Investigation on Dynamic Degradation of SiC MOSFETs after Total Ionizing Dose Radiation

SiC MOSFETs are increasingly gaining attentions from aerospace industry due to their superior radiation tolerance and low loss. The influences of total ionizing dose (TID) radiation on static characteristics of SiC MOSFETs have been extensively studied in recent years, however, the influence on their switching behaviors has seldom been comprehensively studied yet. In this paper, we comparatively studied the switching characteristics of SiC MOSFETs pre and after γ-ray radiation, and observed that their turn-on time and turn-on loss decrease by 12.78% and 9.19%, turn-off time and turn-off loss increase by 15.92% and 20.79%, respectively, after 500krad radiation under ON-state (i.e., V GS =15V & V DS =0V), while they are 9.91%, 13.31%, 14.87% and 28.51% with same tendency after 500krad radiation under OFF-state (i.e., V GS =0V & V DS =400V). Further analysis indicates that the negative shift of threshold voltage and increment in parasitic capacitances, both of which are induced by accumulation of positive charges in gate oxide, should be directly responsible for the dynamic degradation after γ-ray radiation.