Electron-paramagnetic-resonance study of the Mn²⁺ luminescence center in ZnS:Mn powder and thin films

The number of isolated Mn²⁺ ions and Mn²⁺ clusters in ZnS:Mn powder and thin films has been studied using Mn²⁺ spectra measured at room temperature with an X-band electron-paramagnetic-resonance spectrometer. While the concentration of the isolated Mn²⁺ ions decreases with increasing Mn concentration, the concentration of the clusters increases. At low Mn concentration, the Mn²⁺ ion substitutes for the Zn ion in ZnS:Mn in the cubic phase. At high Mn concentrations, where the ZnS powder has a dominant hexagonal phase, the Mn ion still prefers to substitute for Zn in ZnS:Mn at the cubic site rather than at the hexagonal site.