Ho Soon Min

INFLUENCE OF BATH TEMPERATURE AND PH VALUE ON PROPERTIES OF CHEMICALLY DEPOSITED CU4SNS4 THIN FILMS

Thin films of Cu4SnS4 semiconductors were prepared by chemical bath deposition technique in aqueous solutions. The effects of various bath temperatures (40, 50 and 60 °C) and pH values (pH 0.5, pH 1.0 and pH 1.5) on growth of films were reported. The structure and morphology characteristics of thin films of Cu4SnS4 grown on indium tin oxide glass substrates were investigated by X-ray diffraction and atomic force microscopy techniques. The optical properties were measured to determine the transition type and band gap value. The thin films produced were found to be polycrystalline with orthorhombic structure. The X-ray diffraction data showed that the most intense peak at 20 = 30.2° which belongs to (221) plate of Cu4SnS4. The films deposited at 50 °C were found to have the best photoresponse activity and smaller crystal size. At pH 1.5, the film showed well-covered entire substrate surface and the highest absorption values in AFM and optical study, respectively. The best condition to prepare good quality thin films can be carried out at 50 °C with pH 1.5. The bandgap value was found to be 1.4 eV with direct transition.

UV-VISIBLE STUDIES OF CHEMICAL BATH DEPOSITED NISE THIN FILMS

NiSe thin films were deposited onto microscope glass slides by chemical bath deposition method. Chemical bath deposition method could be a cost-effective technology for the production of terrestrial photoelectrochemical cells. The films obtained were characterized by UV-Visible spectrophotometer. The values of optical band gap have been determined from the absorption spectra. The deposition was carried out under different deposition times (1, 2 and 3 hours) and bath temperatures(40 and 50 °C). Based on the optical absorbance spectra, all the films exhibited a high absorbance in the visible region. The films deposited at longer time showed higher absorbance values. The band gap values obtained were found to be 2.11-2.52 eV.

CATHODIC ELECTRODEPOSITION OF Cu 4 SnS 4 THIN FILMS FROM ACIDIC SOLUTION

In this work the synthesis of copper tin sulfide thin films by electrodeposition is carried out. The films were deposited onto ITO glass substrates from an aqueous solution bath containing copper sulfate, tin chloride and sodium thiosulfate at pH 1 and room temperature. Prior to the deposition, a cyclic voltammetry experiment was carried out between two potential limits (+1000 to -1000 mV versus Ag/AgCl) to probe the effect of the applied potential and to determine the most likely suitable electrodeposition potential for the deposition of copper tin sulfide. The deposition was attempted at various cathodic potentials such as -400, -600, -800, -1000 mV to determine the optimum deposition potential. The films have been characterized by techniques such as optical absorption, Xray diffraction and atomic force microscopy. The XRD patterns show that the films are polycrystalline with orthorhombic structure. The AFM studies reveal the electrodeposited films were smooth, compact and uniform at deposition potentials of –600 mV versus Ag/AgCl. The direct optical band-gap energy was obtained to be 1.58 eV.