Development of ultra-wide bandgap amorphous oxide semiconductors for photo-stable electronic devices

• Project/Area Number: 17K14548
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Device related chemistry
• Research Institution: Tokyo Institute of Technology
• Principal Investigator: Kim Junghwan 東京工業大学, 元素戦略研究センター, 助教 (90780586)
• Project Period (FY): 2017-04-01 – 2019-03-31
• Project Status: Completed (Fiscal Year 2018)
• Budget Amount: ¥4,420,000 (Direct Cost: ¥3,400,000、Indirect Cost: ¥1,020,000); Fiscal Year 2018: ¥2,210,000 (Direct Cost: ¥1,700,000、Indirect Cost: ¥510,000); Fiscal Year 2017: ¥2,210,000 (Direct Cost: ¥1,700,000、Indirect Cost: ¥510,000)
• Keywords: 酸化物TFT / アモルファス酸化物半導体 / TFT / 光劣化 / 酸化物半導体デバイス / 光劣化のない電子デバイス

Outline of Final Research Achievements

The transparency of oxide semiconductors is a significant feature that enables the fabrication of fully transparent electronics.　Unfortunately, practical transparent electronics using amorphous oxide semiconductors (AOSs) have not yet been realized, owing　to significant photo-instabilities of these materials. In this work, we examined the electronic structures of a variety of AOSs and found that their ionization potentials vary　greatly, depending upon the specific metal cations. This finding enabled us to 　increase the optical bandgap by modifying the VBM levels, resulting in a high mobility of 9 cm2/Vs and an ultra-wide bandgap of 3.8 eV for amorphous Zn-Ga-O (a-ZGO).

Academic Significance and Societal Importance of the Research Achievements

アモルファス酸化物半導体は低温プロセスながらも高い性能を示すため、非常に魅力のある半導体材料である。また、アモルファス酸化物半導体の持つ透明さは透明エレクトロニクスの実現を期待させる。しかし、従来のアモルファス酸化物半導体の持つ光劣化により透明のまま使うことが出来ない。本研究はこのような問題点を解決しており、また、高性能、高安定なアモルファス酸化物半導体の設計指針を提案している。このような結果は今後、透明素子のような次世代エレクトロニクスの開発に繋がると考えられる。

Research Products

• [Journal Article] Ultra-wide bandgap amorphous oxide semiconductors for NBIS-free thin-film transistors (2019)
  • Author(s): Kim Junghwan、Bang Joonho、Nakamura Nobuhiro、Hosono Hideo
  • Journal Title: APL Materials Volume: 7 Issue: 2 Pages: 022501-022501
  • DOI: 10.1063/1.5053762
  • Peer Reviewed / Open Access
• [Journal Article] Transition metal-doped amorphous oxide semiconductor thin film phosphor, chromium-doped amorphous gallium oxide (2019)
  • Author(s): Keisuke Ide, Yuki Futakado, Naoto Watanabe, Junghwan Kim, Takayoshi Katase, Hidenori Hiramatsu, Hideo Hosono, Toshio Kamiya
  • Journal Title: Phys. Status Solidi A Volume: 216 Issue: 5 Pages: 1800198-1800198
  • DOI: 10.1002/pssa.201800198
  • Peer Reviewed
• [Journal Article] Electron Affinity Control of Amorphous Oxide Semiconductors and Its Applicability to Organic Electronics (2018)
  • Author(s): Kim Junghwan、Yamamoto Koji、Iimura Soshi、Ueda Shigenori、Hosono Hideo
  • Journal Title: Advanced Materials Interfaces Volume: 5 Issue: 23 Pages: 1801307-1801307
  • DOI: 10.1002/admi.201801307
  • Peer Reviewed
• [Journal Article] Multiple Color Inorganic Thin-Film Phosphor, RE-Doped Amorphous Gallium Oxide (RE = Rare Earth: Pr, Sm, Tb, and Dy), Deposited at Room Temperature (2018)
  • Author(s): N. Watanabe, K. Ide, J. Kim, T. Katase, H. Hiramatsu, H. Hosono, T. Kamiya
  • Journal Title: Phys. Status Solidi A Volume: N/A Issue: 5 Pages: 1700833-1700833
  • DOI: 10.1002/pssa.201700833
  • Peer Reviewed / Open Access
• [Journal Article] Conversion of an ultra-wide bandgap amorphous oxide insulator to a semiconductor (2017)
  • Author(s): J. Kim, T. Sekiya, N. Miyokawa, N. Watanabe, K. Kimoto, K. Ide, Y. Toda, S. Ueda, N. Ohashi, H. Hiramatsu, H. Hosono and T. Kamiya,
  • Journal Title: NPG Asia Materials Volume: 9 Issue: 3 Pages: e359-e359
  • DOI: 10.1038/am.2017.20
  • Peer Reviewed / Open Access / Acknowledgement Compliant
• [Presentation] Stability Issues of High-mobility Oxide TFTs (2019)
  • Author(s): Junghwan Kim, Yu-Shien Shiah, Joonho Bang, Katsumi Abe, Hideo Hosono
  • Organizer: International Thin-Film Transistor Conference (ITC) 2019
  • Int'l Joint Research / Invited
• [Presentation] Development of Ultra-Wide Bandgap Amorphous Oxide Semiconductors for Future Electronics (2018)
  • Author(s): Junghwan kim, Hideo Hosono
  • Organizer: AiMES 2018
  • Int'l Joint Research / Invited
• [Presentation] Hydrogen Anion and Subgap States in Amorphous In-Ga-Zn-O Thin Films (2018)
  • Author(s): Joonho Bang, Satoru Matsuishi, Junghwan Kim, Hideo Hosono
  • Organizer: International Meeting on Information Display (IMID) 2018
  • Int'l Joint Research / Invited
• [Presentation] Material Design of Ultra-Wide Bandgap AOSs and Their Applications in Photo-Stable Electronic Devices (2017)
  • Author(s): Junghwan Kim, Nobuhiro Nakamura, Toshio Kamiya, Hideo Hosono
  • Organizer: AM-FPD
  • Invited
• [Presentation] Correlation between Electronic Structures and Instabilities in Amorphous Oxide Semiconductors (2017)
  • Author(s): Junghwan Kim, Toshio Kamiya, Hideo Hosono
  • Organizer: IMID
  • Invited
• [Presentation] Development of Amorphous Gallium Oxide Semiconductor and its Application to Future Electronic Devices (2017)
  • Author(s): Junghwan Kim, Toshio Kamiya, Hideo Hosono
  • Organizer: IWGO
  • Invited
• [Presentation] Material Design and Development of New Amorphous Oxide Semiconductors for Future Electronics (2017)
  • Author(s): Junghwan Kim, Toshio Kamiya, Hideo Hosono
  • Organizer: ICMaSS
  • Invited