The low-temperature photoluminescence of single crystals exhibited 3 broad emission bands below 2.4eV. The temperature and excitation light-intensity dependences of these bands revealed that all of them originated from close donor-acceptor pair recombination. The temperature dependences of the peak energies of 2 bands in the visible range mirrored the band-gap energy shift. On the other hand, the temperature dependence of the peak energy of the third band in the near-infrared exhibited a complex behavior which involved blue-shifting at low temperatures, red-shifting at intermediate temperatures and another blue-shift close to room temperature. This could be explained only by a configuration coordinate model. A simple calculation indicated that the recombination centres were probably located at nearest-neighbour lattice or interstitial sites.

Donor-Acceptor Pair Recombination in Gallium Sulphide. A.Aydinli, N.M.Gasanly, K.Gökşen: Journal of Applied Physics, 2000, 88[12], 7144-9