄膜・表面物理セミナー(応用物理学会薄膜・表面物理分科会)   (東京) 

    発表年月: 2018年07月

  • ダイヤモンドパワー電界トランジスタの進展

    川原田 洋, 大井信敬, 畢 特, 今西祥一朗, 岩瀧雅幸, 矢部太一, 平岩 篤  [招待有り]

    電子情報通信学会エレクトロニクスソサイティ シリコン材料・デバイス(SDM)研究会   (名古屋大学、愛知) 

    発表年月: 2018年06月

  • Recent Progress of Diamond 2DHG p-FETs for Complementary High Voltage Inverter Application

    H. Kawarada  [招待有り]

    International Symposium on Single Crystal Diamond and Electronics(SCDE 2018),   (Xi'an, China) 

    発表年月: 2018年06月

  • Solution Giant Gate Graphene FET (G3FET) pH Sensor

    Syamsul Mohd, Shaili Falina, M. Hasegawa, Y. Koga, H. Kawarada

    The 12th New Diamond and Nano Carbons Conference (NDNC 2018)   (Arizona, USA) 

    発表年月: 2018年05月

  • Superconductivity in Thin- and Micro-Structured Boron-Doped Diamond

    T. Kageura, M. Hideko, I. Tsuyuzaki, Y. Takano, M. Tachiki, S. Ooi, H.Kawarada

    The 12th New Diamond and Nano Carbons Conference (NDNC 2018)   (Arizona, USA) 

    発表年月: 2018年05月

  • ダイヤモンド2次元正孔ガスFETを利用した相補型パワーインバータへの応用

    川原田 洋

    東北大学電気通信研究所-早稲田大学ナノ・ライフ創新研究機構 共同プロジェクト研究(H29/S2, ナノエレクトロニクスに関する連携研究) 平成29年度研究会   (仙台市、宮城県) 

    発表年月: 2017年12月

  • Diamond Power p-FETs Using Two-Dimensional Hole Gas for Complementary High Voltage Inverter

    H. Kawarada  [招待有り]

    2017 MRS Fall Meeting& Exhibit   (Boston, USA) 

    発表年月: 2017年11月

  • Time-Dependent Dielectric Breakdown of Atomic-Layer-Deposition Al2O3 Films Formed on GaN

    A. Hiraiwa, T. Sasaki, S. Okubo, H. Kawarada

    2017 MRS Fall Meeting & Exhibit   (Boston, USA) 

    発表年月: 2017年11月

  • Effective Boron-Doping Method Using Custom-Built MPCVD System for High Tc Superconducting Diamond

    T. Kageura, M. Hideko, I. Tsuyuzaki, Y. Sasama, T. Yamaguchi, Y. Takano, H.Kawarada

    2017 MRS Fall Meeting & Exhibit   (Boston, USA) 

    発表年月: 2017年11月

  • Leakage-Current Reduction in Atomic-Layer-Deposition Al2O3 Films by Al gate/Al2O3 Interface Engineering Using O3 Treatment

    S. Okubo, D. Matsumura, A. Hiraiwa, H. Kawarada

    2017 MRS Fall Meeting& Exhibit   (Boston, USA) 

    発表年月: 2017年11月

  • Vertical-Type 2DHG Diamond MOSFETs

    N. Oi, T. Kudo, T. Muta, S. Okubo, I. Tsuyuzaki, T. Kageura, M. Inaba, S. Onoda, A. Hiraiwa, H. Kawarada

    2017 MRS Fall Meeting & Exhibit   (Boston, USA) 

    発表年月: 2017年11月

  • Single Crystalline Boron-Doped Diamond Superconducting Quantum Interference Devices

    I. Tsuyuzaki, T. Kageura, M. Hideko, Y. Sasama, T. Yamaguchi, Y. Takano, M.Tachiki, S. Ooi, K. Hirata, S. Arisawa, H. Kawarada

    2017 MRS Fall Meeting Exhibit   (Boston, USA) 

    発表年月: 2017年11月

  • Charge Stability and Coherence Property of Shallow Nitrogen Vacancy Center in Nitrogen Terminated Diamond for DNA Detection

    S. Kawai, H. Yamano, T. Sonoda, K.Kato, J. J. Buendia, E. Suaebah, T. Kageura, M. Inaba, R. Fukuda, T. Okada, M. Haruyama, T. Tanii, K. Yamada, S. Onoda, W. Kada, O. Hanaizumi, A. Stacey, T. Teraji, S. Kono, J. Isoya, H. Kawarada

    2017 MRS Fall Meeting & Exhibit   (Boston, USA) 

    発表年月: 2017年11月

  • Device Simulation of Several C-H MOSFETs Diamond Substrates via Two-Dimensional Negatively Charged Sheet Model

    J.J. Buendia, M. Shibata, M. Syamsul, H. Kawarada

    2017 MRS Fall Meeting & Exhibit   (Boston, USA) 

    発表年月: 2017年11月

  • 高耐圧ダイヤモンドFETの縦型,ノーマリオフ,低オン抵抗への検討

    川原田洋  [招待有り]

    応用物理学会 先進パワー半導体分科会 第4回講演会   (名古屋国際会議場(名古屋)) 

    発表年月: 2017年11月

  • Vertical Diamond MOSFETs, present characteristics and future perfomance

    H. Kawarada

    OIST Diamond Workshop 2017   (Okinawa, Japan) 

    発表年月: 2017年10月

  • Heavily boron-doping for power electronics and superconductivity

    T. Kageura, Y. Takano, H. Kawarada

    OIST Diamond Workshop 2017   (Okinawa, Japan) 

    発表年月: 2017年10月

  • Normally-off Diamond p-FET Application in Cascode with Breakdown Voltage over 1.7 KV

    Te Bi, Junxiong Niu, Nobutaka Oi, Masafumi Inaba, Toshio Sasaki, Hiroshi Kawarada

    International Conference on Materials and Systems for Sustainability 2017   (Nagoya, Japan) 

    発表年月: 2017年09月

  • Diamond Transistors for Power Electronics and Biosensing

    H. Kawarada  [招待有り]

    International conference on Materials and Systems for Sustainability 2017 (ICMaSS 2017)/iLIM-2   (Nagoya, Japan) 

    発表年月: 2017年09月

  • Current Conduction in Al2O3 Films Formed by Atomic Layer Deposition Using Water and Ozone as Oxidant

    A. Hiraiwa, S. Okubo, D. Matsumura, H. Kawarada

    International conference on Materials and Systems for Sustainability 2017 (ICMaSS 2017)/iLIM-2   (Nagoya, Japan) 

    発表年月: 2017年09月

  • Single Crystalline Boron-doped Diamond Superconducting Quantum Interference Devices

    T.Kageura, I.Tyuyuzaki, M.Hideko, Y.Sasama, T.Yamaguchi, Y.Takano, M.Tachiki, S.Ooi, K.HIrata, S.Arisawa, H.Kawarada

    International conference on Materials and Systems for Sustainability 2017 (ICMaSS 2017)/iLIM-2   (Nagoya, Japan) 

    発表年月: 2017年09月

  • Growth of Diamond Nanocylinder Forest Using Template-Assisted Antenna-Edge Type Microwave Plasma Chemical Vapor Deposition

    W. Fei, M.Inaba, Y.Hirano, H.Masuda, H.Kawarada

    International conference on Materials and Systems for Sustainability 2017 (ICMaSS 2017)/iLIM-2   (Nagoya, Japan) 

    発表年月: 2017年09月

  • Vertical-type 2DHG Diamond MOSFETs

    N. Oi, T. Kudo, T. Muta, S. Okubo, I. Tsuyuzaki, T. Kageura, M. Inaba, S. Onoda, A. Hiraiwa, H. Kawarada

    2017 International Conference on Solid State Devices and Materials   (Sendai, Japan) 

    発表年月: 2017年09月

  • Charge Stability of Shallow Nitrogen Vacancy Center in Diamond with Radical Exposure Nitridation Surface for DNA Detection

    S. Kawai, H. Yamano, T. Sonoda, M. Kajiya, K.Kato, J. J. Buendia, T. Kageura, M. Inaba, R. Fukuda, T. Okada, I. Higashimata, M. Haruyama, T. Tanii, K. Yamada, S. Onoda, W. Kada, O. Hanaizumi, A. Stacey, T. Teraji, S. Kono, J. Isoya, H. Kawarada

    2017 International Conference on Solid State Devices and Materials   (Sendai, Japan) 

    発表年月: 2017年09月

  • Boron-doped Diamond Superconducting Quantum Interference Devices with Two Step-Edge Josephson Junctions

    I. Tsuyuzaki, T. Kageura, M. Hideko, Y. Sasama, T. Yamaguchi, Y. Takano, M. Tachiki, K. Hirata, S. Ooi, S. Arisawa, H. Kawarada

    2017 International Conference on Solid State Devices and Materials   (Sendai, Japan) 

    発表年月: 2017年09月

  • Current conduction in H2O-grown ALD-Al2O3 films on Si substrate

    S.Okubo, D.Matsumura, K.Horikawa, A.Hiraiwa, H.Kawarada

    2017 International Conference on Solid State Devices and Materials   (Sendai, Japan) 

    発表年月: 2017年09月

  • Normally-off Diamond p-FET Application in Cascode with Breakdown Voltage over 1.7KV

    Te Bi, Junxiong Niu, Nobutaka Oi, Masafumi Inaba, Toshio Sasaki, Hiroshi Kawarada

    The 2017 international conference on Soild State Devices and Materials   (Sendai, Japan) 

    発表年月: 2017年09月

  • Common Gate Boron Doped Diamond (BDD) Solution Gate FET for pH sensor

    M.Shaili, Y.Shintani, H.Kawarada

    The 2017 international conference on Soild State Devices and Materials   (Sendai, Japan) 

    発表年月: 2017年09月

  • Normally-off and vertical diamond power FETs using 2 dimensional hole gas

    H. Kawarada  [招待有り]

    2017 International Symposium on Single Crystal Diamond and Electronics (SCDE2017)   (Xi’an, China) 

    発表年月: 2017年06月

  • Superconducting Single Crystal Diamond SQUID

    T.Kageura, M.Hideko, I.Tsuyuzaki, Y.Sasama, T.Yamaguchi, Y.Takano, M.Tachiki, S.Ooi, K.Hirata, S.Arisawa, H.Kawarada

    The 11th New Diamond and Nano Carbons 2017   (Cairns, Australia) 

    発表年月: 2017年05月

  • Heteroepitaxial diamond FET for power electronics application

    M.Syamsul, J.J. Buendia, N. Oi, S. Okubo, H.Kawarada

    The 11th New Diamond and Nano Carbons 2017   (Cairns, Australia) 

    発表年月: 2017年05月

  • Precise Control of Voltage Threshold by Electrochemical Oxygen Termination Boron-doped Diamond Solution- Gate Field Effect transistor (SGFET) for PH sensor

    M.S Shaili, T. Naramura, M.Inaba, Y.Shintani, H.Kawarada

    The 11th New Diamond and Nano Carbons 2017   (Cairns, Australia) 

    発表年月: 2017年05月

  • Normally-off Diamond p-FET Application in Cascode with 1735 V Breakdown Voltage

    Te Bi, J. Niu, N. Oi, M. Inaba, T. Sasaki, H. Kawarada

    The 11th New Diamond and Nano Carbons 2017   (Cairns, Australia) 

    発表年月: 2017年05月

  • N-V中心NMRのためのダイヤモンド表面の電荷安定性

    川原田 洋, 山野 颯, 河合 空, 梶家 美貴, 加藤かなみ, 蔭浦 泰資, 稲葉 優文, 岡田 拓真, 東又格, 春山 盛善, 谷井 孝至, 山田 圭介, 小野田 忍, 寺地 徳之, 加田 渉, 花泉 修, 磯谷 順一

    第64回応用物理学会春季学術講演会   (横浜市、神奈川) 

    発表年月: 2017年03月

  • Normally-off Diamond MOSFETs in Cascode Configuration with Breakdown Voltage over 1.7kV

    J. Niu, T. Bi, D. Matsumura, T. Kudo, M. Inaba, T. Sasaki, H.Kawarada

    Hasselt Diamond Workshop 2017 - SBDD XXII   (Hasselt, Belgium) 

    発表年月: 2017年03月

  • Amine termination of Nanocrystalline Diamond surface by Nitrogen Radical Beam (NRB) for Biosensing Application

    E. Suaebah, Y. Seshimo, T. Naramura, M. Hasegawa, H. Kawarada

    7th Annual Basic Science International Conference   (Malang, Indonesia) 

    発表年月: 2017年03月

  • 2次元正孔ガス層による耐圧>1600VダイヤモンドpチャネルMOSFET

    川原田 洋, 北林 祐哉, 柴田 将暢, 松村 大輔, 工藤 拓也, 牟田 翼, 大井 信敬, 稲葉 優文, 平岩 篤

    「電子デバイス界面テクノロジー研究会—材料・プロセス・デバイス特性の物理—」(第22回研究会)   (三島市、静岡県) 

    発表年月: 2017年01月

  • Lattice strain in superconducting boron-doped diamond

    T. Kageura, M. Shibata, Y. Sasama, T. Yamaguchi, Y. Takano, H. Kawarada

    IWSRFM 2016 (International Workshop on Superconductivity and Related Functional Materials)   (Tsukuba, Japan) 

    発表年月: 2016年12月

  • Boron-doped diamond SQUID with regrowth-induced step edge structure Josephson junction

    M. Hideko, T. Kageura, I. Tuyuzaki, M. Shibata, Y. Kitabayashi, Y. Sasama, T. Yamaguchi, Y. Takano, M. Tachiki, S. Ooi, K. Hirata, S. Arisawa, H. Kawarada

    IWSRFM 2016(International Workshop on Superconductivity and Related Functional Materials)   (Tukuba, Japan) 

    発表年月: 2016年12月

  • Atomic-Layer-Deposition Temperature Effect on Current Conduction in Al2O3 Films as Investigated Using Space-Charge-Controlled Field Emission Model

    A. Hiraiwa, D. Matsumura, H. Kawarada

    2016 MRS Fall Meeting & Exhibit   (Boston, USA) 

    発表年月: 2016年11月

  • Vertically Oriented Graphite Layer Formed on (001) Diamond by Hot Implantation and High Temperature Annealing

    M. Inaba, H. Yamano, T. Kageura, H. Kawarada

    2016 MRS Fall Meeting& Exhibit   (Boston, USA) 

    発表年月: 2016年11月

  • Over 2000 V Breakdown Voltage of Normally-off C-H Diamond MOSFETs with high threshold voltage

    T. Kudo, Y. Kitabayashi, D. Matsumura, Y. Hayashi, M. Inaba, A. Hiraiwa, H. Kawarada

    2016 MRS Fall Meeting & Exhibit   (Boston, USA) 

    発表年月: 2016年11月

  • Superconducting Boron-doped Diamond Josephson Junction with Regrowth-induced Step Edge Structure

    M. Hideko, T. Kageura, I. Tuyuzaki, M. Shibata, Y. Kitabayashi, Y. Sasama, T. Yamaguchi, Y. Takano, M. Tachiki, S. Ooi, K. Hirata, S. Arisawa, H. Kawarada

    2016 MRS Fall Meeting & Exhibit   (Boston, USA) 

    発表年月: 2016年11月

  • Charge State Stabilization of Shallow Nitrogen Vacancy Centers in Diamond by Oxygen Ambient Surface Modification

    H. Yamano, K. Kato, T. Kageura, M. Inaba, T. Okada, I. Higashimata, M. Haruyama, T. Tanii, S. Onoda, W. Kada, O. Hanaizumi, T. Teraji, J. Isoya, H. Kawarada

    2016 MRS Fall Meeting & Exhibit   (Boston, USA) 

    発表年月: 2016年11月

  • Common-Gate Measurement System of Solution-Gate Field-Effect Transistor for pH Sensing

    K. Igarashi, T. Naramura, S. Falina, S. Abe, M. Inaba, Y. Shintani, A. Hiraiwa, H. Kawarada

    2016 MRS Fall Meeting & Exhibit   (Boston, USA) 

    発表年月: 2016年11月

  • The Electron States of Shallow NV Centers after DNA Immobilization on Partially NH 2 Terminated Diamond

    K. Kato, H. Yamano, T. Kageura, M. Inaba, M. Haruyama, Evi Suaebah, O.Hanaizumi, W. Kada, S. Onoda, T. Teraji, J. Isoya, H. Kawarada

    2016 MRS Fall Meeting & Exhibit   (Boston, USA) 

    発表年月: 2016年11月

  • Vertical MOSFETs-Using C-H Diamond with Trench-Channel

    T. Muta, N. Oi, M. Inaba, T. Saito, D. Matsumura, T. Kudo, A. Hiraiwa, H. Kawarada

    2016 MRS Fall Meeting & Exhibit   (Boston, USA) 

    発表年月: 2016年11月

  • Diamond Nanocylinder Forest Formed by Porous Alumina Template

    W. Fei, M. Inaba, Y. Hirano, H. Masuda, H. Kawarada

    2016 MRS Fall Meeting & Exhibit   (Boston, USA) 

    発表年月: 2016年11月

  • Stacking Faults and Twins Induced by Lattice Relaxation in Superconducting Boron-Doped Diamond Synthesized by Microwave Plasma Chemical Vapor Deposition

    T. Kageura, M. Hideko, M. Shibata, Y. Sasama, T. Yamaguchi, Y. Takano, H.Kawarada

    2016 MRS Fall Meeting & Exhibit   (Boston, USA) 

    発表年月: 2016年11月

  • Development of New Amorphous Oxide Semiconductor by Controlling Defects

    T. Kamiya, K. Ide, H. Hiramatsu, Y. Setsuhara, A. Hiraiwa, H. Kawarada, H. Hosono

    The 1st International Symposium on Creation of Life Innovation Materials for Interdisciplinary and International Researcher Development (iLIM-1)   (Osaka, Japan) 

    発表年月: 2016年10月

  • Complementary Study for Effects of Annealing on Density and Pore Structures in Amorphous In-Ga-Zn-O Thin-Film Transistors

    K. Ide, M. Ota, K. Takenaka, Y. Setsuhara, A. Hiraiwa, H. Kawarada, H. Hiramatsu, H. Hosono, T. Kamiya

    The 1st International Symposium on Creation of Life Innovation Materials for Interdisciplinary and International Researcher Development (iLIM-1)   (Osaka, Japan) 

    発表年月: 2016年10月

  • Current Conduction in Atomic-Layer-Deposition Al2O3 as Investigated Based on Space-Charge-Controlled Field Emission Model

    A. Hiraiwa, D. Matsumura, S. Okubo, H. Kawarada

    The 1st International Symposium on Creation of Life Innovation Materials for Interdisciplinary and International Researcher Development (iLIM-1)   (Osaka, Japan) 

    発表年月: 2016年10月

  • Superconducting (111) Boron-doped Diamond Josephson Junction with Regrowth-induced (001) Step Edge Structure

    M. Hideko, T. Kageura, I. Tuyuzaki, M. Shibata, Y. Kitabayashi, Y. Sasama, T. Yamaguchi, Y. Takano, M. Tachiki, S. Ooi, K. Hirata, S. Arisawa, H. Kawarada

    2016 International Conference on Solid State Devices and Materials   (Tukuba, Japan) 

    発表年月: 2016年09月

  • Vertical MOSFET using C-H Diamond with Trench-channel

    T. Muta, T. Saito, M. Inaba, D. Matsumura, T. Kudo, Y. Kitabayashi, A. Hiraiwa, H. Kawarada

    2016 International Conference on Solid State Devices and Materials   (Tukuba, Japan) 

    発表年月: 2016年09月

  • Coherence Properties and Charge Stability of Shallow Implanted Nitrogen Vacancy Centers in 12C enriched Diamond

    H. Yamano, K. Kato, T. Kageura, M. Inaba, T. Okada, I. Higashimata, M. Haruyama, T. Tanii, S. Onoda, W. Kada, O. Hanaizumi, T. Teraji, J. Isoya, H. Kawarada

    2016 International Conference on Solid State Devices and Materials   (Tsukuba, Japan) 

    発表年月: 2016年09月

  • Planer Diamond P-channel MOSFETs with Breakdown Voltage VB > 1.8kV and High Drain Current Density by 2DHG

    H.Kawarada, Y.Kitabayashi, M.Syamsul N.S.B, M.Shibata, D.Matsumura, T.Kudo, A.Hiraiwa  [招待有り]

    2016 International Conference on Solid State Devices and Materials   (Tsukuba, Japan) 

    発表年月: 2016年09月

  • Gate Threshold Voltage Control of C-H Diamond MOSFETs

    T. Kudo, Y. Kitabayashi, D. Matsumura, Y. Hayashi, M. Inaba, A. Hiraiwa, H. Kawarada

    International Conference on Solid State Devices and Materials   (Tsukuba, Japan) 

    発表年月: 2016年09月

  • High endurance white polycrystalline diamond FET for power device application

    M.Syamsul, Y.Kitabayashi, D.Matsumura, H.Kawarada

    2016. International Conference on Diamond and Carbon Materials   (Montpellier, France) 

    発表年月: 2016年09月

  • Cost effective white polycrystalline diamond FET using 2D hole gas

    M.Syamsul, Y.Kitabayashi, D.Matsumura, H.Kawarada

    2016. NANO KOREA 2016 Symposium   (Ilsan, Korea) 

    発表年月: 2016年07月

  • Diamond Power MOSFETs using 2 Dimensional Hole Gas

    H. Kawarada  [招待有り]

    2016 Asia-Pacific Workshop on Fundamentals and Applications of Advanced Semiconductor Devices (AWAD2016)   (Hakodate, Japan) 

    発表年月: 2016年07月

  • Amine termination of nanocrystalline diamond surface by nitrogen radical beam (NRB) for biosensing application

    E. Suaebah, Y. Seshimo, T. Naramura, M. Hasegawa, H. Kawarada

    10th International Conference on New Diamond and Nano Carbons(NDNC2016   (Xi’an, China) 

    発表年月: 2016年06月

  • Diamond MOSFETs Using 2D Hole Gas with 1700V Breakdown Voltage

    H. Kawarada, T. Yamada, D. Xu, Y. Kitabayashi, M. Shibata, D. Matsumura, M. Kobayashi, T. Saito, T. Kudo, M. Inaba, A. Hiraiwa

    28th International Symposium on Power Semiconductor Devices and ICs   (Prague, Czech Republic) 

    発表年月: 2016年06月

  • Diamond as Power Electronics Platform

    H. Kawarada, Y. Kitabayashi, M. Shibata, D. Matsumura, T. Saito, T. Kudo, T. Muta, M. Inaba, A. Hiraiwa  [招待有り]

    10th International Conference on New Diamond and Nano Carbons(NDNC2016)   (Xi’an, China) 

    発表年月: 2016年05月

  • Diamond as Power Electronics Platform

    H. Kawarada, Y. Kitabayashi, M. Shibata, D. Matsumura, T. Saito, T. Kudo, T. Muta, M. Inaba, A. Hiraiwa  [招待有り]

    10th International Conference on New Diamond and Nano Carbons(NDNC2016)   (Xi’an, China) 

    発表年月: 2016年05月

  • Growth of diamond nanorods using antenna-edge-type microwave plasma-assisted chemical vapor deposition

    W. Fei, M.Inaba, Y.Hirano, H.Masuda, H.Kawarada

    10th International Conference on New Diamond and Nano Carbons(NDNC2016)   (Xi’an, China) 

    発表年月: 2016年05月

  • Electric properties of Au ohmic-contact on hydrogen-terminated surface-conductive diamond (001)

    S. Kono, M. Inaba, A. Hiraiwa, H. Kawarada

    10th Intern. Conf. New Diamond Nano Carbonds   (Xi'an China) 

    発表年月: 2016年05月

  • Growth of diamond nanorods using antenna-edge-type microwave plasma-assisted chemical vapor deposition

