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Master

Affiliation (Master)

  • Faculty of Information Science and Technology　Electronics for Informatics　Integrated Systems Engineering

Affiliation (Master)

  • Faculty of Information Science and Technology　Electronics for Informatics　Integrated Systems Engineering

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Profile and Settings

Profile and Settings

  • Name (Japanese)

    Katsuhiro

  • Name (Kana)

    Tomioka

  • Name

    200901095124047349

Alternate Names

Achievement

Research Interests

  • Thin film growth   結晶成長   量子構造   ナノワイヤ   半導体物性   半導体デバイス物理   

Research Experience

  • 2022/04 - Today Hokkaido University Distinguished Researcher
  • 2019/04 - Today Hokkaido University Graduate School og Information Science and Technology and Research Center for Integrated Quantum Electronics(RCIQE)
  • 2016/06 - 2019/03 Hokkaido Unversity GS-IST Associate Professor
  • 2015/01 - 2016/05 Hokkaido University GS-IST Assistant Professor
  • 2009/10 - 2014/12 Japan Science and Technology Agency PRESTO-Research Fellow
  • 2009/04 - 2009/09 G.S. IST, Hokkaido University Researcher (Global COE)
  • 2008/04 - 2009/03 JSPS Researcher (PD)
  • 2007/04 - 2008/03 JSPS Researcher (DC2)

Education

  • 2005/04 - 2008/03  Hokkaido University  Graduate School of Information Science and Technology  Division of Electronics for Informatics
  • 2003/04 - 2005/03  Gunma University
  • 1999/04 - 2003/03  Gunma University

Committee Memberships

  • 2019 - Today   International Conference of Metal Organic Vapor Phase Epitaxy (ICMOVPE)   International Advisory Committee

Awards

  • 2022/10 北海道経産局 第7回 NoMaps Dream Pitch 最優秀賞・NEDO賞・NICT賞
     燃えない近未来デバイス技術プラットフォーム
  • 2022/02 北海道 北海道科学技術奨励賞
     半導体ナノワイヤ成長技術とその次世代電子デバイスへの応用
  • 2017/12 MRS Symposium Best Paper Award
  • 2017/04 公益財団法人 船井情報科学振興財団 第16回船井学術賞
     
    受賞者: 冨岡 克広
  • 2016/12 The JSPS Prize
     
    受賞者: Tomioka Katsuhiro
  • 2016/09 国際固体素子・材料国際会議論文賞(SSDM Paper Award)
  • 2016/02 国立大学法人 北海道大学 平成27年度 研究総長賞(奨励賞)
     
    受賞者: 冨岡 克広
  • 2015/11 東北大学 電気通信研究所（RIEC） 第5回 RIEC Award
     
    受賞者: 冨岡 克広
  • 2015/11 一般財団法人 エヌエフ基金 研究開発奨励賞優秀賞
     
    受賞者: 冨岡 克広
  • 2015/10 一般財団法人 エヌエフ基金 研究開発奨励賞
     
    受賞者: 冨岡 克広
  • 2015/04 文部科学省 科学技術分野の文部科学大臣表彰・若手科学者賞
     
    受賞者: 冨岡克広
  • 2014/06 一般財団法人 安藤研究所 第27回安藤研究所研究奨励賞
     
    受賞者: 冨岡克広
  • 2014/03 一般財団法人 丸文財団 第17回丸文研究奨励賞
     
    受賞者: 冨岡克広
  • 2014/02 電子情報通信学会 エレクトロニクスソサイエティ招待論文賞
     
    受賞者: 冨岡克広
  • 2010/09 Japan Science and Applied Physics Young Scientist Oral Presentation Award
     MOVPE選択成長法と再成長によるシリコン基板上のGaAs/InAs/GaAsナノワイヤ量子井戸の作製 
    受賞者: Tomioka Katsuhiro
  • 2009/08 MRS 2009 spring meeting Session Best poster award
  • 2009/07 IWPSN Committee International Workshop on Photon and Spins in Nanostructure (IWPSN) Best Poster Award
     
    受賞者: 冨岡克広

Published Papers

  • Masahiro Sasaki, Tomoya Akamatsu, Katsuhiro Tomioka, Junichi Motohisa
    Nanotechnology 35 (19) 195604 - 195604 0957-4484 2024/02/20 
    Abstract We carried out in situ annealing of InP nanowires (NWs) in a metal-organic vapor phase epitaxial (MOVPE) growth reactor to control and reduce the tip size of InP NWs. InP NWs were grown by selective-area (SA) MOVPE on partially masked (111)A InP substrates, and annealing was successively applied in tertiarybutylphosphine (TBP) ambient. Initially, the InP NWs had a hexagonal cross-section with $\{11\bar{2}\}$ facets vertical to the substrates; they became tapered, and the edges were rounded by annealing. By appropriately selecting the annealing temperature and initial NW diameter, the tip size of the NW was reduced and NWs with a tip size of 20 nm were successfully formed. Subsequently, a thin InAsP layer was grown on the annealed NWs and their photoluminescence was investigated at low temperatures. The characterization results indicated the formation of InAsP quantum dots (QDs) emitting in the telecom band. Our approach is useful for reducing the size of the NWs and for the controlled formation of InAsP QDs embedded in InP NWs in photonic devices compatible with telecom bands.
  • Junichi Motohisa, Akamatsu Tomoya, Okamoto Manami, Tomioka Katsuhiro
    Japanese Journal of Applied Physics 63 (3) 03SP08 - 03SP08 0021-4922 2024/02/08 
    Abstract We report the growth and characterization of InP/InAsP/InP nanowires (NWs) and NW LEDs (NW-LEDs), which emit light at telecom wavelengths. InP-based NWs were grown by selective-area metal-organic vapor-phase epitaxy, and a thin InAsP layer was embedded in the NWs. The NW exhibited emission lines in their low-temperature photoluminescence spectra, suggesting the formation of quantum dots (QDs) in the NW. NW-LED operation was demonstrated at both room and low temperatures in the telecom band, but it was found that the emission wavelength range and blueshift behavior induced by current injection differed considerably between room and low temperatures. Our results suggest that an efficient path for carrier injection into the active InAsP layer should be explored for NW-QD-based single-photon sources operating via current-injection.
  • Hironori Gamo, Chen Lian, Junichi Motohisa, Katsuhiro Tomioka
    ACS Nano 1936-0851 2023/08/24 [Refereed]
  • Katsuhiro Tomioka, Kazuharu Sugita, Junichi Motohisa
    Advanced Photonics Research 4 (7) 2699-9293 2023/04/20 [Refereed]
     
    Nanometer‐scaled light sources using III–V compound semiconductor nanowires (NWs) on Si are expected as building blocks for next‐generation Si photonics, bioimaging, on‐chip microscopy, and light detection and ranging (LiDAR) techniques. This is, however, limited in a few materials systems due to complexity in integration of the vertical III–V NWs on Si and device process flow. Suppressing optical loss in the NW materials beyond the optical diffraction remains difficult in enhancing light extraction. Herein, the effect of the vertical metal‐clad architectures for the vertical nano‐light‐emitting diodes (LEDs) using GaAs/GaAsP‐related core–multishell NWs heterogeneously integrated on Si is investigated. The grown core–multishell NW is composed of a radial n‐GaAs/n‐GaAsP/p‐GaAs/p‐GaAsP double heterostructure. The vertical metal‐clad NW‐LEDs show suppression of carrier overflow effect and rapid enhancement of electrical luminescence.
  • Yuki Azuma, Shun Kimura, Hironori Gamo, Junichi Motohisa, Katsuhiro Tomioka
    Japanese Journal of Applied Physics 62 (SC) SC1011 - SC1011 0021-4922 2022/12/30 [Refereed]
     
    Abstract We characterized the current injection and electroluminescence (EL) properties of wurtzite (WZ) InP nanowire (NW) light-emitting diodes (LEDs) with axial junctions. The EL spectra of two samples with the same LED junction structure exhibited two different behaviors. One showed a single EL peak originating from the zinc-blende (ZB)-InP bandgap. The other showed two EL peaks originating from the ZB and WZ phases. This difference in EL behavior is attributed to the difference in the contact position and to depletion layer spreading. Clarification of the origin of the different EL peaks is important for optimizing the NW-LED structure.
  • S Kimura, H Gamo, Y Katsumi, J Motohisa, K Tomioka
    Nanotechnology 33 (30) 305204  2022/05 [Refereed]
  • Akinobu Yoshida, Hironori Gamo, Junichi Motohisa, Katsuhiro Tomioka
    Scientific Reports 12 (1) 2021/12 [Refereed][Not invited]
     
    AbstractHeteroepitaxy has inherent concerns regarding crystal defects originated from differences in lattice constant, thermal expansion coefficient, and crystal structure. The selection of III–V materials on group IV materials that can avoid these issues has however been limited for applications such as photonics, electronics, and photovoltaics. Here, we studied nanometer-scale direct integration of InGaAs nanowires (NWs) on Ge in terms of heterogenous integration and creation of functional materials with an as yet unexplored heterostructure. We revealed that changing the initial Ge into a (111)B-polar surce anabled vertical InGaAs NWs to be integrated for all In compositions examined. Moreover, the growth naturally formed a tunnel junction across the InGaAs/Ge interface that showed a rectification property with a huge current density of several kAcm−2 and negative differential resistance with a peak-to-valley current ratio of 2.8. The described approach expands the range of material combinations for high-performance transistors, tandem solar cells, and three-dimensional integrations.
  • Scaling effect on vertical gate-all-around FETs using III-V NW-channels on Si
    Katsuhiro Tomioka, Junichi Motohisa
    IEEE SNW 2021 Tech. Dig. 51 - 52 2021/06 [Refereed]
  • Katsuhiro Tomioka
    Compound Semiconductor V 40 - 45 2021/05 [Refereed][Invited]
  • Katsuhiro Tomioka, Hironori Gamo, Junichi Motohisa, Takashi Fukui
    2020 IEEE International Electron Devices Meeting (IEDM) 2020/12/12 [Refereed][Not invited]
  • Katsuhiro Tomioka, Junichi Motohisa, Takashi Fukui
    Scientific Reports 10 (1) 2020/12 [Refereed][Not invited]
  • Tomoya Akamatsu, Katsuhiro Tomioka, Junichi Motohisa
    Nanotechnology 31 (39) 394003 - 394003 0957-4484 2020/09/25 [Refereed][Not invited]
  • Yoshiki Tai, Hironori Gamo, Junichi Motohisa, Katsuhiro Tomioka
    ECS Transactions 98 (6) 149 - 153 2020/09/23 [Refereed][Not invited]
  • Katsuhiro Tomioka, Fumiya Ishizaka, Junichi Motohisa, Takashi Fukui
    Applied Physics Letters 117 (12) 123501 - 123501 0003-6951 2020/09/21 [Refereed][Not invited]
  • Hironori Gamo, Katsuhiro Tomioka
    IEEE Electron Device Letters 41 (8) 1169 - 1172 0741-3106 2020/08 [Refereed][Not invited]
  • Akiyama Toru, Katayama Ryuji, Tomioka Katsuhiro
    Journal of the Japanese Association for Crystal Growth 日本結晶成長学会 47 (3) n/a  0385-6275 2020
  • K.Tomioka, H. Gamo, J. Motohisa
    ECS Transactions 92 (4) 71 - 78 2019/10 [Refereed][Not invited]
  • 冨岡 克広
    応用物理 88 (4) 245 - 251 2019/04 [Refereed][Invited]
  • J. Motohisa, H. Kameda, M. Sasaki, K. Tomioka
    Nanotechnology 30 (13) 134002 - 134002 0957-4484 2019/03 [Refereed][Not invited]
  • K. Chiba, A. Yoshida, K. Tomioka, J. Motohisa
    ACS PHOTONICS 6 (2) 260 - 264 2330-4022 2019/02 [Refereed][Not invited]
  • Tomioka Katsuhiro, Akiyama Toru, Katayama Ryuji
    Journal of the Japanese Association for Crystal Growth 日本結晶成長学会 46 (2) n/a  0385-6275 2019
  • Yusuke Minami, Akinobu Yoshida, Junichi Motohisa, Katsuhiro Tomioka
    J. Cryst. Growth 506 135 - 139 2018/10 [Refereed][Not invited]
  • Hironori Gamo, Katsuhiro Tomioka
    J. Cryst. Growth 500 58 - 62 2018/10 [Refereed][Not invited]
  • Kohei Chiba, Katsuhiro Tomioka, Akinobu Yoshida, Junichi Motohisa
    AIP ADVANCES 7 (12) 125304 – 1 - 125304 – 5 2158-3226 2017/12 [Refereed][Not invited]
     
