UV-VISIBLE STUDIES OF CHEMICAL BATH DEPOSITED NISE THIN FILMS

Abstract

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. Key words-chemical bath deposition, nickel selenide, thin films, UV-visible spectrophotometer, metal chalcogenide. Introduction Metal chalcogenides and their mixtures are attractive and useful system for solar energy conversion studies by photoelectrochemical means. Two important factors that should be considered in producing these materials are the band gap energy matching the solar spectrum and the competitiveness of production cost. The rationale for this is that thin films modules are expected to be cheaper to manufacture owing to their reduced material costs, energy costs, handling costs and capital costs. Nickel selenide is a semiconductor which is suitable for applications in solar cells, sensor and laser materials. Films of nickel selenide have previously been prepared by thermal evaporation and chemical bath deposition. Among various other methods, the chemical bath deposition method is found to be a cheap and simple way to deposit metal chalcogenide thin films such as CuS [1], CdS [2], SnS2 [3], CdSe [4], In2S3 [5], ZnS [6], Sb2S3 [7], PbSe [8], CuInSe2 [9], SbCuS [10], Pb1-xFexS [11],and CuInS2 [12] The properties of materials prepared by the chemical bath deposition method are critically dependent on various preparative parameters such as the pH of the solution, deposition time, bath temperature, complexing agent, concentration of metal and chalcogenide ions. The present studies are focused on the deposition of NiSe thin films using the chemical bath deposition method. We have demonstrated for the first time to deposit NiSe thin films using Na2EDTA as complexing agent. The depositions were carried out under different deposition times (1, 2 and 3 hours) and bath temperatures (40 and 50 °C). The films were characterized by UV-Visible spectrophotometer. The values of optical band gap have been determined from the absorption spectra.