Origin of blue luminescence in Mg-doped GaN

In this work, dual acceptor-bound exciton peaks are observed by low-temperature photoluminescence. The peaks correspond to the dual Mg-related acceptor levels in GaN based on the Haynes rule. By calibrating the energy-level structure, a mechanism for the origin of blue luminescence (BL) in Mg-doped GaN is proposed. The BL band is separated by thermal treatment at different temperatures, confirming the rationality of the dual-factor origin of the BL band. As the annealing temperature increases, the PL spectrum and the p-type conductivity of Mg-doped GaN also change. The experimental results indicate that there is not necessarily a relationship between the BL band and p-type conductivity in GaN grown by metalorganic chemical vapor deposition.