Department of Engineering and Applied Sciences

Nomura Ichirou

  (野村 一郎)

Profile Information

Affiliation
Professor, Faculty of Science and Technology, Department of Engineering and Applied Sciences, Sophia University
Degree
工学士(上智大学)
工学修士(上智大学)
博士(工学)(上智大学)

Other name(s) (e.g. nickname)
NOMURA ICHIROU
Researcher number
00266074
J-GLOBAL ID
200901053354827454
researchmap Member ID
5000041413

1988-1994 Study on AlGaInP red-jight semiconductor laser diodes.
1995-current Development and device application of II-VI compound semiconductors on InP substrates.

(Subject of research)
Development of novel functional optical devices using compound semiconductors

(Proposed theme of joint or funded research)
Development of full color emission devices


Papers

 62
  • Jumpei Yamada, Ai Mizuno, Tatsuya Honda, Keigo Yoshida, Rie Togashi, Ichirou Nomura, Tomohiro Yamaguchi, Tohru Honda, Katsumi Kishino
    Nanotechnology, 34(43) 435201-435201, Aug 14, 2023  Peer-reviewed
    Abstract In this study, the growth behavior of Indium gallium nitride (InGaN)-based nanocolumn arrays was investigated, and red emission nanocolumn micro-light emitting diodes (μ-LEDs) were fabricated. The internal structure of the InGaN/GaN superlattice (SL) layer under the multiple-quantum-well (MQW) active layers was evaluated using scanning transmission electron microscopy (STEM) analysis. It was revealed that the InGaN crystal plane at the top of the nanocolumn changed from the c-plane, (1-102) plane, to the (10-11) plane as the number of SL pairs increased. A semipolar (10-11) plane was completely formed on top of the nanocolumn by growing InGaN/GaN SLs over 15–20 pairs, where the InGaN/GaN SL layers were uniformly piled up, maintaining the (10-11) plane. Therefore, when InGaN/AlGaN MQWs were grown on the (10-11) plane InGaN/GaN SL layer, the growth of the (10-11) plane semipolar InGaN active layers was observed in the high-angle annular dark field (HAADF)-STEM image. Moreover, the acute nanocolumn top of the (10-11) plane of the InGaN/GaN SL underlayer did not contribute to the formation of the c-plane InGaN core region. Red nanocolumn μ-LEDs with an φ12 μm emission window were fabricated using the (10-11) plane MQWs to obtain the external quantum efficiency of 1.01% at 51 A cm−2. The process of nanocolumn μ-LEDs suitable for the smaller emission windows was provided, where the flat p-GaN contact layer contributed to forming a fine emission window of φ5 μm.
  • Kenta Ishii, Ryosuke Amagasu, Ichirou Nomura
    Journal of Crystal Growth, 512 96-99, Feb 6, 2019  Peer-reviewed
  • Yudai Momose, Ichirou Nomura
    Journal of Electronic Materials, 47(8) 1-4, May 24, 2018  Peer-reviewed
    Conduction band discontinuity (ΔEc) of MgSe/ZnCdSe heterojunctions were evaluated using n–i–n diodes consisting of an undoped i-MgSe layer sandwiched by n-doped ZnCdSe layers. The n–i–n diodes were fabricated on InP substrates by molecular beam epitaxy. Injection current density versus applied voltage (J–V) characteristics of the n–i–n diodes were measured at 77 K and room temperature. In addition, the theoretical J–V characteristics of the n–i–n diode were calculated while varying ΔEc. By fitting the theoretical data to the experimental data, ΔEc was estimated to be 1.2 eV from the result at 77 K. This value is similar to the ΔEc estimated from the literature.
  • Koji Fukushima, Tomohiro Shiraishi, Ryohei Kobayashi, Katsumi Kishino, Ichirou Nomura
    PHYSICA STATUS SOLIDI C: CURRENT TOPICS IN SOLID STATE PHYSICS, VOL 13 NO 7-9, 13(7-9) 665-668, 2016  Peer-reviewed
    The application of indium tin oxide (ITO) as the p-cladding layer of II-VI compound semiconductor laser diodes (LDs) on InP substrates was investigated. The waveguide analysis of the LD structures revealed that the optical confinement effect around the active layer was obviously improved by changing the p-cladding layer from the conventional MgSe/BeZnTe superlattice to ITO. For example, the estimated optical confinement factors were 0.15 and 0.27 for the conventional and ITO LD structure, respectively, when the emission wavelength was 580 nm. In addition, we investigated optimum LD structures, considering the optical and carrier confinements at the active layer. In experiments, light emitting devices with an ITO layer were fabricated on InP substrates via molecular beam epitaxy and radio-frequency (RF) magnetron sputtering. Yellow emissions at 582 nm were observed by current injections at room temperature. These results indicate that ITO is a promising p-cladding layer material for II-VI LDs on InP substrates. (C) 2016 WILEY-VCH Verlag GmbH & Co.
  • Ryohei Kobayashi, Shingo Takamatsu, Koji Fukushima, Katsumi Kishino, Ichirou Nomura
    PHYSICA STATUS SOLIDI C: CURRENT TOPICS IN SOLID STATE PHYSICS, VOL 13 NO 7-9, 13(7-9) 669-672, 2016  Peer-reviewed
    II-VI-compound-semiconductor laser diode (LD) structures on InP substrates were investigated using device simulations and waveguide analysis. Our simulations showed that electron injection from the n-cladding into the active layer is hindered by the n-side barrier layer between the n-cladding and active layer. Consequently, holes are not injected into the active layer but instead leak to the n-side layers. It was shown that carrier injection efficiency can be improved by removing the n-barrier. On the contrary, no large differences were observed between the optical confinement factors of the LD structures with and without the n-barrier layer. In ex-periments, we have fabricated the LD structures with and without the n-barrier layer on InP substrates using molecular beam epitaxy. The turn-on voltage of the device without the n-barrier was smaller than that for the device with the n-barrier by about 5 V. Spontaneous orange emissions around 603 nm were observed for the devices without the n-barrier. In contrast, no emission was observed for the devices with the n-barrier. These results prove that the carrier injection into the active layer is enhanced by the removal of the n-barrier, leading to improved the device performances. (C) 2016 WILEY-VCH Verlag GmbH & Co.

