Density functional studies of defects and defect-related luminescence in M g3 N2

Mg3N2 is a promising material for light-emitting-diode applications. However, the microscopic origin of the broad yellow photoluminescence in Mg3N2 remains unknown. Here, defect properties and defect-related optical transitions are investigated based on the hybrid functional calculation. Our results show that the nitrogen vacancy introduces multiple localized defect states within the band gap, which play a dominant role in luminescent properties of Mg3N2. Common impurities like hydrogen, oxygen, and carbon and their complexes with native defects are also studied. Compared with isolated VMg, VMg-H and VMg-ON complexes have shallower transition levels. Our calculated optical excitation and emission peaks associated with isolated VN are in good agreement with those observed in experiments. In addition, the impurity CN is also a potential source for the observed yellow emission in Mg3N2.