Impact of Vth shift on Ron in E/D-mode GaN-on-Si power transistors: Role of dynamic stress and gate overdrive

In this work, we revealed the impacts of Vth shift on Ron in enhancement-/depletion-mode (E/D-mode) GaN transistors under dynamic AC (1 k-1 MHz) stress. With newly developed fast dynamic characterization techniques, we achieved data acquisition within 120 ns after each stress pulse throughout the entire stress time ranging from 10−7 s up to 103 s. Vth shift and the consequent Ron increase under dynamic stress, which are more relevant to high-frequency switching operation, exhibits frequency dependence and is smaller than that under conventionally used static stress. Furthermore, distinctive Ron's susceptibilities to Vth shift between E-mode and D-mode GaN transistors are revealed and analyzed. The correlation between Vth shift and Ron facilitates the assessment on how much Vth shift a GaN power switch can tolerate.