Researcher Database

Junichi Motohisa
Faculty of Information Science and Technology Electronics for Informatics Integrated Systems Engineering
Professor

Researcher Profile and Settings

Affiliation

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

Job Title

  • Professor

URL

Research funding number

  • 60212263

J-Global ID

Research Interests

  • 選択成長   有機金属気相成長   量子ドット   結晶成長   半導体   フォトニック結晶   表面超格子   フォトルミネセンス   ヘテロ構造   論理回路   半導体ナノワイヤ   有機金属気相成長法   再成長   マスクパターン   線欠陥・点欠陥導入構造   スーパーアトム   人工結晶   多段原子ステップ   光取り出し効率   原子ステップ   顕微フォトルミネセンス   ナノ構造周期配列構造   人工原子   フォトニックバンドギャップ   単一光子光源   加工基板   3角格子   時間領域差分(FDTD)法   電界効果トランジスタ   フォトニック結晶スラブ   半導体デバイス   半導体物性   半導体ナノ構造   半導体結晶成長   

Research Areas

  • Manufacturing technology (mechanical, electrical/electronic, chemical engineering) / Electric/electronic material engineering
  • Nanotechnology/Materials / Optical engineering and photonics
  • Manufacturing technology (mechanical, electrical/electronic, chemical engineering) / Electronic devices and equipment
  • Manufacturing technology (mechanical, electrical/electronic, chemical engineering) / Electric/electronic material engineering
  • Nanotechnology/Materials / Crystal engineering
  • Nanotechnology/Materials / Applied materials

Academic & Professional Experience

  • 2006/04 - Today Hokkaido University
  • 2001/04 - 2006/03 Hokkaido University Research Center for Integrated Quantum Electronics
  • 1994/04 - 2001/03 Hokkaido University
  • 1993/04 - 1994/03 Hokkaido University

Research Activities

Published Papers

  • Yusuke Minami, Akinobu Yoshida, Junichi Motohisa, KatsuhiroTomioka
    Journal of Crystal Growth 506 135 - 139 2019/01 [Refereed][Not invited]
  • Kohei Chiba, Katsuhiro Tomioka, Akinobu Yoshida, Junichi Motohisa
    AIP ADVANCES 7 (12) 125304  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).
  • Akinobu Yoshida, Katsuhiro Tomioka, Fumiya Ishizaka, Junichi Motohisa
    JOURNAL OF CRYSTAL GROWTH 464 75 - 79 0022-0248 2017/04 [Refereed][Not invited]
     
    We report the growth of InGaAs nanowires (NWs) on Ge(111) substrates using selective-area metal-organic vapor-phase epitaxy (SA-MOVPE) for novel InGaAs/Ge hybrid complementary metal-oxide-semiconductor (CMOS) applications. Ge(111) substrates with periodic arrays of mask opening were prepared, and InGaAs was selectively grown on the opening region of Ge(111). A uniform array of InGaAs NWs with a diameter around 100 nm was successfully grown using appropriate preparation of the initial surfaces with an AsH3 thermal treatment and flow-rate modulation epitaxy (FME). We found that optimizing partial pressure of AsH3 and the number of FME cycles improved the yield of vertical InGaAs NWs. Line-scan profile analysis of energy dispersive X-ray (EDX) spectrometry showed that the In composition in the InGaAs NW was almost constant from the bottom to the top. Transmission electron microscope (TEM) analysis revealed that the interface between InGaAs NW and Ge had misfit dislocations, but their distance was longer than that expected from the difference in their lattice constants.
  • Shougo Yanase, Hirotaka Sasakura, Shinjiro Hara, Junichi Motohisa
    JAPANESE JOURNAL OF APPLIED PHYSICS 56 (4) 04CP04  0021-4922 2017/04 [Refereed][Not invited]
     
    We attempted to control the density and size of InP-based nanowires (NWs) and nanowire quantum dots (NW-QDs) during selective-area metalorganic vapor phase epitaxy. InP nanowire arrays with a 5 mu m pitch and an average NW diameter d of 67nm were successfully grown by optimization of growth conditions. InAsP quantum dots were embedded in these density-controlled InP NW arrays, and clear single-photon emission and exciton-biexciton cascaded emission were confirmed by excitation-dependent photoluminescence and photon correlation measurements. (C) 2017 The Japan Society of Applied Physics
  • Fumiya Ishizaka, Yoshihiro Hiraya, Katsuhiro Tomioka, Junichi Motohisa, Takashi Fukui
    NANO LETTERS 17 (3) 1350 - 1355 1530-6984 2017/03 [Refereed][Not invited]
     
    We demonstrated the formation of all-wurtzite (WZ) InP/AlInP core-multishell (CMS) nanowires (NWs) by selective-area growth with the crystal structure transfer method. The CMS NWs consisting of an AlInP-based double heterostructure showed that the crystal structure of the multi shell succeeded to the WZ phase from the WZ InP NW by the crystal structure transfer method. Transmission electron microscopy revealed that the core shell interface had a few stacking faults due to lattice mismatch. In addition, lattice constants of WZ AlInP with a variation of Al content were determined by X-ray diffraction reciprocal space mappings, and the WZ AlInP shell had tensile strain along the c-axis. The WZ AlInP shells (Al content: 25-54%) showed cathode luminescence emissions at 1.6-2.1 eV, possibly related to In-rich domains due to composition fluctuation in the WZ AlInp shell.
  • Fumiya Ishizaka, Yoshihiro Hiraya, Katsuhiro Tomioka, Junichi Motohisa, Takashi Fukui
    Japanese Journal of Applied Physics 56 (1) 010311  1347-4065 2017/01/01 [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.
  • Akinobu Yoshida, Katsuhiro Tomioka, Fumiya Ishizaka, Kohei Chiba, Junichi Motohisa
    SEMICONDUCTORS, DIELECTRICS, AND METALS FOR NANOELECTRONICS 14 75 (5) 265 - 270 1938-5862 2016 [Refereed][Not invited]
     
    III-V compound semiconductors and Ge are promising future channel materials because of their high carrier mobility. For example the electron mobility of InAs is about 20 times faster than that of Si at room temperature and hole mobility of Ge is about 5 times faster than that of Si. In this paper, we report direct integration of InGaAs nanowires (NWs) on Ge(111) substrate by selective-area metal organic vapor phase epitaxy (SA-MOVPE) for realization of high carrier mobility InGaAs/Ge hybrid CMOS applications, and characterization of the composition and growth modes of InGaAs NWs by X-ray diffraction (XRD) measurement.
  • Daisuke Uchida, Masayuki Ikebe, Junichi Motohisa, Eiichi Sano
    Journal of Signal Processing 19 (6) 219 - 226 2015 [Refereed][Not invited]
  • Zhixin Cui, Rajagembu Perumal, Tomotsugu Ishikura, Keita Konishi, Kanji Yoh, Junichi Motohisa
    APPLIED PHYSICS EXPRESS 7 (8) 085001  1882-0778 2014/08 [Refereed][Not invited]
     
    InAs nanowire with < 110 > orientation is proposed for use as an electron spin transport channel for application to spintronics devices, particularly the Datta-Das spin transistor. Stable zinc blende crystal NWs were grown using a molecular beam epitaxy system. Subsequently, global back-gate NW field effect transistors were fabricated, and the superiority of the electrical transport properties within our resultant < 110 > NWs was demonstrated by comparing the field-effect mobility with a < 111 > NW control sample. Additionally, single NW Hall-bar devices were fabricated, which allowed us to obtain the transport properties accurately, and Hall effect measurements were successfully taken at different temperatures. (C) 2014 The Japan Society of Applied Physics
  • Junichi Motohisa, Yoshinori Kohashi, Satoshi Maeda
    NANO LETTERS 14 (6) 3653 - 3660 1530-6984 2014/06 [Refereed][Not invited]
     
    We investigated far-field (FF) emission patterns of nanowire light-emitting diodes (NW-LEDs). NW-LEDs were fabricated using vertical InP-NW arrays with axial pn-junctions grown on InP (111)A substrates, and the emission intensity of NW-LEDs was measured as a function of view angle theta, where theta = 0 degrees indicates the direction normal to the substrate or that along the NWs. For NW arrays with pitch a of around 1 mu m, we found a clear dip in the emission intensity at theta = 0 degrees, which was explained by an analogy with dipole antenna, or a smaller contribution of the lowest order guided modes for emission as compared with higher order guided and free-space radiation modes. Results of the simulation of radiation patterns by the finite-difference time-domain method and near-field to far-field transformation are also described. They also confirm that the dip at 6 = 00 is specific to light emission from NWs. We also investigated the dependence of the FF pattern on the pitch of the NW array, and the observation was qualitatively explained by the relative contribution of the guided and free-space radiation modes.
  • Daisuke Uchida, Masayuki Ikebe, Junichi Motohisa, Eiichi Sano, Akira Kondou
    JAPANESE JOURNAL OF APPLIED PHYSICS 53 (4) 04EE20  0021-4922 2014/04 [Refereed][Not invited]
     
