Total-Ionizing-Dose Radiation-Induced Leakage Current Degradation in p-GaN Gate HEMTs

In this work, total-ionizing-dose (TID) radiation-induced drain leakage current (I-off) degradation in p-GaN gate high electron mobility transistors (HEMTs) is studied. Irradiation-induced I-off degradation is dominated by source current and substrate current, and irradiation damage mechanism is revealed. Irradiation-induced holes are trapped at GaN channel under the gate and near the buffer/transition layer interface, which would lower energy barrier for electron injection and increase I-off. Electron traps are generated in the buffer layer under both irradiation and high electric field, which would raise energy barrier in the buffer for electron and suppress the increase of I-off. The combined effect of the hole trapping and the electron trap generation results in nonmonotonic degradation of I-off with TID. Deep-level transient spectroscopy and capacitance test results show that irradiation-induced electron trap is not recoverable, while the hole trapping under the gate could anneal with time.