Point defect luminescence associated with stacking faults in magnesium doped zincblende GaN

The luminescence characteristics and the relation between the distribution of impurities and stacking faults (SFs) in Mg-doped zincblende gallium nitride (zb-GaN:Mg) have been investigated by cathodoluminescence (CL) and atom probe tomography (APT). Four peaks have been identified in the CL emission spectrum, and the possible related recombination mechanisms have been proposed. The main peak at 3.23 eV is associated with excitonic transitions, while the other three, having lower energies at about 3.15, 3.02, and 2.92 eV, respectively, are related to donor-to-acceptor (DAP) transitions involving different acceptor energy levels. These DAP peaks were significantly more intense on or close to SFs compared to the surrounding defect-free material, indicating an enrichment of point defects near SFs. This finding was supported by APT measurements, where Mg showed a tendency to segregate toward SFs in zb-GaN.