    W. Fei, M.Inaba, Y.Hirano, H.Masuda, H.Kawarada

    10th International Conference on New Diamond and Nano Carbons(NDNC2016)   (Xi’an, China) 

    発表年月: 2016年05月

  • Electric properties of Au ohmic-contact on hydrogen-terminated surface-conductive diamond (001)

    S. Kono, M. Inaba, A. Hiraiwa, H. Kawarada

    10th Intern. Conf. New Diamond Nano Carbonds   (Xi'an China) 

    発表年月: 2016年05月

  • Physical Properties of Superconducting Boron-Doped Diamonds

    T.Kageura, M.Shibata, M.Hideko, Y.Sasama, T.Yamaguchi, Y.Takano, H.Kawarada

    2016 MRS Spring Meeting & Exhibit   (Phoenix, USA) 

    発表年月: 2016年03月

  • Normally-Off C-H Diamond MOSFET with the Breakdown Voltage of Above 2000V

    H.Kawarada, Y.Kitabayashi, M.Shibata, Y.Hayashi, A.Hiraiwa

    2016 MRS Spring Meeting & Exhibit   (Phoenix, USA) 

    発表年月: 2016年03月

  • Physical Properties of Superconducting Boron-Doped Diamonds

    T.Kageura, M.Shibata, M.Hideko, Y.Sasama, T.Yamaguchi, Y.Takano, H.Kawarada

    2016 MRS Spring Meeting & Exhibit   (Phoenix, USA) 

    発表年月: 2016年03月

  • Normally-Off C-H Diamond MOSFET with the Breakdown Voltage of Above 2000V

    H.Kawarada, Y.Kitabayashi, M.Shibata, Y.Hayashi, A.Hiraiwa

    2016 MRS Spring Meeting & Exhibit   (Phoenix, USA) 

    発表年月: 2016年03月

  • Diamond functionalization for Biosensing Application

    E. Suaebah, T. Naramura, M. Hasegawa, H. Kawarada

    2016. The 6th Basic Science International Meeting   (Malang, Indonesia) 

    発表年月: 2016年03月

  • Direct partial CH3 termination into carboxyl terminated diamond surface for biosensor

    E. Suaebah, T. Naramura, H. Kawarada

    2016.The 6th Basic Science International Meeting   (Malang, Indonesia) 

    発表年月: 2016年03月

  • Diamond functionalization for Biosensing Application

    E. Suaebah, T. Naramura, M. Hasegawa, H. Kawarada

    2016. The 6th Basic Science International Meeting   (Malang, Indonesia) 

    発表年月: 2016年03月

  • Direct partial CH3 termination into carboxyl terminated diamond surface for biosensor

    E. Suaebah, T. Naramura, H. Kawarada

    2016.The 6th Basic Science International Meeting   (Malang, Indonesia) 

    発表年月: 2016年03月

  • High Voltage Breakdown 1.8 kV Hydrogenated Black Diamond Field Effect Transistor

    M.Syamsul.N.B.S.B, Y. Kitabayashi, D. Matsumura, T. Saito, H. Kawarada

    2015 MRS Fall Meeting & Exhibit   (Boston, USA) 

    発表年月: 2015年11月

  • Diamond based Biosensor on Direct Carboxyl Termination for Biomolecule Activation

    E. Suaebah, T. Naramura, M. Myodo, M. Hasegawa, H. Kawarada

    2015 MRS Fall Meeting & Exhibit   (Boston, USA) 

    発表年月: 2015年11月

  • Trench-Channel Vertical MOSFET Using C-H Diamond Surface

    T. Saito, M. Kobayashi, Y. Kitabayashi, D. Matsumura, M. Inaba, A. Hiraiwa, H. Kawarada

    2015 MRS Fall Meeting & Exhibit   (Boston, USA) 

    発表年月: 2015年11月

  • High-Temperature Electric-Insulation Characteristics of High-Temperature-ALD-Grown Al2O3 Films

    D. Matsumura, A. Hiraiwa, H. Kawarada

    2015 MRS Fall Meeting & Exhibit   (Boston, USA) 

    発表年月: 2015年11月

  • Structural and Electrical Properties of Double-Domain Heteroepitaxial AlN on (001) Diamond Substrate

    Y. Hayashi, W. Ono, D. Matsumura, A. Hiraiwa, H. Kawarada

    2015 MRS Fall Meeting & Exhibit   (Boston, USA) 

    発表年月: 2015年11月

  • Device Simulation of C-H Diamond MOSFETs based on 2DHG formed by 2D Fixed Negative Charge

    M.Shibata, Y.Kitabayashi, A.Hiraiwa, H. Kawarada

    (Boston, USA) 

    発表年月: 2015年11月

  • C-H Diamond MOSFETs with 1.7 kV Breakdown Voltage and >190mA/mm Current Density

    Y. Kitabayashi, T. Yamada, Dechen Xu, T. Saito, D. Matsumura, A. Hiraiwa, H. Kawarada

    2015 MRS Fall Meeting & Exhibit   (Boston, USA) 

    発表年月: 2015年11月

  • High-Reliability SiO2 Films Formed on Diamond by Thermal Oxidation of Si

    T. Hara, A. Hiraiwa, H. Kawarada

    2015 MRS Fall Meeting & Exhibit   (Boston, USA) 

    発表年月: 2015年11月

  • Metal-Catalyst Free Carbon Nanotube Growth from Templete Carbon Nanotube Forest Formed by SiC Surface Decomposition

    Y. Hirano, M. Inaba, K. Suzuki, W. Fei, W. Norimatsu, M. Kusunoki, H. Kawarada

    2015 MRS Fall Meeting & Exhibit   (Boston, USA) 

    発表年月: 2015年11月

  • New High-Temperature Instability of ALD-Al2O3 MIS Capacitors

    D. Matsumura, A. Hiraiwa, H. Kawarada

    IWDTF (International Workshop on DIELECTRIC THIN FILMS FOR FUTURE ELECTRON DEVICES SCIENCE AND TECHNOLOGY)   (Tokyo, Japan) 

    発表年月: 2015年11月

  • Direct Partial CH3 Termination into Carboxyl

    Evi Suaebah, T. Naramura, H. Kawarada

    IEEE SENSORS 2015   (Busan, South Korea) 

    発表年月: 2015年11月

  • Schottky barrier height lowering at silicon carbide by carbon nanotubes

    M. Inaba, K. Suzuki, Y. Hirano, W. Norimatsu, M. Kusunoki, H. Kawarada

    16th International Conference on Silicon Carbide and Related Materials (ICSCRM2015)   (Giardini Naxos, Italy) 

    発表年月: 2015年10月

  • Characterization of Polycrystalline Doped-diamond Electrolyte-solution-gate Field-effect Transistor pH Sensor with/without termination control

    Y. Shintani, K. Ogawa, H. Kawarada

    The 66th Annual Meeting of the International Society of Electrochemistry   (Taiwan) 

    発表年月: 2015年10月

  • All-solid-State pH Sensor utilizing Termination-controlled Boron-doped Diamond Surface as pH-sensitive/pH-less-sensitive Interface

    Y. Shintani, K. Ogawa, H. Kawarada

    The 66th Annual Meeting of the International Society of Electrochemistry   (Taiwan) 

    発表年月: 2015年10月

  • Trench-channel MOSFET using C-H Diamond Surface

    T. Saito, M. Kobayashi, T. Yamada, D. Xu, Y. Kitabayashi, D. Matsumura, M. Inaba, A. Hiraiwa, H. Kawarada

    2015 International Conference on Solid State Devices and Materials   (Sapporo, Japan) 

    発表年月: 2015年09月

  • Effect of Stacking Faults on Magnetic Flux Pinning in BoronDoped Superconducting Diamond Films

    M. Shibata, T. Kageura, T. Yamaguchi, Y. Takano, H. Kawarada

    2015 International Conference on Solid State Devices and Materials   (Sapporo, Japan) 

    発表年月: 2015年09月

  • 1.7 KV Breakdown C-H Diamond MOSFETs with High Drain Current Density

    Y. Kitabayashi, T. Yamada, D. Xu, T. Saito, D. Matsumura, A. Hiraiwa, H.Kawarada

    2015 International Conference on Solid State Devices and Materials   (Sapporo, Japan) 

    発表年月: 2015年09月

  • High Voltage H-terminated Diamond MOSFETs using 2D Hole Gas with >1600V Breakdown and High Current Density

    H. Kawarada, T. Yamada, D. Xu, H. Tsuboi, Y. Kitabayashi, A. Hiraiwa  [招待有り]

    International Conference on Diamond and Carbon Materials   (Bad Homburg, Germany) 

    発表年月: 2015年09月

  • Physical properties of superconducting diamond for quantum devices

    T.Kageura, M.Shibata, T.Yamaguchi, Y.Takano, H.Kawarada

    Diamond Quantum Sensing Workshop 2015   (Takamatsu, Japan) 

    発表年月: 2015年08月

  • Diamond surface fluorescence for device sensing

    M. Inaba, H. Yamano, K. Kato, T. Kageura, M. Shibata, S. Onoda, T. Teraji, J. Isoya, T. Tanii, H. Kawarada

    Diamond Quantum Sensing Workshop 2015   (Takamatsu, Japan) 

    発表年月: 2015年08月

  • Diamond transistors and superconducting devices for N-V center research

    H. Kawarada

    Diamond Quantum Sensing Workshop 2015   (Takamatsu, Japan) 

    発表年月: 2015年08月

  • Lattice strain analysis of superconducting boron doped diamond

    T. Kageura, M. Shibata, T. Yamaguchi, Y. Takano, H. Kawarada

    The 6th NIMS/MANA-Waseda University International Symposium   (Tokyo, Japan) 

    発表年月: 2015年07月

  • In-plane conductivity of carbon nanotube forest formed on silicon carbide

    M. Inaba, C.-Y. Lee, K. Suzuki, H. Kawarada

    The 6th NIMS/MANA-Waseda University International Symposium   (Tokyo, Japan) 

    発表年月: 2015年07月

  • Carbon nanotubes growth by thermal CVD from the ends of CNT forest on SiC

    Y. Hirano, M. Inaba, M Shibuya, K Suzuki, W Norimatsu, M Kusunoki, H Kawarada

    NT15: The Sixteenth International Conference on the Science and Application of Nanotubes   (Nagoya, Japan) 

    発表年月: 2015年06月

  • Low Schottky barrier height at carbon nanotube and silicon carbide interface for power electronic devices

    M. Inaba, K. Suzuki, M. Shibuya, C.-Y. Lee, Y. Masuda, N. Tomatsu, A.Hiraiwa, M. Kusunoki, H. Kawarada

    NT15: The Sixteenth International Conference on the Science and Application of Nanotubes   (Nagoya, Japan) 

    発表年月: 2015年06月

  • High-reliability Passivation of Diamond Surface Conduction Layer Using High-temperature H2O-oxidant ALD Growth of Al2O3

    A. Hiraiwa, T. Saito, D. Matsumuara, H. Kawarada

    AVS 15th International Conference on Atomic Layer Deposition   (Portland, USA) 

    発表年月: 2015年06月

  • Diamond Power MOSFETs with >1600V Breakdown Voltages and High Current Density

    H. Kawarada  [招待有り]

    2015 International Symposium on Single Crystal Diamond and Electronics (SCDE 2015)   (Xi'an, China) 

    発表年月: 2015年06月

  • Lattice strain dependence of superconducting boron-doped diamond thin film critical thickness

    T. Kageura, M. Shibata, T. Sasagawa, H.Kawarada

    AMDI-6:The 6th International Symposium on Advanced Materials Development and Integration of Novel Structural Metallic and Inorganic Materials   (Tokyo, Japan) 

    発表年月: 2015年06月

  • In plane conductivity of dense carbon nanotube forest Formed on silicon carbide for CNT contact evaluation

    M. Inaba, K. Suzuki, Y. Hirano, W. Norimatsu, M. Kusunoki, H. Kawarada

    AMDI-6:The 6th International Symposium on Advanced Materials Development and Integration of Novel Structural Metallic and Inorganic Materials   (Tokyo, Japan) 

    発表年月: 2015年06月

  • Carbon nanotube synthesis by non-catalytic CVC from dense carbon nanotube forest

    M. Inaba, Y. Hirano, M. Shibata, K. Suzuki, C. Lee, M. Myodo, A. Hiraiwa, W. Norimatsu, M. Kusunoki, H. Kawarada

    9th International Conference on New Diamond and Nano Carbons   (Shizuoka, Japan) 

    発表年月: 2015年05月

  • In-plane conductivity of dense CNT forest formed on Silicon carbide and contact resistivity estimation of parallel adjacent CNT

    M. Inaba, C. Lee, K. Suzuki, Y. Hirano, M. Shibuya, M. Myodo, W. Norimatsu, M. Kusunoki, H. Kawarada

    9th International Conference on New Diamond and Nano Carbons   (Shizuoka, Japan) 

    発表年月: 2015年05月

  • Lattice Strain Analysis of Superconducting Boron-Doped Diamond Film by X-ray Diffraction

    T. Kageura, M. Shibata, T. Yamaguchi, Y.Takano, H.Kawarada

    9th International Conference on New Diamond and Nano Carbons   (Shizuoka, Japan) 

    発表年月: 2015年05月

  • Isotope analysis of diamond-surface passivation effect of Al2O3 formed using a high-temperature H2O-oxidant ALD method

    A. Hiraiwa, T. Saito, D. Matsumuara, H. Kawarada

    9th International Conference on New Diamond and Nano Carbons   (Shizuoka, Japan) 

    発表年月: 2015年05月

  • High power diamond MOSFETs with >1600V breakdown and >100mA/mm current density

    H. Kawarada, T. Yamada, D. Xu, H. Tsuboi, T. Saito, Y. Kitabayashi, A. Hiraiwa

    9th International Conference on New Diamond and Nano Carbons   (Shizuoka, Japan) 

    発表年月: 2015年05月

  • Diamond Surface Functionalization Via Carboxyl Termination for ATP 16 Detection

    E. Suaebah, T. Naramura, M. Myodo, M. Inaba, X. Wang, R. A. Rahim, H. Kawarada

    9th International Conference on New Diamond and Nano Carbons   (Shizuoka, Japan) 

    発表年月: 2015年05月

  • Wide Temperature (10K- 700K) and High Voltage (~1000V) Operation of C-H Diamond MOSFETs for Power Electronics Application

    H. Kawarada, H. Tsuboi, T. Yamada, D. Xu, T. Saito, A. Hiraiwa

    IEDM 2014: IEEE International Electron Devices Meeting   (San Francisco, CA, USA) 

    発表年月: 2014年12月

  • Stability and Formation of Surface Hole Accumulation at C-H Diamond Surface

    H. Kawarada, A. Hiraiwa  [招待有り]

    2014 MRS Fall Meeting & Exhibit   (Boston, USA) 

    発表年月: 2014年11月

  • Fabrication of Diamond Rods for Power Device Application

    M. Kobayashi, M. Inaba, M.Syamsul.N.S.B, A. Hiraiwa, H. Kawarada

    2014 MRS Fall Meeting & Exhibi   (Boston, USA) 

    発表年月: 2014年11月

  • Analysis of Superconducting Boron-Doped Diamond Thin Film Using X-Ray Diffraction

    T. Kageura, M. Shibata, T. Yamaguchi, Y. Takano, H. Kawarada

    2014 MRS Fall Meeting & Exhibit   (Boston, USA) 

    発表年月: 2014年11月

  • Schottky Barrier Height of Carbon Nanotubes to n-Type 4H-SiC for High Power Device Electrodes

    K. Suzuki, M. Inaba, M. Shibuya, C.-Y. Lee, M. Myodo, Y. Hirano, A. Hiraiwa, W. Norimatsu, M. Kusunoki, H. Kawarada

    2014 MRS Fall Meeting & Exhibit   (Boston, USA) 

    発表年月: 2014年11月

  • Nearly 1000V Breakdown Characteristic of C-H Diamond Lateral MOSFETs with Al2O3 Gate Insulator

    T. Yamada, H. Tsuboi, D. Xu, Y. Kitabayashi, T. Saito, D. Matsumura, A. Hiraiwa, H. Kawarada

    2014 MRS Fall Meeting & Exhibit, Boston   (Boston, USA) 

    発表年月: 2014年11月

  • Stable Performance of C-H Bonds Diamond MOSFETs at 10K-673K

    D. Xu, H. Tsuboi, T. Yamada, Y. Kitabayashi, T. Saito, D. Matsumura, A. Hiraiwa, H. Kawarada

    2014 MRS Fall Meeting & Exhibit   (Boston, USA) 

    発表年月: 2014年11月

  • Electric Property of SiO2/Diamond Structure

    Y. Seshimo, T. Hara, Y. Hayashi, T. Hakamata, W. Ono, A.Hiraiwa, H. Kawarada

    2014 MRS Fall Meeting & Exhibit   (Boston, USA) 

    発表年月: 2014年11月

  • Effect of Lattice Strain for Diamond superconductivit

    T. Kageura, M. Shibata, T. Sasagawa, H.Kawarada

    The 5th International Symposium on Advanced Materials Development and Integration of Novel Structured Metallic and Inorganic Materials (AMDI-5)   (Tokyo, Japan) 

    発表年月: 2014年11月

  • Carbon nanotube forest for ohmic and heat dissipative electrode of silicon carbide power devices

    M. Inaba, K. Suzuki, M. Shibuya, C.-Y. Lee, M. Myodo, Y. Hirano, A. Hiraiwa, W. Norimatsu, M. Kusunoki, H. Kawarada

    The 5th International Symposium on Advanced Materials Development and Integration of Novel Structured Metallic and Inorganic Materials (AMDI-5)  

    発表年月: 2014年11月

  • C-H surface diamond FETs for high voltage (>500V) and wide temperature(-263℃-+400℃) operation

    H. Kawarada

    Japan-France Joint Diamond Workshop 2014   (Oita Japan) 

    発表年月: 2014年10月

  • Characterization of Termination-controlled Boron-doped Polycrystalline Diamond Electrolyte-solution-gate Field-effect Transistor pH Sensor

    Y. Shintani, T. Saruya, H. Kawarada

    65th Annual Meeting of the International Society of Electrochemistry   (Lausanne, Swiss) 

    発表年月: 2014年08月

  • Superconductivity of Heavily Boron-doped Diamond (111) by Spherical-resonator-Micro-wave-Plasma CVD

    T. Kageura, M. Koga, T. Yamaguchi, Y. Takano, H. Kawarada

    IUMRS-ICA2014, International Union of Materials Research Societies, International Conference in Asia 2014(The 15th IUMRS-ICA)   (Fukuoka,Japan) 

    発表年月: 2014年08月

  • Fluorine-terminated thin boron-doped diamond Solution Gate FET

    M. Kobayashi, Y. Shintani, M. Myodo, H. Kawarada

    IUMRS-ICA2014, International Union of Materials Research Societies, International Conference in Asia 2014(The 15th IUMRS-ICA)   (Fukuoka,Japan) 

    発表年月: 2014年08月

  • Wide Temperature (10-673 K) Operation of C-H Diamond MOSFETs

    D. Xu, H. Tsuboi, T. Naruo, T. Yamada, A. Daicho, T. Saito, K. Kuruma, A. Hiraiwa, H. Kawarada

    IUMRS-ICA2014, International Union of Materials Research Societies, International Conference in Asia 2014(The 15th IUMRS-ICA )   (Fukuoka,Japan) 

    発表年月: 2014年08月

  • 600 V Breakdown voltage of C-H diamond MOSFETs with thick Al2O3 gate insulator

    T.Yamada, T.Naruo, H.Tsuboi, D.Xu, A.Daicho, T.Saito, K.Kuruma, A.Hiraiwa, H.Kawarada

    IUMRS-ICA2014, International Union of Materials Research Societies, International Conference in Asia 2014(The 15th IUMRS-ICA)   (Fukuoka,Japan) 

    発表年月: 2014年08月

  • Surface structure of (111) diamond with recovered surface conduction after heat

    Y. Seshimo, T. Hakamata, W. Ono, Y. Yokoyama, D. Utsunomiya, A. Hiraiwa, H.Kawarada

    IUMRS-ICA2014, International Union of Materials Research Societies, International Conference in Asia 2014(The 15th IUMRS-ICA )   (Fukuoka,Japan) 

    発表年月: 2014年08月

  • In-plane conductivity of dense carbon nanotube forest formed by silicon carbide surface decomposition method

    M. Inaba, C.-Yu Lee, K. Suzuki, M. Shibuya, M.Myodo, A. Hiraiwa, W. Norimatsu, M. Kusunoki, H.Kawarada

    IUMRS-ICA2014, International Union of Materials Research Societies, International Conference in Asia 2014(The 15th IUMRS-ICA )   (Fukuoka,Japan) 

    発表年月: 2014年08月

  • Evaluation of the contact resistivity and Schottky barrier height at CNT/SiC interface by top contact electrode

    K. Suzuki, M. Inaba, M. Shibuya, C.-Yu Lee, M. Myodo, A. Hiraiwa, W. Norimatsu, M. Kusunoki, H.Kawarada

    IUMRS-ICA2014, International Union of Materials Research Societies, International Conference in Asia 2014(The 15th IUMRS-ICA)   (Fukuoka,Japan) 

    発表年月: 2014年08月

  • Diamond Field Effect Transistors for Power Electronics

    H. Kawarada  [招待有り]

    2014 International Symposium on Single Crystal Diamond Electronics and the Fourth Chinese Vacuum Forum(SCDE 2014)   (Xian, China) 

    発表年月: 2014年06月

  • In-plane Conduction of Dense Carbon Nanotube Forest Formed on Silicon Carbide

    M. Inaba, C.-Y. Lee, K. Suzuki, M. Shibuya, M. Myodo, A. Hiraiwa, W. Norimatsu, M. Kusunoki, H. Kawarada

    NT14: The Fifteenth International Conference on the Science and Application of Nanotubes   (Los Angeles, CA, USA) 

    発表年月: 2014年06月

  • CNT/SiC Interface for Power Device Applications

    M. Inaba, K. Suzuki, M. Shibuya, C.-Y. Lee, M. Myodo, A. Hiraiwa, Y. Masuda, W. Norimatsu, M. Kusunoki, H. Kawarada

    The 5th NIMS/MANA-Waseda University International Symposium   (Tsukuba, Japan) 

    発表年月: 2014年03月

  • ダイヤモンド表面固定アプタマーによるトランジスタ型バイオセンサ

    川原田 洋  [招待有り]

    第61回応用物理学会春季学術講演会   (相模原、神奈川) 

    発表年月: 2014年03月

  • Thermal Stability of Diamond Surface C-H Bonds

    T. Hakamata, Y. Seshimo, W. Ono, Y. Yokoyama, D. Utsunomiya, A. Hiraiwa, H. Kawarada

    2013 MRS(Materials Research Society) Fall Meeting & Exhibit   (Boston, MA, USA) 

    発表年月: 2013年12月

  • AlN Heteroepitaxial Growth on Diamond (111) 2x1 Reconstructed Surface by Molecular Beam Epitaxy (MBE)

    T. Hakamata, W. Ono, Y. Yokoyama, D. Utsunomiya, Y. Seshimo, A. Hiraiwa, H. Kawarada

    2013 MRS(Materials Research Society) Fall Meeting & Exhibit   (Boston, MA, USA) 

    発表年月: 2013年12月

  • Revolutionarily enhanced dielectric strength of an ALD-Al2O3 film annealed at a high temperature

    T. Saito, K. Kuruma, A. Daicho, A. Hiraiwa, H. Kawarada

    2013 MRS(Materials Research Society) Fall Meeting & Exhibit   (Boston, MA, USA) 

    発表年月: 2013年12月

  • The optimization of P-type transparent electrode using boron-doped nanodiamond

    M. Koga, T. Kageura, K. Ishak, Y. Shintani, M. Hasegawa, A. Hiraiwa, H. Kawarada

    2013 MRS(Materials Research Society) Fall Meeting & Exhibit   (Boston, MA, USA) 

    発表年月: 2013年12月

  • Electrolyte surrounding-gate FET by mm-long and dense carbon nanotube forest sheet

