The effect of group-I impurities (Li, Na, Cu, Ag), upon the properties of films that had been prepared by means of chemical spray pyrolysis, were investigated. It was shown that the appearance of a photoconductivity band with a maximum at 550nm and a green emission band (510 to 540nm) were associated with the same centers: negatively charged Cd vacancies. An increase in the intensities of these bands after diffusion doping with Li and Na ions, and a decrease after the introduction of Cu and Ag ions, was attributed to the donor-acceptor interaction of diffused group-I impurities with charged Cd vacancies. The absence of a photoconductivity maximum (550nm) and of a green emission in material that had been doped with Na impurity during deposition was attributed to the precipitation of Na (as well as Cu) within the inter-grain spaces of the films.

H.Bidadi, M.Kalafi, H.Tajalli, A.I.Bairmov, T.D.Dzhafarov: Optical Materials, 1996, 6[1-2], 27-33