Near interface traps in SiO_2/4H-SiC metal-oxide-semiconductor field effect transistors monitored by temperature dependent gate current transient measurements

摘要

This letter reports on the impact of gate oxide trapping states on the conduction mechanisms in SiO_2/4H-SiC metal-oxide-semiconductor field effect transistors (MOSFETs). The phenomena were studied by gate current transient measurements, performed on n-channel MOSFETs operated in "gate-controlled-diode" configuration. The measurements revealed an anomalous non-steady conduction under negative bias (V_G ＞ |20 V|) through the SiO_2/4H-SiC interface. The phenomenon was explained by the coexistence of a electron variable range hopping and a hole Fowler-Nordheim (FN) tunnelling. A semi-empirical modified FN model with a time-depended electric field is used to estimate the near interface traps in the gate oxide (N_(trap)~2 × 10~(11) cm~(-2)).