    M. Myodo, M. Inaba, M. Kobayashi, Y. Shintani, A. Hiraiwa, H. Kawarada

    2013 MRS(Materials Research Society) Fall Meeting & Exhibit   (Boston, MA, USA) 

    発表年月: 2013年12月

  • Anomalous Electric Conduction at Al-first AlN/Diamond Interface Formed by Molecular Beam Epitaxy

    W. Ono, Y. Yokoyama, D. Utsunomiya, T. Hakamata, A. Hiraiwa, H.Kawarada

    2013 MRS(Materials Research Society) Fall Meeting & Exhibit   (Boston, MA, USA) 

    発表年月: 2013年12月

  • The dependence of contact resistivity at CNT/SiC interface on SiC doping concentration: CNT new application for SiC power devices

    M. Shibuya, M. Inaba, K. Suzuki, Y. Masuda, A. Hiraiwa, M. Kusunoki, H. Kawarada

    2013 MRS(Materials Research Society) Fall Meeting & Exhibit   (Boston, MA, USA) 

    発表年月: 2013年12月

  • 400°C operation and high breakdown characteristic of hydrogen-terminated diamond MOSFETs with Al2O3 passivation

    H.Tsuboi, T.Naruo, A.Daicho, T.Saito, D.Xu, T.Yamada, K.Kuruma, A.Hiraiwa, H.Kawarada

    2013 MRS(Materials Research Society) Fall Meeting & Exhibit   (Boston, MA, USA) 

    発表年月: 2013年12月

  • Lateral Conductivity of CNT Film on High Resistance Sic Substrate

    C.Y. Lee, M. Inaba, K Suzuki, M. Shibuya, A. Hiraiwa, M. Kusunoki, H. Kawarada

    2013 MRS(Materials Research Society) Fall Meeting & Exhibit   (Boston, MA, USA) 

    発表年月: 2013年12月

  • The I-V characteristics of a termination-controlled polycrystalline diamond field effect transistor pH sensor for using at harsh environment

    Y. Shintani, M. Myodo, M. Kobayashi, S. Ibori, H. Kawarada

    ECS 224th meeting   (San Francisco, USA) 

    発表年月: 2013年10月

  • H-terminated Diamond Field Effect Transistors Operated at 400C

    Hiroshi Kawarada  [招待有り]

    2013 JSAP(Japan Society of Applied Physics )-MRS(Materials Research Society) Joint Symposia   (Kyoto, Japan) 

    発表年月: 2013年09月

  • Evaluation of conduction at CNT/SiC interface of vertically aligned and high density CNT on SiC

    M. Shibuya, M. Inaba, K. Suzuki, Y. Masuda, A. Hiraiwa, M. Kusunoki, H. Kawarada

    2013 JSAP(Japan Society of Applied Physics )-MRS(Materials Research Society) Joint Symposia   (Kyoto, Japan) 

    発表年月: 2013年09月

  • Fabrication of P-type transparent conducting films using by heavily boron-doped nano crystalline diamond

    M. Koga, T. Kageura, Khairul. Ishak, Y. Shintani, M . Hasegawa, A.Hiraiwa, H. Kawarada

    2013 JSAP(Japan Society of Applied Physics )-MRS(Materials Research Society) Joint Symposia   (Kyoto, Japan) 

    発表年月: 2013年09月

  • High-electrical-insulation ALD-Al2O3 for creation and passivation of two-dimensional hole gas on H-terminated diamond surface

    T. Saito, A. Daicho, A. Hiraiwa, H. Kawarada

    2013 JSAP(Japan Society of Applied Physics )-MRS(Materials Research Society) Joint Symposia   (Kyoto, Japan) 

    発表年月: 2013年09月

  • Electrolyte solutiongate FET by mm-long carbon nanotube forest sheet

    M. Myodo, K. Oohara, M. Inaba, M. Kobayashi, Y. Shintani, A. Hiraiwa, H. Kawarada

    2013 JSAP(Japan Society of Applied Physics )-MRS(Materials Research Society) Joint Symposia   (Kyoto, Japan) 

    発表年月: 2013年09月

  • Electric Property of Al-first AlN/Diamond Interface Formed by Molecular Beam Epitaxy

    W. Ono, Y. Yokoyama, R. Kanomota, D. Utsunomiya, T. Hakamata, A. Hiraiwa, H. Kawarada

    2013 JSAP(Japan Society of Applied Physics )-MRS(Materials Research Society) Joint Symposia   (Kyoto, Japan) 

    発表年月: 2013年09月

  • AlN heteroepitaxial growth on diamond (111) 2x1 reconstructed surface by molecular beam epitaxy (MBE)

    T. Hakamata, Y. Yokoyama, W. Ono, D. Utsunomiya, A. Hiraiwa, H. Kawarada

    2013 JSAP(Japan Society of Applied Physics )-MRS(Materials Research Society) Joint Symposia   (Kyoto, Japan) 

    発表年月: 2013年09月

  • High-voltage environment-resistive gate insulator for diamond field-effect transistors with two-dimensional hole gas

    A. Hiraiwa, T. Saito, A. Daicho, H. Tsuboi, T. Naruo, Y. Nozaki, H. Kawarada

    International Conference on Diamond and Carbon Materials   (Riva del Garda, Italy) 

    発表年月: 2013年09月

  • Surface conduction after molecular beam epitaxy of AlN on a 2x1 4clean (111) diamond surface

    A. Hiraiwa, W. Ono, T. Hakamata, Y. Yokoyama, D. Utsunomiya, H. Kawarada

    International Conference on Diamond and Carbon Materials   (Riva del Garda, Ital) 

    発表年月: 2013年09月

  • 400°C operation of hydrogen-terminated diamond MOSFETs with high temperature ALD Al2O3 for gate insulator and passivation

    H.Tsuboi, T.Naruo, A.Daicho, T.Saito, A.Hiraiwa, H.Kawarada

    International Conference on Diamond and Carbon Materials   (Riva del Garda, Italy) 

    発表年月: 2013年09月

  • Evaluation of CNT forest/metal contact resistivity for LSI metallization application

    M. Inaba, M. Shibuya, Y. Masuda, A. Hiraiwa, M. Kusunoki, H.Kawarada

    International Conference on Diamond and Carbon Materials   (Riva del Garda, Italy) 

    発表年月: 2013年09月

  • Diamond Solution-Gate Transistors for Protein Detection by DNA/RNA Aptamers

    H. Kawarada  [招待有り]

    The 6th International Conference on Sensors (AsiaSense 2013)   (Melaka, Malaysia) 

    発表年月: 2013年08月

  • C-H bonded diamond MOS Field Effect Transistor for High Temperature and High Power Application

    H. Kawarada  [招待有り]

    1st French-Japanese Workshop on Diamond power devices   (Chamonix, France) 

    発表年月: 2013年06月

  • High-reliability ALD-Al2O3 gate insulator for diamond 2DHG-FETs

    A. Hiraiwa

    1st French-Japanese Workshop on Diamond power devices   (Chamonix, France) 

    発表年月: 2013年06月

  • Estimation of conduction at CNT/SiC interface of vertically aligned and high density CNT on SiC

    M. Inaba, M. Shibuya, Y. Masuda, A. Hiraiwa, M. Kusunoki, H. Kawarada

    NT13: The Fourteenth International Conference on the Science and Application of Nanotubes   (Espoo, Finland) 

    発表年月: 2013年06月

  • Study of differential FET sensing utilizing termination-controlled diamond surfaces as pH-sensitive/pH-insensitive interfaces

    Y. Shintani, M. Myodo, S. Ibori, H. Kawarada

    New Diamond and Nanocarbon conference (NDNC2013)   (Singapore) 

    発表年月: 2013年05月

  • CNT contact resistivity evaluation from nano size LSI via to power SiC device using conductive AFM

    2012 IUMRS-International Conference on Electronic Materials  

    発表年月: 2012年09月

  • Atomic layer deposition of Al2O3 for passivating hydrogen-terminated diamond

    A. Daicho, T. Saito, S. Sato, T. Kobayashi, R. Nomura, A. Hiraiwa, H.Kawarada

    2012 IUMRS-International Conference on Electronic Materials  

    発表年月: 2012年09月

  • Evaluation for properties of superconducting diamond (111) thin film with Tc(offset) above 10K and its anisotropic effect due to the uniaxial strain

    2012 Materials &amp; Mechanisms of Superconductivity Conference  

    発表年月: 2012年07月

  • Electrical characteristic evaluation of SNS junction by heavlily and lightly Boron-doped diamonds

    2012 Materials &amp; Mechanisms of Superconductivity Conference  

    発表年月: 2012年07月

  • The Effects of Diamond FET-based RNA aptamer sensing for Real Sample HIV-1 Tat Protein detection

    Biosensors 2012  

    発表年月: 2012年05月

  • Heavily Boron-doped DianlOnd and Its Application to Electron Device in Harsh Environment

    NDNC2012  

    発表年月: 2012年05月

  • Formation of highly B-doped Source &amp; Drain layer with TiC ohmic contact for H-terminated diamond MOSFETs

    2009 International Conference on Solid State Devices and Materials  

    発表年月: 2009年10月

  • Formation of highly B-doped Source & Drain layer with TiC ohmic contact for H-terminated diamond MOSFETs

    2009 International Conference on Solid State Devices and Materials  

    発表年月: 2009年10月

  • High hole current density in diamond MOSFETs fabricated on H-terminated IIa-type (111) diamond substrate

    2009 International Conference on Solid State Devices and Materials  

    発表年月: 2009年10月

  • Electric characterization of carbon nanotubes grown at low temperature by remote plasma chemical vapor deposition for LSI interconnects

    2009 International Conference on Solid State Devices and Materials  

    発表年月: 2009年10月

  • ソース・ドレインにボロンドープ層を選択成長させた(111)水素終端ダイヤモンドMOSFETsの電気特性評価

    2009年秋季第70回応用物理学会学術講演会  

    発表年月: 2009年09月

  • 水素終端Ⅱa(111)基板に作成したダイヤモンドMOSFETの高周波特性

    2009年秋季第70回応用物理学会学術講演会  

    発表年月: 2009年09月

  • 高密度カーボンナノチューブの合成と電気二重層キャパシタ電極への応用

    秋季第70回応用物理学会学術講演会  

    発表年月: 2009年09月

  • ダイヤモンド表面におけるアプタマーを介した血小板由来成長因子(PDGF)検出

    2009年秋季第70回応用物理学関係連合講演会  

    発表年月: 2009年09月

  • カルボキシル基修飾したダイヤモンド表面におけるSNPs検出

    2009年秋季第70回応用物理学会学術講演会  

    発表年月: 2009年09月

  • 高濃度ボロンドープダイヤモンド単結晶薄膜の結晶構造とTcの膜厚依存性

    日本物理学会2009年秋季大会  

    発表年月: 2009年09月

  • Cross-Sectional TEM Study and Film Thickness Dependence of Tc in Heavily Boron-Doped Superconducting Diamond

    9th International Conference on Materials and Mechanisms of Superconductivity  

    発表年月: 2009年09月

  • Critical concentrations of superconductor to insulator transition in (111), (001) and (110) CVD boron-doped diamond

    9th International Conference on Materials and Mechanisms of Superconductivity  

    発表年月: 2009年09月

  • Stacked SNS Josephson Junction with heavily B-doped CVD Diamond Superconducting thin film

    9th International Conference on Material and Mechanisms of Superconductivity  

    発表年月: 2009年09月

  • 高濃度ボロンドープダイヤモンド超伝導:TCと結晶性の深さ方向分布との相関

    2009年春季日本物理学会第64回年次大会  

    発表年月: 2009年03月

  • 先端放電型リモートプラズマ低温 CVD 成長によるサブミクロンサイズ CNT ビアの電気特性評価

    2009年春季日本物理学会第64回年次大会  

    発表年月: 2009年03月

  • 表面修飾による水素終端ダイヤモンド表面のイオン感応性制御

    2009年春季日本物理学会第64回年次大会  

    発表年月: 2009年03月

  • ダイヤモンド表面のカルボキシル基修飾による生体分子検出

    2009年春季日本物理学会第64回年次大会  

    発表年月: 2009年03月

  • 水素終端IIa(111)基板に作製したダイヤモンドMOSFETの特性評価

    2009年春季第56回応用物理学会学術講演会  

    発表年月: 2009年03月

  • ボロンドープ層を利用したボトムコンタクト型水素終端ダイヤモンドMOSFETs

    2009年春季第56回応用物理学会学術講演会  

    発表年月: 2009年03月

  • モリブデン/ダイヤモンド界面のモリブデンカーバイド薄層の超伝導特

    2009年春季第56回応用物理学会学術講演会  

    発表年月: 2009年03月

  • 高濃度ボロンドープダイヤモンド超伝導薄膜のTcの膜厚依存性と断面TEM観察

    2009年春季第56回応用物理学会学術講演会  

    発表年月: 2009年03月

  • フッ素終端化ダイヤモンドDNAセンサの表面解析

    2009年春季第56回応用物理学会学術講演会  

    発表年月: 2009年03月

  • Controlled growth of single and double walled carbon nanotubes for densely packed electrodes and super capacitors

    4th Vacuum and Surface Science conference of Asia and Australia  

    発表年月: 2008年10月

  • 高濃度ボロンドープダイヤモンド超伝導薄膜の選択エピタキシャル成長による微細構造作製

    第22回ダイヤモンドシンポジウム  

    発表年月: 2008年10月

  • 先端放電型リモートプラズマCVDによる多層CNT低温成長

    第22回ダイヤモンドシンポジウム  

    発表年月: 2008年10月

  • 高濃度ボロンドープダイヤモンド薄膜における超伝導絶縁体転移の臨界濃度と面方位依存性

    第22回ダイヤモンドシンポジウム  

    発表年月: 2008年10月

  • ダイヤモンド表面の負電荷制御によるRNA/DNA二本鎖の1塩基変異検出

    第22回ダイヤモンドシンポジウム  

    発表年月: 2008年10月

  • フッ素終端化ダイヤモンド表面を用いた1塩基変異DNA検出

    第22回ダイヤモンドシンポジウム  

    発表年月: 2008年10月

  • 水素終端(001),(110),(111)ダイヤモンド表面におけるホール蓄積層の伝導性評価

    第22回ダイヤモンドシンポジウム  

    発表年月: 2008年10月

  • 水素ラジカル照射による酸素終端ダイヤモンドFETsの伝導性発現

    第22回ダイヤモンドシンポジウム  

    発表年月: 2008年10月

  • ダイヤモンド表面修飾のDNAセンシングへの影響評価

    第22回ダイヤモンドシンポジウム  

    発表年月: 2008年10月

  • グラファイトアンテナを用いた先端放電型リモートプラズマCVD法による垂直配向カーボンナノチューブの合成

    第22回ダイヤモンドシンポジウム  

    発表年月: 2008年10月

  • Detection of hybridization affinity between RNA/DNA duplex on functionalized diamond surface

    The 19th European Conference on Diamond, Diamond-Like Materials, Carbon Nanotubes, and Nitrides  

    発表年月: 2008年09月

  • Superconductivity in (111), (001) and (110) boron-doped CVD diamond films

    The 19th European Conference on Diamond, Diamond-Like Materials, Carbon Nanotubes, and Nitrides  

    発表年月: 2008年09月

  • Surface orientation dependence of hole accumulation layer on H-terminated diamond

    The 19th European Conference on Diamond, Diamond-Like Materials, Carbon Nanotubes, and Nitrides  

    発表年月: 2008年09月

  • Electrical characterization of carbon nanotubes formed at low temperatures for LSI interconnects

    The 19th European Conference on Diamond, Diamond-Like Materials, Carbon Nanotubes, and Nitrides  

    発表年月: 2008年09月

  • Selective homoepitaxial growth of heavily boron-doped thin film diamond for FET application

    The 19th European Conference on Diamond, Diamond-Like Materials, Carbon Nanotubes, and Nitrides  

    発表年月: 2008年09月

  • Growth of well-aligned highly dense CNTs by highly dense catalyst particles

    The 19th European Conference on Diamond, Diamond-Like Materials, Carbon Nanotubes, and Nitrides  

    発表年月: 2008年09月

  • 高濃度ボロンドープダイヤモンド薄膜の選択エピタキシャル成長

    秋季第69回応用物理学会学術講演会  

    発表年月: 2008年09月

  • DNAセンシングに適したダイヤモンド表面のイオン感応性評価

    2008年秋季第69回応用物理学会学術講演会  

    発表年月: 2008年09月

  • サブミクロンサイズビアからの多層CNT低温成長

    2008年秋季第69回応用物理学会学術講演会  

    発表年月: 2008年09月

  • 高濃度ボロンドープダイヤモンド薄膜における超伝導絶縁体転移の臨界濃度の評価

    2008年秋季第69回応用物理学会学術講演会  

    発表年月: 2008年09月

  • フッ素終端化ダイヤモンド表面のDNA Hybridizationへの影響

    2008年秋季第69回応用物理学会学術講演会  

    発表年月: 2008年09月

  • 水素終端(110)面を利用したダイヤモンドp-MOSFETの特性評価

    2008年秋季第69回応用物理学会学術講演会  

    発表年月: 2008年09月

  • ダイヤモンド表面のCOO−制御によるRNA probeを用いた生体分子検出

    2008年秋季第69回応用物理学会学術講演会  

    発表年月: 2008年09月

  • 接触抵抗低減による極低温でのダイヤモンドFETの特性改善

    2008年秋季第69回応用物理学会学術講演会  

    発表年月: 2008年09月

  • ボロンドープダイヤモンド超薄膜の超伝導特性評価

    日本物理学会2008年秋季大会  

    発表年月: 2008年09月

  • (111),(001),(110)高濃度ボロンドープダイヤモンド薄膜の超伝導絶縁体転移の臨界濃度

    日本物理学会2008年秋季大会  

    発表年月: 2008年09月

  • キャリアガスによるカーボンナノチューブの層数制御

    第35回フラーレン・ナノチューブ総合シンポジウム  

    発表年月: 2008年08月

  • Lattice expansion and superconductivity in heavily boron-doped diamond thin film

    IWSDRM2008(International Workshop on Superconductivity in Diamond and Related Materials)  

    発表年月: 2008年07月

  • The relationship between Hall coefficient factor and superconductivity of heavily boron doped diamond(Invited)

    IWSDRM2008(International Workshop on Superconductivity in Diamond and Related Materials)  

    発表年月: 2008年07月

  • Mechanism Analysis of Interrupted Growth of Single-Walled Carbon Nanotube Arrays

    9th International Conference on the Science and Application of Nanotubes  

    発表年月: 2008年07月

  • Low temperature growth of carbon nanotubes by remote plasma CVD for future ULSI interconnects

    9th International Conference on the Science and Application of Nanotubes  

    発表年月: 2008年07月

  • Low temperature grown carbon nanotube interconnects for LSI application

    2nd International Conference on New Diamond and Nano Carbons  

    発表年月: 2008年05月

  • On the Mechanism of DNA and RNA Precise Sensing using Diamond Devices(Invited)

    2nd conference on New Diamond &amp; Nano Carbons  

    発表年月: 2008年05月

  • 配線応用のための垂直配向カーボンナノチューブの合成温度の低温化

    2008年春季第55回応用物理学会学術講演会  

    発表年月: 2008年05月

  • Low temperature growth and LSI application of carbon nanotubes (Invited)

    The 4th International Nanotechnology Conference on Communications and Cooperation, Nanotech in Japan  

    発表年月: 2008年04月

  • Detection of Single-mismatched Oligonucleotides on Partially Functionalized Diamond

    2008 MRS Spring Meeting  

    発表年月: 2008年03月

  • 高濃度ボロンドープダイヤモンド超伝導体における結晶格子の伸張

    2008年春季日本物理学会第63回年次大会  

    発表年月: 2008年03月

  • 化学機械研磨により内層を利用した低温成長CNTビアの抵抗値の低減

    第33回フラーレン・ナノチューブ総合シンポジウム  

    発表年月: 2008年03月

  • Growth of super-long straight CNTs by highly dense catalyst particles

    第33回フラーレン・ナノチューブ総合シンポジウム  

    発表年月: 2008年03月

  • 高濃度ボロンドープCVDダイヤモンドの結晶格子伸張

    2008年春季第55回応用物理学関係連合講演会  

    発表年月: 2008年03月

  • ダイヤモンド表面上における1塩基ミスマッチを持ったRNAの検出

    2008年春季第55回応用物理学会学術講演会  

    発表年月: 2008年03月

  • 高密度触媒微粒子によって成長した垂直長尺カーボンナノチューブ

    2008年春季第55回応用物理学会学術講演会  

    発表年月: 2008年03月

  • ボロンドープダイヤモンドの薄膜成長とその電気特性評価

    2008年春季第55回応用物理学会学術講演会  

    発表年月: 2008年03月

  • High-Performance p-channel Diamond MOSFETs with Alumina Gate Insulator

    2007 IEEE International Electron Devices Meeting  

    発表年月: 2007年12月

  • ダイヤモンド表面を用いた1塩基ミスマッチの検出

    第30会日本分子生物学会年会第80回日本生化学会大会合同大会  

    発表年月: 2007年12月

  • 高濃度ボロンドープCVDダイヤモンド超伝導体における結晶格子の伸張

    2007年応用物理学会結晶工学分科会年末講演会  

    発表年月: 2007年12月

  • Cutting of Layered Single-Walled Carbon Nanotubes: Investigation of Interface Structure and Fabrication of Short Single-walled Carbon Nanotube Arrays

    2007 MRS Fall Meeting  

    発表年月: 2007年11月

  • Conductivity Characteristic and BCS pairing in Superconductive Diamond Films

    2007 MRS Fall Meeting  

    発表年月: 2007年11月

  • Growth of Half-Centimeter Long Single- and Double-Walled Carbon Nanotubes by Radical CVD

    Fifth International Symposium on Control of Semiconductor Interfaces  

    発表年月: 2007年11月

  • Bias Dependence of RF Performance and Small-signal Equivalent Circuit in Diamond MISFETs

    Fifth International Symposium on Control of Semiconductor Interfaces  

    発表年月: 2007年11月

  • Surface, Interface and Doping Science of Diamond and FET Applications

    Fifth International Symposium on Control of Semiconductor Interfaces  

    発表年月: 2007年11月

  • ボロンドープ超薄膜の超伝導特性評価

    第21回ダイヤモンドシンポジウム  

    発表年月: 2007年11月

  • 表面修飾されたダイヤモンド表面上におけるRNAの検出

    第21回ダイヤモンドシンポジウム  

    発表年月: 2007年11月

  • 長寿命触媒微粒子による長尺カーボンナノチューブ成長

    第21回ダイヤモンドシンポジウム  

    発表年月: 2007年11月

  • 配線応用に向けた低温成長CNTビアの電気特性評価

    第21回ダイヤモンドシンポジウム  

    発表年月: 2007年11月

  • 超伝導転移を示す高濃度ボロンドープCVDダイヤモンドの異方的な結晶格子伸張

    第21回ダイヤモンドシンポジウム  

    発表年月: 2007年11月

  • LNAを用いたSGFETによるDNA検出

    第21回ダイヤモンドシンポジウム  

    発表年月: 2007年11月

  • 集束イオンビームにより打ち込まれたNi触媒からのCNT成長

    第21回ダイヤモンドシンポジウム  

    発表年月: 2007年11月

  • 高濃度Bドープダイヤモンドの選択エピタキシャル成長とその電気特性評価

    第21回ダイヤモンドシンポジウム,  

    発表年月: 2007年11月

  • Diamond MISFETs Fabricated on Polycrystalline CVD Diamond

    The 34th International Symposium on Compound Semiconductors  

    発表年月: 2007年10月

  • DC and RF Performance of Diamond MISFETs with Alumina Gate Insulator

    International Conference on Silicon Carbide and Related Materials  

    発表年月: 2007年10月

  • Diamond for high frequency devices, DNA sensors and superconductor

    早稲田大学創立125周年シンポジウム・早稲田大学理工学部創設100周年記念シンポジウム  

    発表年月: 2007年10月

  • The effect of Al layer on Fe catalyst for Carbon Nanotube Synthesis

    18th European Conference on Diamond, Diamond-Like Materials, Carbon Nanotubes, and Nitrides  