    Composition controllability of vertical InGaAs nanowires (NWs) on Si integrated by selective area growth was characterized for Si photonics in the optical telecommunication bands. The pitch of pre-patterned holes (NW sites) changed to an In/Ga alloy-composition in the solid phase during the NW growth. The In composition with a nanometer-scaled pitch differed completely from that with a mu m-scaled pitch. Accordingly, the growth morphologies of InGaAs NWs show different behavior with respect to the In/Ga ratio. (c) 2017 Author(s).
  • Kohei Chiba, Katsuhiro Tomioka, Akinobu Yoshida, Junichi Motohisa
    AIP Advances 7 125304  2017/12 [Refereed][Not invited]
  • Katsuhiro Tomioka, Takashi Fukui
    ECS Transaction 80 43 - 52 2017/10 [Refereed][Invited]
  • Fumiya Ishizaka, Yoshihiro Hiraya, Katsuhiro Tomioka, Junithic Motohisa, Takashi Fukui
    Nano Lett. 17 1350 - 1355 2017/02 [Refereed][Not invited]
  • A. Yoshida, K. Tomioka, F. Ishizaka, J. Motohisa
    J. Cryst. Growth 464 75 - 79 2017/01 [Refereed][Not invited]
  • Fumiya Ishizaka, Yoshihiro Hiraya, Katsuhiro Tomioka, Junichi Motohisa, Takashi Fukui
    Jpn. J. Appl. Phys. Institute of Physics 56 (1) 010311 - 10311 0021-4922 2016/12 [Refereed][Not invited]
     
    We report on the selective-area growth and characterization of wurtzite (WZ) InP/AlGaP core–multishell nanowires. Quantum well (QW) structures were fabricated in AlGaP multishells by changing the alloy composition. Transmission electron microscopy revealed that the AlGaP multishells were grown with a WZ structure on the side of the WZ InP core. The lattice constants of the WZ InP core and WZ AlGaP shell were determined by X-ray diffraction. Cathodoluminescence studies showed that the WZ AlGaP QW with an Al composition of 20% exhibited green emissions at 2.37 eV. These results open the possibility of fabricating green light-emitting diodes using WZ AlGaP-based materials.
  • Katsuhiro Tomioka, Junichi Motohisa, Takashi Fukui
    ECS Transaction The Electrochemical Society (ECS) 75 (5) 127 - 134 1938-6737 2016/09 [Refereed][Invited]
     
    Tunnel field-effect transistors (TFETs) with a steep subthreshold-slope (SS) are promising low-power switches for future large-scale integrated circuits (LSIs) with low power consumption and high performance. Recently, we demonstrated vertical TFETs with III-V/Si heterojunctions. This new sort of tunnel junction achieves a steep SS because of its unique figure-of-merit. Here, we report on recent progress on vertical TFETs using Si/III-V heterojunctions and means for boosting on-state current.
  • Akinobu Yoshida, Katsuhiro Tomioka, Fumiya Ishizaka, Kohei Chiba, Junichi Motohisa
    ECS Transaction The Electrochemical Society (ECS) 75 (7) 265 - 270 1938-6737 2016/09 [Refereed][Not invited]
     
    III-V compound semiconductors and Ge are promising futurechannel materials because of their high carrier mobility. Forexample the electron mobility of InAs is about 20 times faster thanthat of Si at room temperature and hole mobility of Ge is about 5times faster than that of Si. In this paper, we report directintegration of InGaAs nanowires (NWs) on Ge(111) substrate byselective-area metal organic vapor phase epitaxy (SA-MOVPE) forrealization of high carrier mobility InGaAs/Ge hybrid CMOSapplications, and characterization of the composition and growthmodes of InGaAs NWs by X-ray diffraction (XRD) measurement.
  • Y. Hiraya, F. Ishizaka, K. Tomioka, T. Fukui
    Applied Physics Express Institute of Physics 9 (3) 035502-1 - 4 1882-0778 2016/02 [Refereed][Not invited]
     
    We grew AlInP on two types of GaN substrate in order to transfer the wurtzite (WZ) structure to grown layers. An AlInP epitaxial layer grown on GaN[Formula: see text] with high-density stacking faults was obtained. X-ray diffraction and Raman scattering analyses indicate that the dominant crystal structure of the AlInP layer grown on GaN[Formula: see text] was WZ. Cathode luminescence measurements at 35 K revealed strong green emissions from the WZ AlInP layer, suggesting an energy band gap change from indirect to direct. These results demonstrate the potential of WZ AlInP as a new candidate for high-efficiency green emission material.
  • Katsuhiro Tomioka
    Nature Digest 13 (1) 36 - 37 1880-0556 2016/01 [Refereed][Invited]
  • Katsuhiro Tomioka, Fumiya Ishizaka, Junichi Motohisa, Takashi Fukui
    2016 COMPOUND SEMICONDUCTOR WEEK (CSW) INCLUDES 28TH INTERNATIONAL CONFERENCE ON INDIUM PHOSPHIDE & RELATED MATERIALS (IPRM) & 43RD INTERNATIONAL SYMPOSIUM ON COMPOUND SEMICONDUCTORS (ISCS) 2016 [Refereed][Not invited]
  • Katsuhiro Tomioka, Junichi Motohisa, Takashi Fukui
    2016 46TH EUROPEAN SOLID-STATE DEVICE RESEARCH CONFERENCE (ESSDERC) 397 - 402 1930-8876 2016 [Refereed][Invited]
     
    Tunnel FETs (TFETs) with steep subthreshold slope have been attracting much attention as building blocks for future low-power integrated circuits and CMOS technology devices. Here we report on recent advances in vertical TFETs using III-V/Si heterojunctions. These heterojunctions, which are formed by direct integration of III-V nanowires (NWs) on Si, are promising tunnel junction for achieving steep subthreshold slope (SS). The III-V/Si heterojunction inherently forms abrupt junctions regardless of precise doping technique because the band discontinuity is determined by only the offset of III-V and Si, and depletion region can be controlled by the III-V MOS structure. Thus, good gate-electrostatic control with a large internal electrical field for modulation of tunnel transport can be achieved. Here we repot on recent advances in the vertical TFETs using the III-V NW/Si heterojunction with surrounding-gate architecture and demonstrate steep-SS behavior and very low parasitic leakage current.
  • Katsuhiro Tomioka
    Nature 526 51 - 52 2015/10 [Refereed][Invited]
  • K. Tomioka, F. Ishizaka, T. Fukui
    Nano Letters 15 7253 - 7257 2015/10 [Refereed][Not invited]
  • K. Tomioka, J. Motohisa, T. Fukui
    ECS Trans. 169 109 - 118 2015/10 [Refereed][Not invited]
  • Katsuhiro Tomioka, Junichi Motohisa, Takashi Fukui
    International Symposium on VLSI Technology, Systems, and Applications, Proceedings 2015- 1930-8868 2015/06/03 [Refereed][Not invited]
     
    MOSFETs using III-V channels with multi-gate architecture and tunnel junctions are promising alternative building blocks for highperformance and low power nanoelectronic circuits. CMOS. In this paper, we review recent advances in direct integration of vertical III-V nanowire (NW)-channel on Si and FET application such as vertical III-V NW surrounding-gate transistors (SGTs) and tunneling FET (TFETs) using III-V NW/Si heterojunctions.
  • Ishizaka Fumiya, Hiraya Yoshihiro, Tomioka Katsuhiro, Fukui Takashi
    Journal of crystal growth Elsevier 411 71 - 75 0022-0248 2015/02 [Refereed][Not invited]
     
    A GaP nanowire is promising from the viewpoint of device applications because when its crystal phase is changed from zinc blende (ZB) to wurtzite (WZ), its band gap changes from indirect to direct. GaP in the WZ phase is theoretically and experimentally shown to have the possibility of "green" emission. Here we report on the growth of WZ GaP in InP/GaP core-shell nanowires by selective-area metal-organic vapor-phase epitaxy (SA-MOVPE). WZ InP nanowires were used as a template for transferring the WZ structure to GaP. Transmission electron microscopy revealed that WZ GaP was grown on the sidewalls of the InP core in the lateral <-2 1 1 > direction and that ZB GaP was grown on the top of the le core in the axial < 1 1 1 > A direction. A growth model for the different crystal structures of the GaP shell is proposed from the viewpoint of the growth direction. The WZ structure is "transferred" from the InP core to the GaP shell only when GaP grows in the direction perpendicular to the WZ stacking direction of the InP core. This so-called "crystal structure transfer" can also be applied to p- and n-doped GaP and is therefore promising for fabricating WZ-GaP-basecl light-emitting diodes. (C) 2014 Elsevier B.V. All rights reserved.
  • Chen Muyi, Nakai Eiji, Tomioka Katsuhiro, Fukui Takashi
    Appl. Phys. Express Institute of Physics 8 (1) 012301 - 12301 1882-0778 2015/01 [Refereed][Not invited]
     
    III–V compound semiconductor nanowire (NW) arrays have exhibited remarkable behavior in photovoltaic applications. We embedded an orderly vertical InP NW array in poly(dimethylsiloxane) (PDMS) and peeled it off from the substrate to form a AuZn contact. The sample with the substrate exhibited a very high average absorptance of 92%. However, when the array was peeled off, the optical absorptance degraded, particularly in the longer-wavelength region. After the AuZn was deposited on the back side of the NW array, the absorptance increased. This technology could enable a new approach for NW-based photovoltaics with a lower fabrication cost.
  • Eiji Nakai, Muyi Chen, Masatoshi Yoshimura, Katsuhiro Tomioka, Takashi Fukui
    Japanese Journal of Applied Physics Institute of Physics 54 (1) 015201 - 015201 0021-4922 2015/01/01 [Refereed][Not invited]
     
