Updated on 2022/11/02

写真a

 
OHNISHI Kazuki
 
Organization
Institute of Materials and Systems for Sustainability Center for Integrated Research of Future Electronics Innovative Devices Section Designated assistant professor
Title
Designated assistant professor

Education 3

  1. Nagoya University   Graduate School of Engineering   Department of Electronics

    2019.4 - 2022.3

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    Country: Japan

  2. Tohoku University   Graduate School of Engineering   Department of Applied Physics

    2017.4 - 2019.3

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    Country: Japan

  3. Tohoku University   Faculty of Engineering

    2013.4 - 2017.3

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    Country: Japan

Awards 3

  1. IEEE Nagoya Section Excellent Student Award

    2022.3  

  2. 第13回ナノ構造エピタキシャル成長講演会発表奨励賞

    2021.12   日本結晶成長学会ナノ構造エピタキシャル成長分科会  

  3. 第50回(2021年春季)応用物理学会講演奨励賞

    2021.9   応用物理学会   HVPE法によって作製されたp型GaNの電気および構造特性評価

 

Papers 10

  1. Tuning the p-type doping of GaN over three orders of magnitude via efficient Mg doping during halide vapor phase epitaxy Reviewed

    Kazuki Ohnishi, Naoki Fujimoto, Shugo Nitta, Hirotaka Watanabe, Shun Lu, Manato Deki, Yoshio Honda, Hiroshi Amano

    Journal of Applied Physics   Vol. 132 ( 14 )   2022.10

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    Authorship:Lead author   Language:Japanese   Publishing type:Research paper (scientific journal)  

    DOI: 10.1063/5.0122292

    Web of Science

    Scopus

  2. Surface kinetics in halide vapor phase epitaxial growth of GaN layers on GaN (0001) freestanding substrates Reviewed

    Kazuki Ohnishi, Naoki Fujimoto, Shugo Nitta, Hirotaka Watanabe, Yoshio Honda, Hiroshi Amano

    Journal of Crystal Growth   Vol. 592   page: 126749 - 126749   2022.8

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    Authorship:Lead author   Language:English   Publishing type:Research paper (scientific journal)   Publisher:Elsevier {BV}  

    DOI: 10.1016/j.jcrysgro.2022.126749

    Web of Science

    Scopus

  3. Ohmic contact on low-doping-density p-type GaN with nitrogen-annealed Mg Reviewed

    Shun Lu, Manato Deki, Jia Wang, Kazuki Ohnishi, Yuto Ando, Takeru Kumabe, Hirotaka Watanabe, Shugo Nitta, Yoshio Honda, Hiroshi Amano

    Applied Physics Letters   Vol. 119 ( 24 ) page: 242104 - 242104   2021.12

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    Language:Japanese   Publishing type:Research paper (scientific journal)   Publisher:{AIP} Publishing  

    DOI: 10.1063/5.0076764

    Web of Science

    Scopus

  4. Vertical GaN p+-n junction diode with ideal avalanche capability grown by halide vapor phase epitaxy Reviewed

    Kazuki Ohnishi, Seiya Kawasaki, Naoki Fujimoto, Shugo Nitta, Hirotaka Watanabe, Yoshio Honda, Hiroshi Amano

    Applied Physics Letters   Vol. 119 ( 15 ) page: 152102 - 152102   2021.10

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    Authorship:Lead author   Language:Japanese   Publishing type:Research paper (scientific journal)   Publisher:{AIP} Publishing  

    DOI: 10.1063/5.0066139

    Web of Science

    Scopus

  5. Electrical properties and structural defects of p-type GaN layers grown by halide vapor phase epitaxy Reviewed

    Kazuki Ohnishi, Yuki Amano, Naoki Fujimoto, Shugo Nitta, Hirotaka Watanabe, Yoshio Honda, Hiroshi Amano

    Journal of Crystal Growth   Vol. 566   page: 126173 - 126173   2021.7

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    Authorship:Lead author   Language:Japanese   Publishing type:Research paper (scientific journal)   Publisher:Elsevier {BV}  

    DOI: 10.1016/j.jcrysgro.2021.126173

    Web of Science

    Scopus

  6. Thermodynamic analysis of the gas phase reaction of Mg-doped GaN growth by HVPE using MgO Reviewed

    Tomoya Kimura, Kazuki Ohnishi, Yuki Amano, Naoki Fujimoto, Masaaki Araidai, Shugo Nitta, Yoshio Honda, Hiroshi Amano, Yoshihiro Kangawa, Kenji Shiraishi