    We propose an inductorless common-mode rejection filter with a gyrator-C network for common-mode-noise reduction. By adopting a gyrator-C network and ladder structure, high-order and small filter circuits with active transformer operation were fabricated. The filter was designed and fabricated in a Taiwan Semiconductor Manufacturing Company (TSMC) 0.18 mu m CMOS process. This filter exhibited a CMRR of 80 dB, output noise voltage of 103 nV/Hz(1/2), third-order input intercept point of 8.8 dBm at 1 MHz operation, and cutoff frequency of under 6 MHz. The total power consumption was 14.8 mW with a 2.5 V supply, and the chip area was 0.7 x 0.4 mm(2). (C) 2014 The Japan Society of Applied Physics
  • Y. Kohashi, S. Hara, J. Motohisa
    MATERIALS RESEARCH EXPRESS 1 (1) 015036  2053-1591 2014/03 [Refereed][Not invited]
     
    We grew gallium-rich (x > 0.50) and indium -rich (x < 0.50) Ini,GaxAs nano wires by catalyst free selective-area metal organic vapor-phase epitaxy (SAMOVPE), and compared their growth dynamics dependence on V/III ratio. It was found that the growth dynamics of In, GaxAs nanowires is clearly dependent on the alloy composition x. Specifically, for gallium rich nanowire growth, the axial growth rate of nanowires initially increased with decreasing V/III ratio, and then started to decrease when the V/III ratio continued to decrease below a critical value. On the other hand, axial growth rate of indium -rich nanowires monotonically decreased with decreasing V/III ratio. In addition, the alloy composition was strongly dependent on the V/III ratio for gallium -rich nanowire growth, while it was relatively independent of the V/III ratio for indium -rich nanowire growth. We discuss the origin of dissimilarity in the growth dynamics dependence on V/III ratio between gallium -rich and indium rich InGaAs nanowire growth, and conclude that it is due to the inherent dissimilarity between GaAs and InAs. Our finding provides important guidelines for achieving precise control of the diameter, height, and alloy composition of nanowires suitable for future nanowire-based electronics.
  • Yuta Kobayashi, Yoshinori Kohashi, Shinjiro Hara, Junichi Motohisa
    APPLIED PHYSICS EXPRESS 6 (4) 045001.1-045001.4  1882-0778 2013/04 [Refereed][Not invited]
     
    We attempted the selective-area metalorganic vapor-phase epitaxial (SA-MOVPE) growth of InAs nanowires (NWs) using a tungsten/dielectric composite mask and fabricated nanowire vertical surrounding-gate field-effect transistors (NW-VSG-FETs), where tungsten served as both the mask in SA-MOVPE growth and the bottom electrode of the FET. The growth of NWs with diameters as low as 100 nm was demonstrated using the composite mask. The fabricated NW-VSG-FET exhibited improved drain current density as compared with our previously reported NW-VSG-FETs, and a larger on/off ratio as compared with previously reported NW-VSG-FETs having similar electrodes at the bottoms of NWs. (C) 2013 The Japan Society of Applied Physics
  • Yoshinori Kohashi, Shinya Sakita, Shinjiroh Hara, Junichi Motohisa
    APPLIED PHYSICS EXPRESS 6 (2) 025502.1-025502.3  1882-0778 2013/02 [Refereed][Not invited]
     
    Control of the diameter and pitch of InGaAs nanowire arrays in selective-area metalorganic vapor-phase epitaxy was investigated. It was found that their nucleation was strongly dependent on the geometry of the mask, resulting in the difficulty of nucleation for a larger mask pitch, particularly for an opening diameter of less than 50 nm. Precise adjustment of the V/III ratio enabled us to control the nucleation independently of the mask pitch for smaller openings, and we successfully obtained 30-nm-diameter InGaAs nanowires independently of the mask pitch by the proposing V/III-ratio-controlled two-step growth method. (C) 2013 The Japan Society of Applied Physics
  • Yasuaki Masumoto, Ken Goto, Shinichi Tomimoto, Premila Mohan, Junichi Motohisa, Takashi Fukui
    JOURNAL OF LUMINESCENCE 133 135 - 137 0022-2313 2013/01 [Refereed][Not invited]
     
    Bimolecular interlayer scattering of electrons was observed in wurtzite InP/InAs/InP core-multishell nanowires by means of femtosecond up-conversion luminescence spectroscopy. Two-body Auger scattering took place in hexagonal InAs nanotubes constituting type-II quantum wires and wells. (c) 2011 Elsevier B.V. All rights reserved.
  • Junichi Motohisa, Kenji Hiruma
    JAPANESE JOURNAL OF APPLIED PHYSICS 51 (11) 11PE07.1-11PE07.7  0021-4922 2012/11 [Refereed][Not invited]
     
    The light absorption of various types of semiconductor nanowire (NW) arrays for photovoltaic applications was calculated. The electromagnetic field in multilayer structures containing NW arrays was calculated by the scattering-matrix treatment developed by Whittaker and Culshaw [ Phys. Rev. B 60 (1999) 2610], and the absorptance spectra Ad (lambda) of the NW arrays were obtained from the transmittance and reflectivity of the structures. The ultimate efficiency eta and weighted average absorptance Aavr of the NW array solar cells were evaluated from Ad (lambda). A general tendency of the light absorption in NW arrays in relation to their structural parameters, such as the pitch a of an NW array and the size d of an NW, was identified, and the differences between the optimum structural parameters of NW arrays in terms of light absorption in the cases of InP, GaAs, Si, and Ge were determined. The maximum eta was obtained for a 375, 350, 700, and 400 nm, for InP, GaAs, Si, and Ge NW arrays with d= a 0: 5, respectively. Moreover, Aavr for multijunction structures consisting of GaAs and Ge NWs and GaAs NWs on a germaninum substrate was also calculated and showed that both of these structures exhibited good light trapping capabilities for photovoltaic applications. It is shown that the photogeneration profiles of carriers in two types of multijunction structures are different. (C) 2012 The Japan Society of Applied Physics
  • Satoshi Maeda, Katsuhiro Tomioka, Shinjiroh Hara, Junichi Motohisa
    JAPANESE JOURNAL OF APPLIED PHYSICS 51 (2) 02BN03.1-02BN03.4  0021-4922 2012/02 [Refereed][Not invited]
     
    We fabricated nanowire light-emitting diodes (LEDs) using InP nanowires (NWs). Indium phosphide NWs with axial p-n junction were grown by selective-area metalorganic vapor phase epitaxy. The results of secondary-electron-microscopy (SEM) observation and photoluminescence measurement showed the formation of wurtzite InP NWs with some mixture of zincblende crystal phase, as expected from the used growth conditions. NW-LEDs were fabricated by sputtering indium tin oxide (ITO) after a planarization process for the top contact and AuZn evaporation for the backside contact. Current-voltage characterisitics showed clear rectifying characteristics with a small leakage current, and fairly linear current-light output characteristics were observed. By designing the pitch of the NW array, emission from individual NWs was confirmed, which opens the possibility for realizing a single NW-LED applicable to single-photon emitters. (C) 2012 The Japan Society of Applied Physics
  • 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.
  • Keitaro Ikejiri, Yusuke Kitauchi, Katsuhiro Tomioka, Junichi Motohisa, Takashi Fukui
    NANO LETTERS 11 (10) 4314 - 4318 1530-6984 2011/10 [Refereed][Not invited]
     
    Indium phosphide (InP) nanowires, which have crystal phase mixing and transition from zinc blende (ZB) to wurtzite (WZ), are grown in intermediate growth conditions between ZB and WZ by using selective-area metalorganic vapor phase epitaxy (SA-MOVPE). The shape of InP nanowires is tapered unlike ZB or WZ nanowires. A growth model has been developed for the tapered nanowires, which is simply described as the relationship between tapered angle and the ratio of ZB and WZ segments. In addition, the peak energy shift in photoluminescence measurement was attributed to the quantum confinement effect of the quantum well of the ZB region located in the polytypic structure of ZB and WZ in nanowires.
  • Katsuhiro Tomioka, Keitaro Ikejiri, Tomotaka Tanaka, Junichi Motohisa, Shinjiroh Hara, Kenji Hiruma, Takashi Fukui
    JOURNAL OF MATERIALS RESEARCH 26 (17) 2127 - 2141 0884-2914 2011/09 [Refereed][Invited]
     
