Investigation of Structural and Optical Properties of Nano Structured Zns Thin Films Prepared by Chemical Bath Deposition for Solar Cell Applications

Author(s): Hariharan Gajendiran, Shenbagavinayagamoorthi, Navneetha Krishnan, Kalaiselvan Palani , Ezhilkumar Krishnamoorthy

Abstract: Thin films of nano structured ZnS were grown on glass substrates by chemical bath deposition technique. The parameters such as time and solution concentration were varied and the optimum conditions were found. Deposition was carried out from an aqueous bath containing thiourea, Zinc Sulphate and ammonia after maintaining  the temperature and pH of the bath at constant values of 90° C and 10(base medium). The effects of deposition time on the structural and optical properties of the grown ZnS thin films were determined. The structural and Optical properties of the formed thin films were investigated by the images obtained from Scanning Electron Microscope, Atomic Force Microscope, UV-Vis Spectrophotometer and four point probe measurement. The images obtained from Scanning Electron Microscope showed that the nano particle were in the range of 129nm to 161nm for 3M concentration and 155nm to 177nm for 4M concentration of solution .The Atomic Force Microscope images showed the smooth deposition for 90min deposition time and 3M concentration compared to 4M concentration. UV-Vis Spectrophotometry measurements in the wavelength range of (300 -700nm) indicates the transparency of around 92% to 96%.The absorption coefficient was obtained as a function of photon energy and the ZnS band gap value was determined in the range of 3.64eV – 3.96eV.The deposition time and solution concentration were optimized for chemical bath deposition and the best deposition of ZnS nano thin films were obtained which can be used for solar cell applications.