Study of Composition and Optical Properties of Chemically Deposited Pd-xSb2S3 Thin Films

The study reports on the effects of different concentration of palladium impurities on the compositional and optical properties of Palladium Doped Antimony Sulphide (Pd-xSb2S3) thin films grown by the chemical bath deposition method. The films were grown at room temperature and other deposition conditions such as the bath temperature, pH, complexing agents were kept constant. The concentration of the dopants were varied between 0.1 M to 0.3 M. The films were annealed at an annealing temperature of 200  oC  for 1 hour. The films were characterised using the Rutherford Back Scattering (RBS) techniques and optical spectroscopy (transmittance versus wavelength, absorbance versus wavelength) to investigate the composition, and optical constants (optical absorption coefficient, energy band gap, and extinction coefficient) respectively. X-ray diffractometry and Scanning electron microscopy were also used to investigate the structural and morphological properties of the layers. The results show that the transmittances of the doped layers were higher compared to the as-deposited layers. The energy band gap was direct, and were found to be decreased for the doped layers, compared to the as-grown films. The values of the energy band gap were typically ≤ 2.30 eV for the former and 2.48 eV for the latter. These values strongly suggest the use of these films in optoelectronic applications especially in solar cell devices.