Normally-off p-GaN Gated AlGaN/GaN HEMTs Using Plasma Oxidation Technique in Access Region

Normally-off p-GaN gated AlGaN/GaN high electron mobility transistors (HEMTs) were developed. Oxygen plasma treatment converted a low-resistive p-GaN layer in the access region to a high-resistive GaN (HR-GaN); that oxygen plasma treatment used an AlN layer as an oxygen diffusion barrier layer to prevent further oxidizing of the underlying AlGaN barrier layer, and to ensure that the low-resistive p-GaN layer in the access region was fully oxidized. Relative to conventional p-GaN gated AlGaN/GaN HEMTs, these AlGaN/GaN HEMTs with HR-GaN layers achieved a lower drain leakage current of 4.4 $\times 10^{-7}$ mA/mm, a higher drain current on/off ratio of 3.9 $\times 10^{9}$ , a lower on-state resistance of 17.1 ${\Omega }\cdot $ mm, and less current collapse.