The structure of radiative and non-radiative recombination centres in activated CdS phosphors

The intensity of photoluminescence (PL) emission bands in quenched CdS:Cu:Cl powder samples is measured and it turns out to be a power function of the concentrations of Cl, Nsub(Cl), and Cu, Nsub(Cu), in the material. The simplifications in which case the quasichemical theory of defect formation in solids gives such a simple dependence are clarified. The method to determine the structure of recombination centres in Asup(II)Bsup(VI) compounds, based on the comparison of experimental and theoretical graphs, is proposed. The method is used for clarifying the nature of r- and k-PL centres (lambdasub(max) = 1030 nm and lambdasub(max) = 780 nm, respectively) and s-centres of non-radiative recombination, and also predominant defects Cl and Cu in CdS:Cu:Cl. The r-, k-and s-centres may be identified with the following defects of crystal lattice of CdS:r-centre - (Cusub(Cd)Clsub(S)), k-centre -(Cusub(Cd))2; s-centre - (Cusub(Cd)Cusub(i))2 at Nsub(Cu) > Nsub(Cl) and Clsub(S) at Nsub(Cu) < Nsub(Cl). The latter two turned out to be predominant defects of Cu and Cl at corresponding relations of Nsub(Cu) and Nsub(Cl). (author)