60 A/W high voltage GaN avalanche photodiode demonstrating robust avalanche and high gain up to 525 K

Abstract

This paper presents a demonstration of a 278 V GaN avalanche photodiode offering a photoresponsivity of 60 A/W and capable of operating at high temperature with a high gain of 105. The GaN n–i–p diode fabricated on a free-standing GaN substrate showed robust avalanche, which has not been observed on any GaN avalanche photodiodes (APDs) grown on foreign substrates. Both electrical and optical characterization studies 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 (0.1 V/K) at a measurement temperature ranging from 300 K to 525 K. The avalanche-induced electroluminescence is also reported here in GaN APDs. The diode demonstrated superior performance by simultaneously offering a high photoresponsivity of 60 A/W, a high gain of 105 up to 525 K, and low dark current (1.5 × 10−5 A/cm2), measured at 0.95 × BV following industry standards.