    We review the position-controlled growth of III-V nanowires (NWs) by selective-area metal-organic vapor-phase epitaxy (SA-MOVPE). This epitaxial technique enables the positioning of the vertical NWs on (111) oriented surfaces with lithographic techniques. Core-shell structures have also been achieved by controlling the growth mode during SA-MOVPE. The core-shell III-V NW-based devices such as light-emitting diodes, photovoltaic cells, and vertical surrounding-gate transistors are discussed in this article. Nanometer-scale growth also enabled the integration of III-V NWs on Si regardless of lattice mismatches. These demonstrated achievements should have broad applications in laser diodes, photodiodes, and high-electron mobility transistors with functionality on Si not made possible with conventional Si-CMOS techniques.
  • 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
    Physical Review B 85, 075324/1-7 (2012) 2011/09 [Refereed][Not invited]
     
    We have investigated the optical properties of a single InAsP quantum dot
    embedded in a standing InP nanowire. A regular array of nanowires was
    fabricated by epitaxial growth and electron-beam patterning. The elongation of
    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 InP nanowire. The
    longitudinal exciton spin relaxation time was evaluated by the degree of the
    random polarization of emission originating from exciton state confined in a
    single nanowire quantum dots by using Mueller Calculus based on Stokes
    parameters representation.
  • Yasuaki Masumoto, Yuuki Hirata, Premila Mohan, Junichi Motohisa, Takashi Fukui
    APPLIED PHYSICS LETTERS 98 (21) 211902  0003-6951 2011/05 [Refereed][Not invited]
     
    The photoluminescence from single InP/InAs/InP core-multishell nanowires (CMNs) was highly linearly polarized in perpendicular to the nanowire long axis. Taking account of dielectric confinement of light field, we found the internal optical dipole squared perpendicular to the nanotube long axis d(0x)(2) is larger than that parallel to the axis d(0z)(2) by two orders of magnitude. With the increase in the thickness of InAs nanotubes, the ratio beta = d(0x)(2)/d(0z)(2) increases. This strong anisotropy in beta comes from nearly perfect wurtzite structure of InP/InAs/InP CMNs and small inclusion of p(z)-character into the Gamma(7)(B)-hole state. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3592855]
  • Shota Fujisawa, Takuya Sato, Shinjiro Hara, Junichi Motohisa, Kenji Hiruma, Takashi Fukui
    JAPANESE JOURNAL OF APPLIED PHYSICS 50 (4) 04DH03.1-04DH03.6  0021-4922 2011/04 [Refereed][Not invited]
     
    We developed a growth method for forming a GaAs quantum well (QW) buried in GaAsP/GaAs heterostructure nanowires (NWs) by selective-area metal organic vapor phase epitaxy (SA-MOVPE). To determine the optimum growth conditions of GaAsP NWs, we varied the [(C4H9)PH2 + AsH3]/[(CH3)(3)Ga] ratio between 20 and 185. As a result, we could obtain NWs with good height uniformity when the ratio was 20. To form such NWs with a GaAs QW, we fabricated GaAs NWs of about 60 nm in diameter before the GaAsP growth. The NW uniformity was considerably improved by introducing GaAs growth. Photoluminescence (PL) measurements at 4.2 K indicated that the QW had a spectral peak about 150 meV higher than the acceptor-related recombination emission peak of GaAs, which is near 1.5 eV. The QW thickness estimated from the spectral peak energy of PL was 5.2 nm, which is in fair agreement with the value calculated from the GaAs growth rate. (C) 2011 The Japan Society of Applied Physics
  • IKEBE MASAYUKI, MOTOHISA JUNICHI
    Proc SPIE 8194 (Pt.1) 819402.1-819402.8  0277-786X 2011 [Not refereed][Not invited]
  • Yukinobu Makihara, Masayuki Ikebe, Junichi Motohisa, Eiichi Sano
    IEEJ Transactions on Electronics, Information and Systems 電気学会 131 (3) 490 - 498 1348-8155 2011 [Refereed][Not invited]
     
    We proposed a new architecture for a phase-locked loop (PLL) obtained by comparing clock periods. We evaluated the use of a clock-period comparator (CPC) for the digitally controlled PLL we propose, where only the frequency should be locked. However, frequency control with the CPC resulted in the phase being locked. Thus, phase-lock operation was also achieved. The theoretical analysis of the phase-lock mechanism was confirmed through system simulations. We discussed about dead-zone problem caused by a time delay of circuits. We evaluated phase-shift direction detector to solve the dead zone problem. We designed the element blocks of the new PLL using a 0.25-μm CMOS process. We confirmed phase-lock operation through SPICE simulations of the MOSFET level. Moreover, we manufactured a trial circuit for the new PLL. We also confirmed phase-lock operation in the proposed PLL through measurements. © 2011 The Institute of Electrical Engineers of Japan.
  • Atsushi Hayashida, Takuya Sato, Shinjiro Hara, Junichi Motohisa, Kenji Hiruma, Takashi Fukui
    JOURNAL OF CRYSTAL GROWTH 312 (24) 3592 - 3598 0022-0248 2010/12 [Refereed][Not invited]
     
    We developed a growth method for forming a GaAs quantum well contained in an AlGaAs/GaAs heterostructure nanowire using selective-area metal organic vapor phase epitaxy To find the optimum growth condition of AlGaAs nanowires we changed the growth temperature between 800 and 850 C and found that best uniformity of the shape and the size was obtained near 800 C but lateral growth of AlGaAs became larger which resulted in a wide GaAs quantum well grown on the top (1 1 1)B facet of the AlGaAs nanowire To form the GaAs quantum well with a reduced lateral size atop the AlGaAs nanowire a GaAs core nanowire about 100 nm in diameter was grown before the AlGaAs growth which reduced the lateral size of AlGaAs to roughly half compared with that without the GaAs core Photoluminescence measurement at 42 K indicated spectral peaks of the GaAs quantum wells about 60 meV higher than the acceptor-related recombination emission peak of GaAs near 1 5 eV The photoluminescence peak energy showed a blue shift of about 15 meV from 1 546 to 1 560 eV as the growth time of the GaAs quantum well was decreased from 8 to 3 s Transmission electron microscopy and energy dispersive X-ray analysis of an AlGaAs/GaAs heterostructure nanowire indicated a GaAs quantum well with a thickness of 5-20 nm buried along the < 1 1 1 > direction between the AlGaAs shells showing a successful fabncation of the GaAs quantum well (C) 2010 Elsevier B V All rights reserved
  • MASUMOTO YASUAKI, GOTO KEN, YOSHIDA SEITARO, SAKUMA YOSHIKI, MOHAN PREMILA, MOTOHISA JUNICHI, FUKUI TAKASHI
    Phys Rev B Condens Matter Mater Phys 82 (7) 075313.1-075313.5  1098-0121 2010/08 [Refereed][Not invited]
  • Katsuhiro Tomioka, Junichi Motohisa, Shinjiroh Hara, Kenji Hiruma, Takashi Fukui
    NANO LETTERS 10 (5) 1639 - 1644 1530-6984 2010/05 [Refereed][Not invited]
     
    We report on integration of GaAs nanowire-based light-emitting-diodes (NW-LEDs) on Si substrate by selective-area metalorganic vapor phase epitaxy. The vertically aligned GaAs/AlGaAs core-multishell nanowires with radial p-n junction and NW-LED array were directly fabricated on Si. The threshold current for electroluminescence (EL) was 0.5 mA (current density was approximately 0.4 A/cm(2)), and the EL intensity superlinearly increased with increasing current injections indicating superluminescence behavior. The technology described in this letter could help open new possibilities for monolithic- and on-chip integration of III-V NWs on Si.
  • Yusuke Kitauchi, Yasunori Kobayashi, Katsuhiro Tomioka, Shinjiro Hara, Kenji Hiruma, Takashi Fukui, Junichi Motohisa
    NANO LETTERS 10 (5) 1699 - 1703 1530-6984 2010/05 [Refereed][Not invited]
     
