The effect of annealing on vacuum-evaporated copper selenide and indium telluride thin films

Copper selenide and indium telluride thin films were prepared by a vacuum evaporation technique. The as-deposited films were annealed in a vacuum at different temperatures and the influence on composition, structure and optical properties of copper selenide and indium telluride films was investigated using energy dispersive X-ray analysis, X-ray diffraction, scanning electron microscopy and optical transmission measurements. From the compositional analysis, the as-deposited copper selenide and indium telluride films which were annealed at 473 and 523 K, respectively, were found to possess the nearly stoichiometric composition of CuSe and InTe phases. However, the films annealed at 673 K showed the composition of Cu2Se and In4Te3 phases. The structural parameters such as, particle size and strain were determined using X-ray diffractograms of the films. Optical transmittance measurements indicated the existence of direct and indirect transitions in copper selenide films and an indirect allowed transition in indium telluride films.