Threshold Voltage Stability Study on Power SiC MOSFETs Using High-k Dielectrics

We present the first study on the threshold voltage stability of vertical 1.2kV and 1.7kV SiC power MOSFETs using high-k gate dielectrics including static and dynamic testing. Bidirectional transfer characteristics indicate barely any hysteresis due to the high quality of the SiC/high-k interface compared to SiO2 control devices. Additionally, the threshold voltage shift is significantly lower compared to commercially available SiC MOSFETs and is independent of gate voltage ramp and starting gate voltages. Turn-on sweeps at elevated temperatures reveal virtually no dependence of the Miller plateau with regards to the off-state gate-source voltage, a result which is comparable to Si MOSFET technology.