    Japanese Journal of Applied Physics   Vol. 59 ( 8 ) page: 088001 - 088001   2020.8

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    Language:Japanese   Publishing type:Research paper (scientific journal)   Publisher:{IOP} Publishing  

    DOI: 10.35848/1347-4065/aba0d5

    Scopus

  7. Halide vapor phase epitaxy of p-type Mg-doped GaN utilizing MgO Reviewed

    Kazuki Ohnishi, Yuki Amano, Naoki Fujimoto, Shugo Nitta, Yoshio Honda, Hiroshi Amano

    Applied Physics Express   Vol. 13 ( 6 ) page: 061007 - 061007   2020.6

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    Authorship:Lead author   Language:Japanese   Publishing type:Research paper (scientific journal)   Publisher:{IOP} Publishing  

    DOI: 10.35848/1882-0786/ab9166

    Scopus

  8. Reuse of ScAlMgO4 substrates utilized for halide vapor phase epitaxy of GaN Reviewed

    Kazuki Ohnishi, Shigeyuki Kuboya, Tomoyuki Tanikawa, Takuya Iwabuchi, Kazuya Yamamura, Noriyuki Hasuike, Hiroshi Harima, Tsuguo Fukuda, Takashi Matsuoka

    Japanese Journal of Applied Physics   Vol. 58 ( {SC} )   2019.6

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    Authorship:Lead author   Language:Japanese   Publishing type:Research paper (scientific journal)   Publisher:{IOP} Publishing  

    ScAlMgO4 (SCAM) substrates with a small lattice-mismatch to GaN and c-plane cleavability are promising for fabricating high-quality free-standing GaN wafers. To reduce the cost in the fabrication of free-standing GaN wafers, the reuse of a SCAM substrate is demonstrated. By cleaving a SCAM substrate which has been already utilized for the growth of a thick GaN film by halide vapor phase epitaxy, the atomically flat surface can be obtained. The threading dislocation density of a 320 μm thick GaN film grown on this cleaved SCAM substrate is 2.4 × 107 cm-2, which is almost the same as that on a new SCAM substrate. This result indicates that a SCAM substrate can be reused for GaN growth.

    DOI: 10.7567/1347-4065/ab06ab

    Scopus

  9. Three-dimensional imaging of threading dislocations in GaN crystals using two-photon excitation photoluminescence Reviewed

    Tomoyuki Tanikawa, Kazuki Ohnishi, Masaya Kanoh, Takashi Mukai, Takashi Matsuoka

    Applied Physics Express   Vol. 11 ( 3 ) page: 031004 - 031004   2018.3

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:{IOP} Publishing  

    The three-dimensional imaging of threading dislocations in GaN films was demonstrated using two-photon excitation photoluminescence. The threading dislocations were shown as dark lines. The spatial resolutions near the surface were about 0.32 and 3.2 mu m for the in-plane and depth directions, respectively. The threading dislocations with a density less than 10(8)cm(-2) were resolved, although the aberration induced by the refractive index mismatch was observed. The decrease in threading dislocation density was clearly observed by increasing the GaN film thickness. This can be considered a novel method for characterizing threading dislocations in GaN films without any destructive preparations. (c) 2018 The Japan Society of Applied Physics

    DOI: 10.7567/apex.11.031004

    Web of Science

    Scopus

  10. Halide vapor phase epitaxy of thick GaN films on ScAlMgO4substrates and their self-separation for fabricating freestanding wafers Reviewed

    Kazuki Ohnishi, Masaya Kanoh, Tomoyuki Tanikawa, Shigeyuki Kuboya, Takashi Mukai, Takashi Matsuoka

    Applied Physics Express   Vol. 10 ( 10 ) page: 101001 - 101001   2017.10

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    Authorship:Lead author   Language:English   Publishing type:Research paper (scientific journal)   Publisher:{IOP} Publishing  

    Halide vapor phase epitaxy of thick GaN films was demonstrated on ScAlMgO<inf>4</inf>(SCAM) substrates, and their self-separation was achieved. The 320-µm-thick GaN film was self-separated from the SCAM substrate during the cooling process after the growth. This separation phenomenon occurred because of both the c-plane cleavability of SCAM and the difference in the thermal-expansion coefficients between GaN and SCAM. The dark-spot densities for the GaN films on the SCAM substrates were approximately 30% lower than those on sapphire substrates. These results indicate that SCAM substrates are promising for fabricating a high-quality freestanding GaN wafer at a low cost.

