Degradation of 600V GaN HEMTs under Repetitive Short Circuit Conditions

Abstract

This paper descirbes impact of repetitive short-circuit stress on commercially available 600V e-mode GaN HEMTs with p-GaN gate. The devices were subjected to up to 105 short circuit stress cycles at 100V and 300V drain voltage. Tests at voltages over 300V resulted in destruction of the devices. Electrical characteristics were measured prior to, and after each sequence of pulses to observe gradual effects of repetitive SC stress. The devices were also analysed by DLTS. A shift in all of the measured characteristics was observed. Amount of the shift does not correlate with the number of SC cycles, which suggests more parameters of the devices are affected. The shifts were also more pronounced at higher drain voltage. The trapping was also analysed using DLTS. Due to high complexity of the spectra, only the traps verified by simulation were investigated. At 100V stress voltage, the shift in DLTS spectra was small, at 200V it was significant. Full analysis of possible origin of the observed deep levels is still ongoing.