Effects of Mg-doping temperature on the structural and electrical properties of nonpolar a-plane p-type GaN films

Abstract

Nonpolar (11-20) a-plane p-type GaN films were successfully grown on r-plane sapphire substrate with metal organic chemical vapor deposition (MOCVD) system. The effects of Mg-doping temperature on the structural and electrical properties of nonpolar p-type GaN film are investigated in detail. It is found that all the surface morphology, crystalline quality, strains, and electrical properties of nonpolar a-plane p-type GaN films are interconnected, and are closely related to the Mg-doping temperature. This means that a proper performance of nonpolar p-type GaN can be expected by optimizing the Mg-doping temperature. In fact, a hole concentration of 1.3×1018 cm-3, a high Mg activation efficiency of 6.5 %, an activation energy of 114 meV for Mg acceptor, and a low anisotropy of 8.3 % in crystalline quality were achieved with a growth temperature of 990 ℃. This approach to optimize the Mg-doping temperature of the nonpolar a-plane p-type GaN film provides an effective way to fabricate high-efficiency optoelectronic devices in the future.