Gate Lifetime of P-Gate GaN HEMT under DC and Switching Overvoltage Stress

Abstract

This paper investigates the gate lifetime of Schottky-Type p-gate GaN HEMTs (SP-HEMTs) under positive gate voltage G stress. The VG stress is implemented in both the DC bias and the switching at various frequencies (fsw). For the switching stress, the impacts of two switching schemes, i.e., drain-And-source grounded (DSG) and inductive hard switching (HSW), on the gate lifetime are studied. The switching stress features the repetitive, resonant G ringing with an average G of 12 V/ns produced by a VG-overshoot-generation circuit. It is found that, in either the DC or switching case, the gate lifetime shows a power-law relation with the G-stress magnitude and can be fitted by Weibull distribution. At sw up to 100 kHz, the switching lifetime is determined by the switching cycle numbers. The maximum allowable VG values for a 10-year lifetime extracted under the DC bias and the 100 kHz DSG switching are found to be similar (6V). A higher VG limit of 10 V is revealed under the 100-kHz HSW condition. These results provide new insights of GaN HEMT gate lifetime under static and dynamic stresses and provide useful reference for the gate qualification.