Degradation Mechanism of 4H-SiC MOSFET under 10 MeV Proton Irradiation

The degradation behavior of 1200 V planar-gate 4H-SiC MOSFETs under 10 MeV proton irradiation was investigated by combining Geant4 energy-deposition simulation, electrical characterization, deep-level transient spectroscopy (DLTS) analysis, and double-pulse switching tests. Irradiation was performed at a fluence of 1×10¹² cm⁻². The simulation results show that energy deposition in the sensitive regions is dominated by ionizing effects. After irradiation, the device exhibits a pronounced negative threshold-voltage shift and longer turn-off delay. In addition, both the C_gs–V_gs and C_gd–V_gs characteristics shift toward lower gate voltage. Trap extraction from electrical measurements further shows that the increase in oxide-trapped charge is much larger than that in interface-trap density, indicating that the degradation in the gate-oxide/near-interface region is mainly governed by oxide-trapped charge buildup. Meanwhile, the off-state leakage current increases significantly after irradiation. DLTS results further reveal significant increases in the concentrations of the deep-level traps E2 (EC−0.72 eV) and E3 (EC−0.93 eV), which are considered to participate in trap-assisted leakage transport under reverse bias and thus contribute to leakage degradation.