Threshold voltage drift (PBTI) in GaN D-MODE MISHEMTs: Characterization of fast trapping components

V_TH drift of GaN MISHEMTs under positive gate stress (PBTI) is shown to have a distinct fast component, independent of the gate dielectric material or details of the device architecture. The trap(s) responsible for this V_TH degradation component are located at the GaN side of the GaN/dielectric interface. Since these fast traps have capture- and emission -times of the order of 10μs and 1ms respectively, its impact is not evident in the traditional DC characterization, yet it severely impacts device lifetime projections.