X射线辐照诱导的p-GaN肖特基栅HEMT阈值电压不稳定性

p-GaN Schottky-gate structure E-mode HEMTs have great potential for irradiation applications, yet their threshold voltage ( V _ TH ) instability is still under investigation. In this work, by constructing an X-ray irradiation online monitoring system with adjustable dose and integrated peripheral bias circuit, irradiation dose- and drain bias-dependent V _ TH instability are comprehensively investigated. Under irradiation-only conditions, the device exhibits a negative V _ TH shift with low-dose irradiation, followed by a positive V _ TH shift with high-dose irradiation. By performing numerical simulations, Hall measurements, and C–V tests, it is revealed that the negative V _ TH shift is dominated by the p-GaN activation-induced V _ TH instability mechanism, rather than the gate-related hole injection mechanism. The corresponding activation efficiency of p-GaN increases from 1.3% (unirradiated device) to 1.5% (0.11-Sv irradiation). Furthermore, acceptor-like defects are identified as the main cause of positive V _ TH shift. The low-frequency 1/f noise experimental results show that the density of defect states at different doses is higher than that of unirradiated devices. Moreover, under the synergistic effect of irradiation and drain bias, the device still exhibits a positive V _ TH shift, which can be explained by the modified charge storage mechanism. These results provide important insights into the V _ TH instability of p-GaN Schottky-gate structure high electron mobility transistors (p-GaN HEMTs) under irradiation conditions.