Misc.

 13
  • NOMA Tomohiro, HAYASHI Hiroaki, FUKUSHIMA Daishi, KONNO Yuta, NOMURA Ichirou, KISHINO Katsumi
    Technical report of IEICE. LQE, 114(338) 117-120, Nov 27, 2014  
    Nitride has an attractive feature of bandgap engineering from ultraviolet to infrared. However, a lot of defects in nitride inhibit the feature. In this study, we demonstrated nitride nanocolumn on Si wafer that is expected realization of large-scale/low-cost devices. Furthermore, nanocolumn structure is expected to suppress propagation of dislocation. We employed a sputter-deposited AlN nucleation layer, because it is so difficult to grow nitride crystal on Si wafer. We successfully fabricated a single crystalline GaN nanocolumns array even on the sputter-deposited film containing high-density dislocations. Single-peak PL emission in wide visible range from integrated InGaN/GaN MQW, and control of PL peak wavelength by pre-patterning were also demonstrated.
  • NOMURA Ichirou, KISHINO Katsumi, EBISAWA Tomoya, KUSHIDA Shun, TASAI Kunihiko, NAKAMURA Hitoshi, ASATSUMA Tsunenori, NAKAJIMA Hiroshi
    IEICE technical report, 108(351) 53-58, Dec 5, 2008  
    MgZnCdSe, BeZnTe, and BeZnSeTe II-VI compound semiconductors grown on InP substrates are very attractive for middle visible range, especially green light emitting devices. We have developed these materials and emitting devices composed of BeZnSeTe active, MgSe/ZnCdSe superlattice (SL) n-cladding, and MgSeBeZnTe SL p-cladding layers. Long lifetime operations beyond 5000h were achieved for the devices, which shows a remarkable improvement of the aging characteristic of II-VI devices. We succeeded in photopumped green lasing at room temperature for the double heterostructures having a BeZnSeTe active layer to indicate a high potentiality of BeZnSeTe as an active layer of green laser diodes.
  • KISHINO Katsumi, NOMURA Ichirou
    Technical report of IEICE. LQE, 103(527) 45-48, Dec 12, 2003  
    Novel II-VI compound materials such as MgZnCdSe, BeZnTe, and their related superlattices (SLs) grown on InP substrates were proposed for wide-range visible optical devices such as laser diodes (LDs) and light emitting diodes (LEDs).Visible LEDs consisting of ZnCdSe/BeZnTe SL active, MgSe/BeZnTe SL p-cladding, and MgSe/ZnCdSe SL n-cladding layers were fabricated to obtain wide-range visible electro luminescence (EL) emissions from 554 (yellow-green) to 644 nm (red). For yellow (575nm) LEDs, a long lifetime more than 3500 hours was demonstrated to show high reliability of the LEDs. LDs with ZnCdSe active layers were fabricated. Yellow-green lasing operations around 560 nm were successfully achieved under pulsed current injection at 77 K, for the first time.
  • SHINOZAKI Wataru, NOMURA Ichirou, SHIMBO Hiroyuki, HATTORI Hiroshi, SANO Takashi, CHE Song-Bek, KIKUCHI Akihiko, SHIMOMURA Kazuhiko, KISHINO Katsumi
    1998 354-355, Sep 7, 1998  
  • HATTORI Hiroshi, NOMURA Ichirou, SHINBO Hiroyuki, NAGANO Takeshi, HARAGUCHI Masaru, MORITA Toshihiro, KIKUCHI Akihiko, KISHINO Katsumi
    1997 216-217, Sep 16, 1997  

Books and Other Publications

 2

Presentations

 268

Professional Memberships

 1

Research Projects

 20

Other

 173
  • Apr, 2006
    講義科目と演習科目をリンクさせ、講義で学習した内容についてなるべく速やかに演習を行い、理解を深められるようにしている。また、演習を持ち込み不可の試験形式で行うことで演習を受ける前の講義の復習を促し、習熟度が増すようにしている。一方、講義科目では演習に加え中間及び期末試験を実施し、これにより学習到達度を評価している。
  • Apr, 2006
    情報関連の講義では、資料の配布やレポート提出を学内のPCやネット上で行うなど情報機器を有効利用し、授業運営の効率化を図っている。
  • Apr, 2006
    講義中では、各項目毎に質問を受け付けたり、簡単な例題を解いて内容をより理解できるように努めている。
  • Apr, 2000
    研究によって得たれた結果や成果等は速やかにメールで関係者に配布し、またデータベースに保存することで情報の共有化を図るように指導している。
  • Apr, 1994
    毎年8月にグループ内の研究会を開催し、それまでの研究成果のまとめや今後の方針について議論する。これにより研究の進め方や成果の取り纏め、報告の仕方等の指導を行っている。