Influence of trivalent (Bi, Sb) metal ions on the photosensitivity of doped Cu2Se thin films

In this work pure and trivalent (Bi and Sb) ions doped copper selenide (Cu2Se) thin films were prepared by chemical bath deposition. The effect of structural, morphological and optical properties of trivalent doped Cu2Se thin films were analyzed by X-ray diffraction (XRD) patterns, scanning electron microscope (SEM), diffuse reflectance spectroscopy technique. XRD analysis shows the formation of cubic structure of Cu2Se thin film and the trivalent doping slightly suppress the intensity of the polycrystalline peaks with shift in the major peak position. SEM images shows well defined spherical grains population are more over the surface. The homogeneous Cu2Se films formation is witnessed by field emission SEM and transmission electron microscopy analysis. The pure and Bi doped Cu2Se thin films show higher absorption in the visible region than the Sb doped Cu2Se thin films. The band gap is found to be in the range of 1.70-2.33 eV. The Bi doped films shows higher photo sensitivity.