Temperature dependence of luminescence from ZnS0.11Se0.89 random and ordered alloys

Temperature dependence of the luminescence spectra was investigated for a ZnS0.11Se0.89 random alloy and a (ZnSe)1/(ZnS0.22Se0.78)1 ordered alloy with equivalent mean sulfur compositions. The luminescence peak for the random alloy as a function of temperature shows anomalous behavior, while that for the ordered alloy exhibits normal behavior. From the temperature dependence of luminescence intensity for the random alloy, the quenching process can be understood with additional thermal activation energy besides exciton dissociation energy. Through the analysis of the temperature variation of the luminescence line width, the exciton–optical phonon coupling constant is found to be reduced in the random alloy. The results of this study demonstrate that exciton is localized by the potential fluctuation in the random alloy and that the potential fluctuation is significantly constrained in the ordered alloy.