Effects of heavy ion irradiation on inverse piezoelectric degradation for GaN HEMT

This paper investigates the impact of heavy ion irradiation on the inverse piezoelectric effect in p-GaN HEMT devices. Heavy ion irradiation introduces donor-type defects in the p-GaN layer and acceptor-type defects in the AlGaN barrier and at the AlGaN/GaN interface, leading to a positive shift in threshold voltage (Vth), reduced transconductance (Gm), and increased on-resistance (RDS(on)). During subsequent inverse piezoelectric stress, the pre-existing donor-type defects locally modulate the electric field distribution, resulting in a lower electric field strength acting on the barrier layer in the irradiated devices compared to the unirradiated ones. This leads to a reduction in the generation of acceptor defects during the inverse piezoelectric process, and finally the parameters variations in irradiated devices after the inverse piezoelectric test is smaller than that subjected solely to the inverse piezoelectric effect.