The effects of phosphorus implantation on the activation of magnesium doped in GaN at different dopant concentration ratios have been systematically investigated. Hall effect measurements show that P implantation improves the hole concentration, and that this improvement is dependent on P/Mg dopant concentration ratio and annealing conditions. This phenomenon is attributable to the reduction in self-compensation that results from the formation of deep donors and the enhanced Mg atom activation, which is in reasonable agreement with the optical properties observed by photoluminescence measurements. In addition, a new photoluminescence peak resulting from P-related transitions is also observed, evidently owing to the recombination of electrons from the shallow native donors with holes previously captured by isoelectronic P traps.
