Evaluations of threshold voltage stability on COTS SiC DMOSFETs using fast measurements

Threshold voltage (Vt) stability of commercial SiC DMOSFETs during bias-temperature stressing was evaluated using the fast-Ic and fast Id-Vgs measurement techniques at both room and elevated temperatures. Unipolar bias stress results confirmed that there is a rapid recovery of Vt and that all vendors' devices showed the same basic charge-trapping behavior, although some differences were observed in negative bias response at high temperatures. In situ Vt measurements during 10 kHz gate switching showed stable device operation at room temperature but accelerating Vt drift and increasing switching oxide trap densities when operated at 175 °C. Vt hysteresis during high temperature gate switching indicates the presence of a mobile ion or polarization effect in addition to the expected interface- and oxide-trap charging mechanisms.