Impact of Proton Irradiation on Performance Degradation of Quasi-Vertical GaN SBDs With Different Drift Region Thicknesses

This manuscript presents a comparative study on the performance degradation of quasi-vertical GaN Schottky barrier diodes with different drift-layer thicknesses (Sample A: 1 μm N⁻- GaN; Sample B: 4.5 μm N⁻-GaN) under 200 keV proton irradiation. Both devices exhibit a slight reduction in schottky barrier height after irradiation, which is attributed to radiation-induced acceptor-like interface states participating in charge transport. At the same applied bias, Sample B shows a more pronounced degradation in electrical performance due to the spatial coupling between the irradiation-induced defect distribution and the high electric field region. In Sample B, the coincidence of the defect peak with the high-field region in the drift layer enhances trap-assisted tunneling and electric-field variation. In contrast, Sample A benefits from a structural design in which the defect peak is spatially separated from the critical depletion region, thereby mitigating degradation. Furthermore, the competing roles of donor- and acceptor-like defects in modulating the depletion width and conduction-band bending are identified as a fundamental mechanism governing the reverse leakage behavior.