Heavy Ion-Induced Single-Event Leakage Current and Burnout in Homojunction GaN p-i-n Diodes

The impact of edge termination design on heavy-ion induced single-event leakage current (SELC) and single-event burnout (SEB) is investigated in homojunction gallium nitride (GaN) vertical p-i-n diodes. The implementation of hybrid edge termination (HET) improves electric field management at the anode edge, thereby increasing the breakdown voltage and enhancing resilience to heavy-ion exposure. Cf-252 fission-fragment irradiation leads to SELC steps and catastrophic SEB. A heavy ion strike from a Cf-252 fission fragment forms a highly conductive region due to the generation of an electron–hole plasma along the ion path. Joule heating due to the high current through this region aids the generation of nitrogen vacancies that permanently enhance leakage current, leading to SELC steps. At elevated voltages, similar mechanisms can trigger SEB. The high current along the transient plasma wire can lead to bond breaking and mass transport along the ion path. The released electrical energy initiates a microexplosion in regions of high mechanical stress, causing GaN decomposition and further nitrogen vacancy formation in the epilayer and the substrate. The chains of N vacancies and metallic Ga produced by GaN decomposition create a high-conductivity pathway and lead to catastrophic failure.