Investigation on the Cumulative Degradation in p-GaN Gate HEMTs Under Synergistic Electrical Stress and Heavy Ion Irradiation

In this work, the synergistic effects of electrical stress and heavy-ion irradiation on the cumulative degradation of p-GaN gate AlGaN/GaN high electron mobility transistors (HEMTs) are systematically investigated. The devices were irradiated with Ta ions (LET = 76.3 MeV ⋅ cm2/mg) under the drain bias slightly lower than the single-event burnout (SEB) threshold voltage ( VSEB) . The saturated drain current ( IDsat) exhibits a pronounced cumulative degradation with increasing heavy-ion fluence under off-state electrical stress. Electrical characterization results show that neither electrical stress nor irradiation alone induces significant degradation, whereas their synergistic effect leads to severe performance degradation. Furthermore, analyses based on low-frequency noise (LFN) and capacitance deep-level transient spectroscopy ( C -DLTS) reveal a substantial increase in trap density in the p-GaN layer after irradiation. The increased traps within the p-GaN layer degrade carrier transport in the channel, mainly through enhanced Coulomb scattering and mobility reduction, accompanied by a partial reduction in the effective 2DEG density.