Photoluminescence data, due to recombination at discrete donor-acceptor pairs in epitaxial N-implanted (1013/cm2) layers, were presented. The experimental data were explained with the aid of a theoretical calculation, of a type-II spectrum, which involved the substitution of In donors for Zn and of N acceptors for Se. Two-hole transitions which involved up to 6S3/2 states of the N acceptor were also reported. The experimental values of these excited states were in good agreement with those which were obtained by using an effective-mass calculation. A sharp line which was superposed upon the broad donor-acceptor pair band, and whose peak position had a constant separation from the excitation energy, was also reported. This separation was about 0.0009eV larger than the 1S-2S energy spacing for the N acceptor. It was shown that this line might be due either to resonant inelastic scattering of the exciting photons by acceptor impurities, or to the selective excitation of discrete donor-acceptor pairs.

K.Shahzad, B.A.Khan, D.J.Olego, D.A.Cammack: Physical Review B, 1990, 42[17], 11240-4