Comparison Study of Surge Current Capability of Body Diode of SiC MOSFET and SiC Schottky Diode

The superior performance of the SiC MOSFETs operating in synchronous mode converter without external antiparallel SiC Schottky diodes have been demonstrated recently. However, there are few studies of the surge current capability of the SiC MOSFET's body diode, leading severe concern for its ruggedness in practical power converter applications. The purpose of this paper is to experimentally compare the non-repetitive surge current capability of the SiC MOSFET's intrinsic body diode and SiC Schottky diode, and analyze the physical mechanisms of their degradation after surge current stress. Their surge current capability and electrical characteristics before and after surge current stress are measured and analyzed. Experimental study shows that the non-repetitive peak surge current of the SiC MOSFET's body diode is slightly larger than that of the SiC Schottky diodes. The degradation of the SiC Schottky diode after surge current stress is accompanied with the increase of drain leakage current, while the degradation of the SiC MOSFET after the body diode's surge current stress is accompanied with the variation of the threshold voltage and input capacitance of the SiC MOSFET. The analysis shows that the degradation of the SiC MOSFET after the surge current stress may be correlated with the interface traps of SiC/SiO
₂
interface.