650-V E-Mode p-GaN Gate HEMT with Schottky Source Extension Towards Enhanced Short-Circuit Reliability

A 650-V p-GaN gate HEMT with Schottky source extension is proposed towards enhanced short-circuit (SC) reliability. At higher drain bias, a pinch-off point is formed at the edge of the Schottky source extension, resulting in reduced saturation current. High-voltage pulse I-V characterization is conducted for the devices in the ON-state to evaluate their SC reliability. With the similar OFF-state breakdown voltages (BVs), the proposed device survives a much higher SC pulse voltage compared to the conventional p-GaN gate HEMT. Then, multiple short-circuit (SC) stress/test cycles are applied to the devices. For each stress, the drain voltage is increased by 50 V. The progressive degradation of RON and OFF-state leakage current are recorded after each SC stress. The degradation of the proposed device is much slower than the conventional device. These results indicate that the proposed device is a promising solution for short-circuit rugged GaN power transistors.