[21p-232-1~18] 6.2 Carbon-based thin films

△ [21p-232-9] Normally-Off 2DHG Diamond MOSFETs with High Drain Current Density by Al₂O₃/SiO₂ Interface

〇(M1)Taichi Yabe¹, Nobutaka Oi¹, Kiyotaka Horikawa¹, Satoshi Okubo¹, Jorge J. Buendia¹, Taisuke Kageura¹, Shozo Kono¹, Atsushi Hiraiwa¹, Hiroshi Kawarada^1,2 (1.Waseda Univ., 2.Zaiken)

Keywords:Diamond, MOSFETs, Normally-Off

Hydrogen-terminated diamond MOSFETs with a reported high breakdown voltage characteristic and stable operation in wide temperature range have been reported in previous research. Diamond MOSFETs use Two-Dimensional Hole Gas (2DHG) which is induced by negative adsorbates or passivation film on hydrogen-terminated surface. In general, 2DHG diamond MOSFETs are normally-on since 2DHG channel is induced without gate bias. But power devices are required to be normally-off for safety. Normally-off diamond MOSFETs have already been reported for C-H diamond MOSFETs with partial C-O channel, HfO2-gated diamond MOSFETs and inversion channel diamond MOSFETs. In this study, we demonstrate normally-off MOSFETs by the insertion of thin SiO2 layer in diamond/Al2O3 interface. SiO2 which do not have negative charge is not induced 2DHG. So, normally-off is achieved by insertion of SiO2 into MOS structure. In addition, we could suppress the deterioration of drain current density.