    DOI: 10.7567/apex.10.101001

    Scopus

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Presentations 31

  1. HVPE growth for vertical GaN p-n junction diodes with high breakdown voltages Invited

    Kazuki Ohnishi, Shugo Nitta, Yoshio Honda, Hiroshi Amano

    International Workshop on Nitride Semiconductors 2022 (IWN2022)  2022.10.14 

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    Event date: 2022.10

    Language:English   Presentation type:Oral presentation (invited, special)  

  2. Preparation of thick Mg-doped p-type GaN layers grown by halide vapor phase epitaxy

    2022.9.21 

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    Event date: 2022.9

    Language:Japanese   Presentation type:Oral presentation (general)  

  3. Surface kinetics in HVPE growth of GaN layers on GaN (0001) freestanding substrates

    2022.9.21 

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    Event date: 2022.9

    Language:Japanese   Presentation type:Oral presentation (general)  

  4. Exploration of the origin of reverse leakage current in GaN vertical p-n junction diodes grown by halide vapor phase epitaxy

    2022.9.22 

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    Event date: 2022.9

    Language:Japanese   Presentation type:Oral presentation (general)  

  5. ハライド気相成長法による縦型GaN p-n接合ダイオードの作製

    大西 一生, 川崎 晟也, 藤元 直樹, 新田 州吾, 渡邉 浩崇, 本田 善央, 天野 浩

    第69回応用物理学会春季学術講演会  2022.3.23 

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    Event date: 2022.3

    Language:Japanese   Presentation type:Oral presentation (general)  

  6. GaN高温HVPE成長のための熱力学解析モデルの修正

    松岡 聖, 坂東 もも子, 大西 一生, 後藤 健, 新田 州吾, 村上 尚, 熊谷 義直

    第69回応用物理学会春季学術講演会  2022.3.22 

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    Event date: 2022.3

    Language:Japanese   Presentation type:Oral presentation (general)  

  7. アニールしたMg層による低濃度p型GaNへの接触抵抗低減

    陸 順, 出来 真斗, 王 嘉, 大西 一生, 安藤 悠人, 渡邉 浩崇, 隈部 岳瑠, 新田 州吾, 本田 善央, 天野 浩

    第69回応用物理学会春季学術講演会  2022.3.23 

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    Event date: 2022.3

    Language:Japanese   Presentation type:Oral presentation (general)  

  8. Halide vapor phase epitaxy of p-type GaN for verical GaN power devices Invited

    K. Ohnishi, S. Kawasaki, N. Fujimoto, S. Nitta, H. Watanabe, Y. Honda, H. Amano

    14th International Symposium on Advanced Plasma Science and its Applications for Nitrides and Nanomaterials 15th International Conference on Plasma-Nano Technology (ISPlasma2022/IC-PLANTS2022)  2022.3.7 

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    Event date: 2022.3

    Language:English   Presentation type:Oral presentation (invited, special)  

  9. n型GaNドリフト層の表面平坦化に向けたハライド気相成長条件の検討

    大西一生, 藤元直樹, 新田州吾, 渡邉浩崇, 本田善央, 天野浩

    第13回ナノ構造・エピタキシャル成長講演会  2021.12.2 

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    Event date: 2021.12

    Language:Japanese   Presentation type:Poster presentation  

  10. アモノサーマル製GaN基板上へのHVPE-GaN成長界面で新たに生じる貫通転位の抑制

    森祐人, 新田州吾, 飯田一喜, 守山実希, 大西一生, 藤元直樹, 渡邉浩崇, 田中敦之, 本田善央, 天野浩

    第50回結晶成長国内会議(JCCG-50)  2021.10.27 

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    Event date: 2021.10

    Language:Japanese   Presentation type:Oral presentation (general)  

  11. HVPE成長させたp型GaNの電気的特性および構造欠陥評価 Invited

    大西一生, 天野裕己, 藤元直樹, 新田州吾, 渡邉浩崇, 本田善央, 天野浩

    第82回応用物理学会秋季学術講演会  2021.9.11 

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    Event date: 2021.9

    Language:Japanese   Presentation type:Oral presentation (invited, special)  

  12. HVPE法によって作製されたp型GaNの電気および構造特性評価

    大西一生, 天野裕己, 藤元直樹, 新田州吾, 渡邉浩崇, 本田善央, 天野浩

    第68回応用物理学会春季学術講演会  2021.3.17 

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    Event date: 2021.3

    Language:Japanese   Presentation type:Oral presentation (general)  

