A study on scattering mechanisms of inversion layer mobility in SiC MOSFETs

2021 Fiscal Year Final Research Report

• Project/Area Number: 19K04494
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 21050:Electric and electronic materials-related
• Research Institution: Toyama Prefectural University
• Principal Investigator: Hatakeyama Tetsuo 富山県立大学, 工学部, 教授 (90222215)
• Project Period (FY): 2019-04-01 – 2022-03-31
• Keywords: 電子デバイス / 界面テクノロジー / パワーデバイス / MOSFET / 移動度 / シリコンカーバイド / 散乱機構 / 電気双極子

Outline of Final Research Achievements

At first, to examine the dominant scattering mechanism of the measured mobility at SiC MOS interfaces, we have developed a mobility calculation program based on the scattering theory of two-dimensional electron gas considering the physical properties of SiC. By the comparison between experimental results and calculated results, it has been shown that the dominant deterioration factor of the SiC MOS interface mobility is neither phonon scattering nor Coulomb scattering. Furthermore, we have also shown that the effective electric field dependence and electron concentration dependence of the measured mobility can be reproduced by calculated mobility limited by the scattering originated from the dipoles at the MOS interface. We have investigated the possible mechanism of the formation of dipoles at the interface. It has been concluded that the dominant deterioration factor of mobility at the SiC MOS interfaces is likely to be scattering by high-density of dipoles at the MOS interface.

Free Research Field

電気電子工学 電子デバイス分野

Academic Significance and Societal Importance of the Research Achievements

SiC MOS界面の移動度は、SiC材料自体の移動度と較べて非常に小さく、SiC MOSFETの性能を律速している。そのためSiC MOSFETの活用範囲は界面の移動度の影響が少ない高電圧の電力機器に限定されてい。SiC MOS界面の移動度の改善はSiC MOSFETの活用範囲を広げ、省エネへのインパクトが大きい。一方、SiC MOS界面の移動度改善の研究は20年以上取り組まれていたが、困難な問題であり、十分な成果が上がっていない。本研究はSiCMOS界面の移動度の劣化の物理の本質に迫るものであり、移動度問題解決のロードマップの最初のマイルストーンとなる成果である。