Effects of Mg fluctuation on the electrical and optical properties in p‐GaN/undoped GaN layers dependent on the growth temperature

Abstract

The effects of heavly Mg doping dependent on the growth temperature of p-GaN layers grown on undoped GaN layers by metalorganic chemical vapor deposition (MOCVD) on electrical and optical properties were studied by capacitance–voltage (C–V) and temperature-dependent photoluminescence (TDPL), respectively. At high growth temperature of p-GaN above 1110 °C, optical microscopy images as well as atomic force microscopy (AFM) images show polygonal hillocks on heavily Mg-doped GaN surface. It was also found that fluctuation of Mg concentration ([Mg]) measured by secondary ion mass spectroscopy (SIMS) was increased with increasing growth temperature. These phenomena were appeared to decrease NA–ND and change PL emission from 3.1–3.2 eV of conduction band-to-shallow Mg acceptor (e, A) transition to 2.8–2.9 eV of Mg-related deep donor-to-acceptor pair (DAP) transition.