Steady-state and time-resolved photoluminescence measurements were made of N-doped p-type material at temperatures ranging from 33 to 210K. In samples with a low N content, the photoluminescence spectrum consisted of exciton-related peaks and a band-to-acceptor recombination peak (2.1s lifetime) with LO-phonon replica. An ionization energy of 0.0655eV was proposed for the N-related acceptor. A long-lived (18s) component, which consisted of an asymmetrical broad band that was centered around the acceptor peak, was also detected by means of time-resolved photoluminescence. Samples with a higher N content gave a photoluminescence spectrum that consisted mainly of an asymmetrical long-lived broad band that was attributed to a complex center. The asymmetrical shape of this band was quantitatively accounted for within the framework of the configuration coordinate model for complex centers.

C.Ferrer-Roca, A.Segura, M.V.Andrés, J.Pellicer, V.Muñoz: Physical Review B, 1997, 55[11], 6981-7