    We study the catalyst-free growth of InP nanowires using selective-area metalorganic vapor phase epitaxy (SA-MOVPE) and show that they undergo transition of crystal structures depending on the growth conditions. InP nanowires were grown on InP substrates where the mask for the template of the growth was defined. The nanowires were grown only in the opening region of the mask. It was found that uniform array of InP nanowires with hexagonal cross section and with negligible tapering were grown under two distinctive growth conditions. The nanowires grown in two different growth conditions were found to exhibit different crystal structures. It was also found that the orientation and size of hexagon were different, suggesting that the difference of the growth behavior. A model for the transition of crystal structure is presented based on the atomic arrangements and termination of InP surfaces. Photoluminescence measurement revealed that the transition took place for nanowires with diameters up to 1 mu m.
  • Masaki Igarashi, Masayuki Ikebe, Sousuke Shimoyama, Kenta Yamano, Junichi Motohisa
    Kyokai Joho Imeji Zasshi/Journal of the Institute of Image Information and Television Engineers 映像情報メディア学会 64 (3) 389 - 398 1342-6907 2010/03 [Refereed][Not invited]
     
    We propose a fast 2-D bilateral filtering method without kernel-size dependency. Focusing on weighted local histograms and the central limit theorem combined with applying line buffers of column histograms, enables us to reduce the number of necessary memory accesses and calculations. Numerical experiments demonstrated a reduction in both calculations and kernel-size independency. We used a dual core 2-GHz CPU with our method and were able to achieve one million pixels per 0.5 sec operation without the need for downsampling, Single Instruction/Multiple Data (SIMD) or multi-thread operation.
  • Tomotaka Tanaka, Katsuhiro Tomioka, Shinjiroh Hara, Junichi Motohisa, Eiichi Sano, Takashi Fukui
    APPLIED PHYSICS EXPRESS 3 (2) 025003.1-025003.3  1882-0778 2010 [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(DS, max)/w(G)), maximum transconductance (g(m, max)/w(G)), on-off ratio (I(ON/OFF)), subthreshold slope (SS) of 83 mu A/mu m, 83 mu S/mu m, 10(4), and 320 mV/decade, respectively, for a nanowire diameter of 100 nm. (C) 2010 The Japan Society of Applied Physics DOI: 10.1143/APEX.3.025003
  • Masatoshi Yoshimura, Katsuhiro Tomioka, Kenji Hiruma, Shinjiro Hara, Junichi Motohisa, Takashi Fukui
    JAPANESE JOURNAL OF APPLIED PHYSICS 49 (4) 04DH08.1-04DH08.5  0021-4922 2010 [Refereed][Not invited]
     
    We fabricated InGaAs nanowires (NWs) in SiO2 mask openings on a GaAs(111) B substrate at growth temperatures of 600-700 degrees C using catalyst-free selective-area metal organic vapor phase epitaxy. At a growth temperature of 600 degrees C, particle-like depositions occurred, but they decreased in number and density when the growth temperature was increased to 650 degrees C and disappeared above 675 degrees 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 degrees C, indicating an increase in the Ga composition from 62 to 88% in the InGaAs NWs. (C) 2010 The Japan Society of Applied Physics
  • Hiroatsu Yoshida, Keitaro Ikejiri, Takuya Sato, Shinjiroh Hara, Kenji Hiruma, Junichi Motohisa, Takashi Fukui
    JOURNAL OF CRYSTAL GROWTH 312 (1) 52 - 57 0022-0248 2009/12 [Not refereed][Not invited]
     
    We analyzed twin defects in GaAs nanowires as thin as 100-400 nm and tetrahedral structures as small as 1.0 mu m, which were selectively grown by metal organic vapour-phase epitaxy (MOVPE) within a SiO(2) mask window fabricated on GaAs(1 1 1)B substrates. In particular, we focused on the correlation between the twins and GaAs(1 1 1)B surface reconstructions. We confirmed that the shape of GaAs cyrstals selectively grown on GaAs(1 1 1)B substrates changed from hexagonal nanowires to truncated tetrahedra when the size of the mask opening was increased from 100 to 1000 nm under the same growth conditions. The shape also changed from tetrahedral to hexagonal with decreasing growth temperature (T(g) : 600-800 degrees C) and with increasing arsine (AsH(3)) partial pressure (1.0 x10(-4) to 5.0 x 10(-4) atm). Rotational twins around the < 1 1 1 > axis were found in the tetrahedra by transmission electron microscopy (TEM) and scanning electron microscopy observations. In addition, the probability of twins developing in the tetrahedra increased with decreasing mask opening size, with decreasing T., and with increasing AsH(3) partial pressure. The TEM study also revealed the existence of a high density of rotational twins in the nanowires, and their density increased with decreasing nanowire diameter, suggesting a correlation between the twins and the shape/size of GaAs crystals. These findings were semi-quantitatively compared with a reported phase diagram for GaAs(1 1 1)B surface reconstruction. By analyzing the relationship between twin development and MOVPE conditions, we found that the shape change of GaAs crystals on GaAs(1 1 1)B and the formation of twins coincided well with the transition of GaAs surface reconstruction between the (2 x 2) and (root 19 x root 19) structures. (C) 2009 Elsevier B.V. All rights reserved.
  • Ken Goto, Michio Ikezawa, Shinichi Tomimoto, Bipul Pal, Yasuaki Masumoto, Premila Mohan, Junichi Motohisa, Takashi Fukui
    JAPANESE JOURNAL OF APPLIED PHYSICS 48 (4) 04C203.1-04C203.3  0021-4922 2009/04 [Not refereed][Not invited]
     
    We report on the photoluminescence and time-resolved photoluminescence spectroscopy of wurtzite InP/InAs/InP core-multishell nanowires. Multiple peaks appeared in the photoluminescence spectra owing to the monolayer variation of InAs layers. Each photoluminescence peak has a broad photoluminescence band coming from the inhomogeneous broadening in a core-multishell single nanowire. Inhomogeneous broadening caused time-dependent red shift (spectral diffusion) at a constant energy-loss rate. The long-time-span (similar to 10ns) time-resolved photoluminescence measurement clarified that spectral diffusion takes place in two stages (initially at a fast rate and later at a slow rate). The fast one is ascribed to spectral diffusion on the side of the nanowire and the slow one is ascribed to spectral diffusion at the corner of the nanowire. This suggests that photoexcited excitons in a core-multishell nanowire move from the side of the nanowire toward the corner of the nanowire. (C) 2009 The Japan Society of Applied Physics
  • SHIMOYAMA SOUSUKE, IGARASHI MASAKI, IKEBE MASAYUKI, MOTOHISA JUNICHI
    J Signal Process 13 (2) 151 - 159 1342-6230 2009/03 [Not refereed][Not invited]
  • Hajime Goto, Katsutoshi Nosaki, Katsuhiro Tomioka, Shinjiro Hara, Kenji Hiruma, Junichi Motohisa, Takashi Fukui
    APPLIED PHYSICS EXPRESS 2 (3) 035004.1-035004.3  1882-0778 2009/03 [Not 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-OC), short-circuit current (I-SC) and fill factor (FF) levels of 0.43 V, 13.72 mA/cm(2) 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. (C) 2009 The Japan Society of Applied Physics DOI: 10.1143/APEX.2.035004
  • TOMIOKA KATSUHIRO, KOBAYASHI YASUNORI, MOTOHISA JUNICHI, HARA SHINJIROH, FUKUI TAKASHI
    Nanotechnology 20 (14) 145302 (8 PP.)  0957-4484 2009 [Not refereed][Not invited]
  • Bin Hua, Junichi Motohisa, Yasunori Kobayashi, Shinjiroh Hara, Takashi Fukui
    NANO LETTERS 9 (1) 112 - 116 1530-6984 2009/01 [Not refereed][Not invited]
     
    Highly uniform GaAs/GaAsP coaxial nanowires were prepared via selective-area metal organic vapor phase epitaxy. Photoluminescence spectra from a single nanowire indicate that the obtained heterostructures can produce near-infrared (NIR) lasing under pulsed light excitation. The end facets of a single nanowire form a natural mirror surface to create an axial cavity, which realizes resonance and give stimulated emission. This study is a considerable advance toward the realization of nanowire-based NIR light sources.
  • TOMIOKA Katsuhiro, SATO Takuya, HARA Shinjiroh, MOTOHISA Junichi, FUKUI Takashi
    Journal of the Surface Science Society of Japan 日本表面科学会 29 (12) 726 - 730 0388-5321 2008/12/10 [Not refereed][Not invited]
  • Katsuhiro Tomioka, Junichi Motohisa, Shinjiroh Hara, Takashi Fukui
    Nano Letters 8 (10) 3475 - 3480 1530-6984 2008/10 [Not refereed][Not invited]
     
