Avalanche Capability of Vertical GaN p-n Junctions on Bulk GaN Substrates

Inductive avalanche test results presented in this letter demonstrate that GaN p-n diodes can sustain single-pulse and repetitive inductive avalanche currents. The 0.36-mm² vertical GaN p-n diodes can sustain single-pulse avalanche currents as high as 10 A. The safe zone of the single-pulse avalanche current is limited by peak pulse power and energy deposited in the device. The temperature-dependent behavior of the breakdown voltage and the reverse-voltage at onset of avalanche has a positive temperature coefficient. Repetitive avalanche ruggedness testing was performed by applying 10⁵ pulses at 5-kHz frequency with increasing repetitive stress current. Based on a population of 63 devices, the incremental failure rate under repetitive avalanche current increases with increasing avalanche current. The devices that survive the step stress test sustain no parametric drift under repetitive avalanche.