Forward Bias Gate Breakdown Mechanism in Enhancement-Mode p-GaN Gate AlGaN/GaN High-Electron Mobility Transistors

In this letter, we studied the forward bias gate breakdown mechanism on enhancement-mode p-GaN gate AlGaN/GaN high-electron mobility transistors. To the best of our knowledge, it is the first time that the temperature dependence of the forward gate breakdown has been characterized. We report for the first time on the observation of a positive temperature dependence, i.e., a higher temperature leads to a higher gate breakdown voltage. Such unexpected behavior is explained by avalanche breakdown mechanism: at a high positive gate bias, electron/hole pairs are generated in the depletion region at the Schottky metal/p-GaN junction. Furthermore, at a high gate bias but before the catastrophic gate breakdown, a light emission was detected by a emission microscopy measurement. This effect indicates an avalanche luminescence, which is mainly due to the recombination of the generated electron/hole pairs.