  13. HVPEによる固体ドーパントを用いたp型GaNの結晶成長 Invited

    大西一生, 天野裕己, 新田州吾, 藤元直樹, 本田善央, 天野浩

    第49回結晶成長国内会議(JCCG-49)  2020.11.9 

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    Event date: 2020.11

    Language:Japanese   Presentation type:Oral presentation (invited, special)  

  14. Mg含有セラミックスを不純物源としたMg添加GaNのHVPE成長

    天野裕己, 大西一生, 藤元直樹, 渡邉浩崇, 新田州吾, 本田善央, 天野浩

    第81回応用物理学会秋季学術講演会  2020.9.10 

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    Event date: 2020.9

    Presentation type:Oral presentation (general)  

  15. MgOを利用したハライド気相成長法によるp型GaNの作製

    大西一生, 天野裕己, 藤元直樹, 新田州吾, 本田善央, 天野浩

    第81回応用物理学会秋季学術講演会  2020.9.10 

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    Event date: 2020.9

    Language:Japanese   Presentation type:Oral presentation (general)  

  16. MgOを用いたMgドープGaNのHVPE成長における気相反応の熱力学的解析

    木村友哉, 大西一生, 天野裕己, 藤元直樹, 洗平昌晃, 新田州吾, 本田善央, 天野浩, 寒川義裕, 白石賢二

    第12回ナノ構造・エピタキシャル成長講演会  2020.7.31 

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    Event date: 2020.7

    Presentation type:Poster presentation  

  17. MgOを用いたMg添加GaNのハライド気相成長

    大西一生, 天野裕己, 藤元直樹, 新田州吾, 本田善央, 天野浩

    第67回応用物理学会春季学術講演会  2020.3.14 

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    Event date: 2020.3

    Presentation type:Oral presentation (general)  

  18. HVPE法による不純物含浸セラミックスを用いたMg添加GaN成長

    天野裕己, 大西一生, 藤元直樹, 渡邉浩崇, 新田州吾, 本田善央, 天野浩

    第67回応用物理学会春季学術講演会  2020.3.14 

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    Event date: 2020.3

    Presentation type:Oral presentation (general)  

  19. ハライド気相成長法を用いた高純度GaN成長

    大西一生, 天野裕己, 藤元直樹, 新田州吾, 本田善央, 天野浩

    先進パワー半導体分科会第6回講演会  2019.12.3 

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    Event date: 2019.12

    Presentation type:Poster presentation  

  20. Si台座構造上GaNモノリシック微小二重共振器型第二高調波発生デバイスの作製

    南部誠明, 永田拓実, 塩見圭史, 藤原康文, 大西一生, 谷川智之, 上向井正裕, 片山竜二

    第66回応用物理学会春季学術講演会  2019.3.10 

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    Event date: 2019.3

    Presentation type:Oral presentation (general)  

  21. Reuse of ScAlMgO4 substrates utilized for halide vapor phase epitaxy of GaN

    K. Ohnishi, S. Kuboya, T. Tanikawa, T. Fukuda, T. Matsuoka

    International Workshop on Nitride Semiconductors 2018 (IWN2018)  2018.11.15 

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    Event date: 2018.11

    Presentation type:Oral presentation (general)  

  22. GaN成長に用いたScAlMgO4基板の再利用

    大西一生, 窪谷茂幸, 谷川智之, 福田承生, 松岡隆志

    第65回応用物理学会春季学術講演会  2018.3.17 

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    Event date: 2018.3

    Presentation type:Oral presentation (general)  

  23. Three-dimensional imaging of threading dislocations in thick GaN films by two-photon-excitation photoluminescence

    T. Tanikawa, K. Ohnishi, T. Matsuoka

    第36回電子材料シンポジウム (EMS-36)  2017.11.10 

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    Event date: 2017.11

    Language:Japanese   Presentation type:Poster presentation  

  24. Three-dimensional threading dislocations in GaN crystals by multiphoton-excitation photoluminescence Invited

    T. Tanikawa, K. Ohnishi, T. Matsuoka

    International Conference on Materials and Systems for Sustainability 2017 (ICMaSS 2017)  2017.10.1 

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    Event date: 2017.9 - 2017.10

    Language:English   Presentation type:Oral presentation (invited, special)  

