Optical characterization of doped and undoped ZnS nano particles

The study of nano crystalline semi-conductor thin films received much attention due to various application in opto-electronic and semi-conductor devices. Thin films of ZnS nano-crystals were grown into poly-vinyl alcohol matrix by chemical methods at different pH and volume ratio. A studies on the properties of un-doped and doped (with Mn) ZnS nano-crystalline films were done. The nano structure was characterized with the help of X-ray diffraction (XRD) and Hi- resolution Transmission Electron Microscopy (HRTEM). Surface morphology was studied with the help of Scanning Electron Microscopy (SEM). Particle size was found to be 30 - 40 nm. Optical absorption studies were carried out with UV-VIS Spectrophotometer and showed a strong absorbance at wavelength 297.2 nm with a tendency towards blue shift. Peak of Photo-luminescence (PL) emission spectra was obtained at 346 nm at room temperature. Due to ageing of ZnS thin film, the formation of ZnO crystals were observed. The role of oxygen on the ageing of the films and deficiency of sulphur were studied by X-ray Fluorescence (XRF) method.