Investigation of Off-state Stress Time-Dependent Dynamic On-resistance of Commercial High Voltage GaN HEMTs

The effects of off-state stress time on dynamic on-resistance are investigated in a commercial 650 V GaN power device. A modified double pulse test (DPT) circuit is used to evaluate the dynamic on-resistance degradation with various stress value and time under hard-switching conditions. Our experimental results reveal partial recovery behaviors of dynamic on-resistance with stress voltage increasing. The dynamic on-resistance degradation gets more severe as stress voltage initially increases. Then the dynamic on-resistance reaches a peak value and begins to decrease as the stress voltage further increases. Furthermore, we find that the turning point of maximum dynamic on-resistance occurs at a lower stress voltage with longer stress time. It indicates that stress time is a very important factor affecting the degree of dynamic on-resistance degradation.