Thermodynamics and Kinetics of Three Mg-H-VN Complexes in Mg:GaN from Combined First-Principles Calculation and Experiment

An understanding of the formation and dissociation process of Mg-H defects in GaN is of paramount importance for high efficient GaN-based solid-state lighting. Through a combination of first-principle calculations and experimental observations, we find the existence of three types of Mg related centers forming different Mg-H-V-N complexes in Mg:GaN. Our study shows that the three different arrangements, which differ by the relative position of the H, determine the degree of acceptor passivation by changing their charge state from +3 to +1. The energetic study demonstrates that the relative stability of the defect complexes can vary with the location of the Fermi level, as well as thermal annealing and electron beam irradiation. The inclusion of a V-N is shown to produce an additional variance in optical spectra associated with Mg acceptor activation, resulting from changes in the defect configurations and charge states. Our study shows that these three Mg-H-V-N complexes are key components for understanding the Mg acceptor activation and passivation processes.