    Axial p–i–n junction nanowire (NW) solar cells (SCs) with a position-controlled GaAs-based NW array were fabricated by selective-area metal organic vapor phase epitaxy (SA-MOVPE). The measured electron-beam-induced current (EBIC) signals showed the formation of an axial p–i–n junction, which confirms power generation under sunlight illumination. The series resistance of the NW SCs is much higher than that of conventional planar SCs based on Si or other III–V compound semiconductors. The main difficulty concerning the fabrication of these NW SCs is the degradation of series resistance between the GaAs-based NWs and the indium–tin oxide (ITO) deposited as a transparent electrode. The series resistance of the fabricated GaAs-based NW SCs was reduced by introducing a tin doping contact layer between the ITO and the NW array, which is formed by pulse doping. As a result of this improved structure, the fabricated SCs exhibited an open-circuit voltage of 0.544 V, a short-circuit current of 18.2 mA/cm2, and a fill factor of 0.721 for an overall conversion efficiency of 7.14% under AM1.5G illumination. The series resistance of the SCs could be decreased to 0.132 Ω·cm2, which is one order of magnitude lower than that of the SC without a highly doped contact layer. This reduced series resistance indicates that nanostructure SCs with transparent electrodes and multijunction NW SCs with high efficiencies can be fabricated on a commercial basis in the near future.
  • Katsuhiro Tomioka, Takashi Fukui
    Handbook of Crystal Growth: Second Edition 1 749 - 793 2014/12/24 [Refereed][Not invited]
     
    This chapter summarizes the growth of semiconductor nanocrystals, including quantum well, wire, nanowire, and quantum dot with selective-area growth. The position-controlled growth of nanocrystals by using faceting growth and mechanisms is described. In addition, microchannel epitaxy is outlined as one of the types of selective-area epitaxy.
  • Katsuhiro Tomioka, Takashi Fukui
    JOURNAL OF PHYSICS D-APPLIED PHYSICS 47 (39) 364001  0022-3727 2014/10 [Refereed][Not invited]
     
    We report on the recent progress in electronic applications using III-V nanowires (NWs) on Si substrates using the selective-area growth method. This method could align vertical III-V NWs on Si under specific growth conditions. Detailed studies of the III-V NW/Si heterointerface showed the possibility of achieving coherent growth regardless of misfit dislocations in the III-V/Si heterojunction. The vertical III-V NWs grown using selective-area growth were utilized for high performance vertical field-effect transistors (FETs). Furthermore, III-V NW/Si heterointerfaces with fewer misfit dislocations provided us with a unique band discontinuity with a new functionality that can be used for the application of tunnel diodes and tunnel FETs. These demonstrations could open the door to a new approach for creating low power switches using III-V NWs as building-blocks of future nanometre-scaled electronic circuits on Si platforms.
  • III-V族化合物半導体ナノワイヤ太陽電池
    福井 孝志, 吉村 正利, 中井 栄治, 冨岡 克広
    日本結晶成長学会誌 41 (2) 29 - 34 2014/07 [Refereed][Invited]
  • Katsuhiro Tomioka, Takashi Fukui
    ECS Trans. 61 81  2014/05 [Refereed][Not invited]
  • Katsuhiro Tomioka, Takashi Fukui
    Applied Physics Letters American Institute of Physics 104 (7) 073507 - 73507 0003-6951 2014/02 [Refereed][Not invited]
     
    We report on a fabrication of tunnel field-effect transistors using InGaAs nanowire/Si heterojunctions and the characterization of scaling of channel lengths. The devices consisted of single InGaAs nanowires with a diameter of 30 nm grown on p-type Si(111) substrates. The switch demonstrated steep subthreshold-slope (30 mV/decade) at drain-source voltage (V-DS) of 0.10 V. Also, pinch-off behavior appeared at moderately low VDS, below 0.10 V. Reducing the channel length of the transistors attained a steep subthreshold slope (< 60 mV/decade) and enhanced the drain current, which was 100 higher than that of the longer channels. (C) 2014 AIP Publishing LLC.
  • Masatoshi Yoshimura, Eiji Nakai, Katsuhiro Tomioka, Takashi Fukui
    Applied Physics Letters American Institute of Physics 103 (24) 243111 - 243111 0003-6951 2013/12 [Refereed][Not invited]
     
    Heterojunction solar cells were formed with a position-controlled InP nanowire array sputtered with indium tin oxide (ITO). The ITO not only acted as a transparent electrode but also as forming a photovoltaic junction. The devices exhibited an open-circuit voltage of 0.436 V, short-circuit current of 24.8 mA/cm(2), and fill factor of 0.682, giving a power conversion efficiency of 7.37% under AM1.5G illumination. The internal quantum efficiency of the device was higher than that of the world-record InP cell in the short wavelength range. (C) 2013 AIP Publishing LLC.
  • Katsuhiro Tomioka, Masatoshi Yoshimura, Takashi Fukui
    Nano Letters 13 (12) 5822 - 5826 2013/12 [Refereed][Not invited]
  • Katsuhiro Tomioka, Takashi Fukui
    ECS Transaction 58 (7) 99 - 114 2013/10 [Refereed][Invited]
  • Eiji Nakai, Masatoshi Yoshimura, Katsuhiro Tomioka, Takashi Fukui
    JAPANESE JOURNAL OF APPLIED PHYSICS The Japan Society of Applied Physics 52 (5) UNSP 055002 - 055002-4 0021-4922 2013/05 [Refereed][Not invited]
     
    Semiconductor nanowires (NWs) are good candidate for light-absorbing material in next generation photovoltaic and III--V NW-based multi-heterojunction solar cells using lattice-mismatched material system are expected as high energy-conversion efficiencies under concentrated light. Here we demonstrate core--shell GaAs NW arrays by using catalyst-free selective-area metal organic vapor phase epitaxy (SA-MOVPE) as a basis for multijunction solar cells. The reflectance of the NW array without any anti-reflection coating showed much lower reflection than that of a planar wafer. Next we then fabricated core--shell GaAs NW array solar cells with radial p--n junction. Despite the low reflectance, the energy-conversion efficiency was 0.71% since a high surface recombination rate of photo-generated carriers and poor ohmic contact between the GaAs and transparent indium--tin-oxide (ITO) electrode. To avoid these degradations, we introduced an InGaP layer and a Ti/ITO electrode. As a result, we obtained a short-circuit current of 12.7 mA cm-2, an open-circuit voltage of 0.5 V, and a fill factor of 0.65 for an overall efficiency of 4.01%.
  • Masatoshi Yoshimura, Eiji Nakai, Katsuhiro Tomioka, Takashi Fukui
    Applied Physics Express The Japan Society of Applied Physics 6 (5) 052301 - 052301-4 1882-0778 2013/05 [Refereed][Not invited]
     
    We report surface-passivated core--shell InP nanowire array solar cells fabricated using catalyst-free selective-area metal organic vapor phase epitaxy. Reflectance measurements confirm enhanced light absorption due to significantly reduced reflectance over a wide spectral range. The wide-band-gap outer shell layer of core-multishell nanowires effectively passivates the large surface area of the nanowires, increasing the short-circuit current density and elevating the energy conversion efficiency by 6.35% under AM1.5G illumination. This passivation technique could open a new approach to nanowire-based photovoltaics with higher energy efficiency.
  • Indium Phosphide core-shell nanowire solar cells with wide bandgap window layer
    M. Yoshimura, E. Nakai, K. Tomioka, T. Fukui
    Applied Physics Express 6 052301-1 - 4 2013/05 [Refereed][Not invited]
  • F. Ishizaka, K. Ikejiri, K.Tomioka, T. Fukui
    Japanese Journal of Applied Physics The Japan Society of Applied Physics 52 (4) UNSP 04CH05 - 04CH05-4 0021-4922 2013/04 [Refereed][Not invited]
     
    We studied the growth of indium-rich InGaP nanowires (NWs) on InP (111)A substrates by selective-area metal organic vapor phase epitaxy (SA-MOVPE). We obtained vertically aligned InGaP NWs by optimizing growth conditions, such as group III supply ratio and V/III ratio. We found that the height, diameter, shape, and composition of InGaP NWs depended significantly on the supply ratios of trimethylgallium (TMGa) and trimethylindium (TMIn). As the supply ratio of TMGa was increased, the lateral growth was drastically enhanced, and the uniformity of NWs deteriorated. Furthermore, the sidewall facets of NWs changed from \{\bar{2}11\} to \{\bar{1}10\} as the supply ratio of TMGa was increased, indicating the possibility of structural transition from wurtzite (WZ) to zinc blende (ZB). We propose a possible growth model for such lateral growth, uniformity, and structural transition. Photoluminescence (PL) measurements revealed that the Ga compositions ranged approximately from 0 to 15%. Our results show that highly uniform InGaP NWs can be grown by controlling the growth conditions.
  • Keitaro Ikejiri, Fumiya Ishizaka, Katsuhiro Tomioka, Takashi Fukui
    Nanotechnology IOP Publishing 24 (11) 115304  0957-4484 2013/03 [Refereed][Not invited]
     
    The growth mechanism of GaAs nanowires (NWs) grown on polycrystalline silicon (poly-Si) thin films using selective-area metalorganic vapor-phase epitaxy was investigated. Wire structures were selectively grown in the mask openings on a poly-Si substrate. The appearance ratio of wire structures strongly depended on the growth conditions and deposition temperature of the poly-Si substrate. Evaluation of the grown shapes and growth characteristics revealed that GaAs NWs grown on a poly-Si substrate have the same growth mechanism as conventional GaAs NWs grown on a single-crystalline GaAs or Si substrate. Experiments showed that the wire structure yield can be improved by increasing the Si grain size and/or increasing the Si deposition temperature. The growth model proposed for understanding NW growth on poly-Si is based on the mask opening size, the Si grain size, and the growth conditions. The ability to control the growth mode is promising for the formation of NWs with complex structures on poly-Si thin layers.
  • Katsuhiro Tomioka, Takashi Fukui
    2013 71ST ANNUAL DEVICE RESEARCH CONFERENCE (DRC) 15 - + 1548-3770 2013 [Refereed][Not invited]
  • Katsuhiro Tomioka, Masatoshi Yoshimura, Eiji Nakai, Fumiya Ishizaka, Takashi Fukui
    Technical Digest - International Electron Devices Meeting, IEDM 4.1.4  0163-1918 2013 [Refereed][Not invited]
     
    In this paper, we present recent progress in the integration of vertical III-V nanowire-channels on Si by selective-area epitaxy and demonstrations of high-performance III-V vertical surrounding-gate transistors with high-k dielectrics with an EOT of less than 1 nm, modulation doping technique, and challenges in steep subthreshold-slope switching using III-V nanowire/Si heterojunctions as building blocks for low power circuits. © 2013 IEEE.
  • Katsuhiro Tomioka, Takashi Fukui
    2013 THIRD BERKELEY SYMPOSIUM ON ENERGY EFFICIENT ELECTRONIC SYSTEMS (E3S) 2013 [Refereed][Not invited]
  • Keitaro Ikejiri, Fumiya Ishizaka, Katsuhiro Tomioka, Takashi Fukui
    Nano Letters 12 (9) 4770 - 4774 2012/09 [Refereed][Not invited]
  • Katsuhiro Tomioka, Masatoshi Yoshimura, Takashi Fukui
    Nature 488 (7410) 189 - 192 0028-0836 2012/08 [Refereed][Not invited]
  • Hirotaka Sakuma, Motonobu Tomoda, Paul H. Otsuka, Osamu Matsuda, Oliver B. Wright, Takashi Fukui, Katsuhiro Tomioka, Istvan A. Veres
    APPLIED PHYSICS LETTERS 100 (13) 0003-6951 2012/03 [Refereed][Not invited]
     
