A highly efficient method to fabricate normally-off AlGaN/GaN HEMTs with low gate leakage via Mg diffusion

Abstract

A method to achieve p-type doping gate by Mg diffusion is proposed to fabricate normally-off AlGaN/GaN high electron mobility transistors (HEMTs). The fabrication is completed via first slight etching to introduce defects into the gate region and then rapid annealing to diffuse Mg ions into the AlGaN barrier, thereby forming a p-type doping layer and positively shifted threshold voltage. In addition, the MgO layer formed by thermal oxidation could effectively passivate the surface traps that were caused in the previous etching procedure. The as-fabricated HEMTs demonstrate a low gate leakage of 2 × 10-7mA/mm and a VTH of 1.4 V. This technique offers a simplified and highly effective method to fabricate high performance GaN power devices.