Long-term reliability of gate-oxide in Cascode GaN power devices under proton irradiation with different energies

摘要: Gallium nitride (GaN)-based devices are highly attractive candidates for space and aeronautics due to their wide band gap and high critical electric field. However, the mechanism of radiation damage and long-term application reliability of the device are still unclear. This study systematically examines the degradation mechanisms of gate oxide layers in Cascode GaN power devices under proton irradiation at different energy levels. The typical degradation of electrical properties was observed. Following 25 MeV proton irradiation, the gate leakage current increased from 4.18×10-12 A to 4.42×10-10 A. After 60 MeV proton irradiation, the gate leakage current rose from 3.88×10-12 A to 3.81×10-10 A. In contrast, no significant change in gate current was observed after 100 MeV proton irradiation. Time-dependent dielectric breakdown (TDDB) analysis confirmed an elevated risk of gate current leakage under proton irradiation. Proton irradiation increases defect density in the device oxide layer, leading to the formation of leakage paths. In addition, SRIM simulation results based on Monte Carlo indicated that the interaction cross section between low-energy protons and target nuclei is larger, which will cause more defects in the device, leading to the low-energy proton damage becoming more severe. These radiation-induced defects in the gate oxide layer accelerate dielectric breakdown, ultimately compromising the device's long-term reliability.