Saturation of the cathodoluminescence associated with isoelectronic Te impurity in GdS1-xTex and ZnS1-xTex(x≤0.05) at high excitation levels

Saturation of the cathodoluminescence of CdS1-xTex and ZnS1-xTex (x≤0.05) monocrystals associated with annihilation of excitons localized on isoelectronic impurity, the current density of j electron beam being high, is investigated. At x>5x10-4 the js current density at which radiation efficiency begins to decrease is independent on tellurium concentration, is approximately one-sixth as much in CdS1-xTex as compared to ZnS1-xTex and corresponds to excited level at which average distance between localized excitons is compared to the size of localization region. By increase of j with j>js, emissive power is varied as j1/2, characteristic luminescent time is reduced and emission spectrum is not significantly changed. The results obtained are explained in frames of simple model accounting nonradiating Auger recombination of localized excitons