Enhancement-Mode Gate-Recess-Free GaN-Based p-Channel Heterojunction Field-Effect Transistor With Ultra-Low Subthreshold Swing

We report enhancement-mode p-channel heterojunction field-effect transistors (HFETs) without gate recess on a standard p-GaN/AlGaN/GaN high electron mobility transistor (HEMT) platform. The p-GaN in the gate region was partially passivated by a low-power hydrogen plasma treatment process, and the remaining active p-GaN and the underlying AlGaN formed the p-channel. The device showed a record low off-state leakage of <; 10 ^-8 A/mm and subthreshold swing (SS) of 123.0 mV/dec with a threshold voltage ( V _th ) of -0.6 V and high-temperature stability up to 200 °C. These results indicate that the hydrogen plasma treatment is beneficial for suppressing leakages and preserving excellent material quality in the p-channel. With the success of the p-HFETs, the p-GaN/AlGaN/GaN platform can enable the monolithic integration of GaN n- and p-channel transistors without the need for regrowth. This work represents a significant step towards the implementation of the GaN CMOS technology.