ダイヤモンド反転型MOSFETにおけるチャネル移動度の制約因子の解明

2020 Fiscal Year Research-status Report

• Project/Area Number: 20K14773
• Research Institution: Kanazawa University
• Principal Investigator: 張 旭芳 金沢大学, ナノマテリアル研究所, 特任助教 (30857404)
• Project Period (FY): 2020-04-01 – 2022-03-31
• Keywords: Diamond inversion MOSFET / Al2O3/diamond interface / Electrical property / Characterization

Outline of Annual Research Achievements

We fabricated the world’s first inversion-channel MOSFET while it suffered from the low channel mobility. One main reason is attributed to the high Dit. Here, we propose a novel technique to form OH-termination to improve the interface quality of Al2O3-diamond by using H-diamond followed by wet annealing, instead of the previous OH-termination formed on O-diamond. The interface quality is significantly improved based on our careful electrical characterization. Furthermore, the trap properties at Al2O3-diamond interface were examined by conductance method. This study is meaningful for deep understanding of the interface states and is beneficial for developing more effective passivation techniques to improve the interface quality and device performance.

Current Status of Research Progress

2: Research has progressed on the whole more than it was originally planned.

Reason

In this project, aiming at the low channel mobility of the inversion-type diamond MOSFFETs, which is mainly attributed to the high interface state density, the OH-termination was achieved by using H-diamond followed by wet annealing. The interface trap density is reduced and the trap property at Al2O3/diamond interface is elucidated, and the corresponding work was published on CARBON and APL.

Strategy for Future Research Activity

During FY 2021, we will further investigate the effect of border traps in the Al2O3 by using the equivalent circuit model, to understand their effect on the device performance of diamond MOSFETs. Moreover, we would like to use the split C-V method to clarify the mechanism of the carrier transport of the diamond MOSFET.

Causes of Carryover

Since COVID-19, I cannot attend the international conferences and a small amount of the funding is left. During FY2021, I will use this budget to buy more diamond substrates and if possible, I would like to attend international conferences.

Research Products

• [Journal Article] Inversion channel MOSFET on heteroepitaxially grown free-standing diamond (2021)
  • Author(s): Xufang Zhang, Tsubasa Matsumoto, Yuta Nakano, Hitoshi Noguchi, Hiromitsu Kato, Toshiharu Makino, Daisuke Takeuchi, Masahiko Ogura, Satoshi Yamasaki, Christoph E. Nebel, Takao Inokuma, and Norio Tokuda
  • Journal Title: CARBON Volume: 175 Pages: 615-619
  • DOI: 10.1016/j.carbon.2020.11.072
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Energy distribution of Al2O3/diamond interface states characterized by high temperature capacitance-voltage method (2020)
  • Author(s): Xufang Zhang, Tsubasa Matsumoto, Ukyo Sakurai, Toshiharu Makino, Masahiko Ogura, Satoshi Yamasaki, Mitsuru Sometani, Dai Okamoto, Hiroshi Yano, Noriyuki Iwamuro, Takao Inokuma, and Norio Tokuda
  • Journal Title: CARBON Volume: 168 Pages: 659-664
  • DOI: 10.1016/j.carbon.2020.07.019
  • Peer Reviewed / Open Access
• [Journal Article] Insight into Al2O3/diamond interface states with high-temperature conductance method (2020)
  • Author(s): Xufang Zhang, Tsubasa Matsumoto, Ukyo Sakurai, Toshiharu Makino, Masahiko Ogura, Mitsuru Sometani, Satoshi Yamasaki, Christoph E. Nebel, Takao Inokuma, and Norio Tokuda
  • Journal Title: Applied Physics Letters Volume: 117 Pages: 092104
  • DOI: 10.1063/5.0021785
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Presentation] Deep Interface Trap Analysis for Al2O3/Diamond MOS Structure by High-temperature Conductance Method (2020)
  • Author(s): Xufang Zhang
  • Organizer: NDNC
  • Int'l Joint Research