Avalanche Ruggedness of GaN p-i-n Diodes Grown on Sapphire Substrate

Avalanche capability plays critical roles in safe operation of GaN-based high power devices and systems. In this study, GaN-based quasi-vertical p-i-n diodes on sapphire substrate with avalanche capability are fabricated, and for the first time, their avalanche ruggedness is investigated. Repeated avalanche breakdown tests suggest the representative features of avalanche-capability degradation, reduction in breakdown voltage, and rise in reverse leakage current. Further numerical simulations reveal the localization of avalanche breakdown, while subsequent pulsed current-voltage measurements identify that the thermal heating effect generated during localized avalanche multiplication is responsible for the device degradation in avalanche ruggedness.