    We investigate the vibrational modes of a triangular array of anisotropic, hexagonal GaAs nanopillars on a GaAs substrate through ultrafast changes in optical reflectivity. By comparison with simulations, we identify GHz resonances, mode shapes, and damping. In addition, by varying the pillar diameter, height, and pitch, we distinguish collective and localized modes. A proper understanding of substrate-attached nanostructure dynamics will lead to better characterization of nanosensors based on perturbations to vibrational resonances. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.3696380]
  • Takashi Fukui, Masatoshi Yoshimura, Eiji Nakai, Katsuhiro Tomioka
    AMBIO 41 119 - 124 0044-7447 2012/03 [Refereed][Not invited]
     
    We demonstrate position-controlled III-V semiconductor nanowires (NWs) by using selective-area metalorganic vapor phase epitaxy and their application to solar cells. Efficiency of 4.23% is achieved for InP core-shell NW solar cells. We forma 'flexible NW array' without a substrate, which has the advantage of saving natural resources over conventional thin film photovoltaic devices. Four junction NW solar cells with over 50% efficiency are proposed and discussed.
  • Longitudinal and Transverse Exciton Spin Relaxation in Single InP/InAsP/InP Nanowire Quantum Dots
    H. Sasakura, C. Hermannstädter, S. N. Dorenbos, N. Akopian, M. P. van Kouwen, J. Motohisa, Y. Kobayashi, H. Kumano, K. Kondo, K. Tomioka, T. Fukui, I. Suemune, V. Zwiller
    Phys. Rev. B 85 075324  2012/02 [Refereed][Not invited]
  • Sasakura H., Dorenbos S. N., Akopian N., van Kouwen M. P., Motohisa J., Kobayashi Y., Kumano H., Kondo K., Tomioka K., Fukui T., Suemune I., Zwiller V.
    Phys. Rev. B American Physical Society 85 (7) 075324-1 - 075324-7 1098-0121 2012/02 [Refereed][Not invited]
     
    We have investigated the optical properties of a single InAsP quantum dot embedded in a standing InP nanowire. Elongation of the transverse exciton-spin relaxation time of the exciton state with decreasing excitation power was observed by first-order photon correlation measurements. This behavior is well explained by the motional narrowing mechanism induced by Gaussian fluctuations of environmental charges in the nanowire. The longitudinal exciton-spin relaxation time is evaluated by the degree of the random polarization of emission originating from exciton states confined in a single-nanowire quantum dot by using Mueller calculus based on Stokes parameters representation. The reduction in the random polarization component with decreasing excitation power is caused by suppression of the exchange interaction of electron and hole due to an optically induced internal electric field by the dipoles at the wurtzite and zinc-blende heterointerfaces in the InP nanowire.
  • Katsuhiro Tomioka, Takashi Fukui
    NanoScience and Technology 58 67 - 101 1434-4904 2012 [Refereed][Not invited]
     
    The III-V nanowires (NWs) on Si are promising building blocks for future nanoscale electrical and optical devices on Si platforms.We review positioncontrolled growth of III-V NWs on Si substrate by selective-area growth and discuss how to control growth directions of III-V NW on Si. Finally, we demonstrate the integrations of III-V NW-based light-emitting diodes (LEDs) array on Si. These demonstrations should have broad applications in laser diodes and photodiodeswith functionality not enabled by conventional NW. © Springer-Verlag Berlin Heidelberg 2012.
  • Katsuhiro Tomioka, Masatoshi Yoshimura, Takashi Fukui
    Digest of Technical Papers - Symposium on VLSI Technology 47 - 48 0743-1562 2012 [Refereed][Not invited]
     
    In this paper, we propose tunneling field-effect transistors (TFETs) using III-V nanowire (NW)/Si heterojunctions and experimentally demonstrate steep-slope switching behaviors using InAs NW/Si heterojunction TFET with surrounding-gate architecture and high-k dielectrics. Control of resistances in this device structure is important for achieving steep-slope switching. A minimum subthreshold slope (SS) of the TFET is 21 mV/dec at VDS of 0.10 - 1.00 V. © 2012 IEEE.
  • Tomioka Katsuhiro, Takashi Fukui
    応用物理 81 (1) 59 - 64 2012/01 [Refereed][Not invited]
  • Yoshinori Kohashi, Takuya Sato, Keitaro Ikejiri, Katsuhiro Tomioka, Shinjiroh Hara, Junichi Motohisa
    JOURNAL OF CRYSTAL GROWTH 338 (1) 47 - 51 0022-0248 2012/01 [Refereed][Not invited]
     
    Indium-rich InGaAs nanowires were grown on an InP (111)B substrate by catalyst-free selective-area metal-organic vapor phase epitaxy, and the growth-temperature dependence of growth rate and composition was studied. In particular, nanowire growth rate rapidly decreases as growth temperature increases. This tendency is opposite (for a similar temperature range) to that found in a previous study on selective-area growth of gallium-rich InGaAs nanowires. This difference between indium-rich and gallium-rich nanowires suggests that the influence of growth temperature on the growth of InGaAs nanowires is dependent on the group-III supply ratio. On the basis of previous experimental observations in InAs and GaAs nanowires, temperature dependence of nanowire growth rate and its dependence on group-III supply ratio are predicted. A guideline to determine the optimum growth conditions of InGaAs nanowires is also discussed. (C) 2011 Elsevier B.V. All rights reserved.
  • K. Hiruma, K. Tomioka, P. Mohan, L. Yang, J. Noborisaka, B. Hua, A. Hayashida, S. Fujisawa, S. Hara, J. Motohisa, T. Fukui
    Journal of Nanotechnology Vol. 2012 169284-1 - 169284-29 1687-9503 2012 [Refereed][Invited]
     
    The fabrication of GaAs- and InP-based III-V semiconductor nanowires with axial/radial heterostructures by using selective-area metal-organic vapor-phase epitaxy is reviewed. Nanowires, with a diameter of 50-300nm and with a length of up to 10μm, have been grown along the «111» B or «111» A crystallographic orientation from lithography-defined SiO2 mask openings on a group III-V semiconductor substrate surface. An InGaAs quantum well (QW) in GaAs/InGaAs nanowires and a GaAs QW in GaAs/AlGaAs or GaAs/GaAsP nanowires have been fabricated for the axial heterostructures to investigate photoluminescence spectra from QWs with various thicknesses. Transmission electron microscopy combined with energy dispersive X-ray spectroscopy measurements have been used to analyze the crystal structure and the atomic composition profile for the nanowires. GaAs/AlGaAs, InP/InAs/InP, and GaAs/GaAsP core-shell structures have been found to be effective for the radial heterostructures to increase photoluminescence intensity and have enabled laser emissions from a single GaAs/GaAsP nanowire waveguide. The results have indicated that the core-shell structure is indispensable for surface passivation and practical use of nanowire optoelectronics devices. Copyright © 2012 K. Hiruma et al.
  • Katsuhiro Tomioka, Tomotaka Tanaka, Takashi Fukui
    ECS Transactions 41 (3) 61 - 69 2011/11 [Refereed][Not invited]
  • Katsuhiro Tomioka, Keitaro Ikejiri, Tomotaka Tanaka, Junichi Motohisa, Shinjiroh Hara, Kenji Hiruma, Takashi Fukui
    Journal of the Material Society 26 (17) 2127 - 2141 0884-2914 2011/09 [Refereed][Not invited]
  • Katsuhiro Tomioka, Tomotaka Tanaka, Shinjiro Hara, Kenji Hiruma, Takashi Fukui
    IEEE Journal of Selected Topics in Quantum Electronics 17 (4) 1112 - 1129 1077-260X 2011/08 [Refereed][Invited]
  • Keitaro Ikejiri, Yusuke Kitauchi, Katsuhiro Tomioka, Junichi Motohisa, Takashi Fukui
    Nano Letters 11 (10) 4314 - 4318 1530-6984 2011/08 [Refereed][Not invited]
  • Katsuhiro Tomioka, Takashi Fukui
    Applied Physics Letters 98 (8) 083114  0003-6951 2011/02 [Refereed][Not invited]
  • Junichi Motohisa, Katsuhiro Tomioka, Bin Hua, Kumar S.K. Varadwaj, Shinjiroh Hara, Kenji Hiruma, Takashi Fukui
    Advances in III-V Semiconductor Nanowires and Nanodevices 145 - 157 2011 [Refereed][Not invited]
     
    We describe the growth and optical properties of III-V semiconductor nanowires and their application to nanoscale photonic devices such as Fabry-Perot cavity, waveguides, optically-pumped lasers, and lightemitting diodes. The nanowires were grown by selective-area metalorganic vapor phase epitaxy (SA-MOVPE) on the (111) oriented substrates. Nanowires containing heterostructures in their radial direction, that is, core-shell heterostructures, have also been realized by controlling the growth mode during SA-MOVPE. The nanowires were characterized by micro-photoluminescence measurements and those detached from the grown substrate showed resonant peaks associated with Fabry-Perot cavity modes. It was simultaneously shown that core-shell hetereostructured nanowires exhibited stronger photoluminescence than bare nanowires due to reduced surface non-radiative recombination. Furthermore, core-shell nanowires exhibited lasing oscillation originating from the cavity formed by both end facets at pulsed-laser excitation. Meanwhile, electroluminescence from core-shell nanowires was also demonstrated. © 2011 Bentham Science Publishers Ltd. All rights reserved.
  • Katsuhiro Tomioka, Masatoshi Yoshimura, Takashi Fukui
    2011 IEEE INTERNATIONAL ELECTRON DEVICES MEETING (IEDM) 773 - 776 2011 [Refereed][Not invited]
     
    In this paper, direct integration of vertical InGaAs nanowires (NWs) on Si substrate without buffering techniques, and fabrication of InGaAs NW surrounding-gate transistors (SGTs) with high-k gate dielectrics is reported for the first time. Furthermore, we investigated a passivation technique using InGaAs/InP/InAlAs/InGaAs core-multishell (CMS) structure, and showed enhancement of transconductance (G(m)) and I-ON/I-OFF ratio of the InGaAs CMS NW-SGT. The peak G(m) for the InGaAs-related CMS NW-SGT was 500 mu S/mu m at V-DS of 1.00V, and I-ON/I-OFF ratio was similar to 10(9).
  • Sasakura H, Kumano H, Suemune I, Dorenbos S. N, Kouwen M, P. van, Zwiller V, Kabayashi Y, Motohisa J, Tomioka K, Fukui T, Herm, stadter C
    Meeting Abstracts of the Physical Society of Japan 一般社団法人 日本物理学会 66 (0) 1342-8349 2011 [Not refereed][Not invited]
  • Y. Takayama, K. Tomioka, S. Hara, T. Fukui, J. Motohisa
    physica status solidi c 8 (2) 272 - 274 2010/11 [Refereed][Not invited]
  • S. N. Dorenbos, H. Sasakura, M. P. van Kouwen, N. Akopian, S. Adachi, N. Namekata, M. Jo, J. Motohisa, Y. Kobayashi, K. Tomioka, T. Fukui, S. Inoue, H. Kumano, C. M. Natarajan, R. H. Hadfield, T. Zijlstra, T. M. Klapwijk, V. Zwiller, I. Suemune
    APPLIED PHYSICS LETTERS 97 (17) 171106  0003-6951 2010/10 [Refereed][Not invited]
     