    発表年月: 2007年09月

  • Expansion of crystalline lattice in heavily B-doped CVD diamond superconductivity

    18th European Conference on Diamond, Diamond-Like Materials, Carbon Nanotubes, and Nitrides  

    発表年月: 2007年09月

  • Electrical properties of vertically-aligned carbon nanotubes grown in via-holes at low temperatures for future interconnects

    18th European Conference on Diamond, Diamond-Like Materials, Carbon Nanotubes, and Nitrides  

    発表年月: 2007年09月

  • Evaluation of channel mobility for diamond MISFETs from gate-to-channel capacitance measurement

    18th European Conference on Diamond, Diamond-Like Materials, Carbon Nanotubes, and Nitrides  

    発表年月: 2007年09月

  • Detection of mismatched DNA on functionalized diamond surface by controlling surface charge

    18th European Conference on Diamond, Diamond-Like Materials, Carbon Nanotubes, and Nitrides  

    発表年月: 2007年09月

  • Fabrication of H-terminated diamond MISFETs utilizing TiC ohmic layer

    18th European Conference on Diamond, Diamond-Like Materials, Carbon Nanotubes, and Nitrides  

    発表年月: 2007年09月

  • Effect of Interface on the Superconductivity of Boron Doped Diamond Thin film

    18th European Conference on Diamond, Diamond-Like Materials, Carbon Nanotubes, and Nitrides  

    発表年月: 2007年09月

  • Vertically aligned carbon nanotubes from Ni catalysts implanted by focused-ion-beam

    18th European Conference on Diamond, Diamond-Like Materials, Carbon Nanotubes, and Nitrides  

    発表年月: 2007年09月

  • Electrical properties of carbon nanotubes grown at a low temperature by radical chemical vapor deposition for future LSI interconnects

    2007 International Conference on Solid State Devices and Materials  

    発表年月: 2007年09月

  • 集束イオンビームによる打ち込みNi触媒からのCNT成長(Ⅱ)

    2007年秋季第68回応用物理学会学術講演会  

    発表年月: 2007年09月

  • 表面修飾されたダイヤモンド表面上におけるRNAの検出

    2007年秋季第68回応用物理学会学術講演会  

    発表年月: 2007年09月

  • 化学機械研磨により平坦化したCNTビアの電気特性評価

    2007年秋季第68回応用物理学会学術講演会  

    発表年月: 2007年09月

  • ダイヤモンドFETソース・ドレイン領域のための高濃度B-doped 選択エピタキシャル成長とその電気特性評価

    2007年秋季第68回応用物理学会学術講演会  

    発表年月: 2007年09月

  • ダイヤモンドの表面電荷の調節による1塩基多型DNAの検出

    2007年秋季第68回応用物理学会学術講演会  

    発表年月: 2007年09月

  • (100)、(111)高濃度ボロンドープCVDダイヤモンドにおける異方的な結晶格子伸張

    2007年秋季第68回応用物理学会学術講演会  

    発表年月: 2007年09月

  • Transistor Type DNA Sensor for SNPs Detection Using Diamond Surface

    Nanoscience and Nanotechnology for Biological/Biomedical/Chemical Sensing  

    発表年月: 2007年06月

  • Detection of single-mismatch oligonucleotides on functionalized diamond surface by optical and electrochemical methods

    5th Joint Meeting on Medical Chemistry  

    発表年月: 2007年06月

  • DC and RF characterization of 0.1&#181;m gate length Diamond MISFETs fabricated on polycrystalline diamond

    New Diamond and Nano Carbons 2007  

    発表年月: 2007年05月

  • Diamond MISFETs fabricated on high quality polycrystalline CVD diamond(K. Hirama, H. Takayanagi, S. Yamauchi, Y. Jingu, H. Umezawa, H. Kawarada)

    International Symposium on Power Semiconductor Devices &amp; ICs(19th)  

    発表年月: 2007年05月

  • Diamond MISFETs fabricated on high quality polycrystalline CVD diamond

    19th International Symposium on Power Semiconductor Devices &amp; ICs  

    発表年月: 2007年05月

  • Synthesis of Carbon Nanotubes from Focused Ion Beam Implanted Ni Catalysts

    1st International Conference on New Diamond and Nano Carbons  

    発表年月: 2007年05月

  • Low plasma damage hydrogen-termination process by antenna-edge-plasma

    New Diamond and Nano Carbons 2007  

    発表年月: 2007年05月

  • DC and RF characterization of 0.1µm gate length Diamond MISFETs fabricated on polycrystalline diamond

    New Diamond and Nano Carbons 2007  

    発表年月: 2007年05月

  • A new type DNA immobilization using modified diamond surface and its application for SNPs detection

    NDNC 2007  

    発表年月: 2007年05月

  • Low Temperature Radical Chemical Vapor Deposition of Vertically Aligned CNTs using Size-classified Co Particles for LSI Multi-layer Interconnects

    1st International Conference on New Diamond and Nano Carbons  

    発表年月: 2007年04月

  • CO&lt;SUB&gt;2&lt;/SUB&gt;を用いた先端放電型ラジカルCVDによるカーボンナノチューブ合成(Ⅱ)(真木 翼, 岩崎 孝之, 吉田 剛, 相川 拓海, 野末 竜弘, 近藤 大雄, 川端 章夫, 佐藤 信太郎, 二瓶 端久, 粟野 祐二, 川原田 洋)

    応用物理学会学術講演会(春季第54回)  

    発表年月: 2007年03月

  • 低抵抗多結晶ダイヤモンド基板上に作製したダイヤモンドMISFETの特性評価(平間 一行, 高柳 英典, 山内 真太郎, 神宮 宜克, 梅沢 仁, 川原田 洋)

    応用物理学会学術講演会(春季第54回)  

    発表年月: 2007年03月

  • フッ素系高分子膜による水素終端ダイヤモンドの伝導性の上昇(福本 亘, 田中 雅也, 與原 圭一朗, 山内 真太郎,平間 一行, 川原田 洋)

    応用物理学会学術講演会(春季第54回)  

    発表年月: 2007年03月

  • 超伝導転移を示す高濃度ボロンドープCVDダイヤモンドにおける結晶格子の伸張(入山 慎吾, 竹之内 智大, 石綿 整, 岡田 竜介, 立木 実, 高野 義彦, 石井 明, 石井 聡, 川原田 洋)

    応用物理学会学術講演会(春季第54回)  

    発表年月: 2007年03月

  • Ti/Pt/Au ohmic電極形成と水素ラジカル照射法を利用した水素終端ダイヤモンドMISFETの作製・評価(神宮 宜克, 小柴 亨, 平間 一行, 岩崎 孝之, 梅沢 仁, 川原田 洋)

    応用物理学会学術講演会(春季第54回)  

    発表年月: 2007年03月

  • CO2を用いた先端放電型ラジカルCVDによるカーボンナノチューブ合成(Ⅱ)(真木 翼, 岩崎 孝之, 吉田 剛, 相川 拓海, 野末 竜弘, 近藤 大雄, 川端 章夫, 佐藤 信太郎, 二瓶 端久, 粟野 祐二, 川原田 洋)

    応用物理学会学術講演会(春季第54回)  

    発表年月: 2007年03月

  • ダイヤモンドの表面電荷の調節によるDNA 塩基ミスマッチの検出(久我 翔馬, 梁 正勲, 高橋 宏徳, 宋 光燮, 川原田 洋)

    応用物理学会学術講演会(春季第54回)  

    発表年月: 2007年03月

  • 集束イオンビームによる打ち込みNi触媒からのCNT成長(岩崎 孝之, 小出 敬, 森金 亮太, 目島 壮一, 中山 英樹, 品田 賢宏, 大泊 巌, 川原田 洋)

    応用物理学会学術講演会(春季第54回)  

    発表年月: 2007年03月

  • ボロンドープダイヤモンド超伝導への表面終端及び界面の影響(岡田 竜介, 石綿 整, 竹之内 智大, 入山 慎吾, 立木 実, 高野 義彦, 石井 聡, 奥津 貴史, 上田 真也, 川原田 洋)

    応用物理学会学術講演会(春季第54回)  

    発表年月: 2007年03月

  • 配線応用へ向けたビア構造からのカーボンナノチューブの低温ラジカルCVD 成長(横山 大輔, 岩崎 孝之, 吉田 剛, 佐藤 信太郎, 二瓶 瑞久, 粟野 祐二, 川原田 洋)

    応用物理学会学術講演会(春季第54回)  

    発表年月: 2007年03月

  • 長尺カーボンナノチューブ合成のための先端放電型ラジカルCVD条件最適化とCO2の効果(岩崎 孝之, 真木 翼, 吉田 剛, 相川 拓海, 野末 竜弘, 近藤 大雄, 川端 章夫, 佐藤 信太郎, 二瓶 瑞久, 粟野 祐二, 川原田 洋)

    フラーレン・ナノチューブ総合シンポジウム(第32回)  

    発表年月: 2007年02月

  • Co触媒微粒子を用いた先端放電型ラジカルCVDによるCNT低温合成-LSI配線応用に向けて(横山 大輔, 岩崎 孝之, 吉田 剛, 佐藤 信太郎, 二瓶 瑞久, 粟野 祐二, 川原田 洋)

    フラーレン・ナノチューブ総合シンポジウム(第32回)  

    発表年月: 2007年02月

  • 負電荷保持薄膜のパッシベーションによるダイヤモンドFET特性の改善(福本 亘, 田中 雅也, 平間 一行, 山内 真太郎, 川原田 洋)

    ダイヤモンドシンポジウム(第20回)  

    発表年月: 2006年11月

  • 高濃度ボロンドープCVDダイヤモンド超伝導体における合成条件とTcの関係(入山 慎吾, 竹之内 智大, 石綿 整, 岡田 竜介, 立木 実, 高野 義彦, 石井 聡, 石坂 香子,馬場 輝久, 川原田 洋)

    ダイヤモンドシンポジウム(第20回)  

    発表年月: 2006年11月

  • Ti/Pt/Auオーミック電極を用いた水素終端ダイヤモンドMISFETの作製と評価(神宮 宜克, 小柴 亨, 高柳 英典, 山内 真太郎, 興原 圭一郎, 平間 一行, 岩崎 孝之, 川原田 洋)

    ダイヤモンドシンポジウム(第20回)  

    発表年月: 2006年11月

  • 長尺カーボンナノチューブ合成のための先端放電型ラジカルCVD条件最適化(真木 翼, 岩崎 孝之, 相川 拓海, 川原田 洋)

    ダイヤモンドシンポジウム(第20回)  

    発表年月: 2006年11月

  • 部分的酸素終端表面を用いたSGFET-DNAセンサによる塩基ミスマッチ検出(久我 翔馬, 梁 正勲, 宋 光燮, 川原田 洋)

    ダイヤモンドシンポジウム(第20回)  

    発表年月: 2006年11月

  • ダイヤモンド超伝導への表面・界面の影響(岡田 竜介, 石綿 整, 竹之内 智大, 入山 慎吾, 立木 実, 高野 義彦, 石井 聡, 興津 貴史,上田 真也, 川原田 洋)

    ダイヤモンドシンポジウム(第20回)  

    発表年月: 2006年11月

  • Co触媒微粒子を用いた先端放電型ラジカルCVDによるCNTの低温合成(横山 大輔, 岩崎 孝之, 吉田 剛, 佐藤 信太郎, 二瓶 瑞久, 粟野 祐二, 川原田 洋)

    ダイヤモンドシンポジウム(第20回)  

    発表年月: 2006年11月

  • Synthesis of Very Dense and Vertically Aligned Single-walled Carbon Nanotubes by Radical CVD(T. Yoshida, T. Iwasaki, H. Kawarada)

    2006 MRS Fall Meeting  

    発表年月: 2006年11月

  • Characterization of direct immobilization on functionalized diamond Solution-Gate Field-Effect Transistors for detecting single-mismatch oligonucleotides(J. H. Yang, K. S. Song, S. Kuga, H. Kawarada)

    2006 MRS Fall Meeting  

    発表年月: 2006年11月

  • Detection of DNA Hybridization by Diamond Solution Gate Field Effect Transistors - A New Type of DNA Sensor Based on Charge Detection(H. Kawarada, K. S. Song, J. H. Yang)

    2006 MRS Fall Meeting  

    発表年月: 2006年11月

  • Superconductivity from highly boron-doped diamonds(H. Kawarada, Y. Takano, Y. Yokoya)

    International Symposium on Super conductivity(19th)  

    発表年月: 2006年10月

  • Immobilization of streptavidin using biotin-avidin interaction on the diamond surface(T. Ohki, K. S. Song, G.. J. Zhang, J. H. Yang, I. Ohdomari, H. Kawarada)

    European Conference on Diamond, Diamond-Like Materials, Carbon Nanotubes, and Nitrides(17th)  

    発表年月: 2006年09月

  • Fabrication and Application of low resistive layer by ion irradiation into diamond(T. Koide, T. Arai, S. Mejima, K. Hirama, K. S. Song, D. Ferrer, T. Shinada, I. Ohdomari, H. Kawarada)

    European Conference on Diamond, Diamond-Like Materials, Carbon Nanotubes, and Nitrides(17th)  

    発表年月: 2006年09月

  • Evaluation of effective carrier mobility of two-dimensional accumulation layer on Diamond FET(S. Yamauchi, K. Hirama, T. Koshiba, K. Yohara, H. Takayanagi, H. Kawarada)

    European Conference on Diamond, Diamond-Like Materials, Carbon Nanotubes, and Nitrides(17th)  

    発表年月: 2006年09月

  • Growth of single-walled carbon nanotubes in nano-sized via holes for interconnects(R. Morikane, T. Iwasaki, G. Zhong, T. Edura, K. Tsutsui, Y. Wada, H. Kawarada)

    European Conference on Diamond, Diamond-Like Materials, Carbon Nanotubes, and Nitrides(17th)  

    発表年月: 2006年09月

  • Control of two-dimensional hole gas layer through charged membranes on the hydrogen-terminated diamond surface(M. Tanaka, D.Ogiwara, Y. Sasaki, K.Hirama, K. S. Song, H. Kawarada)

    European Conference on Diamond, Diamond-Like Materials, Carbon Nanotubes, and Nitrides(17th)  

    発表年月: 2006年09月

  • Microwave analysis of 30GHz cut-off frequency diamond MISFETs(K. Hirama, T. Koshiba, H. Takayanagi, K.Yohara, S.Yamauchi, H. Kawarada)

    European Conference on Diamond, Diamond-Like Materials, Carbon Nanotubes, and Nitrides(17th)  

    発表年月: 2006年09月

  • The detection of base pair mismatched DNA using diamond field-effect transistors (FETs)(H. Takahashi, K. Furukawa , K. S. Song, G.. J. Zhang, J. H. Yang, I. Ohdomari, H. Kawarada)

    European Conference on Diamond, Diamond-Like Materials, Carbon Nanotubes, and Nitrides(17th)  

    発表年月: 2006年09月

  • Change of conductivity characteristic in heavily boron-doped diamond films(H. Ishiwata, S. Koizumi, T. Takenouchi, Y. Takano, M. Nagao, T. Hatano, H. Kawarada)

    European Conference on Diamond, Diamond-Like Materials, Carbon Nanotubes, and Nitrides(17th)  

    発表年月: 2006年09月

  • 負電荷保持薄膜のパッシベーションによるダイヤモンドFET特性の改善(福本 亘, 與原 圭一朗, 田中 雅也,平間 一行, 川原田 洋)

    応用物理学会学術講演会(秋季第67回)  

    発表年月: 2006年08月

  • 高濃度ボロンドープCVDダイヤモンド超伝導体における合成条件とTcの関係(入山 慎吾, 竹之内 智大, 石綿 整, 岡田 竜介, 立木 実, 高野 義彦, 石井 聡, 奥津 貴史, 上田 真也, 川原田 洋)

    応用物理学会学術講演会(秋季第67回)  

    発表年月: 2006年08月

  • 水素終端ダイヤモンドP型表面蓄積層におけるO2-イオンの影響(田中 雅也, 大木 貴史, 平間 一行, 宋 光燮, 川原田 洋)

    応用物理学会学術講演会(秋季第67回)  

    発表年月: 2006年08月

  • カルモジュリンを用いたダイヤモンド電解質ゲートFET によるCa2+の検出(大木 貴史, 出川 宗里, 本橋 秀樹, 宋 光燮, 川原田 洋)

    応用物理学会学術講演会(秋季第67回)  

    発表年月: 2006年08月

  • 先端放電型プラズマによるダイヤモンド正孔蓄積層の低温回復(神宮 宜克, 小柴 亨, 高柳 英典, 山内 真太郎, 與原 圭一郎, 平間 一行, 岩崎 孝之, 川原田 洋)

    応用物理学会学術講演会(秋季第67回)  

    発表年月: 2006年08月

  • CO2を用いた先端放電型マイクロ波プラズマCVDによるカーボンナノチューブ合成(真木 翼, 岩崎 孝之, 相川 拓海, 川原田 洋)

    応用物理学会学術講演会(秋季第67回)  

    発表年月: 2006年08月

  • 収束イオンビームによるBイオンダイヤモンドの半導体特性(小出 敬, 目島 壮一, 平間 一行, 坪内 信輝,小倉 政彦,茶谷原 昭義,鹿田 真一, 品田 賢宏, 大泊 巌, 川原田 洋)

    応用物理学会学術講演会(秋季第67回)  

    発表年月: 2006年08月

  • 表面修飾を用いたSGFET-DNAセンサの特性(久我 翔馬, 梁 正勲, 高橋 宏徳, 宋 光燮, 川原田 洋)

    応用物理学会学術講演会(秋季第67回)  

    発表年月: 2006年08月

  • MISFET構造を用いたダイヤモンド2次元正孔ガスの低温特性評価(岡田 竜介, 石綿 整, 竹之内 智大, 入山 慎吾, 立木 実, 高野 義彦, 石井 聡, 奥津 貴史, 上田 真也, 川原田 洋)

    応用物理学会学術講演会(秋季第67回)  

    発表年月: 2006年08月

  • LSI多層配線応用のための先端放電型ラジカルCVDによる垂直配向CNTの低温合成(横山 大輔, 岩崎 孝之, 吉田 剛, 佐藤 信太郎, 二瓶 瑞久, 粟野 祐二, 川原田 洋)

    応用物理学会学術講演会(秋季第67回)  

    発表年月: 2006年08月

  • RF power evaluation of diamond MISFETs using load pull measurement(K. Hirama, S. Yamauchi, H. Takayanagi, K. Yohara, T. Koshiba, M. Satoh and H. Kawarada)

    電子材料シンポジウム(第25回)  

    発表年月: 2006年07月

  • Enhanced Growth of Millimeter Long Vertically Aligned Single-Walled Carbon Nanotubes by Edge Growth(T. Iwasaki, G. Zhong, H. Kawarada)

    Nanotube 2006  

    発表年月: 2006年06月

  • RF diamond MISFETs using surface accumulation layer(K. Hirama, T. Koshiba, K. Yohara, H. Takayanagi, M. Satoh, H. Kawarada)

    International Symposium on Power Semiconductor Devices And ICs(18th)  

    発表年月: 2006年06月

  • RF power characteristics of diamond MISFETs utilizing hole accumulation layer(K.Hirama, S.Yamauchi, M.Satoh, H. Kawarada)

    joint International Conference on New Diamond Science and Technology and the Applied Diamond Conference  

    発表年月: 2006年05月

  • Highly sensitive label-free DNA diamond FET biosensor based on the negative charge of DNA(K. S. Song, T. Hiraki, K. Furukawa, J. H. Yang, H. Kawarada)

    The joint International Conference on New Diamond Science and Technology and the Applied Diamond Conference  

    発表年月: 2006年05月

  • Detection of the label-free target oligonucleotides on diamond SGFETs by using direct amination and CAC(J. H. Yang, K. S. Song, G. J. Zhang, S. Yoshinori, I. Ohdomari, H. Kawarada)

    The joint International Conference on New Diamond Science and Technology and the Applied Diamond Conference  

    発表年月: 2006年05月

  • Dense hole accumulation induced by O2- ions on hydrogen-terminated diamond surface: A new model for subsurface conductivity(H. Kawarada, D. Ogiwara, M. Tanaka, Y. Sasaki, K. Hirama and K. S. Song)

    The joint International Conference on New Diamond Science and Technology and the Applied Diamond Conference  

    発表年月: 2006年05月

  • Millimeter Long Vertically Aligned Single-Walled Carbon Nanotubes by an ultra long lifetime of catalysts(T. Iwasaki, G. Zhong, T. Yoshida, T. Aikawa, R. Morikane, H. Kawarada)

    NSTI Nanotech 2006  

    発表年月: 2006年05月

  • Electric-field assisted DNA sensors using diamond FETs(K. S. Song, T. Hiraki, K. Furukawa, J. H. Yang, H. Kawarada)

    BIOSENSORS 2006  

    発表年月: 2006年05月

  • Characterization of controlled hybridization kinetics on diamond field effect transistor for detecting label-free oligonucleotides(J. H. Yang, K. S. Song, Y. Sasaki. H. Kawarada)

    BIOSENSORS 2006  

    発表年月: 2006年05月

  • ハイブリダイゼーション速度調節によるSGFET−DNAセンサの特性(梁 正勲, 宋 光燮, 佐々木 順紀, 古川 慧, 平木 貴博, 高橋 宏徳, 川原田 洋)

    応用物理学会学術講演会(第53回)  

    発表年月: 2006年03月

  • ホール蓄積層を用いたダイヤモンドMISFETのパワー特性(平間 一行, 山内 真太郎, 佐藤 允也, 川原田 洋)

    応用物理学会学術講演会(第53回)  

    発表年月: 2006年03月

  • 濃度10%のボロンドープダイヤモンドの電気特性(石綿 整, 小泉 聡, 手塚 真一郎, 竹之内 智大, 高野 義彦, 長尾 雅則, 坂口 勲, 羽多野 毅, 川原田 洋)

    応用物理学会学術講演会(第53回)  

    発表年月: 2006年03月

  • 配線応用へ向けたナノサイズビア構造からの単層カーボンナノチューブ成長(森金 亮太, 岩崎 孝之, 鍾 国倣, 江面 知彦, 筒井 謙, 和田 恭雄, 川原田 洋)

    応用物理学会学術講演会(第53回)  

    発表年月: 2006年03月

  • ダイヤモンドへのイオン照射による 局所低抵抗層の形成とその応用(小出 敬, 新井 達也, 目島 壮一, 平間 一行, 宋 光燮, ドミンゴ フェレール, 品田 賢宏, 大泊 巌, 川原田 洋)

    応用物理学会学術講演会(第53回)  

    発表年月: 2006年03月

  • 高濃度ボロンドープCVDダイヤモンド超伝導体におけるJc評価②(手塚 真一郎, 石綿 整, 竹之内 智大, 高野 義彦, 長尾 雅則, 坂口 勲, 立木 実, 羽多野 毅, 川原田 洋)

    応用物理学会学術講演会(第53回)  

    発表年月: 2006年03月

  • SGFET-DNAセンサにおける電圧印加によるSNPs検出(高橋 宏徳, 古川 慧, 宋 光燮, 張 国軍, 梁 正勲, 大泊 巌, 川原田 洋)

    応用物理学会学術講演会(第53回)  

    発表年月: 2006年03月

  • Detection of the label-free DNA on diamond SGFETs by direct amination and CAC(J. H. Yang, K. S. Song, G. J. Zhang, I. Ohdomari, H. Kawarada)

