Influence of the off-state gate-source voltage on the transient drain current response of SiC MOSFETs

In this work we investigate the effect of negative off-state gate-source voltages on SiC MOSFETs. With increasingly negative VGS, Off voltages, a more pronounced drain current over-shoot immediately after turn-on is observed. This effect is most noticeable in saturation, where the drain current is determined primarily by the channel. The phenomenon is attributed to positively charged oxide- and interface-traps that temporarily enhance the inversion charge in the channel before they are gradually neutralized. The amount of charged traps depends on the position of the valence band edge in accumulation, hence the VGS, Off dependence. Two distinct components with very different time constants are observed.