Special features of Fowler–Nordheim stress degradation of SiC-MOSFETs

Abstract

SiC-MOSFETs have been markedly developed, and the main issues remaining are high-temperature stability and gate-oxide integrity. In this paper, we report special features of Ids–Vgs and Ig–Vgs characteristics of commercially available SiC-MOSFETs during high-gate-voltage and high-temperature stress. Moreover, we introduce simple analytical models that reveal the effects of the trapped charges on the characteristics. Interface states around the conduction-band edge are suggested to be the key mechanisms of Fowler–Nordheim stress degradation (FN degradation) as well as negative bias temperature instability (NBTI), which affects both mobility and carrier density. Hole trapping is also important in FN degradation as well as NBTI. Near-interfacial electron trapping and detrapping found in positive bias temperature instability (PBTI) is also observed in FN degradation. A continuous Ig increase during FN stress, which is the most specific to SiC-MOSFETs, is related to the observation that near-interfacial electron trapping has little effect on FN tunneling.