    ACS National Meeting(231st)  

    発表年月: 2006年03月

  • 高濃度ボロンドープCVDダイヤモンドにおけるキャリア密度の評価(石綿 整, 手塚 真一郎, 竹之内 智大, 高野 義彦, 長尾 雅則, 坂口 勳, 立木 実, 川原田 洋)

    ニューダイヤモンドシンポジウム(第19回)  

    発表年月: 2005年11月

  • 放電型マイクロ波プラズマCVD法による単層カーボンナノチューブの成長制御(森金 亮太, 岩崎 孝之, 鍾 国倣, 相川 拓海, 吉田 剛, 川原田 洋)

    ニューダイヤモンドシンポジウム(第19回)  

    発表年月: 2005年11月

  • ダイヤモンド表面への重金属イオン照射による局所低抵抗層の形成とその応用(小出 敬, 新井 達也, 目島 壮一, 平間 一行, ドミンゴ フェレール, 宋 光燮, 品田 賢宏, 大泊 巌, 川原田 洋)

    ニューダイヤモンドシンポジウム(第19回)  

    発表年月: 2005年11月

  • 高濃度ボロンドープCVDダイヤモンド超伝導体におけるJc評価(手塚 真一郎, 石綿 整, 竹之内 智大, 高野 義彦, 長尾 雅則, 坂口 勲, 立木 実, 羽多野 毅, 川原田 洋)

    ニューダイヤモンドシンポジウム(第19回)  

    発表年月: 2005年11月

  • ダイヤモンドSGFETのpH感応性と時間応答(坂本 琢磨, 佐々木 順紀, 大木 貴史, 出川 宗里, 平木 貴博, 梁 正勲, 宋 光燮, 川原田 洋)

    ニューダイヤモンドシンポジウム(第19回)  

    発表年月: 2005年11月

  • ダイヤモンドSGFET-DNAセンサにおけるハイブリダイゼーション制御(高橋 宏徳, 古川 慧, 宋 光燮, 張 国軍, 梁 正勲, 大泊 巌, 川原田 洋)

    ニューダイヤモンドシンポジウム(第19回)  

    発表年月: 2005年11月

  • DNA detection and biosensing application of diamond transistors(K. S. Song, M. Degawa, Y. Sasaki, K. Furukawa, T. Ohki, T. Hiraki, J. H. Yang, H.Kawarada)

    2005 Symposium on Nanoscale Materials, Processes and Devices  

    発表年月: 2005年11月

  • A novel method of DNA immobilization on diamond by aromatic carboxylic compound(J. H. Yang, K. S. Song, G. J. Zhang, M. Degawa, Y. Sasaki, I. Ohdomari, H. Kawarada)

    2005 Symposium on Nanoscale Materials, Processes and Devices  

    発表年月: 2005年11月

  • Diamond RF Transistors on H-Terminated Diamond Surface Channel(H. Umezawa, H. Hirama, T. Arai, H. Takayanagi, T. Koshiba, K. Yohara, S. Mejima, M. Satoh, H. Kawarada)

    2005 Symposium on Nanoscale Materials, Processes and Devices  

    発表年月: 2005年11月

  • Detection of Ions and DNA Hybridization using Diamond Solution Gate FETs(H. Kawarada, K. Furukawa, Y. Sasaki, J. H. Yang, K. S. Song)

    2005 Symposium on Nanoscale Materials, Processes and Devices  

    発表年月: 2005年11月

  • Diamond FET biosensor to actualize the detection of SNP based its charge detection(K. S. Song, G. J. Zhang, K. Furukawa, T. Hiraki, Y. Sasaki, J. H. Yang, I. Ohdomari, H. Kawarada)

    2005 MRS Fall Meeting  

    発表年月: 2005年11月

  • Diamond field-effect transistors (FETs) applying for the charge detection biosensors(K. S. Song, G. J. Zhang, K. Furukawa, T. Hiraki, Y. Sasaki, J.H. Yang, I. Ohdomari, H. Kawarada)

    2005 Instrumental Methods of Analysis Modern Trends and Applications Crete  

    発表年月: 2005年10月

  • Synthesis of Millimeter Long Vertically Aligned Single-Walled Carbon Nanotubes by Point-Arc Microwave Plasma Cvd(T. Iwasaki, T. Yoshida, T. Aikawa, G. F. Zhong, I. Ohdomari, H. Kawarada)

    2005 AIChE Annual Meeting  

    発表年月: 2005年10月

  • Detection of Ions and DNA Hybridization Using Diamond Solution Gate Fets(H. Kawarada, K. S. Song)

    2005 AIChE Annual Meeting  

    発表年月: 2005年10月

  • Influence of Negative Adsorption on Hydrogen Terminated P-Type Diamond Surface(D. Ogiwara, M. Tanaka, Y. Sasaki, K. Hirama, K. S. Song, H. Umezawa, H. Kawarada)

    2005 AIChE Annual Meeting  

    発表年月: 2005年10月

  • 微細ダイヤモンド電解質溶液ゲートFETを用いた高感度DNAセンサ(平木 貴博, 宋 光燮, 張 国軍, 梁 正勲, 大泊 巌, 川原田 洋)

    応用物理学会学術講演会(第66回)  

    発表年月: 2005年09月

  • 高濃度ボロンドープCVD ホモエピタキシャルダイヤモンドの超伝導特性II(竹之内 智大, 手塚 真一郎, 石綿 整, 高野 義彦, 長尾 雅則, 坂口 勲, 立木 実, 羽多野 毅, Hoesch Moritz, 福田 竜生, 水木 純一郎, 川原田 洋)

    応用物理学会学術講演会(秋季第66回)  

    発表年月: 2005年09月

  • 表面修飾した超分散性ダイヤモンド(UDDs)の分散性評価(村上 泰規, 中野 善和, 梁 正勲, 宋 光燮, 張 国軍, 梅沢 仁, 川原田 洋)

    応用物理学会学術講演会(第66回)  

    発表年月: 2005年09月

  • ダイヤモンドの気相合成-半導体から超電導まで(川原田 洋)

    応用物理学会学術講演会(第66回)  

    発表年月: 2005年09月

  • 高濃度ボロンドープCVD ダイヤモンドにおけるキャリア密度の評価(石綿 整, 手塚 真一郎, 竹之内 智大, 高野 義彦, 長尾 雅則, 坂口 勲, 立木 実, 羽多野 毅, 川原田 洋)

    応用物理学会学術講演会(第66回)  

    発表年月: 2005年09月

  • 高密度・垂直配向単層カーボンナノチューブの成長機構解明(森金 亮太, 岩崎 孝之, 鐘 国倣, 相川 拓海, 吉田 剛, 川原田 洋)

    応用物理学会学術講演会(第66回)  

    発表年月: 2005年09月

  • 昇温ダイヤモンド表面へのNiイオン照射による局所低抵抗領域の電気特性(小出 敬, 新井 達也, 目島 壮一, 宋 光燮, ドミンゴ フェレール, 品田 賢宏, 大泊 巌, 川原田 洋)

    応用物理学会学術講演会(第66回)  

    発表年月: 2005年09月

  • 高濃度ボロンドープCVDダイヤモンド超伝導体におけるJc評価構造の検討(手塚 真一郎, 石綿 整, 竹之内 智大, 高野 義彦, 長尾 雅則, 坂口 勲, 立木 実, 羽多野 毅, 川原田 洋)

    応用物理学会学術講演会(第66回)  

    発表年月: 2005年09月

  • 高周波ダイヤモンドMISFETにおけるホールキャリア速度の向上(山内 真太郎, 平間 一行, 小柴 亨, 与原 圭一朗, 高柳 英典, 佐藤 允也, 宋 光燮, 小倉 政彦, 齊藤 丈靖, 朴 慶浩, 藤森 直治, 川原田 洋)

    応用物理学会学術講演会(第66回)  

    発表年月: 2005年09月

  • ダイヤモンドSGFETのpH感応性と時間応答(佐々木 順紀, 大木 貴史, 出川 宗里, 平木 貴博, 梁 正勲, 宋 光燮, 川原田 洋)

    応用物理学会学術講演会(第66回)  

    発表年月: 2005年09月

  • ダイヤモンドSGFET-DNAセンサにおけるハイブリダイゼーション検出の温度依存特性(高橋 宏徳, 古川 慧, 宋 光燮, 張 国軍, 梁 正勲, 大泊 巌,川原田 洋)

    応用物理学会学術講演会(第66回)  

    発表年月: 2005年09月

  • Fabrication of Low Resistive Layer in Diamond Surface by Ni Ion Irradiation at Low Doses using FIB(S. Mejima; T. Arai; K. Hirama; H. Umezawa; F. Domingo; T. Shinada; I. Ohdimari; H. Kawarada)

    NT'L CONFERENCE ON SILICON CARBIDE AND RELATED MATERIALS 2005  

    発表年月: 2005年09月

  • Influences of B-Doped Layer under the Channel of H-Terminated DiamondFETs(T. Koshiba; K. Hirama; T. Saito; M. Ogura, M. Sato; H. Umezawa; K. H. Park; H. Kawarada)

    INT'L CONFERENCE ON SILICON CARBIDE AND RELATED MATERIALS 2005  

    発表年月: 2005年09月

  • The Improvement of RF Performance for Diamond MISFETs with Miniaturization of Gate Length(H. Takayanagi, K. Hirama、 M. Satoh、 H. Kawarada)

    INT'L CONFERENCE ON SILICON CARBIDE AND RELATED MATERIALS 2005  

    発表年月: 2005年09月

  • Drift and hysteresis characteristics on the pH sensitive diamond SGFET(Y. Sasaki, T. Ohki, K. S. Song, M. Degawa, H. Kawarada)

    European Conference on Diamond, Diamond-Like Materials, Carbon Nanotubes, Nitrides &amp; Silicon Carbide(16th)  

    発表年月: 2005年09月

  • Dispersibility evaluation of ultra-dispersed diamonds(UDDs) immobilized biological molecules(Y. Murakami, Y. Nakano, G. J. Zhang, K. S. Song, H. Kawarada)

    European Conference on Diamond, Diamond-Like Materials, Carbon Nanotubes, Nitrides &amp; Silicon Carbide(16th)  

    発表年月: 2005年09月

  • The miniaturized diamond electrolyte solution- gate FET (SGFET) to realize in vivo diagnostics of disease(T. Hiraki, K. S. Song, G. J. Zhang, J. H. Yang, I..Ohdomari, H. Kawarada)

    European Conference on Diamond, Diamond-Like Materials, Carbon Nanotubes, Nitrides &amp; Silicon Carbide(16th)  

    発表年月: 2005年09月

  • How to achieve millimeter long vertically aligned single-walled carbon nanotubes by plasma assistant CVD?(T. Aikawa, T. Yoshida, T. Iwasaki, G. F. Zhong, H. Kawarada)

    European Conference on Diamond, Diamond-Like Materials, Carbon Nanotubes, Nitrides &amp; Silicon Carbide(16th)  

    発表年月: 2005年09月

  • Development of diamond MISFETs with oxide gate insulator(K. Yohara, K. Hirama, M. Satoh, H. Umezawa, H. Kawarada)

    European Conference on Diamond, Diamond-Like Materials, Carbon Nanotubes, Nitrides &amp; Silicon Carbide(16th)  

    発表年月: 2005年09月

  • Ultra sensitive label-free diamond DNA biosensor to detect its molecular negative charge(K. Furukawa, K. S. Song, G. J. Zhang, J. H. Yang, I. Ohdomari, H. Kawarada)

    European Conference on Diamond, Diamond-Like Materials, Carbon Nanotubes, Nitrides &amp; Silicon Carbide(16th)  

    発表年月: 2005年09月

  • Controlled growth of single-walled carbon nanotubes by point-arc microwave plasma CVD(G. F. Zhong, T. Iwasaki, T. Yoshida, T. Aikawa, H, Kawarada)

    European Conference on Diamond, Diamond-Like Materials, Carbon Nanotubes, Nitrides &amp; Silicon Carbide(16th)  

    発表年月: 2005年09月

  • Influence of negatively charged adsorbates on Hydrogen-terminated p-type diamond surface(D. Ogiwara, M. Tanaka, Y. Sasaki, K. Hirama, K..S. Song, H. Kawarada)

    European Conference on Diamond, Diamond-Like Materials, Carbon Nanotubes, Nitrides &amp; Silicon Carbide(16th)  

    発表年月: 2005年09月

  • 高密度・垂直配向単層カーボンナノチューブの成長機構解明(岩崎 孝之, 鍾 国倣, 相川 拓海, 吉田 剛, 川原田 洋)

    フラーレン・ナノチューブ総合シンポジウム(第29回)  

    発表年月: 2005年07月

  • High Yield Selective Growth of Millimeter Long, Vertically Aligned Single-walled Carbon Nanotubes at Low Temperatures(G. Zhong, T. Iwasaki, I. Ohdomari, H. Kawarada)

    International Conference on the Science and Application of Nanotubes(6th)  

    発表年月: 2005年06月

  • Hysteresis characteristic on the pH sensitive diamond SGFET(T. Ohki, Y. Sasaki, J. Yang, K. S. Song, H. Umezawa, H. Kawarada)

    International Conference on New Diamond Science and Technology(10th)  

    発表年月: 2005年05月

  • Super long catalyst life time over 20 hours for the growth of single-walled and multiwalled carbon Nanotubes(T. Aikawa, T. Yoshida, T. Iwasaki, R. Hosaka, G. Zhong, H. Kawarada)

    International Conference on New Diamond Science and Technology(10th)  

    発表年月: 2005年05月

  • Fablication of low resistive layer in diamond surface by Ni ion irradiation with controlling substrate temperature(S. Mejima, H. Hata, T. Arai, H. Umezawa, J. Kurosawa, D. Ferrer, T. Shinada, I. Ohdomari, H. Kawarada)

    International Conference on New Diamond Science and Technology(10th)  

    発表年月: 2005年05月

  • Control of p-type surface conductivity through charged membranes on the hydrogen-terminated diamond surface(M. Tanaka, D. Ogiwara, Y. Sasaki, K. S. Song, H. Umezawa, H. Kawarada)

    International Conference on New Diamond Science and Technology(10th)  

    発表年月: 2005年05月

  • Development of diamond MISFETs with low-temperature oxided alumina gate insulator(K. Yohara, K. Hirama, T. Saitoh, K. Park, M. Satoh, H. Umezawa, H. Kawarada)

    International Conference on New Diamond Science and Technology(10th)  

    発表年月: 2005年05月

  • High-Performance MISFET Using High-Mobility Substrate and Alminum Oxide Gate Insulator(K. Hirama, T. Koshiba, K. Yohara, H. Takayanagi, M. Satoh, H. Umezawa, H. Kawarada, T. Saitoh, K. Park, N. Fujimori)

    ADC/Nanocarbon(2005)  

    発表年月: 2005年05月

  • 低温酸化絶縁膜を用いたダイヤモンドMISFETの特性評価(与原 圭一朗, 平間 一行, 齊藤 丈靖, 朴 慶浩, 佐藤 允也, 梅沢 仁, 川原田 洋)

    応用物理学関係連合講演会(春季第52回)  

    発表年月: 2005年03月

  • 目島 壮一, 畑 英夫, 新井 達也, 梅沢 仁, 黒沢 淳, ドミンゴ フェレール, 品田 賢宏, 大泊 巌, 川原田 洋(目島 壮一, 畑 英夫, 新井 達也, 梅沢 仁, 黒沢 淳, ドミンゴ フェレール, 品田 賢宏, 大泊 巌, 川原田 洋)

    応用物理学関係連合講演会(春季第52回)  

    発表年月: 2005年03月

  • 微細電解質溶液ゲートFETを用いた高感度バイオセンサ(平木 貴博, 川村 正太, 宋 光燮, 中村 雄介, 佐々木 順紀, 出川 宗里, 梅沢 仁, 川原田 洋)

    応用物理学関係連合講演会(春季第52回)  

    発表年月: 2005年03月

  • 負電荷保持薄膜の表面形成による水素終端ダイヤモンドp型表面伝導の向上(田中 雅也, 荻原 大輔, 平間 一行, 佐々木 順紀, 宋 光燮, 梅沢 仁, 川原田 洋)

    応用物理学関係連合講演会(春季第52回)  

    発表年月: 2005年03月

  • 高濃度ボロンドープCVDホモエピタキシャルダイヤモンドの超伝導特性(竹之内 智大, 小林 健作, 高野 義彦, 長尾 雅則, 坂口 勲, 立木 実, 羽多野 毅, 鍾 国倣, 梅沢 仁, 川原田 洋)

    応用物理学関係連合講演会(春季第52回)  

    発表年月: 2005年03月

  • ダイヤモンドSGFETのpH感応性に対するヒステリシス特性(大木 貴史, 佐々木 順紀, 宋 光燮, 梅沢 仁, 川原田 洋)

    応用物理学関係連合講演会(春季第52回)  

    発表年月: 2005年03月

  • 生体分子固定による超分散性ダイヤモンド(UDDs)の分散性評価(村上 泰規, 中野 善和, 宋 光燮, 張 国軍, 梅沢 仁, 川原田 洋)

    応用物理学関係連合講演会(春季第52回)  

    発表年月: 2005年03月

  • 端放電型マイクロ波プラズマCVDによる長時間成長及び触媒の膜厚と直径の関係(相川 拓海, 吉田 剛, 岩崎 孝之, 保坂 亮太, 鍾 国倣, 川原田 洋)

    応用物理学関係連合講演会(春季第52回)  

    発表年月: 2005年03月

  • 水素終端ダイヤモンドFETチャネル下のBドープ層の影響(小柴 亨, 平間 一行, 高柳 英典, 与原 圭一朗, 齊藤 丈靖, 小倉 政彦, 佐藤 允也, 梅沢 仁, 朴 慶浩, 川原田 洋)

    応用物理学関係連合講演会(春季第52回)  

    発表年月: 2005年03月

  • ゲート長の微細化によるダイヤモンドMISFETの高周波特性の改善(高柳 英典, 平間 一行, 小柴 亨, 与原 圭一郎, 齊藤 丈靖, 朴 慶浩, 佐藤 允也, 梅沢 仁, 川原田 洋)

    応用物理学関係連合講演会(春季第52回)  

    発表年月: 2005年03月

  • 検出に向けたSGFET-DNAセンサの応用(古川 慧, 中村 雄介, 宋 光燮, 張 国軍, 梁 正勲, 梅沢 仁, 大泊 巌, 川原田 洋)

    応用物理学関係連合講演会(春季第52回)  

    発表年月: 2005年03月

  • 配線応用に向けた先端放電型マイクロ波プラズマCVDによるカーボンナノチューブの低温合成(吉田 剛, 相川 拓海, 岩崎 孝之, 鍾 国倣, 大泊 巌, 川原田 洋)

    応用物理学関係連合講演会(春季第52回)  

    発表年月: 2005年03月

  • 配線応用に向けた先端放電型マイクロ波プラズマCVDによるカーボンナノチューブの低温合成(吉田 剛, 川原田 洋)

    フラーレン・ナノチューブ総合シンポジウム(第28回)  

    発表年月: 2005年01月

  • Mass production of very long and vertically aligned single-walled carbon Nanotubes(G. Zhong, H. Kawarada)

    フラーレン・ナノチューブ総合シンポジウム(第28回)  

    発表年月: 2005年01月

  • Bドープ(100)ダイヤモンド水素終端表面を利用したFETの作成(齋藤丈靖,小倉政彦,朴慶浩,大串秀世,平間一行,梅沢仁,川原田洋)

    ダイヤモンドシンポジウム(第18回)  

    発表年月: 2004年11月

  • Niイオン照射によるダイヤモンドFETの低抵抗ソース・ドレイン領域の形成(目島 壮一, 新井 達也, 梅沢 仁, 川原田 洋)

    ダイヤモンドシンポジウム(第18回)  

    発表年月: 2004年11月

  • 微細ダイヤモンド電解質溶液ゲートFETのバイオセンサへの 利用(平木貴博,川村正太,宋光燮,梅沢仁,川原田洋)

    ダイヤモンドシンポジウム(第18回)  

    発表年月: 2004年11月

  • 高濃度ボロンドープCVDダイヤモンドの超伝導特性(竹之内智大, 小林健作, 高野義彦, 立木実, 羽多野毅, 鍾国倣, 梅沢仁, 川原田洋)

    ダイヤモンドシンポジウム(第18回)  

    発表年月: 2004年11月

  • 生体分子を固定した超分散ダイヤモンドの評価(村上泰規,中野善和,張国軍,梅沢仁,宋光燮, 川原田洋)

    ダイヤモンドシンポジウム(第18回)  

    発表年月: 2004年11月

  • ダイヤモンド表面オゾン処理によるトランジスタ特性制御(小柴 亨, 平間 一行,梅沢 仁, 川原田 洋)

    ダイヤモンドシンポジウム(第18回)  

    発表年月: 2004年11月

  • SGFETを利用した電荷検出型ラベルフリーDNAセンサ(古川慧,中村雄介,張国軍,宋光燮,梅沢仁, 川原田洋)

    ダイヤモンドシンポジウム(第18回)  

    発表年月: 2004年11月

  • The label-free DNA detection using diamond FET based on its molecular charge(Y. Nakamura, K. S. Song, G. Zhang, J. H. Yang, K. Furukawa, S. Kawamura, Y. Sasaki, M. Degawa, H. Umezawa, I. Ohdomari, H. Kawarada)

    2004 MRS Fall Meeting  

    発表年月: 2004年11月

  • Low Temperature Plasma Enhanced Chemical Vapor Deposition of Carbon Nanotubes and Nanofibers(T. Iwasaki, Y. Yoshida, T. Aikawa, R. Hosaka, K. Honda, G. Zhong, Y. Furukawa, I. Ohdomari, H. Kawarada)

    2004 MRS Fall Meeting  

    発表年月: 2004年11月

  • Super conductivity in heavily B-doped CVD Diamond thin Film(K. Kobayashi, T. Tekenouchi, Y. Takano, M. Nagao, I. Sakaguchi, M. Tachiki, T. Hatano, G. Zhong, H. Umezawa, H. Kawarada)

    2004 MRS Fall Meeting  

    発表年月: 2004年11月

  • High power RF Diamond FETs with Low Resistive Source/Drain Carbide Ohmic Layer using Focused Ni Ion Irradiation(H. Hata, T. Arai, S. Mejima, H. Umezawa, D. Ferrer, T. Shinada, I. Ohdomari, H. Kawarada)

    2004 MRS Fall Meeting  

    発表年月: 2004年11月

  • The pH sensitivity on the hydrogenated diamond surface and its application to biosensors(K. S. Song, Y. Nakamura, M. Degawa, Y. Sasaki, H. Umezawa, H. Kawarada)

    SE-Heraeus-Seminar. Biofunctional Interfaces: Basic Science and Applications(334th)  

    発表年月: 2004年10月

  • A novel method of DNA immobilization on diamond by aromatic carboxylic compound; hybridization to compare fluorescence intensities(J. H. Yang, K. S. Song, H. Umezawa, H. Kawarada)

    SE-Heraeus-Seminar. Biofunctional Interfaces: Basic Science and Applications(334th)  

    発表年月: 2004年10月

  • Biosensing mechanism of solution gate diamond FETs(H. Kawarada, H. Umezawa, K. S. Song)

    SE-Heraeus-Seminar. Biofunctional Interfaces: Basic Science and Applications(334th)  

    発表年月: 2004年10月

  • Biosensing mechanism of solution gate diamond FET(H, Kawarada, K. S. Song, H. Umezawa, Y. Nakamura, Y. Sasaki, M. Degawa)

    SE-Heraeus-Seminar. Biofunctional Interfaces: Basic Science and Applications(334th)  

    発表年月: 2004年10月

  • DIAMOND FIELD EFFECT TRANSISTORS FOR RF, NANO, AND BIO APPLICATIONS(H. Kawarada, H. Umezawa, K. S. Song)

