Analyzing the role of hole injection on the short circuit performance of p-GaN gate power HEMTs

Abstract

The detailed failure mechanism of GaN HEMTs in the high voltage regime, where the short circuit withstand time (SCWT) is smaller than 1 μs, is still in discussion. A bipolar failure mechanism has previously been suggested implying that intentional hole injection would play a major role in device robustness. In this work, we study the role of hole injection in the failure mechanism of p-GaN HEMTs at a drain-source voltage of VDS = 600 V. SCWT is compared in three device types: 1) a normally-ON (NON) p-GaN HEMT without intentional hole injection, 2) a NON p-GaN hybrid-drain-embedded HEMT, where holes are injected from the hybrid-drain and 3) a normally-OFF p-GaN HEMT with hole injection from the gate. For the same drain switching current and VDS = 600 V no significant changes in the median SCWT have been found. This implies that intentional hole injection is not a major controlling factor in the bipolar failure mechanism of p-GaN HEMTs.