Gate Resistance Effect on Short-circuit Robustness of p-GaN HEMTs

Abstract:
This paper depicts the effect of Gate Resistance (RG) on the robustness of 650 V normally-off Gallium Nitride (GaN) High Electron Mobility Transistors (HEMTs) under Short-Circuit (SC) conditions through qualitative and experimental analysis. Tests were performed on Devices Under Test (DUTs) at various RG values, while maintaining the Drain-Source Voltage (VDS) and the Gate-Source Voltage (VGS) con-stant. Overall, the DUTs demonstrated good robustness under single SC conditions. By increasing RG, a significant increase in the energy dissipated during the SC stress (ESC) before failure was observed. Besides, the initial peak of the Drain current (ID) appears to decrease as RG increases. However, by conducting repetitive SCs of very short durations, ESC does not seem to be affected by the variation in RG and the DUTs appear to be able to withstand more SC cycles by increasing RG. The results suggest that two failure mechanisms may occur. The first one, under long SC stresses, where failure appears to be primarily caused by dissipated energy and temperature increase. The second one, under repetitive SCs of short duration, which remains unclear, especially as in this situation, energy does not seem to be the main cause of failure.