Effect of nonstoichiometry on structural and optical properties of nanostructured Bi2S3 thin films prepared chemically at room temperature

A solution growth technique has been employed for the deposition of stoichiometric and non-stoichiometric Bi2S3 thin films from acidic bath on the ultrasonically cleaned glass substrate at room temperature, using sodium thiosulphate (Na2S2O3) as sulphide ion source. Ethylene diamine tetraacetic acid (EDTA) is used as a complexing agent to get quality films. The parameters such as pH of the solution, deposition rate and composition of elements have been optimized for obtaining quality films. The series of films are prepared by change in volume of sulphur precursor, keeping the volume of bismuth precursor constant. The values of band gap energy go on decreasing with increasing at% of sulphur (with decrease in at% of bismuth) in Bi2S3. The X-ray studies, chemical analysis and optical measurements of the film material were carried out and results are discussed.