Analysis of the Temperature-Dependent Mechanism of MIS-HEMT in Negative Bias Stress Under X-Ray Irradiation

In this study, metal-insulator-semiconductor high electron mobility transistors (MIS-HEMTs) were subjected to X-ray irradiation during negative bias stress (NBS) to investigate the combined effects of a negative gate bias, temperature variation, and radiation exposure. The results revealed that under X-ray irradiation, the threshold voltage (${V}_{\text {th}}\text {)}$negative shift showed an opposite trend with the temperature increasing compared to that in nonirradiated conditions. However, theon-state current (${I}_{\text {on}}\text {)}$decreased with the temperature increasing, exhibiting more severe degradation under irradiation. The analysis indicated that the opposite${V}_{\text {th}}$trend primarily resulted from depassivation of precursors induced by X-ray irradiation in the Si3N4layer. As the temperature increased, a competitive mechanism between gate-injected electrons and degradation-induced holes mitigated the negative shift in${V}_{\text {th}}$. Moreover, variations in${I}_{\text {on}}$were mainly attributed to electron injection from the gate field plate (G-FP), further confirming the generation of defects in the Si3N4layer caused by X-ray. In addition, positive gate biases during the experiments of the recovery phase and TCAD simulations were employed to verify carrier injection behavior, while single-pulse measurements further support the presence of X-ray-induced defects. This work proposes a temperature-dependent physical mechanism under NBS when exposed to X-ray irradiation, with the view to extending the applicability of D-mode MIS-HEMTs in high-radiation environments.