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 Vegard's law.