Elucidation of atomic structure and dynamics of carrier trap sites

2022 Fiscal Year Final Research Report

• Project/Area Number: 21K18706
• 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: Tohoku University
• Principal Investigator: Cho Yasuo 東北大学, 未来科学技術共同研究センター, 特任教授 (40179966)
• Project Period (FY): 2021-07-09 – 2023-03-31
• Keywords: 走査型非線形誘電率顕微鏡 / 時間分解走査型非線形誘電率顕微鏡 / 界面準位密度

Outline of Final Research Achievements

A major breakthrough in the characterization of GaN MOS interfaces has been achieved: it has been found that GaN interfaces exhibit potential barrier fluctuations that are larger than the thermal energy and are difficult for carriers to overcome. This result overturned the common belief in the semiconductor industry that the interface is homogeneous, including the distribution of defects, and pointed out that it is impossible to realize high-mobility power MOS devices using wide-gap semiconductors without solving this potential fluctuation problem. Furthermore, he developed and completed a SNDMR apparatus. The magnetic field can be rotated 360°C and applied up to 5000G or more, and the temperature can be controlled from cryogenic (30K) to room temperature.

Free Research Field

電気電子材料工学

Academic Significance and Societal Importance of the Research Achievements

SNDMRの装置開発を行い完成した。磁場は360℃回転でき5000G以上までかけられ、温度は極低温（30K)から常温迄コントロール可能とした。スピン反転用マイクロ波磁界の周波数可変範囲と最高強度はそれぞれ1～20GHzと0.23Gで、ESR計測に十分な値を達成している。
実際の実験条件を想定し、欠陥密度Nt＝1012cm-2の測定サンプルを半径150 nmの探針電極を用いて信号検出を行うという仮定のもと試算を行ったところ、1.3×10-19 F/V程度の信号強度が得られるとの結果を得ており、現行のSNDMによって十分検出可能な信号強度である事が分かった。