Investigation of safe operating area and behavior of unclamped inductive switching on 4H-SiC VDMOSFET

The electrical safe operating area (eSOA) of the transmission -line pulse (TLP) test and the electrical behavior of the unclamped inductive switching (UIS) test on a 4H-SiC 600-V vertical double -implanted MOSFET (VDMOSFET) were investigated in this work. The snapback phenomenon of the 100-ns and 1000-ns TLP I -V curves can be inferred to be the triggering on of the parasitic BJT in the VDMOSFET. Moreover, the holding voltage of the 1000-ns TLP I -V curve was lower than that of the 100-ns TLP I -V curve, which can be attributed to the severer self -heating effect in the 1000-ns TLP test. In the UIS test, different experiments were conducted by varying pulse widths, gate resistances, and external inductors. The longer the falling time of the gate bias applied to the VDMOSFET, the lower the overshooting peak voltage on the drain side will be. Furthermore, the methods for improving the eSOA characteristic and the UIS ruggedness were also discussed and summarized in this work.