Annealing effect on structural and optical properties of diluted magnetic semiconducting $Zn_{1-x}Mn_xS$ nanostructured films

Nanostructured $Zn_{1-x}Mn_xS$ films $(0 \leq x \leq 0.25)$ were deposited on glass substrates by simple resistive thermal evaporation technique. All the films were deposited at 300 K and the films were annealed at 573 K for 2 h in a vacuum of $2 \times 10^{-6} mbar$. All the deposited films were characterized by chemical, structural, morphological, optical and photoluminescence studies. Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM) studies showed that all the films investigated were in nanocrystalline form with the particle size lying in the range 10-25 nm. All the films exhibited cubic structure and the lattice parameter varied linearly with composition. The $Zn_{1-x}Mn_xS$ films showed an absorption coefficient $> 10^4 cm^{-1}$ with the energy band gap 3.44-4.04 eV measured at room temperature. The nanostructured $Zn_{0.90}Mn_{0.10}S$ films exhibit high photoluminescence intensity at room temperature