Growth and Cathofoluminescence of Zns:Mn Thin Films

Abstract

A novel technique of incorporating dopants in a thin film was designed. It was successfully used to dope ZnS thin films with Mn. Cathodoluminescent (CL) properties of these Mn activated ZnS films were studied. For a constant accelerating potential and beam current density, the CL emission intensity was found to increase with Mn content up to -2 wt% Mn. A further increase in the Mn content lead to a decrease in the CL intensity. The optimum Mn content is different than that for electroluminescence (-0.7 wt%) and photoluminescence (-1.6 wt%). Emission spectra of ZnS:Mn with a higher Mn content (> 1.64 wt%) show an additional red band besides the usual 580 nm yellow band. The relative intensity of the red band to the yellow band increases with the Mn content. The phenomenon of concentration quenching and the red emission seem to be interrelated; an attempt has been made to explain the physical basis behind these phenomena. Coverage of rough ceramic substrates by ZnS thin films deposited by vacuum evaporation and atomic layer epitaxy (ALE) has been investigated. The results suggest a uniform coverage in the case of ALE deposited films, while those deposited by vacuum evaporation show a shadowing effect.