    We report the experimental demonstration of single-photon and cascaded photon pair emission in the infrared, originating from a single InAsP quantum dot embedded in a standing InP nanowire. A regular array of nanowires is fabricated by epitaxial growth on an electron-beam patterned substrate. Photoluminescence spectra taken on single quantum dots show narrow emission lines. Superconducting single photon detectors, which have a higher sensitivity than avalanche photodiodes in the infrared, enable us to measure auto and cross correlations. Clear antibunching is observed [g((2))(0) = 0.12] and we show a biexciton-exciton cascade, which can be used to create entangled photon pairs. (C) 2010 American Institute of Physics. [doi:10.1063/1.3506499]
  • Masatoshi Yoshimura, Katsuhiro Tomioka, Kenji Hiruma, Shinjiroh Hara, Junichi Motohisa, Takashi Fukui
    Journal of Crystal Growth 315 (1) 148 - 151 2010/09 [Refereed][Not invited]
  • 冨岡克広, 福井孝志
    月刊ディスプレイ テクノタイムズ社 7 (7) 39 - 46 1341-3961 2010/07 [Not refereed][Invited]
  • K. Tomioka, J. Motohisa, S. Hara, K. Hiruma, T. Fukui
    Nano Letters 10 (5) 1639 - 1644 1530-6984 2010/04 [Refereed][Not invited]
  • Yusuke Kitauchi, Yasunori Kobayashi, Katsuhiro Tomioka, Shinjiro Hara, Kenji Hiruma, Takashi Fukui, Junichi Motohis
    Nano Letters 10 (5) 1699 - 1703 1530-6984 2010/04 [Refereed][Not invited]
  • Masatoshi Yoshimura, Katsuhiro Tomioka, Kenji Hiruma, Shinjiro Hara, Junichi Motohisa, Takashi Fukui
    Japanese Journal of Applied Physics Published by the Japan Society of Applied Physics through the Institute of Pure and Applied Physics 49 (4) 04DH08-1 - 04DH08-4 0021-4922 2010/04 [Refereed][Not invited]
     
    We fabricated InGaAs nanowires (NWs) in SiO2 mask openings on a GaAs(111)B substrate at growth temperatures of 600–700 °C using catalyst-free selective-area metal organic vapor phase epitaxy. At a growth temperature of 600 °C, particle-like depositions occurred, but they decreased in number and density when the growth temperature was increased to 650 °C and disappeared above 675 °C. The heights and growth rates of the NWs increased when the growth temperature was increased and the mask opening diameter was decreased from 300 to 50 nm. Photoluminescence (PL) spectra measured for the NWs indicated a blue shift in the peak from 0.95 to 1.3 eV as the growth temperature was increased from 600 to 700 °C, indicating an increase in the Ga composition from 62 to 88% in the InGaAs NWs.
  • T. Tanaka, K.Tomioka, S. Hara, J. Motohisa, E. Sano, T. Fukui
    Applied Physics Express Japan Society of Applied Physics 3 (2) 025003-1 - 025003-3 1882-0778 2010/01 [Refereed][Not invited]
     
    We report on the fabrication and characterization of vertical InAs nanowire channel field effect transistors (FETs) with high-$k$/metal gate-all-around structures. Single InAs nanowires were grown on Si substrates by the selective-area metalorganic vapor phase epitaxy method. The resultant devices exhibited n-channel FET characteristics with a threshold voltage of around $-0.1$ V. The best device exhibited maximum drain current ($I_{\text{DS,max } }/w_{\text{G } }$), maximum transconductance ($g_{\text{m,max } }/w_{\text{G } }$), on--off ratio ($I_{\text{ON/OFF } }$), subthreshold slope ($\mathit{SS}$) of 83 μA/μm, 83 μS/μm, $10^{4}$, and 320 mV/decade, respectively, for a nanowire diameter of 100 nm.
  • Yasunori Kobayashi, Junichi Motohisa, Katsuhiro Tomioka, Shinjiro Hara, Kenji Hiruma, Takashi Fukui
    2010 22ND INTERNATIONAL CONFERENCE ON INDIUM PHOSPHIDE AND RELATED MATERIALS (IPRM) 1092-8669 2010 [Refereed][Not invited]
     
    We grew InAsP and InP/InAsP/InP heterostructure NWs (NWs) by selective-area MOVPE and carried out micro-photoluminescence (mu-PL) measurement. We investigated growth conditions for InAsP NWs and that embedded in InP NWs, and obtained exciton and biexciton emissions from InAsP QDs at optimized growth conditions. Negative binding energy of biexciton was observed due to the strong Coulomb interaction between the holes in the QDs.
  • J. Motohisa, K. S. K. Varadwaj, K. Tomioka, T. Fukui
    2010 15TH OPTOELECTRONICS AND COMMUNICATIONS CONFERENCE (OECC) 214 - + 2010 [Refereed][Not invited]
     
    We report on the optical properties of III-V semiconductor nanowires (NWs) grown by by selective-area matalorganic vapor phase epitaxy and its application to photonic devices. Results for NWs containing heterostructures are mainly discussed.
  • T. Fukui, K. Tomioka, S. Hara, K. Hiruma, J. Motohisa
    PROCEEDINGS OF 2010 CONFERENCE ON OPTOELECTRONIC AND MICROELECTRONIC MATERIALS AND DEVICES (COMMAND 2010) 209 - 210 1097-2137 2010 [Refereed][Not invited]
     
    We fabricated various kinds of III-V semiconductor nanowires and core-shell nanowires using selective area metalorganic vapor phase epitaxy (SA-MOVPE) on (111) oriented substrates, such as GaAs, GaAs/AIGaAs, InP, InPllnAsllnP on III-V substrates, and InAs and GaAs on Si. As for device applications, we fabricated GaAs/GaAsP core-shell nanowire photo-excited lasers, and InP core-shell pn junction solar cells. We also demonstrate III-V semiconductor nano-wires grown on Si (111) substrates.
  • T. Fukui, K. Tomioka, S. Hara, K. Hiruma, J. Motohisa
    2010 22ND INTERNATIONAL CONFERENCE ON INDIUM PHOSPHIDE AND RELATED MATERIALS (IPRM) 1092-8669 2010 [Refereed][Not invited]
     
    We fabricated various kinds of III-V semiconductor nanowires and core-shell nanowires using selective area metalorganic vapor phase epitaxy (SA-MOVPE) on (111) oriented substrates, such as GaAs, GaAs/AlGaAs, InP, InP/InAs/InP on III-V substrates, and InAs and GaAs on Si. As for device applications, we fabricated GaAs/GaAsP core-shell nanowire photo-excited lasers, and InP core-shell pn junction solar cells. I will also introduce III-V semiconductor nanowires grown on Si (111) substrates
  • Masaharu Yoshioka, Katsuhiro Tomioka, Shinjiroh Hara, Takashi Fukui
    iiWAS2010 - 12th International Conference on Information Integration and Web-Based Applications and Services 871 - 874 2010 [Refereed][Not invited]
     
    We are developing a framework for knowledge creation in nanodevice development, based on collaboration between nanodevice engineers and computer science researchers. Development of nanodevices requires a variety of knowledge some of this knowledge is tacit, based on the user's experience. Therefore, it is difficult to become a good engineer in this development process. We propose the concept of "Evidence-based experiment planning" and develop a process for supporting experiment planning in nanodevice development. This system applies knowledge discovery techniques to records of previous experiments to extract experienced engineers' tacit knowledge. Copyright 2010 ACM.
  • H. Goto, K. Nosaki, K. Tomioka, S. Hara, K. Hiruma, J. Motohisa, T. Fukui
    Applied Physics Express Japan Society of Applied Physics 2 (3) 035004-1 - 035004-3 1882-0778 2009/02 [Refereed][Not invited]
     
    We report on the formation of core--shell pn junction InP nanowires using a catalyst-free selective-area metalorganic vapor-phase epitaxy (SA-MOVPE) method. A periodically aligned dense core--shell InP nanowire array was fabricated and used in photovoltaic device applications. The device exhibited open-circuit voltage ($V_{\text{OC } }$), short-circuit current ($I_{\text{SC } }$) and fill factor (FF) levels of 0.43 V, 13.72 mA/cm2 and 0.57, respectively, which indicated a solar power conversion efficiency of 3.37% under AM1.5G illumination. This study demonstrates that high quality core--shell structure nanowire fabrication is possible by SA-MOVPE and that the nanowire arrays can be used in integrated nanowire photovoltaic devices.
  • K. Tomioka, Y. Kobayashi, J. Motohisa, S. Hara, T. Fukui
    Nanotechnology 20 145302  2009 [Not refereed][Not invited]
  • H. Sasakura, H. Kumano, I. Suemune, J. Motohisa, Y. Kobayashi, M. van Kouwen, K. Tomioka, T. Fukui, N. Akopian, V. Zwiller
    16TH INTERNATIONAL CONFERENCE ON ELECTRON DYNAMICS IN SEMICONDUCTORS, OPTOELECTRONICS AND NANOSTRUCTURES (EDISON 16) 193 01232  1742-6588 2009 [Refereed][Not invited]
     
    We report optical properties of InP/InAsP/InP nanowire quantum dots and single-photon Fourier spectroscopy of an exciton in a single InAsP quantum dot embedded in an InP nanowire. The coherent length of the time-averaged emission originating from the single InAsP QD was measured by a Mach-Zehnder interferometer inserted in the photoluminescence path. Effects of fluctuations in surrounding excess charges trapped in the InP nanowire were investigated by excitation power and energy dependencies.
  • L. Yang, J. Motohisa, K. Tomioka, J. Takeda, T. Fukui, M-M Geng, L-X. Jia, L. Zhang, Y-L. Liu
    Nanotechnology 19 275304-1 - 275304-7 2008/05 [Refereed][Not invited]
  • J. Noborisaka, T. Sato, J. Motohisa, K. Tomioka, S. Hara, T. Fukui
    Device Research Conference - Conference Digest, DRC 177 - 178 1548-3770 2008 [Refereed][Not invited]
  • Katsuhiro TOMIOKA, Takuya SATO, Shinjiroh HARA, Junichi MOTOHISA, Takashi FUKUI
    Hyomen Kagaku The Surface Science Society of Japan 29 (12) 726 - 730 0388-5321 2008 [Not refereed][Not invited]
     
