Development of atomic-layer heterojunction based hot electron emitters toward ultra-high speed transistors

• Project/Area Number: 18K18861
• Research Category: Grant-in-Aid for Challenging Research (Exploratory)
• Allocation Type: Multi-year Fund
• Review Section: Medium-sized Section 21:Electrical and electronic engineering and related fields
• Research Institution: Osaka University
• Principal Investigator: Masayoshi Tonouchi 大阪大学, レーザー科学研究所, 教授 (40207593)
• Project Period (FY): 2018-06-29 – 2020-03-31
• Project Status: Completed (Fiscal Year 2019)
• Budget Amount: ¥6,370,000 (Direct Cost: ¥4,900,000、Indirect Cost: ¥1,470,000); Fiscal Year 2019: ¥2,080,000 (Direct Cost: ¥1,600,000、Indirect Cost: ¥480,000); Fiscal Year 2018: ¥4,290,000 (Direct Cost: ¥3,300,000、Indirect Cost: ¥990,000)
• Keywords: テラヘルツデバイス / ホットエレクトロン / 超格子 / 歪緩和 / テラらヘルツ帯音響フォノン / カーボンナノチューブ / エキシトン / 半導体表面高速電荷 / テラヘルツ波 / 2次元原子層材料 / 原子層材料 / ヘテロ接合 / 超高速トランジスタ

Outline of Final Research Achievements

InGaN/InGaN heterostructures with thicknesses of 1.5, 2,4 and 3.0 nm in the InGaN layer were fabricated as an example of atomic layer heterostructures. The heterojunction was irradiated with a femtosecond laser, and the relationship between propagation and charge dynamics in the GaN was studied, where optical carrier injection in InGaN quantum wells resolves the distortion in the heterojunction surface stress and simultaneously generates terahertz acoustic phonon pulses. (Currently writing a paper.)
We have also developed a new theoretical equations to describe the fast electron dynamics near the surface of a graphene/semiconductor by means of photo-excitation of the carrier injection at the junction surface.We also studied the photo excitation of the excitonsin carbon nanotubes,which are good candidates as a base material of the hot electron emitting junnctions, and reveal their ultrafast fast carrier dynamics.

Academic Significance and Societal Importance of the Research Achievements

原子層ヘテロ接合極限高速トランジスタ開発に向けて、光励起による電荷注入について検討した。GaN/InGaN超格子を作製し、電荷注入により、ヘテロ接合内の歪が解放されると同時にテラヘルツ帯音調フォノンが生成伝搬し、表面で強いテラヘルツ波を放射することを見出した。また、エミッター開発に不可欠な高速光電荷の振る舞いを記述する新しい理論式を提案し、高速トランジスターベース材料として、グラフェン・ナノチューブの利用も検討した。その結果、ナノチューブの高速エキシトン解離のメカニズムを明らかにするなど、今後の高速デバイス開発に資するホットエレクトロンエミッターの基礎を築いた。

Research Products

• [Int'l Joint Research] ライス大学(米国)
• [Journal Article] Terahertz Excitonics in Carbon Nanotubes: Exciton Autoionization and Multiplication (2020)
  • Author(s): Filchito Renee G. Bagsican, Michael Wais, Natsumi Komatsu, Weilu Gao, Lincoln W. Weber, Kazunori Serita, Hironaru Murakami, Karsten Held, Frank A. Hegmann, Masayoshi Tonouchi, Junichiro Kono, Iwao Kawayama, and Marco Battiato
  • Journal Title: Nano Lett. 2020 Volume: 20,05 Issue: 5 Pages: 3098-3105
  • DOI: 10.1021/acs.nanolett.9b05082
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Simplified formulas for the generation of terahertz waves from semiconductor surfaces excited with a femtosecond laser (2020)
  • Author(s): Masayoshi Tonouchi
  • Journal Title: Journal of Applied Physics Volume: in press
  • Peer Reviewed
• [Presentation] Contact-free THz nano-seismology in InGaN/GaN Multiple Quantum Wells (2019)
  • Author(s): Abdul Mannan, I. Kawayama, K. Yamahara, F.R. Bagsican, H. Murakami, T. Langer, H. Bremers, U.Rossow, D. Turchinovich, A. Hangleiter, and M. Tonouchi
  • Organizer: Global Nonophotonics 2019
  • Int'l Joint Research
• [Presentation] Near surface built-in field of wide gap semiconductors studied by LTEM (2019)
  • Author(s): Masayoshi Tonouchi
  • Organizer: Global Nonophotonics 2019
  • Int'l Joint Research / Invited
• [Presentation] Opto-science and engineering using nanomaterials for fundamentals and applications (2019)
  • Author(s): Masayoshi Tonouchi
  • Organizer: The 3rd IMS-INSD Joint Workshop on Frontier Nanomaterials
  • Int'l Joint Research / Invited
• [Presentation] Terahertz Emission from a Photoconductive Antenna Switch Based on Aligned Single-Chirality Semiconducting Carbon Nanotubes (2019)
  • Author(s): Filchito Renee G. Bagsican, Iwao Kawayama, Michael Wais, Natsumi Komatsu, Kazunori Serita, Weilu Gao, Lincoln Weber, Marco Battiato, Hironaru Murakami, Frank A. Hegmann, Junichiro Kono, and Masayoshi Tonouchi
  • Organizer: 21st International Conference on Electron Dynamics in Semiconductors, Optoelectronics and Nanostructures
  • Int'l Joint Research
• [Presentation] Characteristics of THz emissions from Bi2Te3/Te striped structure (2019)
  • Author(s): F. Murakami, K. Serita, H. Murakami, R. Dalipi, A. M. Urbas, A. Materna, M. Buza, D. A. Pawlak, M. Tonouchi, and I. Kawayama
  • Organizer: 21st International Conference on Electron Dynamics in Semiconductors, Optoelectronics and Nanostructures
  • Int'l Joint Research
• [Presentation] Terahertz radiation from InGaN/GaN Multiple Quantum Wells (2019)
  • Author(s): Abdul Mannan, I. Kawayama, K. Yamahara, F.R. Bagsican, H. Murakami, T. Langer, H. Bremers, U. Rossow, D. Turchinovich, A. Hangleiter, and M. Tonouchi
  • Organizer: 21st International Conference on Electron Dynamics in Semiconductors, Optoelectronics and Nanostructures
  • Int'l Joint Research
• [Presentation] Bi2Te3/Teストライプ構造を有する試料からのテラヘルツ放射特性 (2018)
  • Author(s): 村上史和，芹田和則，村上博成，R. Dalipi，A. M. Urbas，A. Materna，M. Buza，D. A. Pawlak，斗内政吉，川山巌
  • Organizer: 2019年春季 第66回 応用物理学会春季学術講演会