Resonant excitation of infra-red emission in GaN:(Mn,Mg)

By combining experimental photoluminescence excitation spectroscopy and calculations based on density functional theory and many-body Green's functions, the most efficient excitation channels of infra-red (IR) emission from Mn-Mg$_{k}$ paramagnetic complexes stabilized in GaN:(Mn,Mg) are here identified. Moreover, a Tanabe-Sugano energy diagram for 3$d^{2}$Mn$ ^{5+}$ is reconstructed and Mn-Mg$_{3}$ are singled out as the predominant configurations responsible for the IR emission. The correlation of intensity of the individual emission lines as a function of temperature and excitation energy, allows assigning them to well defined and specific optical transitions.