Influence of preparation parameters on physical properties of Bi2S3 films prepared by the spray pyrolysis method

Polycrystalline Bi,S, thin films of orthorhombic phase were prepared by a spray pyrolysis technique on an amorphous substrate. The influence of substrate temperature, T-s, in the range of 180-500 degreesC and solution molarity (0.05-0.4 mol) on the structural, electrical and optical properties were studied in detail. The crystal structure and orientation of the prepared films were investigated by X-ray diffraction pattern. The grain size of Bi2S3 was changed between 7.4 and 11.6 nm as the film thickness increased from 50 to 300 nm. Surface roughness, grain size and cross-section analysis were measured by the atomic force microscopy. A decrease in film thickness improves the transmission. This improvement can be attributed to the perfection and stoichiometry of the films. The optical band gap of the films decreased from 2.22 to 1.58 eV due to increasing the solution molarity (film thickness) from 50 to 300 nm. (C) 2001 Elsevier Science B.V. All rights reserved.