EPR investigations on ZnS: Mn thin films prepared by hot wall technique

Abstract

Electron paramagnetic resonance (EPR) spectra of ZnS:Mn thin films deposited on a glass substrate by hot wall (HW) technique have been examined in connexion with their photoluminescence. In the EPR spectra, which are typical for polycrystalline ZnS:Mn with cubic structure, marked decrease in the peak-to-peak linewidths of respective hyperfine lines is observed as is the thickness of ZnS:Mn film increased until 0.5 μm, suggesting that there is a large distortion of the crystal field surrounding manganese (II) at the thickness below 0.5 μm. With respect to the manganese concentration, the formation of manganese clusters which have magnetic exchange interaction among them is supported by the fact that the relative intensity of the resonance with hyperfine lines to the broad one without hyperfine structure decreases with the total manganese (II) concentration in the ZnS film. Also, variation of the linewidths of both resonances implies that the dipole-dipole and exchange interactions among manganese (II) ions increase until the total manganese (II) concentration approaches 1.5mol%. It is therefore reasonalble that quenching of the photoluminescence reveals at the manganese concentration.