    We report on control of growth directions of InAs nanowires on Si substrate. We achieved to integrate vertical InAs nanowires on Si by modifying initial Si(111) surface in selective-area metal-organic vapor phase epitaxy with flow-rate modulation mode at low temperature. Cross-sectional transmission electron microscope and Raman scattering showed that misfit dislocation with local strains were accommodated in the interface. © 2008 American Chemical Society.
  • Keitaro Ikejiri, Takuya Sato, Hiroatsu Yoshida, Kenji Hiruma, Junichi Motohisa, Shinjiroh Hara, Takashi Fukui
    NANOTECHNOLOGY 19 (26) 265604 (8 PP.)  0957-4484 2008/07 [Not refereed][Not invited]
     
    GaAs nanowires were selectively grown by metal-organic vapour-phase epitaxy within a SiO(2) mask window pattern fabricated on a GaAs( 111) B substrate surface. The nanowires were 100-3000 nm in height and 50-300 nm in diameter. The height decreased as the mask window diameter was increased or the growth temperature was increased from 700 to 800 degrees C. The dependence of the nanowire height on the mask window diameter was compared with a calculation, which indicated that the height was inversely proportional to the mask window diameter. This suggests that the migration of growth species on the nanowire side surface plays a major role. Tetrahedral GaAs grew at an early stage of nanowire growth but became hexagonal as the growth process continued. The calculated change in Gibbs free energy for nucleation growth of the crystals indicated that tetrahedra were energetically more favourable than hexagons. Transmission and scanning electron microscopy analyses of a GaAs nanowire showed that many twins developed along the [111] B direction, suggesting that twins had something to do with the evolution of the nanowire shape from tetrahedron to hexagon.
  • Shinji Hashimoto, Junichiro Takeda, Akihiro Tarumi, Shinjiro Hara, Junichi Motohisa, Takashi Fukui
    JAPANESE JOURNAL OF APPLIED PHYSICS 47 (5) 3354 - 3358 0021-4922 2008/05 [Not refereed][Not invited]
     
    We report on a promising approach for the formation of compound semiconductor two-dimensional photonic crystal slabs utilizing selective-area metal-organic vapor phase epitaxy (SA-MOVPE). The selective-area growth process for the submicron-sized air holes of InP-based semiconductors was investigated on InP(111)A and (111)B substrates with a periodic array of hexagonal SiO(2) masks. By optimizing growth conditions, a highly uniform array of hexagonal air holes in InP and InGaAs with a 500 nm pitch was formed on (111)B substrates. We also fabricated air-hole arrays with InP/InGaAs/InP double heterostructures on InP(111)B, and confirmed photoluminescence from an InGaAs quantum well at low temperatures. [DOI: 10.1143/JJAP.47.3354]
  • Hiroko Iguchi, Shinjiroh Hara, Junichi Motohisa, Takashi Fukui
    JAPANESE JOURNAL OF APPLIED PHYSICS 47 (4) 3253 - 3256 0021-4922 2008/04 [Not refereed][Not invited]
     
    The authors report that the formation of MnAs nanoclusters (NCs) on GaInAs (1 1 1)A surfaces strongly depends on metal-organic vapor phase epitaxial growth conditions. It was confirmed from the atomic force microscope observation that deep holes were formed on the surfaces under low V/Mn ratio and high growth temperature conditions, in addition to the formation of MnAs NCs. From the results of cross-sectional transmission electron microscope observation, these deep holes were formed on the underlying GaInAs layers, and MnAs NCs were embedded in the GaInAs (1 1 1)A layers. The formation of these embedded MnAs NCs was possibly caused by the phenomenon of "endotaxy". From the experimental results of thermal treatments of the samples, it was revealed that the deep holes were formed on the GaInAs (1 1 1)A surfaces even after the thermal annealing in the atmosphere of Mn source gas and hydrogen. Therefore, we concluded that high AsH(3) partial pressure (V/Mn ratio) conditions were required for the MnAs growth on GaInAs (1 1 1)A surfaces.
  • Hiruma Kenji, Ikejiri Keitaro, Yoshida Hiroatsu, Tomioka Katsuhiro, Motohisa Junichi, Hara Shinjiroh, Fukui Takashi
    Journal of the Japanese Association of Crystal Growth 日本結晶成長学会 34 (4) 224 - 232 0385-6275 2008/01/31 [Not refereed][Not invited]
     
    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.
  • Masayuki Ikebe, Masaki Igarashit, Junichi Motohisat
    Kyokai Joho Imeji Zasshi/Journal of the Institute of Image Information and Television Engineers 一般社団法人映像情報メディア学会 62 (3) 376 - 383 1342-6907 2008 [Not refereed][Not invited]
     
    We investigated a negative feedback method for adding functionality to a CMOS image sensor, Our sensor effectively uses the method to set any intermediate voltage into a photodiode capacitance while a pixel circuit is in motion. The negative feedback reset functions as a noise cancellation technique and can obtain intermediate image data during charge accumulation. Using the above features, we achieved duplicated interlaced processing and were able to output framedifference images without frame buffers. The experimental results obtained with a chip fabricated using a 0.25-μm CMOS process demonstrate that intra-frame motion detection is an effective application of negative feedback resetting.
  • Ying Ding, Junichi Motohisa, Bin Hua, Shinjiroh Hara, Takashi Fukui
    NANO LETTERS 7 (12) 3598 - 3602 1530-6984 2007/12 [Not refereed][Not invited]
     
    Hexagonal cylindrical InP nanowires with a wurtzite structure were fabricated by selective-area metalorganic vapor-phase epitaxy (SA-MOVPE). The microcavity modes and waveguides in InP nanowires were investigated by photoluminesence (PL) spectra. Optical mode analysis for InP nanowires with different lengths reveals the axial Fabry-Perot cavity in InP nanowires, which were formed between the two end facets of nanowires. In addition, T-branch subwavelength guiding and optical coupling in InP nanowires were observed.
  • Katsuhiro Tomioka, Junichi Motohisa, Shinjiroh Hara, Takashi Fukui
    JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS & EXPRESS LETTERS 46 (45-49) L1102 - L1104 0021-4922 2007/12 [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.
  • Jinichiro Noborisaka, Takuya Sato, Junichi Motohisa, Shinjiro Hara, Katsuhiro Tomioka, Takashi Fukui
    JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS BRIEF COMMUNICATIONS & REVIEW PAPERS 46 (11) 7562 - 7568 0021-4922 2007/11 [Not 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 100nm) were grown by catalyst-free selective-area metalorganic 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.
  • 本久 順一
    Solid state physics アグネ技術センタ- 42 (10) 661 - 666 0454-4544 2007/10 [Not refereed][Not invited]
  • IGUCHI Hiroko, HARA Shinjiroh, MOTOHISA Junichi, FUKUI Takashi
    Extended abstracts of the ... Conference on Solid State Devices and Materials 2007 66 - 67 2007/09/19 [Not refereed][Not invited]
  • Bin Hua, Junichi Motohisa, Ying Ding, Shinjiroh Hara, Takashi Fukui
    APPLIED PHYSICS LETTERS 91 (13) 131112-131112-3  0003-6951 2007/09 [Not refereed][Not invited]
     
    The authors present the formation of Fabry-Perot cavity in single GaAs nanowire prepared by selective-area metal organic vapor phase epitaxy. The grown nanowires with hexagonal cross section are highly uniform and vertically oriented. Microphotoluminescence measurements of single GaAs nanowire exhibit periodic peaks in the intensity, which are suggestive of the longitudinal modes of a Fabry-Perot cavity. The cavity is formed along the length of the nanowire and the (111) facets of both ends act as reflecting mirrors. Additionally, optical waveguides in GaAs nanowires were also observed. (C) 2007 American Institute of Physics.
  • Noboru Ooike, Junichi Motohisa, Takashi Fukui
    JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS BRIEF COMMUNICATIONS & REVIEW PAPERS 46 (7A) 4344 - 4350 0021-4922 2007/07 [Not refereed][Not invited]
     
    We studied the states working in the memory operation of GaAs narrow-wire field-effect transistors (FETs) with embedded InAs quantum dots (QDs). The GaAs narrow-wire FETs with a few InAs QDs above the channel were fabricated by selective-area metal organic vapor-phase epitaxy (SA-MOVPE). The drain current, measured by sweeping the gate voltage forward and backward, exhibited clear clockwise hysteresis due to the charging of electrons into the states induced by InAs QDs with a threshold voltage Shift (Delta V-th) of 30 mV at 20 K. To better understand the mechanism of this memory operation, we studied the traps concerning the InAs QDs by drain-current deep-level transient spectroscopy (DLTS). Peaks representing three kinds of electron traps concerning InAs QDs were observed in the DLTS spectra. These peaks exhibited different dependences on the applied gate pulsed voltage during the DLTS measurement. In comparison with the temperature dependence Of Delta V-th, we found that our memory operation was attributed to one localized state introduced by InAs QDs.
  • Kohei Tsumura, Shintaro Nomura, Pamela Mohan, Junichi Motohisa, Takashi Fukui
    JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS & EXPRESS LETTERS 46 (17-19) L440 - L443 0021-4922 2007/05 [Not refereed][Not invited]
     
