E-mode p-FET-bridge HEMT: Toward high VTH, low reverse-conduction loss and enhanced stability

A novel p-GaN gate topology is proposed to simultaneously achieve high threshold voltage (V TH ), low reverse-conduction loss, and enhanced V TH stability in E-mode p-GaN gate HEMT. The proposed gate structure consists of a conventional Schottky-type p-GaN gate and a normally-on p-FET bridge connecting source and gate. By modulating the V TH of the p-FET, a wide-range positive V TH can be achieved without suffering subthreshold voltage degradation. Owing to the well-grounded p-GaN through the normally-on p-channel, "floating p-GaN layer" is eliminated, and stable V TH can be achieved. In addition, the normally-on p-FET bridge can intrinsically decouple the reverse-conduction turn-on voltage (V RT ) from the forward threshold voltage (V TH ) without any area sacrifice, which enables separate engineering of V RT and V TH so that low-loss reverse conduction and high threshold voltage can be simultaneously realized.