Influence of substrate temperature on copper bismuth sulfide thin films deposited by electron beam evaporation method

Electron beam evaporated copper bismuth sulfide thin films were deposited on the glass substrates at 200, 300, 400 and 500 °C. Substrate temperature of 300 and 400 °C formed single phase Cu₄Bi₄S₉ and Cu₄Bi₉S₁₀ films respectively whereas substrate temperature of 500 °C formed mixed phases of Cu₄Bi₄S₉ and Cu₄Bi₉S₁₀ film. Surface morphology of the film deposited at 400 °C was examined by scanning electron microscopy which showed the distribution of homogeneous spherical particles on the film surface. Energy dispersive spectra recorded for these films confirmed the presence of copper, bismuth and sulfur elements in the films. The direct optical band gap energy of the films deposited at different temperature showed variation from 1.47 to 1.64 eV and the absorption coefficient in the order of 10⁶ cm^-1. (author)