Enhanced gate breakdown and electroluminescence in p-GaN gate HEMTs under pulsed switching conditions

In this work, enhanced gate breakdown under pulsed switching conditions were observed and investigated in Schottky-type p-GaN gate HEMTs. The pulsed time-dependent breakdown (TDB) and pulsed gate breakdown characteristics both featured a positive frequency dependence. At a gate bias of 10 V, the effective total lifetime extended from 170 s to 670 s with the switching frequency increased from 5 Hz to 10 kHz. By time-dependent electroluminescence (TDEL) characteristics on devices with semi-transparent gate electrodes, the high-energy ultraviolet emission increased at a higher switching frequency, indicating an enhanced hole injection into the p-GaN/AlGaN/GaN heterostructure. The enhanced hole injection annihilated more injected electrons, leading to the suppressed hot-electron effect, as well as the enhanced gate breakdown.