The origin of the red luminescence in Mg-doped GaN

TL;DR

This study investigates the origin of red luminescence in Mg-doped GaN using ODMR and PAS, revealing vacancy-related defects as the cause of the 1.8 eV emission through correlation with vacancy concentrations.

Contribution

It provides new experimental evidence linking vacancy-related defects to red luminescence in Mg-doped GaN, clarifying the emission mechanism.

Findings

Red photoluminescence correlates with vacancy concentrations.

Deep centers involved in recombination are vacancy-related.

Emission involves electrons from both effective mass and deeper donors.

Abstract

Optically-detected magnetic resonance (ODMR) and positron annihilation spectroscopy (PAS) experiments have been employed to study magnesium-doped GaN layers grown by metal-organic vapor phase epitaxy. As the Mg doping level is changed, the combined experiments reveal a strong correlation between the vacancy concentrations and the intensity of the red photoluminescence band at 1.8 eV. The analysis provides strong evidence that the emission is due to recombination in which electrons both from effective mass donors and from deeper donors recombine with deep centers, the deep centers being vacancy-related defects.