    The oscillation of photoluminescence peak energies is observed in InAs quantum tubes depending on the magnetic flux through the tube. The oscillation is shown to be due to the Aharonov-Bohm effect of a charged exciton in a quantum tube. No quadratic shift in photoluminescence peak energies is observed, which is a characteristic feature of a thin quantum tube with a single channel surrounding the magnetic flux through the tube.
  • Kohei Tsumura, Shintaro Nomura, Pamela Mohan, Junichi Motohisa, Takashi Fukui
    JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS & EXPRESS LETTERS 46 (17-19) L440 - L443 0021-4922 2007/05 [Not refereed][Not invited]
     
    The oscillation of photoluminescence peak energies is observed in InAs quantum tubes depending on the magnetic flux through the tube. The oscillation is shown to be due to the Aharonov-Bohm effect of a charged exciton in a quantum tube. No quadratic shift in photoluminescence peak energies is observed, which is a characteristic feature of a thin quantum tube with a single channel surrounding the magnetic flux through the tube.
  • B. Pal, K. Goto, M. Ikezawa, Y. Masumoto, P. Mohan, J. Motohisa, T. Fukui
    2007/02/06 [Not refereed][Not invited]
     
    Time- and spectrally-resolved PL from a periodic array of InP/InAs/InP
    core-multishell nanowires is presented. InAs layer shows multipeak PL spectra.
    PL decay is nonexponential and very slow, with decay rate depending on energy.
  • MOTOHISA Junichi, FUKUI Takashi
    應用物理 応用物理学会 75 (3) 296 - 302 0369-8009 2006/03/10 [Not refereed][Not invited]
  • MOTOHISA JUNICHI, FUKUI TAKASHI
    Proc SPIE 6370 63700B.1-63700B.11  0277-786X 2006 [Not refereed][Not invited]
  • P Mohan, J Motohisa, T Fukui
    APPLIED PHYSICS LETTERS 88 (1) 013110-013110-3  0003-6951 2006/01 [Not refereed][Not invited]
     
    We report the realization of ordered arrays of single-crystalline InAs nanotubes by a simple pure-eptiaxial approach. The process involved the fabrication of lattice-mismatched InP/InAs core-shell nanowires using selective area metalorganic vapor phase epitaxy on InP (111)A substrates. The subsequent removal of the InP core resulted in vertically aligned InAs nanotubes which were highly uniform with well-defined features and controllable dimensions. Transmission electron microscopy studies confirmed that the nanotubes were single-crystalline with wurtzite crystal structure and temperature-dependent transport measurements revealed that they were conductive without any intentional doping. The realization of such conductive InAs nanotubes opens up new possibilities for both fundamental studies and future device applications. (c) 2006 American Institute of Physics.
  • D Nataraj, N Ooike, J Motohisa, T Fukui
    APPLIED PHYSICS LETTERS 87 (19) 193103.1-193103.3  0003-6951 2005/11 [Not refereed][Not invited]
     
    Narrow wirelike openings were defined on SiO2-masked GaAs (001) substrates by electron-beam lithography and wet chemical etching methods. A one-dimensional GaAs channel-coupled InAs quantum dot memory device was fabricated in this opened area by the selective-area metal-organic vapor phase epitaxy. Drain current measurement by sweeping the gate voltage forward and backward showed clear hysteresis up to 180 K due to electrons charging into the quantum dots with a threshold voltage difference (Delta V-th) of 165 mV at 20 K and 29 mV at 180 K. Comparison of experimental Delta V-th values with the theoretically calculated ones showed that around 300 and 50 electrons were responsible for the memory operation at 20 and 180 K, respectively. Real time measurements showed that the write/erase states of the memory device were discriminated for more than 5 min at 20 K and about 100 s at 77 K. (C) 2005 American Institute of Physics.
  • YANG LIN, MOTOHISA JUNICHI, FUKUI TAKASHI
    Opt Eng 44 (7) 078002.1-078002.7  0091-3286 2005/07 [Not refereed][Not invited]
  • Y Miyoshi, F Nakajima, J Motohisa, T Fukui
    APPLIED PHYSICS LETTERS 87 (3) 033501.1-033501.3  0003-6951 2005/07 [Not refereed][Not invited]
     
    We demonstrate single-electron operation of a 1 bit adder circuit using GaAs single-electron tunneling transistors (SETs). GaAs dot and wire coupled structures for the fabrication of SETs were grown by a selective-area metalorganic vapor-phase epitaxy technique. The logic circuit was realized based on a binary decision diagram architecture using Coulomb blockade (CB) in GaAs dots and switching operations were achieved in a single-electron mode because of the CB effects. Through this architecture, a 1 bit adder circuit was realized with three SETs, two of which were for AND logic and one with two input gates for exclusive OR (XOR). Both AND and XOR operations were demonstrated at 1.9 K, which indicated successful fabrication of the 1 bit adder. (c) 2005 American Institute of Physics.
  • J Noborisaka, J Motohisa, T Fukui
    APPLIED PHYSICS LETTERS 86 (21) 213102.1-213102.3  0003-6951 2005/05 [Not refereed][Not invited]
     
    We report on the fabrication of GaAs hexagonal nanowires surrounded by {110} vertical facets on a GaAs (111) B substrate using selective-area (SA) metalorganic vapor-phase epitaxial (MOVPE) growth. The substrate for SA growth was partially covered with thin SiO2, and a circular mask opening with a diameter d(0) of 50-200 nm was defined. After SA-MOVPE, GaAs nanowires with a typical diameter d ranging from 50 to 200 nm and a height from 2 to 9 μ m were formed vertically on the substrate without any catalysts. The size of the nanowire depends on the growth conditions and the opening size of the masked substrate. A possible growth mechanism is also discussed. © 2005 American Institute of Physics.
  • L Yang, J Motohisa, T Fukui
    JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS BRIEF COMMUNICATIONS & REVIEW PAPERS 44 (4B) 2531 - 2536 0021-4922 2005/04 [Not refereed][Not invited]
     
    The standard plane wave expansion (PWE) method with the supercell method was used to calculate the band diagrams of photonic crystal slabs (PCSs) with hexagonal optical atoms. A hole-type PCS with hexagonal optical atoms has almost the same width of first band gap for the TE-like mode as its two-dimensional (2D) counterpart. However, the first band gap of a pillar-type PCS with hexagonal optical atoms shrinks considerably compared with that of its 2D counterpart. The hole-type PCS with normal hexagonal optical atoms has a slightly wider first band gap for TE-like modes than does that with orthogonal hexagonal optical atoms. PCSs with normal and orthogonal hexagonal optical atoms have band gaps that can be compared to those of PCSs with circular optical atoms. Hence they are appropriate structures for fabricating PC devices. The dispersion curves of line-defect PC waveguides were also calculated by the PWE method with the supercell method and several potential methods for modulating their dispersion curves were also discussed. Modulating the width of the line defect and the size of the optical atoms along the line defect were proved to be effective ways for obtaining a single-mode line-defect PC waveguide with a large bandwidth.
  • FUKUI Takashi, MOTOHISA Junichi
    應用物理 応用物理学会 73 (5) 593 - 598 0369-8009 2004/05/10 [Not refereed][Not invited]
  • P Mohan, J Motohisa, T Fukui
    APPLIED PHYSICS LETTERS 84 (14) 2664 - 2666 0003-6951 2004/04 [Not refereed][Not invited]
     
    The experimental realization of two-dimensional semiconductor artificial lattice based on InAs quantum wires is reported here. Artificial Kagome lattice fabricated using InAs quantum wires of unit cell size 0.7 mum has been theoretically proved to show ferromagnetism. Fabrication of such a structure with InAs quantum wires was attempted by selective area metalorganic vapor phase epitaxy using GaAs (111)A substrates. Temperature-dependent growth mode change was observed and Volmer-Weber growth mode at high temperature inhibited the formation of uniform structure. Low temperature and low AsH3 partial pressure resulted in the successful fabrication of 0.7 mum period InAs-based Kagome lattice structure. (C) 2004 American Institute of Physics.
  • P Mohan, F Nakajima, M Akabori, J Motohisa, T Fukui
    APPLIED PHYSICS LETTERS 83 (4) 689 - 691 0003-6951 2003/07 [Not refereed][Not invited]
     
