Overcurrent turn-off robustness and stability of the switching behavior of SiC MOSFET body diodes

SiC MOSFETs are gaining more importance in power-conversion and automotive applications, especially in the voltage class from 650 V, 1200 V and above. One of the main advantages of using MOSFETs is the internal body diode, which can be used for current commutation without an external diode. In a fast-switching (high-current) application, the commutation loop stray inductance (L-p) leads to high overvoltage during the diode turn-off. Depending on the circuit conditions and decrease in the respective reverse-current (di(r)/dt), this could also mean that the body diode is operated partly in an avalanche mode. Therefore, the SiC MOSFET must endure avalanche capability under such conditions that a sudden failure during reverse recovery can be avoided. This work investigates the overcurrent turn-off robustness of the SiC MOSFET body diode for different MOSFET technologies (planar and trench cell structure) from different manufacturers. The influence of bipolar degradation on the reverse-recovery behavior is also investigated.