High-performance enhancement-mode p-channel GaN MISFETs with steep subthreshold swing

We report an enhancement-mode (E-mode) p -channel GaN heterojunction field-effect transistor with a metal-insulator-semiconductor gate structure. A 60 mV/dec subthreshold swing is experimentally achieved in the E-mode GaN p -channel transistors on an unintentionally doped GaN interlayer for the first time by using a low-power plasma gate recessing etch and gate dielectric deposition pre-treatment. The fabricated p -channel transistors exhibit excellent E-mode performance with a threshold voltage of −1.53 V, an effective on-resistance of 1.0 kΩ .mm, a peak transconductance of 1.0 mS/mm, and a high ION/IOFF ratio > 10^7 . Bi-directional gate sweep measurements on the p-channel devices show a threshold voltage shift of 0.12 V and an increased subthreshold swing of 107 mV/dec. In addition, the dual-channel conduction mechanism in the p -channel GaN transistors is presented and discussed.