    We report on the growth of III-V compound semiconductor nanowires by selective-area MOVPE. Position-controlled growth of GaAs nanowire, and InP/InAs/InP core-multi shell nanowires are reviewed. The nanowires are oriented to <111>B or <111>A directions and they have hexagonal cross-section surrounded with {1-10} vertical side facets and (111)B or A top surface. Also, we can control the growth direction to axial or radial by changing the growth parameters. InP/InAs/InP core-multi shell nanowires whose well thickness is of several monolayers are fabricated by using this method. We also review on the growth of vertical GaAs nanowires on Si substrate and fabrication of InGaAs nanowire-FETs.
  • TOMIOKA K.
    Nano Lett. 8 (10) 3475 - 3480 1530-6984 2008 [Not refereed][Not invited]
  • 比留間 健之, 池尻 圭太郎, 吉田 浩惇, 冨岡 克広, 本久 順一, 原 真二郎, 福井 孝志
    日本結晶成長学会誌 34 (4) 36 - 44 0385-6275 2008/01 [Refereed][Not invited]
  • J. Noborisaka, T. Sato, J. Motohisa, S. Hara, K. Tomioka, T. Fukui
    Japanese Journal of Applied Physics Published by the Japan Society of Applied Physics through the Institute of Pure and Applied Physics 46 (11) 7562 - 7568 0021-4922 2007/11 [Refereed][Not invited]
     
    Single InGaAs nanowire-top-gate metal–semiconductor field-effect transistors (MESFETs) were fabricated and characterized. Silicon-doped n-InGaAs nanowires (with a typical diameter of 100 nm) were grown by catalyst-free selective-area metal–organic vapor-phase epitaxy (SA-MOVPE). The FETs of single nanowires on SiO2-coated Si substrates were fabricated by defining metal contacts at both ends of the nanowires and the metal top gate between contacts. According to the measurements of drain current–voltage and gate transfer characteristics, the top-gate MESFETs exhibited significant enhancements in device performance characteristics compared with FETs under back-gate operation; that is, a peak transconductance of 33 mS/mm and a current on–off ratio of $10^{3}$ were obtained. A possibility for further improvements in FET characteristics was also considered.
  • K. Tomioka, P. Mohan, J. Noborisaka, S. Hara, J. Motohisa, T. Fukui
    Journal of Crystal Growth 298 644  2007 [Not refereed][Not invited]
  • Tomioka Katsuhiro, Motohisa Junichi, Hara Shinjiroh, Fukui Takashi
    Jpn J Appl Phys Japan Society of Applied Physics 46 (45) L1102 - L1104 0021-4922 2007 [Not refereed][Not invited]
     
    Crystallographic structure of InAs nanowires, which were grown by selective-area metalorganic vapor phase epitaxy on (111)B-oriented substrates, was investigated by transmission electron microscopy (TEM). The TEM images showed that the nanowires had many stacking faults along the growth direction. Statistical analysis of the atomic-layer stacking showed that InAs nanowires contained both zincblende and wurtzite crystal phases, whose transition took place in every one to three monolayers. This specific crystal phase transition resulted in peculiar electron diffraction patterns. The stacking of the atomic layers had no distinct correlation with the diameter of the nanowires.
  • L. Yang, J. Motohisa, J. Takeda, S. Hara, K. Tomioka, T. Fukui
    Nanotechnology 18 105302-1 - 105302-5 2007/01 [Refereed][Not invited]
  • L. Yang, J. Motohisa, J. Takeda, K. Tomioka, T. Fukui
    Applied Physics Letters 89 203110-1 - 203110-3 2006/11 [Refereed][Not invited]
  • K. Uchida, K. Tomioka, S. Adachi
    Journal of Applied Physics American Institute of Physics 100 (3) 014301-1 - 014301-5 0021-8979 2006/07 [Refereed][Not invited]
     
    Stable ultraviolet (UV) photoluminescence (PL) has been observed at room temperature in poroussilicon (PSi) fabricated by photoetching in aqueous alkali fluoride solutions. The aqueous solutionsused are 1 M NaF and 1 M KF.They give an alkaline reaction caused by partial hydrolysis. The PLpeaks at ～3.3 eV have a full width at half maximum of ～0.1 eV, which is much smaller than thosereported previously (?0.5 eV). Spectral analyses suggest that both quantum confinement andsurface passivation effects enable the observation of UV emission in NaF- and KF-prepared PSisamples.
  • TOMIOKA K.
    Applied Physics Letters American Institute of Physics 87 (25) 251920-1 - 251920-3 0003-6951 2005/12 [Refereed][Not invited]
     
    A new method of fabricating porous silicon emitting in the ultraviolet (UV) spectral region ispresented. This method uses photoetching in an aqueous salt (KF) solution. Strong UVphotoluminescence is observed at ～3.3 eV with a full width at a half maximum of ～0.1 eV, whichis much narrower than those reported previously. Fourier transform infrared spectroscopy suggeststhat the surface oxide produced during photoetching plays an important role in the UV emission ofthe KF-prepared PSi.
  • Katsuhiro Tomioka, Sadao Adachi
    Journal of Applied Physics American Institute of Physics 98 (7) 073551-1 - 073551-7 0021-8979 2005/10 [Refereed][Not invited]
     
    The structural and optical properties of porous GaP have been studied by scanning electronmicroscopy, spectroscopic ellipsometry, and photoluminescence (PL) spectroscopy. Porous GaPlayers were fabricated by anodic etching in HF:H2O:C2H5OH=1:1:2 electrolyte on n-type (100)and (111)A substrates. The morphology of the porous GaP layer is found to depend strongly on thesurface orientation. Apart from the red emission band at ～1.7 eV, a supra-band-gap (EgX) emissionhas been clearly observed on the porous GaP (111)A sample. The anodic porous layer on the (100)substrate, on the other hand, has shown only the red emission at 300 K and both red and greendonor-acceptor pair emissions at low temperatures. The correlation between the PL properties andthe porous morphology is discussed. An optical transition model is also proposed for the explanationof the PL emission properties of the porous GaP samples.
  • Sadao Adachi, Katsuhiro Tomioka
    Electrochemical Solid-State Letters 8 (10) G251 - G253 1099-0062 2005/08 [Refereed][Not invited]
  • Katsuhiro Tomioka, Sadao Adachi
    Journal of the Electrochemical Society 152 (3) G173 - G178 0013-4651 2005/01 [Refereed][Not invited]

MISC

  • TOMIOKA Katsuhiro, FUKUI Takashi  電気学会研究会資料. EDD, 電子デバイス研究会  2012-  (30)  45  -50  2012/03/07
  • Sakuma Hirotaka, Tomoda Motonobu, Matsuda Osamu, Fukui Takashi, Tomioka Katsuhiro, Veres Istvan A., Wright Oliver B.  Proceedings of Symposium on Ultrasonic Electronics  31-  153  -154  2010/12/06
  • Motohisa Junichi, Tanaka Tomotaka, Tomioka Katsuhiro, Fukui Takashi  Proceedings of the IEICE General Conference  2010-  (2)  "SS  -45"  2010/03/02
  • Sakuma Hirotaka, Tomoda Motonobu, Matsuda Osamu, Fukui Takashi, Tomioka Katsuhiro, Wright Oliver B.  Proceedings of Symposium on Ultrasonic Electronics  30-  209  -210  2009/11/18
  • Sakuma Hirotaka, Tomoda Motonobu, Matsuda Osamu, Fukui Takashi, Tomioka Katsuhiro, Wright Oliver B.  Proceedings of Symposium on Ultrasonic Electronics  29-  19  -20  2008/11/11  
    We investigate the vibrational modes of GaAs nanopillars of hexagonal cross section on a GaAs substrate using an ultrafast optical technique. The motions of the pillars after excitation with visible light pulses are detected using a time-delayed infrared light pulses. Thickness modes of the pillars are detected in the 10-30 GHz range.
  • HIRUMA Kenji, IKEJIRI Keitaro, YOSHIDA Hiroatsu, TOMIOKA Katsuhiro, MOTOHISA Junichi, HARA Shinjiroh, FUKUI Takashi  Journal of the Japanese Association of Crystal Growth  34-  (4)  224  -232  2007/11/30  
    GaAs and InAs nanowires were selectively grown by using metal-organic vapor-phase epitaxy. The nanowires were as thin as several tens to several hundreds nanometers and as long as several micronmeters. Scanning electron microscope observations showed that the growth direction of nanowires was parallel to the <111> B crystallographic orientation. It was found by a transmission electron microscopy analysis that the crystal structure of the GaAs nanowire was zincblende with rotational twins around the <111> axis. For the GaAs nanowires, the density of twins along the <111> direction increased as the nanowire diameter decreased. The growth mechanism was understood based upon a model that the GaAs nanowire was composed of stacked thin-layers with interfaces containing rotational twins.

Books etc

  • Emerging Devices for Low-Power and High-Performance Nanosystems: Physics, Novel Functions, and Data Processing
    Tomioka Katsuhiro (ContributorChapter 2 - Several Challenges in Steep-Slope Tunnel Field-Effect Transistors)
    Pan Stanford 2018/08 (ISBN: 9814800112) 450
  • Novel Compound Semiconductor Nanowires – Materials, Devices, and Applications
    Tomioka Katsuhiro (ContributorChapter 14 – III-V Nanowires: Transistor and photovoltaic applications)
    Pan Stanford Publishing 2017/11 (ISBN: 9814745766) 53 p. 464 – 516
  • Handbook of Crystal Growth, Second Edition edited by T. Nishinaga, P. Rudolph, and T. Kuech
    Katsuhiro Tomioka, Takashi Fukui (ContributorChapter 4 in Volume: 2A - Growth of Semiconductor Nanocrystals)
    Elsevier 2014/12 (ISBN: 9780444563699)
  • ナノワイヤ最新技術の基礎と応用展開
    冨岡克広 (Contributor第III編第3章 - ナノワイヤのトランジスタ応用)
    株式会社シーエムシー出版 2013/03 (ISBN: 9784781307602) 241 208-223
  • Semiconductor Nanowire and Their Optical Applications
    Katsuhiro Tomioka, Takashi Fukui (ContributorChapter 3: III-V Semiconductor Nanowires on Si by Selective-Area Metal-Organic Vapor Phase Epitaxy.)
    Springer 2012/01 (ISBN: 3642224792)
  • Advances in III-V Semiconductor Nanowires and Nanodevices, edited by J. Li, D. Wang, and R. R. LaPierre
    Junichi Motohisa, Katsuhiro Tomioka, Bin Hua, Kumar S, K. Varadwaj, Shinjiroh Hara, Kenji Hiruma, Takashi Fukui (ContributorIII-V Semiconductor Nanowire Light Emitting Diodes and Lasers)
    Bentham Science Publisher 2011/11

