Effect of the shape of the fundamental absorption edge on the shape of the green-luminescence spectrum of CdS crystals

The relation between the shape of the green-luminescence spectra and the absorption spectra at 77 K and also the dependence of the shape of the green-luminescence spectrum on the excitation intensity and the temperature in the range 77-4.2 K, were investigated in CdS crystals with different concentrations N-d of shallow uncompensated donors. It was shown that the increase in the intensity of the phonon replicas with respect to the intensity of the zero-phonon line with increasing N-d is due to the shift of the absorption edge into the region of longer wavelengths as a result of the effect of the fields of ionized shallow donors on the edge of the conduction band. (C) 1996 American Institute of Physics.