Degradation Mechanisms of Gate Leakage in GaN-Based HEMTs at Low Dose Rate Irradiation

In this paper, we investigated an experimental analysis of the degradation caused by low dose rate irradiation in GaN-based high-electron-mobility transistors (HEMTs) with a p-type gate. Combined with experimental frequency-dependent conductance ( $\text{G}_{\mathrm {p}}/\omega)$ analyses and TCAD simulations, it has been demonstrated that the negative shifts in both $\text{I}_{\mathrm {d}}$ - $\text{V}_{\mathrm {gs}}$ and $\text{V}_{\mathrm {th}}$ are primarily due to the formation of donor-like traps near the p-GaN/AlGaN interface, which is a result of the dehydrogenation of pre-existing defects during low dose rate irradiation. Additionally, the results of the TCAD simulations, indicate that the trap-assisted tunneling (TAT) process, which involves the recombination of trap-assisted holes with electrons in the p-GaN layer, may dominate the physical mechanisms responsible for the increase in gate leakage current ( $\text{I}_{\mathrm {g}}$ - $\text{V}_{\mathrm {gs}}$ ). These results may provide a basis for understanding the role of radiation-induced traps on electrical parameters degradations for p-GaN gate HEMTs.