Robust avalanche in GaN leading to record performance in avalanche photodiode

This abstract presents a study on the avalanche capability of GaN p-i-n diode leading to the achievement of 60A/W, 278V GaN avalanche photodiode. The GaN p-i-n diode fabricated on a free-standing GaN substrate was avalanche capable due to optimal edge termination. Both electrical and optical characterizations were conducted to validate the occurrence of avalanche in these devices. The device showed a positive temperature coefficient of breakdown voltage, which follows the nature of avalanche breakdown. The positive coefficient was measured to be 3.85 ×10-4 K-1 (0.1V/K) under a measurement temperature ranges from 300 K to 525 K. Moreover, the fabricated device showed excellent performance as an avalanche photo detector with record device metrics: (1) record high photoresponsivity of 60 A/W; (2) high optical gain of 105; and (3) low cark current. Robust avalanche is a key requirement in various device applications and necessary for their reliable operation.