    Int. Semionar on Advances in Carbon Electronics(3rd)  

    発表年月: 2004年10月

  • ダイヤモンド表面に芳香族化合物を利用したDNAの固定化(梁正勲, 宋光燮, 張国軍, 川村正太, 中村雄介, 佐々木順紀, 出川宗里, 梅沢仁, 大泊巌, 川原田洋)

    応用物理学会学術講演会(秋季第65回)  

    発表年月: 2004年09月

  • 高品質ゲート絶縁膜を用いたダイヤモンドMISFETと界面評価(与原圭一朗, 平間一行, 宮本真吾, 松平弘樹, 高柳英典, 小柴亨, 目島壮一, 齊藤丈靖, 知京豊裕, 鯉沼秀臣, 長谷川顕, 藤森直治, 梅沢仁, 川原田洋)

    応用物理学会学術講演会(秋季第65回)  

    発表年月: 2004年09月

  • 金属イオン照射による低抵抗ソース・ドレインオーミック層の形成(目島壮一, 畑英夫, 新井達也, 梅沢仁, ドミンゴフェルール, 品田賢宏, 大泊巌, 川原田洋)

    応用物理学会学術講演会(秋季第65回)  

    発表年月: 2004年09月

  • タンパク質を固定した電解質ゲートダイヤモンドFET(本橋秀樹, 出川宗里, 宋光燮, 中村雄介, 川村正太, 佐々木順紀, 梅沢仁, 川原田洋)

    応用物理学会学術講演会(秋季第65回)  

    発表年月: 2004年09月

  • 微細ダイヤモンド電解質溶液ゲートFETのバイオセンサ応用(平木貴博, 川村正太, 宋光燮, 中村雄介, 佐々木順紀, 出川宗里, 梅沢仁, 川原田洋, 古川慧, 大木貴史, 田中雅也, 本橋秀樹)

    応用物理学会学術講演会(秋季第65回)  

    発表年月: 2004年09月

  • 水素終端ダイヤモンドP型表面伝導における負イオンの影響(II)(田中雅也, 荻原大輔, 平間一行, 佐々木順紀, 宋光燮, 梅沢仁, 川原田洋)

    応用物理学会学術講演会(秋季第65回)  

    発表年月: 2004年09月

  • 高濃度ボロンドープCVDダイヤモンドの超伝導特性(竹之内智大, 小林健作, 高野義彦, 長尾雅則, 坂口勲, 立木実, 羽田野毅, 鍾国倣, 梅沢仁, 川原田洋)

    応用物理学会学術講演会(秋季第65回)  

    発表年月: 2004年09月

  • ダイヤモンド表面のpH感応性(大木貴史, 佐々木順紀, 宋光燮, 中村雄介, 川村正太, 出川宗里, 田中雅也, 平木貴博, 梅沢仁, 川原田洋, 本橋秀樹)

    応用物理学会学術講演会(秋季第65回)  

    発表年月: 2004年09月

  • 超分散ダイヤモンド(UDD)を用いた生体分子固定とその評価(村上泰規, 中野善和, 宋光燮, 梅沢仁, 座古保, 船津高志, 本多光太郎, 古川行夫, 川原田洋)

    応用物理学会学術講演会(秋季第65回)  

    発表年月: 2004年09月

  • カーボンナノチューブ低電力大面積合成のための先端放電型マイクロ波プラズマCVD装置(相川拓海, 吉田剛, 岩崎孝之, 保坂亮太, 鍾国倣, 川原田洋)

    応用物理学会学術講演会(秋季第65回)  

    発表年月: 2004年09月

  • ダイヤモンド表面オゾン処理によるトランジスタ特性制御(小柴亨, 平間一行, 高柳英典, 竹之内智大, 目島壮一, 与原圭一朗, 齊藤丈靖, 佐藤允也, 梅沢仁, 朴慶治, 藤森直治, 川原田洋)

    応用物理学会学術講演会(秋季第65回)  

    発表年月: 2004年09月

  • De-embedding手法を用いたダイヤモンドRFトランジスタの真性特性評価(高柳英典, 平間一行, 小柴亨, 目島壮一, 与原圭一朗, 佐藤允也, 梅沢仁, 川原田洋)

    応用物理学会学術講演会(秋季第65回)  

    発表年月: 2004年09月

  • 電解質ゲートダイヤモンドFETを利用したDNAセンサ(古川慧, 中村雄介, 宋光燮, 張国軍, 梁正勲, 川村正太, 梅沢仁, 大泊巌, 川原田洋)

    応用物理学会学術講演会(秋季第65回)  

    発表年月: 2004年09月

  • 端放出型マイクロ波プラズマCVDによる垂直配向・高密度単層カーボンナノチューブの低温合成(吉田剛, 岩崎孝之, 保坂亮太, 本多光太郎, 鍾国倣, 古川行夫, 大泊巌, 川原田洋)

    応用物理学会学術講演会(秋季第65回)  

    発表年月: 2004年09月

  • Immobilization of biological molecule using ultra-dispersed diamond and its application(Y. Nakano, H. Umezawa, G-J. Zhang, Y. Kaibara, K. S. Song, T. Zako, T. Funatsu, K. Honda, Y. Furukawa, H. Kawarada)

    European Conference on Diamond, Diamond-Like Materials, Carbon Nanotubes, Nitrides &amp; Silicon Carbide(15th)  

    発表年月: 2004年09月

  • Mechanism on the nonvolatile memory effect on diamond in-plane-gated field-effect transistors(Y. Itoh, Y. Sumikawa, K. Kobayashi, H. Umezawa, H. Kawarada)

    European Conference on Diamond, Diamond-Like Materials, Carbon Nanotubes, Nitrides &amp; Silicon Carbide(15th)  

    発表年月: 2004年09月

  • Modification of diamond thin films utilizing electron beam and focused-ion beam(T. Arai, H. Hata, H. Umezawa, D. Ferrer, T. Shinada, I. Ohdomari, H. Kawarada)

    European Conference on Diamond, Diamond-Like Materials, Carbon Nanotubes, Nitrides &amp; Silicon Carbide(15th)  

    発表年月: 2004年09月

  • The antenna-edge-type microwave plasma-assisted chemical vapor deposition for carbon nanotube growth(R. Hosaka, G. Zhong, T. Iwasaki, H. Kawarada)

    European Conference on Diamond, Diamond-Like Materials, Carbon Nanotubes, Nitrides &amp; Silicon Carbide(15th)  

    発表年月: 2004年09月

  • The bio-application of electrolyte-solution-gate diamond FETs(M. Degawa, K. S. Song, Y. Nakamura, Y. Sasaki, S. Kawamura, H. Umezawa, H. Kawarada)

    European Conference on Diamond, Diamond-Like Materials, Carbon Nanotubes, Nitrides &amp; Silicon Carbide(15th)  

    発表年月: 2004年09月

  • Biosensors Based on Diamond Transistors(H. Kawarada, H. Umezawa, H. Kanazawa, Y. Nakamura, Y. Kaibara, M. Degawa, Y. Sasaki, K. S. Song)

    European Conference on Diamond, Diamond-Like Materials, Carbon Nanotubes, Nitrides &amp; Silicon Carbide(15th)  

    発表年月: 2004年09月

  • Low temperature synthesis of highly oriented and very dense single-walled carbon nanotubes by remote microwave plasma chemical vapour deposition(G. F. Zhong, H. Kawarada, I. Ohdomari)

    European Conference on Diamond, Diamond-Like Materials, Carbon Nanotubes, Nitrides &amp; Silicon Carbide(15th)  

    発表年月: 2004年09月

  • Miniaturized electrolyte solution gate FET on polycrystalline diamond(S. Kawamura, K. S. Song, H. Umezawa, Y. Nakamura, Y. Sasaki, M. Degawa, H. Kawarada)

    European Conference on Diamond, Diamond-Like Materials, Carbon Nanotubes, Nitrides &amp; Silicon Carb(15th)  

    発表年月: 2004年09月

  • Diamond MISFETs for High Frequency Applications(H. Umezawa, H. Kawarada)

    2004 International Conference on Solid State Devices and Materials  

    発表年月: 2004年09月

  • Diamond Field Effect Transistors for Microwave Devices and Biosensing Applicaton(H. Kawarada, H. Umezawa, S. MIyamoto, H. Matsudaira, K. S. Song)

    ADC  

    発表年月: 2004年08月

  • 水素終端ダイヤモンドP型表面伝導における負イオンの影響(荻原大輔、川原田洋)

    応用物理学会学術連合講演会(第51回)  

    発表年月: 2004年03月

  • ダイヤモンドin-plane-gated FETにおけるヒステリシス特性の光エネルギー(伊藤裕、川原田洋)

    応用物理学会学術連合講演会(第51回)  

    発表年月: 2004年03月

  • pH-sensitivity of aminated diamond surface(Y. Sasaki, K. Song, H. Kanazawa, Y. Nakamura, S. Kawamura, M. Degawa, Y. Kurihara, H. Umezawa, H. Kawarada)

    International Conference on New Diamond Science and Technology(The 9th)  

    発表年月: 2004年03月

  • Hysteresis characteristics of diamond in-plane-gated FETs for nonvolatile memory device(Y. Itoh, Y. Sumikawa, K. Kobayashi, H. Umezawa, H. Kawarada)

    International Conference on New Diamond Science and Technology(The 9th)  

    発表年月: 2004年03月

  • Structural investigation of conical carbon nanofibers(T. Iwasaki, G. Zhong, I. Ohdomari, H. Kawarada)

    International Conference on New Diamond Science and Technology(The 9th )  

    発表年月: 2004年03月

  • Nano-scale surface modification of diamond utilizing gas-introdeced electron beam(T. Arai, H. Hata, H. Umezawa, Y. Kaibara, K. Song, H. Kawarada)

    International Conference on New Diamond Science and Technology(The 9th )  

    発表年月: 2004年03月

  • Glucose biosensors using electrolyte-solution-gate diamondFETs(M. Degawa, K. Song, H. Kanazawa, Y. Nakamura, Y. Sasaki, S. Kawamura, Y. Kurihara, H. Umezawa, H. Kawarada)

    International Conference on New Diamond Science and Technology(The 9th )  

    発表年月: 2004年03月

  • Enzyme immobilized biosensor based on surface modified diamond field effect transistors(K. S. Song, H. Kanazawa, Y. Nakamura, S. Kawamura, M. Degawa, Y. Sasaki, H. Umezawa, H. Kawarada)

    International Conference on New Diamond Science and Technology(The 9th )  

    発表年月: 2004年03月

  • RF characteristic of diamond transistor with low resistance(K. Hirama, S. Miyamoto, H. Matsudaira, K. Song, H. Umezawa, H. Kawarada)

    International Conference on New Diamond Science and Technology(The 9th )  

    発表年月: 2004年03月

  • “Diamond MIS transistors for high frequency applications(H. Kawarada, K. Hirama, H. Matsudaira, S. Miyamoto, M. Satoh, H. Umezawa)

    International Conference on New Diamond Science and Technology(The 9th)  

    発表年月: 2004年03月

  • Systematic study of parameters on the synthesis of conical carbon nanofibers(G. Zhong, T. Iwasaki, H. Kawarada, I. Ohdomari)

    International Conference on New Diamond Science and Technology(The 9th )  

    発表年月: 2004年03月

  • Functionalized diamond surface by DNA covalent immobilization for bio-sensing applications(Functionalized diamond surface by DNA covalent immobilization for bio-sensing applications)

    International Conference on New Diamond Science and Technology(The 9th )  

    発表年月: 2004年03月

  • 超分散性ダイヤモンドを用いたナノバイオアプリケーション(中野善和, 梅沢仁, 張国軍, 宋光燮, 貝原雄, 座古保, 船津高志, 川原田洋)

    ダイヤモンドシンポジウム(第17回)  

    発表年月: 2003年11月

  • ダイヤモンドin-plane-gated FETのヒステリシス特性(伊藤裕, 澄川雄, 小林健作, 立木実, 梅沢仁, 川原田洋)

    ダイヤモンドシンポジウム(第17回)  

    発表年月: 2003年11月

  • 水素終端表面伝導層を用いたサブミクロンダイヤモンドFETのDC・RF特性(梅沢仁、川原田洋)

    電子情報通信学会  

    発表年月: 2003年09月

  • 多結晶ダイヤモンド基板を用いた微細電解質溶液ゲートFET(川村正太、川原田洋)

    電気化学秋季大会  

    発表年月: 2003年09月

  • 電解質ゲートダイヤモンドFETのpH感応性とバイオセンサ応用(金澤啓史、川原田洋)

    電気化学秋季大会  

    発表年月: 2003年09月

  • Biosensors based on diamond transistors

    European Conference on Diamond, Diamond-like Materials, Carbon Nanotubes, Nitrides and Silicon Carbide (the 14th )  

    発表年月: 2003年09月

  • Current-voltage hysteresis behaviour of Diamond in-plane-gated field effect transistors(Y. Sumikawa, M. Tachiki, K. Kobayashi, H. Umezawa, H. Kawarada)

    European Conference on Diamond, Diamond-like Materials, Carbon Nanotubes, Nitrides and Silicon Carbide(the 14th )  

    発表年月: 2003年09月

  • pH-dependence of electrolyte-solution-gate field-effect-transistors using aminated diamond surface(Y. Nakamura, K. S. Song, H. Kanazawa, T. Sakai, H. Umezawa, M. Tachiki, H. Kawarada)

    European Conference on Diamond, Diamond-like Materials, Carbon Nanotubes, Nitrides and Silicon Carbide(the 14th )  

    発表年月: 2003年09月

  • Surface potential measurements for DNA-immobilized diamond(Y. Kaibara, H. Umezawa, M. Tachiki, H. Hata, K. S. Song, G.. J. Zhang, I. Ohdomari, H. Kawarada)

    European Conference on Diamond, Diamond-like Materials, Carbon Nanotubes, Nitrides and Silicon Carbide(the 14th)  

    発表年月: 2003年09月

  • RF-Diamond-MISFETs on High-Mobility Diamond Substrates(S. Miyamoto, H. Matsudaira, M. Kohno, K. Hirama, H. Umezawa, M. Tachiki, H. Kawarada)

    European Conference on Diamond, Diamond-like Materials, Carbon Nanotubes, Nitrides and Silicon Carbide(the 14th )  

    発表年月: 2003年09月

  • Sub-micron gate Diamond MISFETs characteristics(H. Matsudaira, S. Miyamoto, K. Hirama, H. Umezawa, H. Kawarada)

    European Conference on Diamond, Diamond-like Materials, Carbon Nanotubes, Nitrides and Silicon Carbide(the 14th)  

    発表年月: 2003年09月

  • Cathodoluminescence of excitons and electron hole liquid of type Ⅱa diamond(H. Kawai, K. Nakazawa, M. Tachiki, H. Umezawa, H. Kawarada)

    European Conference on Diamond, Diamond-like Materials, Carbon Nanotubes, Nitrides and Silicon Carbide(the 14th )  

    発表年月: 2003年09月

  • Nano-scale surface modification of diamond utilizing Gas-Introduced Electron Beam Lithography (GIEBL)(H. Hata, H. Umezawa, Y. Kaibara, K. S. Song, M. Tachiki, H. Kawarada)

    European Conference on Diamond, Diamond-like Materials, Carbon Nanotubes, Nitrides and Silicon Carbide(the 14th )  

    発表年月: 2003年09月

  • ゲート抵抗低減によるダイヤモンドMISFETの高周波特性の改善(平間一行, 宮本真吾, 松平弘樹, 小林健作, 河野真宏, 梅沢仁, 川原田洋)

    応用物理学会(第64回)  

    発表年月: 2003年08月

  • ガス導入電子線描画装置による微細領域へのマスクレスダイヤモンド表面修飾(新井達也, 畑英夫, 梅沢仁, 貝原雄, 宋光燮, 川原田洋)

    応用物理学会(第64回)  

    発表年月: 2003年08月

  • ダイヤモンド微細in-plane-gated FETにおける特性解析(小林健作, 立木実, 澄川雄, 伊藤裕, 梅沢仁, 川原田洋)

    応用物理学会(第64回)  

    発表年月: 2003年08月

  • 電解質ゲートダイヤモンドFETを利用したグルコースセンサ(出川宗里, 宋光燮, 金澤啓史, 中村雄介, 川村正太, 佐々木順紀, 栗原裕介, 梅沢仁, 川原田洋)

    応用物理学会(第64回)  

    発表年月: 2003年08月

  • 電解質ゲートダイヤモンドFETを用いたダイヤモンド表面のpH感応性評価(佐々木順紀, 宋光燮, 金澤啓史, 中村雄介, 川村正太, 出川宗里, 栗原裕介, 梅沢仁, 川原田洋)

    応用物理学会(第64回)  

    発表年月: 2003年08月

  • 高密度励起子下におけるⅡa型ダイヤモンドの電子正孔液滴と束縛励起子(荻原大輔, 河井啓朗, 松平弘樹, 梅沢仁, 川原田洋)

    応用物理学会(第64回)  

    発表年月: 2003年08月

  • ダイヤモンドin-plane-gated FETのヒステリシス特性(伊藤裕, 澄川雄, 小林健作, 立木実, 梅沢仁, 川原田洋)

    応用物理学会(第64回)  

    発表年月: 2003年08月

  • Urea sensor used hydrogen-terminated polycrystalline diamond FETs(K. S. Song, T. Sakai, H. Kanazawa, N. Fujihara, Y. Nakamura, S. Kawamura, H. Umezawa, M. Tachiki, H. Kawarada)

    Electrochemical Society 2003  

    発表年月: 2003年04月

  • Potential-Sensitive Detection of Charged Biomolecules on Functional Diamond Surface(H. Umezawa, M. Tachiki, Y. Kaibara, T. Sakai, K. S. Song, H. Ishizaka, H. Kawarada)

    Electrochemical Society 2003  

    発表年月: 2003年04月

  • Chemically Modified Diamond Surfaces for Chemical Sensor Applications(H. Umezawa, H. Kawarada)

    2003 MRS(Spring Meeting)  

    発表年月: 2003年04月

  • アミノ修飾されたダイヤモンド電解質溶液ゲートFETのpH依存性(中村雄介, 宋光燮, 金澤啓史, 堺俊克, 梅沢仁, 立木実, 川原田洋)

    応用物理学会(第50回)  

    発表年月: 2003年03月

  • 水素終端多結晶ダイヤモンドFETを利用した尿素センサ(宋光燮, 堺俊克, 金澤啓史, 藤原直樹, 中村雄介, 川村正太, 梅沢仁, 立木実, 川原田洋)

    応用物理学会(第50回)  

    発表年月: 2003年03月

  • 微細電解質溶液ゲートFETの作製[Ⅱ](川村正太, 藤原直樹, 宋光燮, 金澤啓史, 堺俊克, 梅沢仁, 川原田洋)

    応用物理学会(第50回)  

    発表年月: 2003年03月

  • ダイヤモンド in-plane-gated FETの相互コンダクタンス向上とヒステリシス効果(小林健作, 立木実, 坂野時習, 澄川雄, 梅沢仁, 川原田洋)

    応用物理学会(第50回)  

    発表年月: 2003年03月

  • DNA修飾ダイヤモンドにおける表面電位測定(貝原雄, 梅沢仁, 畑英夫, 金澤啓史, 宋光燮, 張国軍, 立木実, 川原田洋)

    応用物理学会(第50回)  

    発表年月: 2003年03月

  • ハイパワートランジスタの最適化構造(河野真宏, 宮本真吾, 松平弘樹, 石坂博明, 中澤一志, 宋光燮, 梅沢仁, 立木実, 川原田洋)

    応用物理学会(第50回)  

    発表年月: 2003年03月

  • 高密度励起下におけるⅡa型ダイヤモンドの励起子と電子正孔液滴のCL評価(河井啓朗, 中澤一志, 梅沢仁, 立木実, 川原田洋)

    応用物理学会(第50回)  

    発表年月: 2003年03月

  • ダイヤモンド表面へのDNAの固定化及びハイブリダイゼーション

    応用物理学会(第50回)  

    発表年月: 2003年03月

  • Diamond nanofabrication and electronics for biosensing application(M. Tachiki , H. Kawarada)

    Surface and Bulk Defects in CVD Diamond Films Ⅷ  

    発表年月: 2003年02月

  • RF Characteristics of Diamond Surface Channel FETs(H. Umezawa, S. Miyamoto, H. Matsudaira, H. Ishizaka, M. Tachiki, H. Kawarada)

    TWHM 2003  

    発表年月: 2003年01月

  • Diamond Power Transistors(H. Umezawa, H. Kawarada)

    2002 MRS(Fall Meeting)  

    発表年月: 2002年12月

  • フッ素・酸素・アミノ基によるダイヤモンドの微細領域表面化学修飾(畑英夫, 梅沢仁, 石坂博明, 貝原雄, 金澤啓史, 藤原直樹, 堺俊克, 宋光燮, 張国軍, 立木実, 座古保, 船津和夫, 川原田洋)

    ダイヤモンドシンポジウム(第16回)  

    発表年月: 2002年11月

  • ダイヤモンドISFETへのオゾン処理の影響(中村雄介, 金澤啓史, 堺俊克, 宋光燮, 梅沢仁, 立木実, 川原田洋)

    ダイヤモンドシンポジウム(第16回)  

    発表年月: 2002年11月

  • 多結晶ダイヤモンド基板を用いた微細電解質溶液ゲートFETの作製(川村正太, 藤原直樹, 宋光燮, 金澤啓史, 堺俊克, 梅沢仁, 川原田洋)

    ダイヤモンドシンポジウム(第16回)  

    発表年月: 2002年11月

  • ダイヤモンドin-plane-gated FETのゲートリーク電流の低減(小林健作, 立木実, 梅沢仁, 坂野時習, 澄川雄)

    ダイヤモンドシンポジウム(第16回)  

    発表年月: 2002年11月

  • 表面チャネル型ダイヤモンドFETの特性評価(河野真宏, 宮本真吾, 松平弘樹, 石坂博明, 中澤一志, 宋光燮, 梅沢仁, 立木実, 川原田洋)

    ダイヤモンドシンポジウム(第16回)  

    発表年月: 2002年11月

  • Nanoscale Characterization of the Modified Functional Diamond Surface by Kelvin Force Microscope(M. Tachiki , H. Kawarada)

    Internatioal Colloquium on Scanning Probe Microscopy(10th)  

    発表年月: 2002年11月

  • KFMによる水素終端ダイヤモンド表面微細構造の評価(立木実、川原田洋)

    応用物理学会(第63回)  

    発表年月: 2002年09月

  • 高温高圧合成Ⅱaダイヤモンドにおける励起子発光の非線形増加(中澤一志、川原田洋)

    応用物理学会(第63回)  

    発表年月: 2002年09月

  • 水素終端ダイヤモンドを用いたイオン感応性FETへのオゾン処理の影響(中村雄介、川原田洋)

    応用物理学会(第63回)  

    発表年月: 2002年09月

  • 微細電解質溶液ゲートFETの作製(川村正太、川村正太)

    応用物理学会(第63回)  

    発表年月: 2002年09月

  • ダイヤモンドin-plane-gated FETのゲートリーク電流の低減(小林健作、川原田洋)

    応用物理学会(第63回)  

    発表年月: 2002年09月

  • 表面パッシベートされた微細ダイヤモンドFETの高周波諸特性(宮本真吾、川原田洋)

    応用物理学会(第63回)  

    発表年月: 2002年09月

  • Cryogenic operation of diamond surface-channel electronic devices(H. Ishizaka, H. Kawarada)

    SSDM 2002  

    発表年月: 2002年09月

  • Control of tunnel barrier in slit structure by side gate potential for diamond single gate hole transistors(Y. Sumikawa, H. Kawarada)

    13th European Conference on Diamond,Diamond-like Materials,Carbon Nanotubes,Nitrides &amp; Silicon Carbide(Diamond 2002)  

