Effect of Mn concentration on the cathodo- and photoluminescence of ZnS:Mn

A novel method of calibrated doping of Mn in ZnS thin films has been used to study room-temperature cathodo- and photoluminescence characteristics of ZnS:Mn films for a Mn concentration range of 0.07–26.4 wt. %. It was observed that the luminescent intensity increases with Mn concentration up to ∼2 wt. %, beyond which intensity decreases. Emission spectra revealed a lower energy peak in addition to the 580-nm yellow peak for higher dopant concentration. The occurrence of this red peak and quenching of yellow emission is probably at approximately the same activator concentration (∼2 wt. %). We attribute these to the phenomenon of energy transfer to energy sinks via unexcited Mn.