    Artificial two-dimensional semiconductor Kagome lattice structures formed by quantum wires can show ferromagnetism when the flatband is half filled, even though it does not have any magnetic elements. Experimental realization of such a Kagome lattice structure is reported. The structure, with different pattern periods, was formed with GaAs quantum wires by selective area metalorganic vapor phase epitaxy on GaAs (111)B substrates. To overcome the lateral overgrowth and to improve the shape of smaller period pattern, flow rate modulation epitaxy was employed and a GaAs Kagome lattice structure with 1 mum period was effectively grown. (C) 2003 American Institute of Physics.
  • T Kusuhara, F Nakajima, J Motohisa, T Fukui
    JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS 41 (4B) 2508 - 2512 0021-4922 2002/04 [Not refereed][Not invited]
     
    We investigate the formation of InAs quantum dots (QDs) on the top of AlGaAs ridge wire structures along the [(1) over bar 10] direction by selective-area metalorganic vapor phase epitaxy (SA-MOVPE) and study their size distribution. It is found that the size distribution of QDs depends on the top width W of AlGaAs wires and growth amount theta of InAs. InAs dot size across the AlGaAs wires are limited by W and it becomes uniform for narrower W. In contrast, the size along the wire exhibits nonuniformity, particularly for narrower W and large theta. In addition, the shapes of InAs dot change depending on W. The results are discussed based on the diffusion of In from facets and masked area and the coalescence of QDs.
  • WG van der Wiel, S De Franceschi, JM Elzerman, S Tarucha, LP Kouwenhoven, J Motohisa, F Nakajima, T Fukui
    PHYSICAL REVIEW LETTERS 88 (12) 0031-9007 2002/03 [Not refereed][Not invited]
     
    We report a strong Kondo effect (Kondo temperature similar to4 K) at high magnetic field in a selective area growth semiconductor quantum dot. The Kondo effect is ascribed to a singlet-triplet transition in the ground state of the dot. At the transition, the low-temperature conductance approaches the unitary limit. Away from the transition, for low bias voltages and temperatures, the conductance is sharply reduced. The observed behavior is compared to predictions for a two-stage Kondo effect in quantum dots coupled to single-channel leads.
  • F Nakajima, Y Ogasawara, J Motohisa, T Fukui
    JOURNAL OF APPLIED PHYSICS 90 (5) 2606 - 2611 0021-8979 2001/09 [Not refereed][Not invited]
     
    We describe a method for fabricating GaAs dot arrays and dot-wire coupled structures having periodic nanofacets which uses selective area metalorganic vapor phase epitaxy. First, a thin GaAs buffer layer and an AlGaAs layer are grown on a masked substrate having wirelike openings with periodic width modulation. The width of AlGaAs wirelike structure is naturally squeezed by the periodic combination of nanofacets, and its top (001) surface is partially isolated by a self-limited region. Next, an AlGaAs/GaAs quantum well structure is fabricated on the substrate to form dots on the narrower top terraces, wires on the wider terraces, and ridge wires in the self-limited region. Cathodoluminescence images clearly showed dot arrays and dot-wire coupled structures were formed using this method. A single electron transistor with the same structure was also fabricated, and clear Coulomb blockade oscillation was observed. We also describe single electron tunneling devices with these dot arrays and dot-wire coupled structures. (C) 2001 American Institute of Physics.
  • T Harada, Y Oda, J Motohisa, T Fukui
    JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS 39 (12B) 7090 - 7092 0021-4922 2000/12 [Not refereed][Not invited]
     
    We describe periodic nano-faceting structures formed naturally on patterned vicinal (110) GaAs grown by metal-organic vapor phase epitaxy (MOVPE). Periodic trenches are formed along the [1-10] direction on initial surfaces with pattern periods of 2 mum. 1 mum, 800 nm, and 600 nm. Periodic nano-faceting structures consisting of (110) and (111)B surfaces are clearly formed on the GaAs grown surfaces, and the periods are almost exactly equal to the pattern periods. The growth modes are observed from cross-sectional scanning electron microscope (SEM) images of GaAs/AlGaAs multilayer growth. The growth rate of the (111)B sidewall facets is higher than that of the (110) terraces, which indicates that quantum wire (QWR) structures can be formed naturally at step edges. Quantum well (QW) structures of GaAs/In0.18Ga0.82As/GaAs are also grown on patterned vicinal substrates. A photoluminescence (PL) spectrum at 4 K shows two sharp emission peaks from QWs on the (111)B sidewall facets at a lower energy and on the (110) terraces at a higher energy. These results suggest that it is possible to fabricate QWR arrays with high uniformity on (111)B sidewall facets.
  • K Yamatani, N Akabori, S Motohisa, T Fukui
    JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS 38 (4B) 2562 - 2565 0021-4922 1999/04 [Not refereed][Not invited]
     
    We investigated the potential modulation in a novel lateral surface superlattice (LSSL) structure which was realized by utilizing multiatomic steps. The structure was grown by metalorganic vapor-phase epitaxy (MOVPE) on vicinal GaAs substrates to introduce periodic thickness modulation to the channel GaAs layer with spontaneously formed multiatomic steps. Devices having split gates were fabricated on the epitaxially grown LSSL structure. The potential modulation was investigated by a potential sweeping technique, where different bias voltages were applied to the split gates to change the minima of the potential across the multiatomic steps. We observed plateaus and oscillations of conductance as a function of the gate voltage. Systematic shifts of these positions were also observed when offset voltages between the two gates were applied and changed. These features are assumed to originate from the potential modulation induced by multiatomic steps.
  • T Ogawa, M Akabori, J Motohisa, T Fukui
    JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS 38 (2B) 1040 - 1043 0021-4922 1999/02 [Not refereed][Not invited]
     
    We have studied surface deformation due to electron-beam irradiation in strained InGaAs/AlGaAs layers grown on GaAs (100) and (311)B planes in a horizontal low-pressure metalorganic vapor phase epitaxy system at about 800 degrees C. The surface deformation was observed in real time using a high-resolution scanning electron microscope at a magnification of 300,000. The surface deformation occurred from the inside of InGaAs/AlGaAs grown layer under the electron-beam irradiated area with the accelerating voltage of 30 kV and the scanning time ranging from 60 to 120 s. The surface deformation was not consist of amorphous-carbon contamination. The mass transport seems to be caused by the residual strain relaxation due to electron-beam irradiation.
  • F Nakajima, K Kumakura, J Motohisa, T Fukui
    JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS 38 (1B) 415 - 417 0021-4922 1999/01 [Not refereed][Not invited]
     
    GaAs single electron transistors (SETs) are successfully fabricated using selectively grown GaAs/AlGaAs modulation doped structures by metalorganic vapor phase epitaxy (MOVPE) on (001) GaAs masked substrates. SET shows clear Coulomb oscillations and Coulomb gaps modulated by gate voltage. GaAs single electron tunneling inverter circuits having a SET and a variable load resistance are also formed. The operation of a resistance-load inverter circuit is confirmed at 1.9K from the transport properties of this SET and input-output characteristics.
  • T Irisawa, J Motohisa, M Akabori, T Fukui
    JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS 37 (3B) 1514 - 1517 0021-4922 1998/03 [Not refereed][Not invited]
     
    We have investigated the delta-doping of Si on GaAs vicinal surfaces on which self-organized multiatomic steps are formed during metalorganic vapor phase epitaxy (MOVPE) and the possibility of its wire-like selective incorporation into step edges to form doping quantum wires (DQWRs). We evaluated the electrical characteristics of delta-doped layers by Hall and C-V measurements and investigated their dependence on misorientation angles of GaAs vicinal substrates and doping time. The incorporation of Si is enhanced by steps. This effect is particularly important at the initial stage of delta-doping when the surface coverage of Si is not high. Our results also suggest that the doping density at multiatomic step regions is higher than at terrace regions. Therefore, it is expected that the selective wire-like incorporation of Si takes place at the step edges, and DQWRs can be realized under suitable growth conditions.
  • Fukui T, Ishizaki J, Hara S, Kumakura K, Motohisa J
    Journal of the Japanese Association of Crystal Growth 日本結晶成長学会 24 (2) 196 - 198 0385-6275 1997/07/01 [Not refereed][Not invited]
     
    GaAs self-organized quantum nano-structures were fabricated by metalorganic chemical vapor deposition on vicinal and patterned GaAs substrates. Using step bunching phenomena during GaAs growth on vicinal GaAs substrate, high density quantumwire array was formed. GaAs quantum dots were also fabricated on GaAs pyramidal structures grown SiNx masked(001)GaAs with square opening.
  • S HARA, J MOTOHISA, T FUKUI, H HASEGAWA
    JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS 34 (8B) 4401 - 4404 0021-4922 1995/08 [Not refereed][Not invited]
     
