Structural behaviour of ZnSxSe1−x films deposited by close-spaced evaporation

ZnSxSe1−x is considered to be one of the potential alternatives to CdS as a window and/or buffer layer in polycrystalline heterojunction solar cells. Thin films of ZnSxSe1−x with compositions x = 0.0, 0.25, 0.5, 0.75 and 1.0 have been prepared using close-spaced evaporation technique. The films were deposited at different substrate temperatures in the range 200–400 °C. The grown films have been characterized using X-ray diffractometer and scanning electron microscope (SEM) in order to determine the crystalline phases present and the surface topography. The X–ray diffraction data showed that the films deposited at substrate temperatures in the range of 275–325 °C were polycrystalline and showed only ZnSxSe1−x phase without any additional phases. These layers had the preferred orientation along the (1 1 1) direction and exhibited cubic structure. The variation of lattice constants with S/Se atomic ratio in the films followed the Vegardʹs law.