    発表年月: 2002年09月

  • Adhension force measurement for the hydrogen-terminated diamond surface and the oxidized area using atomic force microscope(Y. Kaibara, H. Kawarada)

    13th European Conference on Diamond,Diamond-like Materials,Carbon Nanotubes,Nitrides &amp; Silicon Carbide(Diamond 2002)  

    発表年月: 2002年09月

  • Initial growth of heteroepitaxial diamond on Ir(001)/MgO(001) substrates using antenna-edge microwave plasma assisted chemical vapor deposition(T. Fujisaki, H. Kawarada)

    13th European Conference on Diamond,Diamond-like Materials,Carbon Nanotubes,Nitrides &amp; Silicon Carbide(Diamond 2002)  

    発表年月: 2002年09月

  • Field-effect control of the nano-scale channel conductance on hydrogen-terminated diamond surface(T. Banno, H. Kawarada)

    13th European Conference on Diamond,Diamond-like Materials,Carbon Nanotubes,Nitrides &amp; Silicon Carbide(Diamond 2002)  

    発表年月: 2002年09月

  • High Performance diamond MISFETs using CaF2 gate insulator(S. Miyamoto, H. Kawarada)

    13th European Conference on Diamond,Diamond-like Materials,Carbon Nanotubes,Nitrides &amp; Silicon Carbide(Diamond 2002)  

    発表年月: 2002年09月

  • High sensitive electrolyte solution gate FET on polished polycrystalline diamond(N. Fujihara, H. Kawarada)

    13th European Conference on Diamond,Diamond-like Materials,Carbon Nanotubes,Nitrides &amp; Silicon Carbide(Diamond 2002)  

    発表年月: 2002年09月

  • Ion sensitivity of hydrogen-terminated diamond(H. Kanazawa, H. Kawarada)

    13th European Conference on Diamond,Diamond-like Materials,Carbon Nanotubes,Nitrides &amp; Silicon Carbide(Diamond 2002)  

    発表年月: 2002年09月

  • Nonlinear increase of excitonic emision in synthetic type IIa diamond(K. Nakazawa, H. Kawarada)

    International conference New Diamond Science and Technology(8th)  

    発表年月: 2002年07月

  • Nanoelectronics based on diamond surfaces(H. Kawarada, M. Tachiki, H. Umezawa)

    International Conference New Diamond Science and Technology (8th)  

    発表年月: 2002年07月

  • Ozone Treated Channel Diamond FETs(T. Sakai, H. Kawarada)

    International Conference New Diamond Science and Technology (8th)  

    発表年月: 2002年07月

  • Deep sub-micron gate diamond MISFETs(H. Matsudaira, H. Kawarada)

    International Conference New Diamond Science and Technology (8th)  

    発表年月: 2002年07月

  • Nanoelectronics based on diamond surfaces(H. Kawarada, M. Tachiki, H. Umezawa)

    International Conference New Diamond Science and Technology (8th)  

    発表年月: 2002年07月

  • Cryogenic operation of surface channel diamond field-effect transistors(M. Tachiki, H. Kawarada)

    International Cnference New Diamond Science and Technology (8th)  

    発表年月: 2002年07月

  • Characteristic of electrolyte-solution-gate diamond FETs for biosensor(K. S. Song, H. Kawarada)

    World Congress on Biosensors 2002(7th)  

    発表年月: 2002年05月

  • ダイヤモンド水素終端表面におけるハロゲンイオンの影響(堺俊克, 川原田洋)

    電気化学会(第69回)  

    発表年月: 2002年04月

  • Low-temperatures operation of diamond surface -channel field-effect-transistors(M. Tachiki, H. Kawarada)

    2002 MRS(spring meeting)  

    発表年月: 2002年04月

  • Cl-ion sensing using electrolyte-solution-gate diamond FETs(K. S. Song, H. Kawarada)

    2002 MRS(spring meeting)  

    発表年月: 2002年04月

  • ダイヤモンド表面上の電荷と物質吸着の計算化学による評価(米窪大介, 川原田洋)

    応用物理学関係連合講演会(第49回)  

    発表年月: 2002年03月

  • 先端放電型マイクロ波プラズマCVD装置を用いたIr基板上へのヘテロエピタキシャルダイヤモンド核形成初期課程の考察(藤崎豊克, 川原田洋)

    応用物理学関係連合講演会(第49回)  

    発表年月: 2002年03月

  • 硫黄ドープダイヤモンドの電気的及びカソードルミネッセンス評価(中澤一志, 川原田洋)

    応用物理学関係連合講演会(第49回)  

    発表年月: 2002年03月

  • オゾン処理により高抵抗化された水素終端チャネルでのFET特性(宋光燮, 川原田洋)

    応用物理学関係連合講演会(第49回)  

    発表年月: 2002年03月

  • 極低温状態における表面チャネル型ダイヤモンドFETの特性評価(石坂博明, 川原田洋)

    応用物理学関係連合講演会(第49回)  

    発表年月: 2002年03月

  • サイドゲートポテンシャルによるスリット構造トンネル障壁の制御(澄川雄, 川原田洋)

    応用物理学関係連合講演会(第49回)  

    発表年月: 2002年03月

  • ダイヤモンドMISFETの特性改善(松平弘樹, 川原田洋)

    応用物理学関係連合講演会(第49回)  

    発表年月: 2002年03月

  • 水素終端ダイヤモンドのハロゲンイオン感応性(金澤啓史, 川原田洋)

    応用物理学関係連合講演会(第49回)  

    発表年月: 2002年03月

  • CaF2パッシベートされたダイヤモンド表面伝導層の移動度上昇(宮本真吾, 川原田洋)

    応用物理学関係連合講演会(第49回)  

    発表年月: 2002年03月

  • アドヒージョンフォースマッピング測定による水素終端ダイヤモンド表面とAFM局所酸化領域の吸着力評価(貝原雄, 川原田洋)

    応用物理学関係連合講演会(第49回)  

    発表年月: 2002年03月

  • Nanotransistors on diamond surfaces(H. Kawarada)

    International Symposium on Advance Materials (ISAM2002)(9th)  

    発表年月: 2002年03月

  • Cathodoluminescence of n-type diamond(. Ishizaka, H. Umezawa, H. Taniuchi, T. Arima, N. Fujihara, M. Tachiki H. Kawarada)

    ISAM2002  

    発表年月: 2002年03月

  • 表面チャネル型ダイヤモンドトランジスタの高周波・高出力特性(石坂博明, 川原田洋)

    2002年電子情報通信学会総合大会  

    発表年月: 2002年03月

  • ダイヤモンドを活用した新しいデバイスへの展開(川原田洋)

    応用物理学会北陸・信越支部学術講演会  

    発表年月: 2001年12月

  • Adhesion force measurement for hydrogen-terminated diamond surface and AFM lical Insulated area (K. Sugata, H. Kawarada)

    International Colloquium on Scanning Probe Microscopy(9th)  

    発表年月: 2001年12月

  • Fabrication of single hole transistor on hydrogen-terminated diamond using AFM anodic oxidation process(H. Seo, H. Kawarada)

    International Colloquium on Scanning Probe Microscopy(9th)  

    発表年月: 2001年12月

  • ダイヤモンド表面のエレクトロニクス・バイオ応用(川原田洋)

    日本表面科学会講演大会(第21回)  

    発表年月: 2001年11月

  • ダイヤモンド単正孔トランジスタのクーロンブロッケード特性(澄川雄, 川原田洋)

    ダイヤモンドシンポジウム(第15回)  

    発表年月: 2001年11月

  • 高性能化に向けたダイヤモンド微細MISFETの特性解析(松平 弘樹, 梅沢 仁, 立木 実, 大庭 誉士和, 有馬 拓也, 谷内 寛直, 田中 啓章, 藤原 直樹, 石坂 博明, 宮本 真吾, 宋 光燮, 川原田 洋)

    ダイヤモンドシンポジウム(第15回)  

    発表年月: 2001年11月

  • ハロゲンイオンがダイヤモンド水素終端表面伝導層に与える影響(金澤 啓史, 堺 俊克, 荒木 裕太, 宋 光燮, 梅沢 仁, 立木 実, 川原田 洋)

    ダイヤモンドシンポジウム(第15回)  

    発表年月: 2001年11月

  • ダイヤモンドFETの高周波評価(宮本真吾, 川原田洋)

    ダイヤモンドシンポジウム(第15回)  

    発表年月: 2001年11月

  • フォースカーブ測定による水素終端ダイヤモンド表面とAFM局所酸化領域の吸着力評価(貝原 雄, 米窪 大介, 須方 健太, 立木 実, 川原田 洋)

    ダイヤモンドシンポジウム(第15回)  

    発表年月: 2001年11月

  • ディープサブミクロンチャネルダイヤモンドMISFETの作製(有馬拓也, 川原田洋)

    電子情報通信学会ソサイエティ大会  

    発表年月: 2001年09月

  • ダイヤモンドMISFETの高周波評価(谷内寛直, 川原田洋)

    電子情報通信学会ソサイエティ大会  

    発表年月: 2001年09月

  • ダイヤモンドFETの構造最適化による特性改善(宮本 真吾, 石坂 博明, 谷内 寛直, 梅沢 仁, 川原田 洋)

    応用物理学会(第62回)  

    発表年月: 2001年09月

  • The effect of strong acid and alkaline solutions on H-terminated diamond surface chanel FETs(T. Sakai, H. Kawarada)

    European Conference on Diamond ,Diamond-Like Materials,Carbon Nanotubes,Nitrides and Sillicon Carbide(12th)  

    発表年月: 2001年09月

  • Fabrication of heteroepitaxial diamond thin films on Ir(001)/MgO(001) substrates using antenna-adge type microwave plasma assisted chemical vapor deposition(T. Fujisaki, H. Kawarada)

    European Conference on Diamond ,Diamond-Like Materials,Carbon Nanotubes,Nitrides and Sillicon Carbide(12th)  

    発表年月: 2001年09月

  • Fabrication of diamond single hole transistor using AFM anodization process(T. Banno、H.Kawarada)

    European Conference on Diamond ,Diamond-Like Materials,Carbon Nanotubes,Nitrides and Sillicon Carbide(12th)  

    発表年月: 2001年09月

  • Excitonic recombination radiation in phoshorus-and sulfur-doped CVD diamonds(K. Nakazawa, H. Kawarada)

    European Conference on Diamond ,Diamond-Like Materials,Carbon Nanotubes,Nitrides and Sillicon Carbide(12th)  

    発表年月: 2001年09月

  • High performance polycrystalline diamond MISFET(H. Umezawa, H. Kawarada)

    European Conference on Diamond ,Diamond-Like Materials,Carbon Nanotubes,Nitrides and Sillicon Carbide(12th)  

    発表年月: 2001年09月

  • Device simulation for the suppression of short channel effect(H. Tanaka, H. Kawarada)

    European Conference on Diamond ,Diamond-Like Materials,Carbon Nanotubes,Nitrides and Sillicon Carbide(12th)  

    発表年月: 2001年09月

  • High Frequency operation of diamond FETs(H. Ishizaka, H. Kawarada)

    European Conference on Diamond ,Diamond-Like Materials,Carbon Nanotubes,Nitrides and Sillicon Carbide(12th)  

    発表年月: 2001年09月

  • Electrolyte-solution-gate diamond FETs operated in Cl ionic solution(T. Sakai, H. Kawarada)

    2001 international conference on solid state devices and materials  

    発表年月: 2001年09月

  • High frequency applications of polycrystalline diamond field-effect transistors(H. Umezawa, H. Kawarada)

    2001 international conference on solid state devices and materials  

    発表年月: 2001年09月

  • Heteroepitaxial Diamond thin film growth on Ir(001)/MgO(001) substrate by antenna-edge plasma assisted chemical vapor deposition(M. Tachiki, H. Kawarada)

    The thirteenth international conference on crystal growth in conjunction with the eleventh international conference on vapor growth nad epitaxy  

    発表年月: 2001年07月

  • Nanodevice fabrication on hydrogenated diamond surface using atomic force microscope (M. Tachiki, H. Kawarada)

    International workshop on quantum nonplanar nanostructures &amp; nanoelectronics '01(1st)  

    発表年月: 2001年07月

  • Nano scale oxidation on the hydrogen-terminated diamond surface for diamond nano technology(M. Tachiki, H. Kawarada)

    2001 MRS(spring meeting)  

    発表年月: 2001年04月

  • Nanoscale fabrication on hydrogenated diamond surface using atomic force microscope(M. Tachiki , H. Kawarada)

    2001 MRS(spring meeting)  

    発表年月: 2001年04月

  • High frequency performance of diamond field-effect transistor(H. Umezawa, H. Kawarada)

    2001 MRS(spring meeting)  

    発表年月: 2001年04月

  • Fabrication of sub-0.1 micron channel diamond MISFET(H. Umezawa, H. Kawarada)

    2001 MRS(spring meeting)  

    発表年月: 2001年04月

  • Nanoscale local oxidation on hydrogenated diamond surface using atomic force microscope for quantum device fabrication(M. Tachiki, H. Kawarada)

    International symposium on advanced physical field "Growth of Well-defined Nanostructures"(6th)  

    発表年月: 2001年03月

  • Local oxidation on hydrogenated diamond surface using atomic force microscope for quantum nanodevice fabrication(M. Tachiki, H. Kawarada)

    International symposium on diamond electronic devices(3rd)  

    発表年月: 2001年01月

  • High frequency operation of hydrogen-terminated surface-channel diamond field-effect transistors(H. Umezawa, H. Kawarada)

    International symposium on diamond elecronic devices(3rd)  

    発表年月: 2001年01月

  • Electro-chemical applications of diamond(H. Kawarada)

    New Materials for Multifunctional Sensor Applications  

    発表年月: 2000年12月

  • ディープサブミクロンゲートダイアモンドFETの作製(有馬拓也, 川原田洋)

    第47回応用物理学関係連合講演会  

    発表年月: 2000年03月

  • Diamond-SiC界面の構造についてのクラスター計算(Ⅴ)(日根恭子, 川原田洋)

    第47回応用物理学関係連合講演会  

    発表年月: 2000年03月

  • リアクティブ・イオン・エッチングによるダイヤモンド薄膜の微細加工(田辺憲司, 川原田洋)

    第47回応用物理学関係連合講演会  

    発表年月: 2000年03月

  • 水素終端ダイヤモンドFETのマイクロ波デバイス評価(谷内寛直, 川原田洋)

    第47回応用物理学関係連合講演会  

    発表年月: 2000年03月

  • ダイヤモンド表面におけるAFMナノファブリケーションによるトンネル接合の作製(瀬尾北斗, 川原田洋)

    第47回応用物理学関係連合講演会  

    発表年月: 2000年03月

  • AFMによるダイヤモンド表面加工領域の形状変化に対する評価(須方健太, 川原田洋)

    第47回応用物理学関係連合講演会  

    発表年月: 2000年03月

  • 電解質水溶液中のダイヤモンドFET(荒木裕太, 川原田洋)

    第47回応用物理学関係連合講演会  

    発表年月: 2000年03月

  • Local Insulation of Semiconducting Diamond Surfaces using Atomic Force Microscope

    The 7th International Colloquium on Scanning Probe Microscopy/応用物理学会  

    発表年月: 1999年12月

  • セルフアラインシステムを用いた1μmゲート水素終端ダイヤモンドFET(谷内寛直, 川原田洋)

    SiC及び関連ワイドギャップ半導体研究会/応用物理学会  

    発表年月: 1999年12月

  • Nanofabrication on Hydrogen-Terminated Diamond Surface AFM-Probe-Induced Oxidation(M. Tachiki, H. Kawarada)

    International Symposium on Surface Science for Micro-and Nano-Device Fabrication  

    発表年月: 1999年12月

  • 水素終端ダイヤモンドFETにおけるプロセス改善による寄生抵抗の制御(有馬拓也, 川原田洋)

    第13回ダイヤモンドシンポジウム  

    発表年月: 1999年11月

  • セルフアラインプロセスを用いたCu/CaF2/Diamond MISFET(梅沢仁, 川原田洋)

    第13回ダイヤモンドシンポジウム  

    発表年月: 1999年11月

  • ダイヤモンド表面チャネル型電界効果トランジスタのキャリアの量子化を考慮したデバイスシミュレーション(大庭誉士和, 川原田洋)

    第13回ダイヤモンドシンポジウム  

    発表年月: 1999年11月

  • AFMによるダイヤモンド表面機能性の制御(瀬尾北斗, 川原田洋)

    第13回ダイヤモンドシンポジウム  

    発表年月: 1999年11月

  • 走査型プローブ顕微鏡による水素終端ダイヤモンド表面のナノファブリケーションおよび電気特性(須方健太, 川原田洋)

    第13回ダイヤモンドシンポジウム  

    発表年月: 1999年11月

  • Diamond-SiCおよびDiamond-Si界面構造についてのクラスター計算(森田和敏, 川原田洋)

    第13回ダイヤモンドシンポジウム  

    発表年月: 1999年11月

  • アルカリ溶液中におけるダイヤモンドISFET(小川雄史, 川原田洋)

    第13回ダイヤモンドシンポジウム  

    発表年月: 1999年11月

  • Controlling of Adsorbates and Conduction on CVD-grown Diamond Surface by Scanning Probe Microscopev(M. Tachiki, H. Kawarada)

    3rd International Symposium on Control of Semiconductor Interfaces  

    発表年月: 1999年10月

  • High Performance Diamond Surface-Channel Field-Effect Transistors(H. Umezawa, H. Kawarada)

    3rd International Symposium on Control of Semiconductor Interfaces  

    発表年月: 1999年10月

  • AFMによるダイヤモンド表面の吸着原子制御(立木実, 川原田洋)

    第60回応用物理学会学術講演会  

    発表年月: 1999年09月

  • 水素終端ダイヤモンドFETにおけるプロセス改善による相互コンダクタンスの向上(有馬拓也, 川原田洋)

    第60回応用物理学会学術講演会  

    発表年月: 1999年09月

  • AFMを用いた電界支援酸化による水素終端ダイヤモンド表面のナノ加工(福田徹, 川原田洋)

    第60回応用物理学会学術講演会  

    発表年月: 1999年09月

  • 平坦化された多結晶ダイヤモンドにおける酸素プラズマエッチング(田辺憲司, 川原田洋)

    第60回応用物理学会学術講演会(No.2)  

    発表年月: 1999年09月

  • ダイヤモンド表面チャネル型FETのデバイスシミュレーション(津川和夫, 川原田洋)

    第60回応用物理学会学術講演会  

    発表年月: 1999年09月

  • セルフアラインプロセスを用いたダイヤモンドMISFETの製作(谷内寛直, 川原田洋)

    第60回応用物理学会学術講演会  

    発表年月: 1999年09月

  • Diamond-SiC界面の構造についてのクラスター計算(Ⅳ)(森田和敏, 川原田洋)

    第60回応用物理学会学術講演会  

    発表年月: 1999年09月

  • アンドープ水素終端ダイヤモンド表面の電極評価

    第60回応用物理学会学術講演会  

    発表年月: 1999年09月

  • High Performance Diamond Field Effect Transistors Using Hydrogen-Terminated Surfaces for Electron Device and Sensor Applications

    Proc ADC/FCT'99/NEDO,JFCC  

    発表年月: 1999年09月

  • Cluster Calculation of Diamond-SiC Interface Structures(K. Morita, H. Kawarada)

    10th European Conference on Diamond, Diamond-Like Materials, Nitrides and Silicon Carbide  

    発表年月: 1999年09月

  • Fabrication of High Performance 1μm Gate Diamond FET Using Self-Aligned Gate Process(H. Umezawa, H. kawarada)

    10th European Conference on Diamond, Diamond-Like Materials, Nitrides and Silicon Carbide  

    発表年月: 1999年09月

  • Ion Sensitive Field Effect Transistor on Hydrogen-terminated Polycrystalline Diamond Surfaces

    10th European Conference on Diamond, Diamond-Like Materials, Nitrides and Silicon Carbide  

    発表年月: 1999年09月

  • ダイヤモンド水素終端面を用いたISFET(北谷謙一, 川原田洋)

    応用物理学会(第46回)  

    発表年月: 1999年03月

  • 微細化によるダイヤモンドMISFETの特性改善(梅澤仁, 川原田洋)

    応用物理学会(第46回)  

    発表年月: 1999年03月

  • Diamond-SiC界面構造についてのクラスター計算(Ⅲ)(森田和敏, 川原田洋)

    応用物理学会(第46回)  

    発表年月: 1999年03月

  • 先端放電型マイクロ波プラズマCVDによるダイヤモンドの成長(福田徹, 川原田洋)

    ダイヤモンドシンポジウム(第12回)  

    発表年月: 1998年12月

  • セルフアライン法による1μmゲートFETの作製(梅澤仁, 川原田洋)

    ダイヤモンドシンポジウム(第12回)  

    発表年月: 1998年12月

  • リンドープ{111}ホモエピタキシャルダイヤモンド薄膜のCL評価(田辺憲司, 川原田洋)

    ダイヤモンドシンポジウム(第12回)  

    発表年月: 1998年12月

  • セルフアライン法による1μmゲートFETの作製(梅澤仁, 川原田洋)

    応用物理学関連講演会(第59回)  

    発表年月: 1998年09月

  • リンドープ{111}ホモエピタキシャルダイヤモンド薄膜のCL評価(田辺憲司, 川原田洋)

    応用物理学関連講演会(第59回)  

    発表年月: 1998年09月

  • Diamond-Sic界面構造についてのクラスター計算(Ⅱ)(森田和敏, 川原田洋)

    応用物理学関連講演会(第59回)  

    発表年月: 1998年09月

  • 窒素イオン支援レーザー蒸着法により成膜したBCN膜の化学結合性(小川雄史, 川原田洋)

    応用物理学関連講演会(第59回)  

    発表年月: 1998年09月

  • High-Performance Diamond Surface Channel FETs and Their Operation Mechanism (Invited presentation)(K. tsugawa, H. Kawarada)

    9th European Conference on Diamond, Diamond-Like Materials,Nitrides and Silicon Carbide  

    発表年月: 1998年09月

  • FETs Fabrication on Hydrogen-Terminated Polycrystalline Diamond Surfaces(K. Kitatani, H. Kawarada)

    9th European Conference on Diamond, Diamond-Like Materials,Nitrides and Silicon Carbide  

    発表年月: 1998年09月

  • Diamond field effect transistors using hydrogen-terminated surfaces (H. Kawarada)

    Topical Workshop on Heterostructure Microelectronics for Information System Applications  

    発表年月: 1998年08月

  • Surface p-channel Metal-oxide-semiconductor Field Effect Transisitors Fabricated on Hydrogen Terminated(001) Surfaces of Diamond (Invited presentation)(H. Kawarada)

    CIMTEC-World Ceramics Congress &amp;Forum on New Materials, on Diamond, Diamond-Like Materials, Carbon Nanotubes, Nitrides &amp; Silicon Florence  

    発表年月: 1998年08月

  • ダイヤモンド水素終端面を用いたFETの耐圧特性(北谷謙一, 川原田洋)

    第45回応用物理学関係連合講演会/応用物理学会  

    発表年月: 1998年03月

  • Diamond-SiC界面構造についてのクラスター計算(I)(森田和敏, 川原田洋)

    第45回応用物理学関係連合講演会/応用物理学会  

    発表年月: 1998年03月

  • 先端放電型マイクロ波プラズマCVDによるダイヤモンド形成(II)(江田研一郎, 川原田洋)

    第45回応用物理学関係連合講演会/応用物理学会  

    発表年月: 1998年03月

  • 水素終端ダイヤモンド表面を用いたMESFETのデバイスシミュレーション(II)

    第45回応用物理学関係連合講演会/応用物理学会  

    発表年月: 1998年03月

  • マイクロ波プラズマによるダイヤモンド精製の無限大面積技術

    第45回応用物理学関係連合講演会/応用物理学会  

    発表年月: 1998年03月

  • Metal-Semiconductor Field-Effect Transistors on Hydrogen-Terminated Diamond Surfaces

    Synposium on Diamond Electronics Devices' 98  

    発表年月: 1998年03月

  • High-Performance Surface Channel Field Effect Transistors on Hydrogen-Terminated Diamond Surfaces

    ハードエレクトロニクス'98国際ワークショップ  

    発表年月: 1998年02月

  • 平坦化された多結晶ダイヤモンドを用いたMOSFET(北谷謙一, 川原田洋)

    第11回ダイヤモンドシンポジウム/ニューダイヤモンドフォーラム  

    発表年月: 1997年12月

  • 水素終端ダイヤモンド表面をもちいたFETのデバイスシミュレーション

    第11回ダイヤモンドシンポジウム/ニューダイヤモンドフォーラム  

    発表年月: 1997年12月

  • 平坦化された多結晶ダイヤモンドを用いたMOSFET(北谷謙一, 川原田洋)

    第58回応用物理学会学術講演会/応用物理学会  

    発表年月: 1997年10月

  • 水素終端ダイヤモンド表面のMOSFETシミュレーション(森田和敏, 川原田洋)

    第58回応用物理学会学術講演会/応用物理学会  

    発表年月: 1997年10月

  • 先端放電型マイクロ波プラズマCVDによるダイヤモンドの形成

    第58回応用物理学会学術講演会/応用物理学会  

    発表年月: 1997年10月

  • ダイヤモンドのヘテロエピタキシャル成長と電界効果トランジスタ

    学術振興会半導体界面制御技術第154委員会第20回研究会/日本学術振興会  

    発表年月: 1997年10月

  • MESFETs and MISFETs on hydrogen-terminated diamond surfaces (K. Tsugawa, H. Kawarada)

    The International Conference on Silicon Carbide,Ⅲ-Nitride and Related Materials  

    発表年月: 1997年08月

  • ダイヤモンドFETと回路技術の現状

    第107回応用物理学会結晶工学分科会研究会/応用物理学会  

    発表年月: 1997年05月

  • 水素終端ダイヤモンド表面を用いたMISFETの高温動作

    第44回応用物理学関係連合講演会/応用物理学会  

    発表年月: 1997年03月

  • 水素終端ダイヤモンド表面に作製したショットキーダイオードの電気的特性

    第44回応用物理学関係連合講演会/応用物理学会  

    発表年月: 1997年03月

  • 傾斜β-SiC表面上のダイヤモンドヘテロエピタキシャル成長

    第44回応用物理学関係連合講演会/応用物理学会  

    発表年月: 1997年03月

  • β-SiC基板上ヘテロエピタキシャルダイヤモンド薄膜におけるMESFETの作製

    第44回応用物理学関係連合講演会/応用物理学会  

    発表年月: 1997年03月

  • ダイヤモンド自由励起子発光に対する表面処理効果

    第44回応用物理学関係連合講演会/応用物理学会  

    発表年月: 1997年03月

  • Heteroepitaxial Daimond Growth on β-SiC

    Int.Sym.Advanced Materials '97/Nat.Inst.Res.Inorga.Mat.  

