Investigation on the Single-Event Burnout Mechanism and Hardening Design in p-GaN Gate AlGaN/GaN HEMTs

Single-event burnout (SEB) has become a critical reliability concern for p-gallium nitride (GaN) gate AlGaN/GaN high-electron-mobility transistors (HEMTs) operating in radiation environments. In this work, the SEB mechanism of conventional p-GaN gate AlGaN/GaN HEMTs has been systematically investigated, and a novel hardening design has been proposed to suppress device burnout. Under Ta-ions irradiation with a linear energy transfer (LET) of 63.8 MeV $\cdot $ cm²/mg, the 650 V p-GaN gate HEMT exhibited SEB when the drain voltage reached 390 V, with the failure region located near the drain edge. TCAD simulation revealed that the burnout is caused by the high electric field near the drain region. Based on the SEB mechanism, a hardened p-GaN gate HEMT with a drain-connected n-AlGaN cap layer has been designed and verified through TCAD simulation. The proposed structure effectively modulates the electric-field distribution, significantly reducing the peak electric field near the drain after heavy-ion incidence. As a result, the SEB threshold voltage increases from 400 to 700 V under a LET of 0.6 pC/ $\mu $ m, demonstrating a significant improvement in SEB characteristic compared to the conventional p-GaN gate AlGaN/GaN HEMT.