Structural, electrical and optical properties of copper selenide thin films deposited by chemical bath deposition technique

A low cost chemical bath deposition (CBD) technique has been used for the preparation of Cu^sub 2-x^Se thin films on glass substrates. Structural, electrical and optical properties of these films were investigated. X-ray diffraction (XRD) study of the Cu^sub 2-x^Se films annealed at 523 K suggests a cubic structure with a lattice constant of 5.697 Å. Chemical composition was investigated by X-ray photoelectron spectroscopy (XPS). It reveals that absorbed oxygen in the film decreases remarkably on annealing above 423 K. The Cu/Se ratio was observed to be the same in as-deposited and annealed films. Both as-deposited and annealed films show very low resistivity in the range of (0.04-0.15) × 10^sup -5^ Ω-m. Transmittance and Reflectance were found in the range of 5-50% and 2-20% respectively. Optical absorption of the films results from free carrier absorption in the near infrared region with absorption coefficient of 10^sup 8^ m^sup -1^. The band gap for direct transition, E^sub g.dir^ varies in the range of 2.0-2.3 eV and that for indirect transition E^sub g.indir^ is in the range of 1.25-1.5 eV.[PUBLICATION ABSTRACT]