Presentations

  • (Invited) Vertical III-V Nanowire Transistors and Prospects  [Invited]
    Katsuhiro Tomioka
    17th D2T Symposium  2022/09
  • (Invited) Integration of III-V Nanowires on Si and their Device Applications  [Invited]
    Katsuhiro Tomioka, Junichi Motohisa
    14th International Symposium on Advanced Plasma Science and its Applications for Nitrides and Nanomaterials/15th International Conference on Plasma-Nano Technology & Science (ISPlasma2022/IC-PLANTS2022)  2022/03
  • (Invited) Integration of III-V Nanowire on Si and Their Device Application  [Invited]
    Katsuhiro Tomioka, Hironori Gamo, Junichi Motohisa
    International Union of Materials Research Societies - International Conference in Asia 2021 (IUMRS-ICA 2021)  On/Offline hybrid event, Jeju, Korea
  • (Invited) Integration of III-V nanowire LEDs on Si  [Invited]
    Katsuhiro Tomioka, Junichi Motohisa
    The 20th International Meeting on Information Display (IMID 2020)  Online conference, Korea
  • (Invited) InP-based Nanowires Towards On-demand Single Photon Emitters  [Invited]
    Junichi Motohisa, Katsuhiro Tomioka
    XXth International Workshop on Physics of Semiconductor Devices (IWPSD 2019)  Kolkata, India
  • “(Invited) Vertical Tunnel FET Technologies Using III-V/Si Heterojunction  [Invited]
    K. Tomioka, H. Gamo, J. Motohisa
    236th ECS meeting  2019/10
  • Selective-Area Epitaxy of III-V Nanowires on Si and Their Switching Applications  [Invited]
    K. Tomioka, J. Motohisa
    7th International Workshop on Epitaxial Growth and Fundamental Properties of Semiconductor Nanostructures (Semicon Nano 2019)  2019/09
  • Integration of III-V nanowires on Si and their transistor applications (Plenary)  [Invited]
    Katsuhiro Tomioka
    22nd International Conference on Advanced Materials  2018/12
  • Transistor applications using vertical III-V nanowires on Si platform  [Invited]
    K. Tomioka, T. Fukui
    232nd ECS meeting  2017/10
  • MOVPE選択成長法によるナノワイヤ成長とデバイス応用  [Invited]
    冨岡 克広, 本久 順一
    第78回応用物理学秋季学術講演会  2017/09
  • Vertical III-V nanowires on Si and transistor applications  [Invited]
    K. Tomioka, J. Motohisa, T. Fukui
    The 15th International Conference on Advanced Materials (IUMRS-ICAM 2017)  2017/08
  • 半導体ナノワイヤ選択成長と電子デバイス応用  [Invited]
    第9回ナノ構造エピタキシャル成長講演会  2017/07
  • Phase transition from Zinc Blende to Wurtzite and green-yellow emission of AlInP grown by crystal structure transfer method (Invited)  [Invited]
    Takashi Fukui, Yoshihiro Hiraya, Fumiya Ishizaka, Katsuhiro Tomioka
    13th Sweden - Japan QNANO Workshop  2017/03
  • Selective area growth of III-V nanowires on Si and their transistor applications  [Invited]
    K. Tomioka
    2016 HU-SNU Joint Workshop  2016/11
  • Recent progress in vertical Si/III-V tunnel FETs: from fundamentals to current boosting technology  [Invited]
    K. Tomioka, J. Motohisa, T. Fukui
    PRiME 2016  2016/10
  • Advances in Steep-Slope Tunnel FETs  [Invited]
    Katsuhiro Tomioka, Junichi Motohisa, Takashi Fukui
    ESSDERC 2016  2016/09
  • Selective-area growth of III-V nanowires on Si and transistor applications  [Invited]
    Katsuhiro Tomioka, Junichi Motohisa, Takashi Fukui
    The 8th International Conference on Low Dimensional Structures and Devices (LDSD 2016)  2016/08
  • Heterogeneous Integration of InGaAs-Related Nanowires on Si and Their Device Applications  [Invited]
    K. Tomioka, F. Ishizaka, J. Motohisa, T. Fukui
    18th International Conference on Metal-Organic Vapor Phase Epitaxy (ICMOVPE-XVIII), San Diego, USA, July 10-15 (2016)  2016/07
  • Vertical transistors using III-V nanowires on Si  [Invited]
    Tomioka Katsuhiro
    2015 CNU-HU Joint Workshop, Daejeon, Korea, Nov. 20th (2015).  2015/11
  • Recent progress in vertical TFET using III-V/Si heterojunction  [Invited]
    K. Tomioka, J. Motohisa, T. Fukui
    Steep Transistors Workshop, Notre Dame, USA, Oct. 5-6 (2015).  2015/10
  • Vertical Tunnel FETs Using III-V Nanowire/Si Heterojunctions  [Invited]
    K. Tomioka, J. Motohisa, T. Fuku
    228th ECS Meeting, phoenix, Arizona, USA  2015/10
  • Vertical III-V nanowire transistors for future low-power switches  [Invited]
    K. Tomioka, T. Fukui
    12th Sweden - Japan QNANO Workshop, Hindas, Sweden, Sep. 24-25 (2015).  2015/09
  • Heterogeneous integration of vertical III-V nanowires on Si and Ge and their applications  [Invited]
    K.Tomioka, J. Motohisa, T. Fukui
    The 20th American Conference on Crystal Growth and Epitaxy and The 17th Biennial Workshop on Organometallic Vapor Phase Epitaxy (ACCGE-20/OMVPE-17), Big Sky, Montana, USA, 2-7 Aug. (2015).  2015/08
  • Vertically Aligned Semiconductor Nanowire Array and Their Applications (Invited)  [Invited]
    T. Fukui, F. Ishizaka, K. Tomioka
    Compound Semiconductor Week 2015 (CSW2015), Santa Barbara, USA, June 28 - July 2 (2015).  2015/06
  • III-V nanowire channel on Si: From high-performance Vertical FET to steep-slope device  [Invited]
    K. Tomioka, J. Motohisa, T. Fukui
    2015 International Symposium on VLSI Technology, Systems and Applications (2015 VLSI-TSA), Hsinchu, Taiwan, April 27-29 (2015)  2015/04
  • シリコン基板上のInAsナノワイヤ縦型サラウンディングゲートFETの作製  [Not invited]
    第70回応用物理学学術講演会  2009
  • GaAs(111)B上にMOVPE選択成長されたInGaAsナノワイヤの成長温度依存性評価  [Not invited]
    第70回応用物理学学術講演会  2009
  • AlGaAs/GaAsコア・マルチシェルナノワイヤ発光ダイオードの作製とSi基板上への集積化  [Not invited]
    第70回応用物理学学術講演会  2009
  • シリコン基板上のGaAsナノワイヤ成長：コヒーレント成長の実現  [Not invited]
    第70回応用物理学学術講演会  2009
  • MOVPE選択成長法によるSi(111)基板上のInAsナノワイヤ成長  [Not invited]
    第55回応用物理学関係連合講演会  2008
  • MOVPE選択成長したInAsナノワイヤの縦型二端子測定  [Not invited]
    第69回応用物理学学術講演会  2008
  • MOVPE選択成長法によるSi基板上のGaAs/AlGaAsコア・シェルナノワイヤの作製  [Not invited]
    第69回応用物理学学術講演会  2008
  • MOVPE選択成長法により作製したInAsナノワイヤのTEM観察  [Not invited]
    第54回応用物理学関連連合講演会  2007
  • MOVPE選択成長法によるSi(111)基板上のIII-V化合物半導体ナノワイヤの作製  [Not invited]
    第68回応用物理学学術講演会  2007

Teaching Experience

  • Information Science IInformation Science I Hokkaido University

Association Memberships

  • JAPANESE ASSOCIATION FOR CRYSTAL GROWTH   IEEE EDS   応用物理学会   

Research Projects

  • Development on strucural phase transition semiconductors
    JST：FOREST
    Date (from‐to) : 2021/04 -2027/03
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (A)
    Date (from‐to) : 2022/04 -2026/03 
    Author : 冨岡 克広, 池辺 将之, 本久 順一
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (A)
    Date (from‐to) : 2021/04 -2025/03 
    Author : 深田 直樹, J. Wipakorn, 宮崎 剛, 本久 順一, 冨岡 克広, 松村 亮
     
    現行の平面型金属・酸化膜・半導体電界効果型トランジスタ（MOSFET）では、微細化した回路素子からのリーク電流による発熱が大きくなるため、従来のスケール則に従った微細化だけでは素子の性能向上に限界が指摘されている。本研究では、IV族半導体Si、Ge、新規高移動度材料として注目されているGeSnから形成される特殊なコアシェルヘテロ接合により高電子移動度型トランジスタ（HEMT）構造を１次元ナノワイヤ内部に形成することで、次世代トランジスタの微細化限界・低消費電力化の課題を解決し、ナノ構造でも不純物散乱のない高移動度デバイスを実現する。 初年度はサイズ・配列制御可能で、大面積での繰り返しパターン形成が容易で時間短縮できるナノインプリント法と反応性イオンエッチング（RIE）法を適用し、i(intrinsic)-Ge/p-Si、逆構造であるp-Si/i-Geおよびp-Si/i-Ge1-xSnxコアシェルナノワイヤ中のコア領域のp-Siおよびi-Geナノワイヤアレイの形成を行った。RIEの条件をSiとGeで最適化することで、直径150nmのi-Geおよびp-Siナノワイヤアレイのサイズ・配列制御に成功した。RIEではナノワイヤ表面にダメージが導入される。そこで、表面ダメージ層を低温オゾン酸化とエッチングで除去し、ナノワイヤ径を高速チャネルのサイズとして利用できる50nmまで縮小化することに成功した。ナノワイヤFET形成のためのプロセスおよび大規模第一原理計算によるコアシェルナノワイヤモデルの構築を行った。
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)
    Date (from‐to) : 2020/04 -2023/03 
    Author : 本久 順一, 冨岡 克広
     
    令和2年度は、ナノワイヤを利用したベクトル光波を発生する素子構造として提案しているもののうち、WGM型の発光特性の評価を行うとともに、そのナノワイヤからのベクトル光波の発生を確認した。具体的には、有機金属気相選択成長法により作製したGaAs/InGaAs/GaAs コアマルチシェル構造のナノワイヤに対し、まず連続光励起下の顕微PL測定により、Q値が200程度の共振モードが複数のナノワイヤで観測されることを確認した。そして、パルス光励起による評価を行ったところ、連続光励起ではブロードな発光しか観測されなかった波長において、励起光強度に対し非線形的に増大する発光ピークを複數のナノワイヤにおいて観測した。これはナノワイヤがレーザ発振していることを強く示している。そして、連続光およびパルス光励起のそれぞれの条件で、発光のピーク強度の偏光依存性を評価したところ、λ/2波長板の回転角に対し90度周期で強度が振動的に変化する一方で、λ/4波長板に対してはその回転角にはほとんど依存しない発光ピークが存在することが明らかとなった。これはナノワイヤからの発光が単純な直線偏光もしくは円偏光とはなっていないことを示している。さらに、パルス光励起の条件下で非常に強度の強い単一ピークが観測されているナノワイヤについて、その発光像を観測したところ、発光像の強度分布が、λ/2波長板の回転角に応じて周期的・空間的に変化することが明らかとなった。この結果は、ナノワイヤからの発光スポットの偏光分布が空間的に一様でなく、そしてまた軸対称となっていることを示しており、以上よりベクトル光波の発生が確認された。同時に発光像のストークス解析を行ったところ、得られたナノワイヤからのベクトル光波は低次のベクトル光波となっていることを示唆する実験結果が得られた。
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Challenging Research (Exploratory)
    Date (from‐to) : 2019/06 -2022/03 
    Author : Tomioka Katsuhiro
     
    In this research, we developed a formation of superlattice NWs by selective-are growth technique and demonstrated vertical diode and vertical gate all-around resonant tunneling transistor (VGAA-RTFET) device using the superlattice nanowires for the first time. The demonstrated VGAA-RTFET device has realized high-speed switching properties with high tunneling current and steep subthreshold slope (SS), and material and device technologies that simultaneously solve the TFET problem of high switching current and steep SS have been realized. This has pioneered a new methodology for low-power switching devices and high-frequency devices.
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)
    Date (from‐to) : 2019/04 -2022/03 
    Author : Tomioka Katsuhiro
     