    Coherent multiatomic steps with extremely straight edges are naturally formed on vicinal (001) GaAs surfaces during metalorganic vapor phase epitaxial growth. GaAs quantum well wires (QWWs) are formed on these self-organized multiatomic steps. In our previous study, a thin AlGaAs layer was grown on GaAs with multiatomic steps as a lower barrier of QWWs. However, the height and spacing of the steps slightly fluctuate on AlGaAs layer surfaces. Therefore, in this experiment, AlAs layer instead of AlGaAs layer was used as a lower barrier layer to improve the uniformity of the height and spacing of the steps. Atomic force microscopy observations and photoluminescence (PL) measurements at 20 K revealed that the underlying coherent GaAs multiatomic steps were well traced by the AlAs barrier layer rather than the AlGaAs barrier layer. Furthermore, we measured the polarization anisotropy of the PL spectra from the QWWs with AlAs. These results suggest that uniform QWWs are successfully formed using multiatomic steps on vicinal (001) GaAs surfaces.
  • K KUMAKURA, K NAKAKOSHI, J MOTOHISA, T FUKUI, H HASEGAWA
    JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS 34 (8B) 4387 - 4389 0021-4922 1995/08 [Not refereed][Not invited]
     
    We have fabricated AlGaAs/GaAs quantum dot structures using selective area metalorganic vapor phase epitaxy (MOVPE). First, GaAs pyramidal structures with fourfold symmetric (011) facet sidewalls are formed on SiNx-masked (001) GaAs with square openings. Once the pyramidal structures were completely formed, no growth occurs on the top or sidewalls of the pyramids. Furthermore, the shape and width of the top area observed using a scanning electron microscope (SEM) and an atomic force microscope (AFM) is shown to be highly uniform. This indicates that self-limited growth occurs. Next, using these uniform pyramids, GaAs quantum dots are overgrown on top of the pyramids under different growth conditions. Sharp photoluminescence (PL) spectra are observed from uniform quantum dots.
  • J MOTOHISA, K KUMAKURA, M KISHIDA, T YAMAZAKI, T FUKUI, H HASEGAWA, K WADA
    JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS BRIEF COMMUNICATIONS & REVIEW PAPERS 34 (2B) 1098 - 1101 0021-4922 1995/02 [Not refereed][Not invited]
     
    We report on a growth process on patterned GaAs (001) substrate during metalorganic vapor-phase epitaxy (MOVPE) and a novel approach for the fabrication of AlGaAs/GaAs quantum dot (QD) structures. The patterned substrate has an array of holes on the surface and those holes are partially filled with GaAs by MOVPE growth, followed by GaAs/AlGaAs quantum well structures. Detailed investigation on the growth process on such patterned substrates revealed the presence of complicated two-dimensional duffusion of Ga and Al between two different surfaces. Formation of GaAs dots was directly confirmed by spatially resolved cathodoluminescence measurements.

Books etc

Conference Activities & Talks

MISC

Industrial Property Rights

Research Grants & Projects

  • 半導体ナノ構造の形成、評価とデバイス、回路応用

Educational Activities

Teaching Experience

  • 卒業論文
    開講年度 : 2020
    課程区分 : 学士課程
    開講学部 : 工学部
  • Advanced Exercise in Electronics for Informatics
    開講年度 : 2020
    課程区分 : 修士課程
    開講学部 : 情報科学研究科
    キーワード : 電子材料物性科学,半導体デバイス工学,量子物性工学,光情報システム科学,先端デバイス工学,先端集積回路工学,情報処理アーキテクチャ,高周波デバイス工学,エネルギー変換デバイス工学,高度集積デバイス工学,ナノ材料・ナノ計測工学,量子情報通信工学,量子情報処理工学
  • Advanced Exercise in Electronics for Informatics
    開講年度 : 2020
    課程区分 : 修士課程
    開講学部 : 情報科学院
    キーワード : 電子材料物性科学,半導体デバイス工学,量子物性工学,光情報システム科学,先端デバイス工学,先端集積回路工学,情報処理アーキテクチャ,高周波デバイス工学,エネルギー変換デバイス工学,高度集積デバイス工学,ナノ材料・ナノ計測工学,量子情報通信工学,量子情報処理工学
  • Semiconductor Device Physics
    開講年度 : 2020
    課程区分 : 修士課程
    開講学部 : 情報科学院
    キーワード : 半導体物性、固体物性、電子輸送、MOSFET、量子構造、量子デバイス、半導体ヘテロ構造、半導体エピタキシャル成長
  • Quantum Device Engineering
    開講年度 : 2020
    課程区分 : 修士課程
    開講学部 : 情報科学研究科
    キーワード : 半導体物性、固体物性、電子輸送、MOSFET、量子構造、量子デバイス、半導体ヘテロ構造、半導体エピタキシャル成長
  • Advanced Study in Electronics for Informatics
    開講年度 : 2020
    課程区分 : 博士後期課程
    開講学部 : 情報科学研究科
    キーワード : 電子材料物性科学,半導体デバイス工学,量子物性工学,光情報システム科学,先端デバイス工学,先端集積回路工学,情報処理アーキテクチャ,高周波デバイス工学,エネルギー変換デバイス工学,高度集積デバイス工学,ナノ材料・ナノ計測工学,量子情報通信工学,量子情報処理工学
  • Advanced Study in Electronics for Informatics
    開講年度 : 2020
    課程区分 : 博士後期課程
    開講学部 : 情報科学院
    キーワード : 電子材料物性科学,半導体デバイス工学,量子物性工学,光情報システム科学,先端デバイス工学,先端集積回路工学,情報処理アーキテクチャ,高周波デバイス工学,エネルギー変換デバイス工学,高度集積デバイス工学,ナノ材料・ナノ計測工学,量子情報通信工学,量子情報処理工学
  • Semiconductor Device Physics
    開講年度 : 2020
    課程区分 : 博士後期課程
    開講学部 : 情報科学院
    キーワード : 半導体物性、固体物性、電子輸送、MOSFET、量子構造、量子デバイス、半導体ヘテロ構造、半導体エピタキシャル成長
  • Quantum Device Engineering
    開講年度 : 2020
    課程区分 : 博士後期課程
    開講学部 : 情報科学研究科
    キーワード : 半導体物性、固体物性、電子輸送、MOSFET、量子構造、量子デバイス、半導体ヘテロ構造、半導体エピタキシャル成長
  • Introduction to Electronics and Information Engineering
    開講年度 : 2020
    課程区分 : 学士課程
    開講学部 : 工学部
    キーワード : 情報理論, 計算機ハードウエア, 電子デバイス, 生体情報, 生命科学, 電子回路, 通信, メディア, ネットワーク, 電気回路, 制御工学
  • Exercise in Electrical and Electronic Engineering IV
    開講年度 : 2020
    課程区分 : 学士課程
    開講学部 : 工学部
    キーワード : 回路の過渡応答,伝送線路の基本特性.pn接合、ショットキー接合、MOS構造、バイポーラトランジスタ、MOSFET,発光遷移と光吸収,光共振器
  • Internship Ⅰ
    開講年度 : 2020
    課程区分 : 学士課程
    開講学部 : 工学部
    キーワード : 創造的人材育成、実践的人材育成、就業体験、国内外インターンシップ
  • Internship Ⅱ
    開講年度 : 2020
    課程区分 : 学士課程
    開講学部 : 工学部
    キーワード : 創造的人材育成、実践的人材育成、就業体験、国内外インターンシップ
  • Semiconductor Devices
    開講年度 : 2020
    課程区分 : 学士課程
    開講学部 : 工学部
    キーワード : pn接合、ショットキー接合、MOS構造、MOSFET、光デバイス、太陽電池、CMOS集積回路
  • Exercise in Technical English
    開講年度 : 2020
    課程区分 : 学士課程
    開講学部 : 工学部
    キーワード : 科学技術英語
  • Exercise in Electrical and Electronic Engineering III
    開講年度 : 2020
    課程区分 : 学士課程
    開講学部 : 工学部
    キーワード : pn接合、トランジスタ、増幅回路、演算増幅器、ブール代数、論理回路

Campus Position History

  • 2020年4月1日 
    2022年3月31日 
    量子集積エレクトロニクス研究センター長

Position History

  • 2020年4月1日 
    2022年3月31日 
    量子集積エレクトロニクス研究センター長


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