Investigation on the Long-Term Reliability of High-Voltage p-GaN HEMT by Repetitively Transient Overcurrent

In this paper, the effects of repetitively transient overcurrent on the long-term reliability of commercial p-GaN high-electron-mobility transistors(HEMTs) are investigated by using RLC pulse-ring-down tests. The devices rated for 650 V/30 A are electrically stressed by peak pulse currents of 90 A, corresponding to 3x of the given rating. It is found that the device ON-state resistance(R-ON) increases by about 20.7% for the device pulsed 500 000 times. The measured results reveal that the reason for the increase in RON is the traps caused by thermal stress concentration during repetitive pulse process. Furthermore, for the device pulsed with larger than 500 000 times, a conductive path is formed through passivation layer because of trap accumulation, which results in a saturation trend in RON and a remarkably increase in the drain leakage current (IDL). However, the high peak currents and large pulse numbers required to produce severe degeneration demonstrate the GaN-based HEMTs have a promising long-term reliability in power switching applications that are susceptible to pulse overcurrent.