Gate leakage mechanisms caused by 60Co gamma irradiation on p-GaN gate AlGaN/GaN HEMTs

Abstract

This study investigates the impact of 60Co γ-ray irradiation on the gate leakage mechanism of Schottky-type p-GaN gate AlGaN/GaN HEMTs. Devices with breakdown voltage of 650 V were irradiated with 60Co γ-ray at a gate bias of VG_stress = 7 V. A significant increase in the forward gate current was observed with increasing irradiation dose. To analyze the gate leakage mechanisms before and after irradiation, temperature-dependent current–voltage (IG–VG) measurements and capacitance deep-level transient spectroscopy were performed. The results indicate that under reverse gate bias, the leakage mechanism consistently remains trap-assisted tunneling (TAT) both before and after irradiation. However, under forward gate bias, the dominant conduction mechanism shifts from Poole–Frenkel emission to TAT as a result of the introduction of hole traps with an energy level of EV + 0.93 eV.