Recombination Processes in Cadmium Sulfide

An experimental study has been carried out on the photoconductivity and luminescence of cadmium sulfide. The two main properties investigated were the photoconductive spectral response, and the relationship between luminescence and photoconductivity. It is found that the observed spectral response can be explained in terms of the dependence of lifetime of conduction electrons on the wavelength of exciting light. The rise and decay of photoconductivity and luminescence have been examined for silver-activated CdS, and for the red and green luminescence of unactivated CdS. It is found that the decay of luminescence is much more rapid than the decay of photoconductivity. An explanation for this behavior is offered, based on the assumption that the luminescence results from the recombination of localized electrons and free holes.