    発表年月: 1997年03月

  • 表面終端処理の自由励起子発光への影響

    第10回ダイヤモンドシンポジウム/ニューダイヤモンドフォーラム  

    発表年月: 1996年12月

  • 金属/水素終端ダイヤモンド界面の電気的特性

    第10回ダイヤモンドシンポジウム/ニューダイヤモンドフォーラム  

    発表年月: 1996年12月

  • β-SiC基板上のヘテロエピタキシャルダイヤモンド薄膜におけるMESFETの作製

    第10回ダイヤモンドシンポジウム/ニューダイヤモンドフォーラム  

    発表年月: 1996年12月

  • E/D構成集積回路とMISFETの作製と評価

    第10回ダイヤモンドシンポジウム/ニューダイヤモンドフォーラム  

    発表年月: 1996年12月

  • ダイヤモンド電子デバイス

    SiCおよび関連ワイドギャップ半導体研究会/応用物理学会  

    発表年月: 1996年11月

  • Surface Characterization of Smooth Heteroepitaxial Diamond Layers on β-SiC (001)

    5th Int.Cof. the New Diamond Science and Technology  

    発表年月: 1996年09月

  • Enhancement/Depletion MESFETs of Diamond and Their Logic Circuits

    5th Int.Cof. the New Diamond Science and Technology  

    発表年月: 1996年09月

  • Device Modeling of High Performance Diamond MESFETs using p-type Surface Semiconductive Layers

    5th Int.Cof. the New Diamond Science and Technology  

    発表年月: 1996年09月

  • Comparative Study of Exitonic Recombination Radiation from Diamonds

    5th Int.Cof. the New Diamond Science and Technology  

    発表年月: 1996年09月

  • Heteroepitaxial Growth of Diamond on SiC (招待講演)

    Gordon Research Conference on "Diamond Film Synthesis"  

    発表年月: 1996年08月

  • Surface Properties of Hydrogen-terminated Diamonds and Their Applications to Electron Devices (招待講演)

    International School of Physics "Enrico Fermi",The Physics of Diamond/イタリア物理学会( )  

    発表年月: 1996年07月

  • β-SiC(100)基板上のダイヤモンドヘテロエピタキシャル成長のAFM観察

    第43回応用物理学関連連合講演会  

    発表年月: 1996年03月

  • メタン・酸素金剛ガスによって成膜されたホモエピタキシャルダイヤモンドのショットキー特性

    第43回応用物理学関連連合講演会  

    発表年月: 1996年03月

  • デプレッションモードダイヤモンドMESFETの作製と評価

    第43回応用物理学関連連合講演会  

    発表年月: 1996年03月

  • 表面伝導層ダイヤモンドMESFETの集積回路への基礎検討

    第56回応用物理学会学術講演会  

    発表年月: 1995年08月

  • 素子分離されたダイヤモンドMESFETの作製と評価II

    第56回応用物理学会学術講演会  

    発表年月: 1995年08月

  • cubic状CVDダイヤモンドのカソードルミネッセンス

    第56回応用物理学会学術講演会  

    発表年月: 1995年08月

  • CVDダイヤモンド表面のSTM/STS観察

    第56回応用物理学会学術講演会  

    発表年月: 1995年08月

  • (110), (111)基板上の燃焼炎 ホモエピタキシャルダイヤモンドの励起子発光

    第56回応用物理学会学術講演会  

    発表年月: 1995年08月

  • Surface and metal contact properties of H-terminated diamonds

    International Conference of Formation of Semiconductor Interfaces-5(招待講演)/Princeton  

    発表年月: 1995年07月

  • Breakdown Mechanism of C-H Diamond MOSFETs Compared with Other Wide Bandgap Materials

    H. Kawarada

    The 12th New Diamond and Nano Carbons Conference (NDNC 2018)   (Arizona, USA) 

    発表年月: 1980年05月

  • ダイヤモンド電界効果トランジスタの高周波デバイスおよびDNAセンサ応用

    応用物理学会シリコンテクノロジー  

▼全件表示

特定課題研究

  • ワイドギャップ半導体高速相補型FETによるノイズレス正弦波パワーインバータの開発

    2020年  

     概要を見る

    本研究では,n-FETにGaNを,p-FETにダイヤモンドというワイドバンドギャップ半導体を利用し、従来型インバータよりも1桁以上高速動作可能な相補型高電圧インバータの基本回路を作製した。縦型ダイヤモンドp-FETを世界に先駆けて開発し、電流密度20kAcm-2以上、オン抵抗2mΩcm2以下を達成した。耐圧は500V以上で、実電流で3Aを達成している。大学の環境で作製するFETとしては非常に高い実電流である。上記の結果は水素終端ダイヤモンド表面(700℃まで安定)を利用したものである。産業応用を考えるとより高温に安定な表面であるシリコン終端表面(1200℃まで安定)を利用したノーマリオフダイヤモンドMOSFETを世界に先駆けて開発した。相補型高電圧インバータをハーフブリッジ回路にてGaN n-FETとダイヤモンド p-FETにより作製し、スイッチング周波数で1MH以上での動作を世界に先駆けて確認した。ダイヤモンドp-FETとGaNのn-FETと組み合わせて,高速高電圧相補型インバータ回路を実現したことは高く評価される

  • ダイヤモンド高密度ナノドーピングによるスピン制御と超伝導(非採択となった2019年度科研費基盤Sと同一タイトル)

    2019年  

     概要を見る

    Nitrogen vacancy (NV) center in diamond is expected as a magneticsensor with high sensitivity at room temperature and single NV center succeededin detecting 1H spins out of the substrate. For improvement magneticsensitivity, both shallow and aligned NV ensemble is required since themagnetic sensitivity is inversely proportional to the root of number of NVcenters. N-terminated (111)surface was fabricated and thin layer (10 nm) of high purity (111) diamond filmwas epitaxially grown on the surface. We confirmed that N density in the highpurity diamond film and the formation of NV ensemble with 2D concentration of about1 x 1011 cm-2 using the confocal PL-intensity mapping.Superconducting quantum interference devices(SQUIDs) are widely used as high-sensitive magnetometers in several fields. However, there is still a problem with material instability in scanningSQUID microscope or quantum bit in quantum computing application. Superconductingboron-doped diamond shows excellent robustness in SQUID characteristics. We havedemonstrated a first single crystalline diamond SQUID, whose Josephson junctions (JJs) were formed by step-edge structure. However, it was operatedat 2.6 K. In this work, we have demonstrated diamond SQUIDs operating at 8.0 Kwell above liquid helium temperature 4.2 K using only (111) growth layer with Tc=10 K by using trench JJs.

  • ダイヤモンドpチャネル電界効果トランジスタによる相補型パワーインバータ

    2018年  

     概要を見る

    相補型インバータの実現にはほぼ同一性能のp-FETおよびn-FETが必須である.n-FETはGaNやSiCで充分な性能が期待されるが,これらの材料ではp-FETの性能がn-FETに対して1/10以下である.これがパワーインバータで相補型が達成されていない原因である.一方,ダイヤモンドのpチャネルFETは,特に水素終端(以下,C-H)ダイヤモンド表面に誘起される2次元正孔ガス(2 dimensional hole gas, 2DHG)をチャネルに利用するFETでは,高い電流駆動特性を有し,SiCやGaNのn-FETに比較し得る性能がでてきた.そこで,p-FETの高耐圧高速化が最も進んでいるダイヤモンドにおいて相補型高電圧回路でのp-FETを担わせることを前提に,ダイヤモンドp-FETの高耐圧化、高電流化、縦型化を行い、世界最高性能のp型パワー半導体デバイスを実現した.

  • 高耐圧ダイヤモンドトランジスタでの窒素空孔センターによる高電界空間分布測定

    2016年  

     概要を見る

    浅いNVセンターの領域に表面チャネル型の電界効果トランジスタ(FET)を形成し、オフ状態の高電界下で空乏層を伸長させることで、電気的にNV-の安定領域を制御する。表面からキャリア(正孔)を追い出し、空乏化するとポテンシャルは下向きに湾曲し、さらに高い電界ではフェルミ準位が真性フェルミ準位(ギャップ中央)よりも高くなる状すなわち反転状態がゲート電極近傍に出現する。これを実現するには高電圧(500V以上)高電界(1MV/cm)下で動作するプレーナー型FETが必要で、それを表面スピンの極めて少ない水素終端ダイヤモンド表面を利用して作製することが可能となった(Sci. Rep. 2017)。

  • ダイヤモンド電解質溶液トランジスタによるDNAセンサの集積化および高速計測

    2007年  

     概要を見る

    課題:ダイヤモンド電解質溶液トランジスタによるDNAセンサの集積化および高速計測液体電解質溶液中で動作するダイヤモンド・トランジスタ(ダイヤモンド電解質溶液FET:SGFET)の微細化やチャネル表面の修飾最適化による感度向上、高速化、ならびに検出物質の微量化により、電荷検出型DNAマイクロアレーの開発、一塩基遺伝子変異(一塩基多型、SNPs)検出を行う。ダイヤモンド表面上に直接修飾された化学反応基は空気中や液体中に安定で、その表面上に固定されたDNAはダイヤモンド表面との強く共有結合し、数十回ハイブリダイゼーションとディネーチャーを繰り返しても離れず安定である。一方、ダイヤモンド表面の吸着構造は一般的な有機化合物の部位であり、その安定性は高い。ダイヤモンド上の吸着原子・分子の変化(特に水素、酸素、フッ素、アミノ基)は、表面の電気伝導性、表面電荷、親水・疎水性に非常に大きな影響を与えるミクロサイズSGFETのチャネル(検出部)をミクロアレーし、その二つのチャネル部分に様々部分的な化学修飾処理した後、complementary DNAや一塩基遺伝子変異(SNPs)を共有結合による固定し、DNAのハイブリダイゼーションとSNPsでのハイブリダイゼーション効率による電位変化に成功した。この場合、固定された生体分子は一種の埋め込みゲートとして機能し、DNAハイブリダイゼーションより僅かな電位の変化を大きなドレイン電流変化とゲート電位変化として増幅できる。さらに、同じデバイス特性からハイブリダイゼーション効率によるcomplementary DNAとSNPsの電位差からSNPs判断が明らかになった。また、トランジスタのゲート長の微細化による相互コンダクタンス(性能)向上によりDNAやSNPsの高感度検出に成功し、ダイヤモンド上にマイクロアレー技術の適用により高速計測が可能になった。今後はDNAより構造的安定性を持つRNAやLNAを適用してcomplementary DNAとSNPsの検出を行い、最適化したダイヤモンドSNPsセンサの製作を行う。

  • 高密度正孔ガスを利用したダイヤモンド高出力マイクロ波および超伝導トランジスタ

    2006年  

     概要を見る

    ダイヤモンドFETの実用化に向けた熱的安定性とデバイス特性の改善を目的とし、平成18年度は以下の研究を行った。(1)PTFEパッシベーションによるホール蓄積層の耐熱性改善(2)ゲート長微細化によるデバイス特性の改善(1) PTFEパッシベーションによるホール蓄積層の耐熱性改善近年の研究によりダイヤモンドホール蓄積層の形成には水素終端に加えて大気中に存在している負イオンの存在が不可欠であることが明らかになりつつある。この負イオンは基板表面に物理吸着しているだけであるため、基板を加熱すると容易に基板表面から脱離する。その結果ホール蓄積層のキャリア密度が低減し、デバイス特性が劣化する。この問題を解決するため本年度はPTFEによるパッシベーションを行った。PTFEを塗布しない場合、室温で7kΩ/□のシート抵抗が200℃に加熱することで35kΩ/□まで劣化するのに対して、PTFEを塗布することで19kΩ/□に抑えられており、PTFEがホール蓄積層のパッシベーションに有効なことが明らかになった。今後はより最適な分子量のPTFEを探索し、高温下でより抵抗劣化の少ないダイヤモンドデバイスの作製を行う。(2) ゲート長微細化によるデバイス特性の改善加速電圧50kVの電子線リソグラフィー装置を利用してゲート長0.15μmのMISFETを作製した。ドレイン・ソース間はAuのウェットエッチングにより作製するがダイヤモンドMISFETの最大電流とオン抵抗はゲート・ソース間、ゲート・ドレイン間の寄生抵抗に大きく依存するため、高精度なエッチングが求められる。本研究では関東化学株式会社のAURUM302,303を用いることによりドレイン・ソース間を1μm以下にすることに成功した。最大ドレイン電流は650mA/mmでありダイヤモンドFETでは現在世界最高である。同MISFETのカットオフ周波数および最大発振周波数はそれぞれ42GHz,50GHzであった。カットオフ周波数はダイヤモンドMISFETで過去最高の値であり、ダイヤモンドMESFET(45GHz)と比較してもほぼ同程度まで改善している。

  • ダイヤモンド電解質溶液トランジスタによるDNA高速計測

    2006年  

     概要を見る

    ダイヤモンドは物理的・化学的に安定であり、広い電位窓、生体適合性、表面修飾が容易であるといった特性を持ち、バイオセンサへの応用が期待されている。我々はこのような性質を持つダイヤモンドの表面を機能化し、電荷検出型バイオセンサである電解質溶液ゲートFET(SGFET)を用いて、DNAの塩基ミスマッチの検出を試みた。行った表面修飾は、水素終端表面の部分的酸素化およびアミノ終端化である。このような表面修飾を行うことで、target DNAの塩基ミスマッチを顕在化させ、一塩基多形(SNPs)の検出に成功した。チャネル表面に固定されたprobe DNAにtarget DNAがハイブリダイゼーションすることによって、チャネル表面の近傍に存在する負電荷の量が変化する。この変化は、ダイヤモンドの表面伝導層に影響を及ぼし、FETのドレイン、ソース間の伝導性を変化させる。この変化が、Vgsの変化として観測できている。Target DNAに塩基ミスマッチが存在すると、DNA二本鎖に熱力学的な安定性は低下する。そのためハイブリダイゼーション効率は低下し、結果的にチャネル近傍の負電荷密度はComp. DNAに対し低下する。このため、Vgsの変化は少なくなる。Comp.DNAをハイブリダイゼーションさせた場合、30分間のハイブリダイゼーションで、Vgsは約5mV変化した。水素終端ダイヤモンド表面に部分的に修飾を施すことで、target DNAの塩基ミスマッチをSGFETの測定により検出することができた。これは、表面に存在する酸素終端の負の表面電荷による影響が働いていると考えることができる。表面が負に帯電することで、target DNAは反発力を受ける。この反発力は、表面へのDNAの物理吸着を抑制するとともに、probe DNAとのハイブリダイゼーションを阻害する方向に働く。この力が働くことにより、ハイブリダイゼーションの効率が変化し、より顕著に塩基ミスマッチを判別することができたと考えられる。このような、ダイヤモンドの表面修飾は非常に簡単なプロセスで行うことができる。

  • ダイヤモンド電界効果型トランジスタによる耐環境バイオセンサ

    1997年  

     概要を見る

    1<_イヤモンドヘテロエピタキシャル成長層でのMESFETヘテロエピタキシャル成長層上に金属半導体電界効果トランジスタ(MESFET)を作成した。ゲート長5μmで相互コンダクタンス7-8mS/mmと同ゲート長のダイヤモンドホモエピタキシャル成長層やシリコンMOSFETと同等レベルであり、これにより感度の高いイオン感応性FET(ISFET)が作成される可能性が得られた。2.デバイスシミュレーションによるダイヤモンドFETの動作解析 ドリフト・拡散モデルによるFETシミュレーションにより、表面p型伝導層のアクセプター分布が1nm以下の拡散長を有する極めて浅いものであることが理解され、イオン感応性の高いチャネル構造になっていることがわかった。3.多結晶層でのMOSFET 表面研磨により平坦化された多結晶ダイヤモンド表面におけるp型表面伝導層をチャネルとして、ゲート長8μmで相互コンダクタンス1mS/mmが得られている。この値はゲート幅を大きく取れるセンサーには十分なトランジスタ性能であり、大型ウェーハが得られる安価な多結晶ダイヤモンド基板において、使い捨てが要求されるバイオセンサーに必要なFETが作製可能なことが示され、工業化へのよい見通しを得ることができた。4.ダイヤモンド表面上でのISFETの製作 ダイヤモンド表面p型伝導層を使用したISFET構造作製のためのプロセス技術を検討した。ここで、重要なのはイオン感応膜となる絶縁層をダイヤモンド表面の水素終端構造を維持したまま作製する成膜技術である。現在、MOSFET作製にはSiOの真空蒸着によるSiOx膜を利用しているが、ボイド等の存在により、液体の浸透に対する稠密性が不十分であり、稠密性の高い感応膜として、還元性雰囲気でのプラズマ・シリコンナイトライド膜あるいは炭化水素膜を検討している。研究成果の発表1) 発表年月日 98年4月、発行所 米国物理学会、発表学会誌名 Appl. Phys. Lett.、論文題目“Surface Morphology and Surface p-Channel Field Effect Transistor on the Heteroepitaxial Diamond Deposited on Inclined β-SiC(001) Surfaces”( H.Kawarada, C.Wild, N.Herres, P.Koidl, Y.Mizuochi, A.Hokazono, and H.Nagasawa, Appl. Phys. Lett. 72 (1998) 1878)2) 発表年月日 98年2月、発行所 応用物理学会、発表学会誌名 応用物理 論文題目“ダイヤモンド電界効果トランジスタの現状と将来”(川原田洋, 応用物理  67 (1998) 128.)3) 発表年月日 98年8月(予定)、発行所 Springer-Verlag、著書名“Low Pressure Synthetic Diamond: Manufacturing and Applications, Chapter 8:Hetero-Epitaxy and Highly Oriented Diamond Deposition”

  • ダイヤモンド・ヘテロエピタキシャル成長層による耐環境電子デバイスの基礎検討

    1995年  

     概要を見る

    研究目的1)高品質SiC層を介したSi基板上のダイアモンドヘテロエピタキシャル成長の核形成過程の制御を行い,膜厚5μm以下で平坦となるダイアモンド単結晶層の形成技術を確立する。2)ヘテロエピタキシャル成長層での金属-半導体接合や金属-絶縁体-半途謡接合の最適化によりFET特性の安定化と相互コンダクタンスの向上を行い,耐環境下での論理回路動作の検討を行う。研究成果1)ヘテロエピタキシャル成長初期過程の制御 ヘテロエピタキシャル核形成に必要なSiC表面の構造に関する重要な知見を,初期成長過程の高分解能SEM観察から得ることが出来た{1}。これにより,初期過程を制御する上で不可欠であるプラズマ,温度,イオン加速エネルギーを最適化することが可能となった。現在最高1011cm-2と異種基板上のダイアモンドとしては非常に高い発生粒子密度を得ることができ,膜厚数μm以下でX線回析による方位ずれ角0.7°の平坦なダイアモンドヘテロエピタキシャル成長を行うことが可能となった。この値はダイアモンドヘテロエピタキシャル成長で現在のところ世界で最良の値である{2}。2)NAND回路,NOR回路,R-Sフリップフロップ回路の動作が確認 ホモエピタキシャル成長層ではあるが,NAND回路,NOR回路,R-Sフリップフロップ回路の動作が確認された。また相互コンダクタンスが10mS/mm以上のFET動作が確認された。これは世界でも初めての成果であり,目的とするヘテロエピタキシャル成長層でもデバイス特性向上において重要な指針となる{3, 4}。3)ヘテロエピタキシャル成長層でもMESFET作製 ゲート長5μm程度の金属-半導体FET(MESFET)を作製した。p型半導体領域としては水素終端表面を使用した。相互コンダクタンスでヘテロエピタキシャル成長層では最も高い5mS/mmを得ている。ソースおよびドレイン形成のためのオーミック電極にはAuを,ゲート形成のためにはA1を使用している。{1} T. Suesada, N. Nakamura, H. Nagasawa, and H. Kawarada, Jpn. Appl. Phys. 34 (1995) 4898{2} H. Kawarada, C. Wild, N. Herres, and P. Koidl, J. Appl. Phys. (1997) (印刷中){3} 日刊工業新聞 1995年5月10日{4} H. Kawarada, M. Itoh, and A. Hokazono, Jpn. Appl. Phys. 35 (1996) L1165

▼全件表示

 

現在担当している科目

▼全件表示

 

委員歴

  • 2014年04月
    -
     

    (社)ニューダイヤモンドフォーラム  顧問

  • 2010年04月
    -
    2014年03月

    New Diamond Forum  Chairman

  • 2010年04月
    -
    2014年03月

    (社)ニューダイヤモンドフォーラム  会長

  • 2012年10月
    -
     

    Science Council of Japan  Member

  • 2012年10月
    -
     

    日本学術会議  連携会員

  • 2005年04月
    -
    2007年03月

    Japan Applied Physics Society  Board Member

  • 2005年04月
    -
    2007年03月

    応用物理学会  理事

▼全件表示