  25. 多光子励起PL法によるGaN結晶の貫通転位の3次元イメージング Invited

    谷川智之, 大西一生, 松岡隆志

    第78回応用物理学会秋季学術講演会  2017.9.7 

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    Event date: 2017.9

    Presentation type:Oral presentation (invited, special)  

  26. 二光子励起フォトルミネッセンス法によるGaN中の貫通転位の三次元分布評価 Invited

    谷川智之, 大西一生, 加納聖也, 向井孝志, 松岡隆志

    第78回応用物理学会秋季学術講演会  2017.9.6 

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    Event date: 2017.9

    Presentation type:Oral presentation (invited, special)  

  27. Three-dimensional analysis of threading dislocation in HVPE-grown GaN using two-photon-excitation photoluminescence

    T. Tanikawa, K. Ohnishi, M. Kanoh, T. Mukai, T. Matsuoka

    12th International Conference on Nitride Semiconductors (ICNS-12)  2017.7.26 

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    Event date: 2017.7

    Language:English   Presentation type:Oral presentation (general)  

  28. HVPE of thick GaN layers on ScAlMgO4 substrates and their self-separation for fabricating free-standing wafers

    K. Ohnishi, M. Kanoh, T. Tanikawa, S. Kuboya, T. Mukai, T. Matsuoka

    12th International Conference on Nitride Semiconductors (ICNS-12)  2017.7.25 

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    Event date: 2017.7

    Language:English   Presentation type:Oral presentation (general)  

  29. 多光子励起フォトルミネッセンス法によるGaNの内部欠陥の三次元観察 Invited

    谷川智之, 大西一生, 藤田達也, 加納聖也, 向井孝志, 松岡隆志

    第9回ナノ構造・エピタキシャル成長講演会  2017.7.14 

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    Event date: 2017.7

    Language:Japanese   Presentation type:Oral presentation (invited, special)  

  30. 二光子励起フォトルミネッセンス法によるGaN中の貫通転位の三次元分布評価

    谷川智之, 大西一生, 加納聖也, 向井孝志, 松岡隆志

    第64回応用物理学会春季学術講演会  2017.3.15 

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    Event date: 2017.3

    Presentation type:Oral presentation (general)  

  31. ハイドライド気相成長法によるScAlMgO4基板上へのGaN厚膜成長と自己剥離プロセス

    大西一生, 加納聖也, 谷川智之, 窪谷茂幸, 向井孝志, 松岡隆志

    第64回応用物理学会春季学術講演会  2017.3.17 

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    Event date: 2017.3

    Presentation type:Oral presentation (general)  

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KAKENHI (Grants-in-Aid for Scientific Research) 1

  1. 高性能GaN系素子作製に向けたハライド気相成長技術の確立

    Grant number:20J13885  2020.4 - 2022.3

    日本学術振興会  科学研究費助成事業 特別研究員奨励費  特別研究員奨励費

    大西 一生, 大西 一生

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    Authorship:Principal investigator 

    Grant amount:\2100000 ( Direct Cost: \2100000 )

    ハライド気相成長(HVPE)法は、成長速度が高く、高純度GaNの作製可能なことから、縦型パワーデバイス作製手法として魅力的である。しかしながら、素子作製に重要なp型GaNのHVPE法による作製は非常に困難であり、本研究開始以前には、信頼に値するp型GaNの報告はなかった。報告者は、HVPE法によるp型GaNの実現に向けて、その成長条件の探索を行い、p型GaNを実現した。また、作製したp型GaNの電気的および構造的特性評価も行った。
    まず、ドーピング原料の探索を行った。アクセプタとしてMgが一般的に使用されているが、HVPE法において適切なMgドーピング原料が存在せず、そのことがp型GaNの作製を困難としていた。申請者は、Mg原料として固体MgOに着目した。MgOにHClガスを供給し、MgCl2を生成することによってドーピングを行うことに成功した。また、供給するHClガスの流量を変化させることによってMg濃度の制御が可能である。
    Mg添加GaNのHall効果測定を行ったところ、p型伝導を示した。キャリア濃度の温度依存性から算出した活性化エネルギーはMgアクセプタの活性化エネルギーと同程度であり、Mgアクセプタがp型伝導に寄与していることを確認した。また、算出したアクセプタ濃度(Na)およびドナー濃度(Nd)のMg濃度依存性を調べたところ、従来の有機金属気相成長法にて作製されるp型GaNとよい一致を示した。これは、本研究にて作製したp型GaNの品質が高いことを示すだけでなく、成長手法にとらわれないp型GaNの物性を反映していることを強く支持する結果である。