p‐GaN Selective Nitridation to Obtain a Normally Off p‐GaN Gate AlGaN/GaN High‐Electron‐Mobility Transistors

In this article, a method of nitrogen plasma treatment is proposed to achieve normally off p‐GaN/AlGaN/GaN high‐electron‐mobility transistors, and the related mechanism is proposed. A nitrogen plasma treatment is employed to deplete holes in the p‐GaN layer to change the surface characteristics. The transition of the p‐GaN layer from p‐type to n‐type results in the formation of the 2D electron gas at the AlGaN/GaN interface. The X‐ray photoelectron spectroscopy (XPS) testing and the fitting of mechanism for reverse gate leakage current both imply that the nitrogen plasma treatment has a beneficial effect on the surface condition. The device exhibits enhanced performance, with threshold voltage of 1.1 V, on/off ratio of 1 × 109, maximum drain current of 245 mA mm−1, and breakdown voltage of 1215 V.