Degradation Mechanism Analysis and Modeling of SiC MOSFETs Under 60Co Gamma Ray Total Ionizing Dose Irradiation

The degradation mechanisms of silicon carbide (SiC) VDMOSFET and trench metal oxide semiconductor field effect transistor (MOSFET) in a 60Co gamma irradiation environment were investigated. The degradation of electrical characteristics of SiC MOSFET in different working states after irradiation with different total ionizing doses (TIDs) was explored. The defects induced during the irradiation process were studied in annealing experiments conducted after irradiation. The reasons for the degradation of SiC MOSFET caused by TID were revealed, and a prediction model of threshold voltage (Vth)shift was proposed and verified through TCAD simulation. TheVth, breakdown voltage (BV), ON-resistance (Ron), input capacitance (Ciss), output capacitance (Coss), and reverse transfer capacitance (Crss)were measured at different irradiation doses and annealing conditions. Experimental results indicated that the degradation of bothRonandCisswas primarily caused by theVthshift. As the doses increased, the shift inVthgradually reached saturation. Similar trends to VDMOSFET were observed in trench MOSFET but with greater sensitivity to TID. In addition, MOSFETs biased at zero voltage exhibited lower shifts inVthcompared with those under high gate bias conditions. Furthermore, the increase in defects in the gate oxide during irradiation and annealing processes were calculated. Finally, a model predictingVthshift path was established, and its accuracy and limitations were determined. This study provides valuable insights into the effect of TID on SiC MOSFETs.