Investigation of threshold voltage stability of SiC MOSFETs

Silicon carbide (SiC) based metal-oxide semiconductor-field-effect-transistors (MOSFETs) show excellent switching performance and reliability. However, compared to silicon devices the more complex properties of the semiconductor-dielectric interface imply some natural peculiarities in threshold voltage variation. This paper analyzes threshold voltage hysteresis effects, bias temperature instability effects (BTI) and their relevance for the switching behavior. Most of the effects can be understood by means of simple physical models and do not harm reliability and performance of the device. It turns out that the standard norm test and readout procedures typically used to characterize threshold voltage and threshold voltage drifts for Si devices are insufficient and need to be adapted for SiC MOSFETs in order to get reproducible and solid results.