The blue Mg-induced 2.8eV photoluminescence band in metal-organic chemical vapor deposited material was studied in samples having various Mg contents. It appeared near to a Mg concentration of 1019/cm3 and, at higher concentrations, dominated the room-temperature photoluminescence spectrum. The excitation power dependence of the 2.8eV band confirmed its donor-acceptor pair recombination nature. It was suggested that the acceptor was isolated MgGa, while the spatially separated deep donor (0.43eV) was attributed to a nearest-neighbor associate of a MgGa acceptor with a N vacancy; formed by self-compensation.

U.Kaufmann, M.Kunzer, M.Maier, H.Obloh, A.Ramakrishnan, B.Santic, P.Schlotter: Applied Physics Letters, 1998, 72[11], 1326-8