    In this research, we developed and explored heterogeneous integration of III-V nanowires heterogeneous for high-speed, low-power, and high-efficiency three-dimensional (3D) circuits application. a nanowire 3D-architecture revolutionized the existing planar integration paradigm, and created a new trend in next-generation electronics. We have created an ultra-efficient tunnel transistors driven by nanowatts based on a new Si/III-V nanowire junction and tunneling transport mechanism. These results would provided new design guidelines for three-dimensional circuit structures based on nanowire TFETs.
  • 化合物半導体ナノワイヤによる立体縦型トランジスタ高速CMOS技術の確立
    一般財団法人 テレコム先端技術研究支援センター：平成３０年度助成
    Date (from‐to) : 2018/04 -2021/03 
    Author : 冨岡 克広
  • 新しい半導体接合を用いた低電圧スイッチ素子の高性能化
    公益財団法人 東電記念財団：2017年度研究助成（基礎研究）
    Date (from‐to) : 2018/04 -2020/03 
    Author : 冨岡 克広
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)
    Date (from‐to) : 2017/04 -2020/03 
    Author : Motohisa Junichi
     
    We attempted the growth of InGaAs nanowires (NWs) on Si substrates by selective-area metalorganic vapor-phase epitaxy. By controlling the supply ratio of source materials of group III atoms, emission from InGaAs NW arrays in the telecommunication bands were successfully confirmed by the low-temperature photoluminescence measurement. InGaAs NW arrays with a vertical pn junction are also fabricated and photocurrent spectroscopy reveals that fabricated NW array exhibited optical bandgap in the telecommunication bands. Emission mechanism of InP-based light-emitting diode (LED) was investigated and radiative tunneling was the dominant emission mechanism in the NW-LEDs. Control of the emission wavelength and size of InAsP quantum dots embedded in InP NWs were attempted and emission from the telecommunication band was demonstrated. NW-LEDs utilizing InAsP/InP heterostructure NWs were also fabricated and confirmed the light emission in the near-infrared regions originating from InAsP layer.
  • 高品質狭ギャップ化合物半導体ナノワイヤ材料の創生と省エネルギー電子素子応用
    公益財団法人 矢崎科学技術振興記念財団：第34回(2016年度)一般研究助成（新材料）
    Date (from‐to) : 2017/04 -2020/03 
    Author : 冨岡 克広
  • IV族/III-V族ヘテロ接合の界面欠陥制御に基づく低電圧スイッチ素子の回路応用
    独立行政法人日本学術振興会：科学研究費助成事業（科学研究費補助金）若手研究（A)
    Date (from‐to) : 2016/04 -2019/03 
    Author : 冨岡 克広
  • 高品質狭ギャップ化合物半導体ナノワイヤ材料の創生と低電圧電子素子応用
    公益財団法人 サムコ科学技術振興財団：第1回(2018年度)一般研究助成
    Date (from‐to) : 2017/10 -2018/10 
    Author : 冨岡 克広
  • 半導体ナノワイヤを用いた新型光検出器 (分担)
    独立行政法人日本学術振興会：科学研究費助成事業 挑戦的萌芽研究
    Date (from‐to) : 2016/04 -2018/03 
    Author : 本久 順一
  • 新しい半導体接合による低電圧スイッチ素子応用と高性能化に関する研究
    公益財団法人 カシオ科学振興財団：第34回（平成28年度）研究助成
    Date (from‐to) : 2016/12 -2017/12 
    Author : 冨岡 克広
  • ナノワイヤ異種集積技術に基づくGe/III-V ハイブリッド電子デバイスの創成
    公益財団法人 マツダ財団：第32回(2016年度)マツダ研究助成
    Date (from‐to) : 2016/11 -2017/11 
    Author : 冨岡 克広
  • ナノワイヤ異種集積技術に基づくGe/III-Vハイブリッド電子デバイスの創成
    公益財団法人 村田学術振興財団：平成28年度 研究助成（自然科学）
    Date (from‐to) : 2016/06 -2017/06 
    Author : 冨岡 克広
  • 化合物半導体ナノワイヤによる光デバイス応用(分担)
    独立行政法人日本学術振興会：科学研究費助成事業（科学研究費補助金）基盤研究（S）
    Date (from‐to) : 2015/04 -2016/03 
    Author : 福井孝志
  • Development of novel hydrogen-generating devices and low-power switch using new semiconductor heterointerfaces
    JST：PRESTO
    Date (from‐to) : 2012/10 -2016/03 
    Author : Tomioka Katsuhiro
  • Si/III-V族半導体超ヘテロ界面の機能化と低電力スイッチ素子の開発
    ＪＳＴ戦略的創造研究推進制度（個人研究型） （個人研究推進事業：さきがけ研究２１‐ＰＲＥＳＴＯ）
    Date (from‐to) : 2009 -2013
  • Si/III-V族化合物半導体ナノワイヤへテロ接合界面のTEM観察評価とその応用に関する研究
    日本科学協会：笹川研究助成
    Date (from‐to) : 2009/04 -2010/03 
    Author : 冨岡 克広
  • 半導体ナノワイヤに形成したコア・シェル量子井戸おける光物性と微小電流注入レーザーへの応用に関する研究
    財団法人光科学技術研究振興財団：研究助成
    Date (from‐to) : 2009/04 -2010/03 
    Author : 冨岡 克広
  • 有機金属気相選択成長法による半導体ナノワイヤへテロ構造作製とその応用に関する研究
    独立行政法人日本学術振興会：特別研究員奨励費 PD
    Date (from‐to) : 2008/04 -2009/03 
    Author : 冨岡 克広
  • 有機金属気相選択成長法による半導体ナノワイヤへテロ構造作製とその応用に関する研究
    独立行政法人日本学術振興会：特別研究員奨励費 DC2
    Date (from‐to) : 2007/04 -2008/03 
    Author : 冨岡 克広

Industrial Property Rights

  • 特願2022-48567:マルチモードスイッチ素子  2022年/03/24
    蒲生 浩憲, 冨岡 克広  北海道大学
  • 米国特許登録 US Patent 10,403,498:Group III-V compound semiconductor nanowire, field effect transistor, and switching element    2019/04
    Katsuhiro Tomioka, Takashi Fukui
  • 特願2015-193196:トンネル電界効果トランジスタ  2015年/09/30
    冨岡 克広, 福井 孝志
  • 中華人民共和国特許登録番号ZL201080043950.2:トンネル電界トランジスタおよびその製造方法  
    冨岡 克広, 福井 孝志, 田中 智隆
  • 特許番号第5655228号:半導体構造物の製造方法  
    冨岡 克広, 福井 孝志, 本久 順一, 原 真二郎
  • 特許番号第5652827号:トンネル電界効果トランジスタおよびその製造方法  
    冨岡 克広, 福井 孝志, 田中 智隆
  • United States Patent No.8895958:発光素子およびその製造方法  
    冨岡 克広, 福井 孝志
  • 台湾出願103137589:III-V族化合物半導体ナノワイヤ、電界効果トランジスタおよびスイッチ素子  2014年/10/30
    冨岡 克広, 福井 孝志
  • PCT出願PCT/JP2014/005463:III-V族化合物半導体ナノワイヤ、電界効果トランジスタおよびスイッチ素子  2014年/10/29
    冨岡 克広, 福井 孝志
  • United States Patent No. 8816324:Semiconductor Device and Method for Manufacturing Semiconductor Device (半導体装置および半導体装置の製造方法)  
    Takashi Fukui, Katsuhiro Tomioka, Junichi Motohisa, Shinjiroh Hara
  • PCT出願PCT/JP2014/004175:トンネル電界効果トランジスタ、その製造方法およびスイッチ素子  2014年/08/12
    冨岡 克広, 福井 孝志
  • United States Patent No.8698254:Tunnel Field Effect Transistor and Method for Manufacturing Same (トンネル効果トランジスタ、その製造方法およびスイッチ素子)  
    Katsuhiro Tomioka, Takashi Fukui, Tomotaka Tanaka
  • 特許5464458:半導体装置及び半導体装置の製造方法    2014/01/31
    福井 孝志, 冨岡 克広, 本久 順一, 原 真二郎
  • 特願2013-226675:III-V族化合物半導体ナノワイヤ、電界効果トランジスタおよびスイッチ素子  2013年/10/31
    冨岡 克広, 福井 孝志
  • 台湾出願103127711:トンネル電界効果トランジスタ、その製造方法およびスイッチ素子  2013年/08/13
    冨岡 克広, 福井 孝志
  • 特願2013-168048:トンネル電界効果トランジスタ、その製造方法およびスイッチ素子  2013年/08/13
    冨岡 克広, 福井 孝志
  • 特願2013-138894:発光素子およびその製造方法  2013年/07/02
    福井 孝志, 石坂 文哉, 冨岡 克広
  • 台湾出願100106528:半導体装置及び半導体装置の製造方法  2011年/02/23
    福井 孝志, 冨岡 克広, 本久 順一, 原 真二郎
  • 米国出願13/581242:半導体装置及び半導体装置の製造方法  2011年/02/23
    福井 孝志, 冨岡 克広, 本久 順一, 原 真二郎
  • 特願2012-501804:半導体装置及び半導体装置の製造方法  2011年/02/23
    福井 孝志, 冨岡 克広, 本久 順一, 原 真二郎
  • 欧州出願11747358.7:半導体装置及び半導体装置の製造方法  2011年/02/23
    福井 孝志, 冨岡 克広, 本久 順一, 原 真二郎
  • PCT出願PCT/JP2011/053909:半導体装置及び半導体装置の製造方法  2011年/02/23
    福井 孝志, 冨岡 克広, 本久 順一, 原 真二郎
  • 米国出願13/499333:トンネル電界効果トランジスタおよびその製造方法  2010年/09/29
    冨岡 克広, 福井 孝志, 田中 智隆
  • 韓国出願10-2012-7007578:トンネル電界効果トランジスタおよびその製造方法  2010年/09/29
    冨岡 克広, 福井 孝志, 田中 智隆
  • 特願2011-534074:トンネル電界効果トランジスタおよびその製造方法  2010年/09/29
    冨岡 克広, 福井 孝志, 田中 智隆
  • 欧州出願10820133.6:トンネル電界効果トランジスタおよびその製造方法  2010年/09/29
    冨岡 克広, 福井 孝志, 田中 智隆
  • PCT出願PCT/JP2010/005862:トンネル電界効果トランジスタおよびその製造方法  2010年/09/29
    冨岡 克広, 福井 孝志, 田中 智隆
  • 米国出願13/513082:発光素子およびその製造方法  2010年/06/04
    冨岡 克広, 福井 孝志
  • 特願2011-544174:発光素子およびその製造方法  2010年/06/04
    冨岡 克広, 福井 孝志
  • PCT出願 PCT/JP2010/003762:発光素子およびその製造方法  2010年/06/04
    冨岡 克広, 福井 孝志
  • 特願2010-040019:半導体装置及び半導体装置の製造方法  2010年/02/25
    本久 順一, 原 真二郎, 福井 孝志, 冨岡 克広
  • 特願2009-273561:トンネル電界効果トランジスタおよびその製造方法  2009年/12/01
    冨岡 克広, 福井 孝志, 田中 智隆
  • 多孔質半導体膜の形成方法
    特許第４２５７４３１号

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