Buffer trapping-induced RON degradation in GaN-on-Si power transistors: Role of electron injection from Si substrate

Buffer traps in GaN-on-Si power devices can interact with electrons injected from Si substrate at high-voltage OFF state, leading to buffer-related dynamic ON-resistance degradation. In this work, we performed transient back-gating measurements on GaN-on-Si power transistors under both high negative and positive substrate biases. The opposite top-to-substrate bias polarities not only yield asymmetric vertical leakage, but also induce distinct buffer-trapping due to the fundamentally different electron injection mechanisms. The injected electrons interact with acceptor and donor traps in the buffer layer, which can impose modulation to the 2DEG channel. It is suggested that suppressing electron injection from Si substrate can possibly enhance devices' dynamic performance and blocking capability.