The structural, optical and electrical properties of the films at different doping concentrations of 0, 2, 4, and 6 % have been investigated using chemical bath deposition technique. Cadmium acetate di-hydrate was used as precursor for preparation of the CdO thin films and Tin (II) chloride was employed as a tin source. The XRD patterns revealed a polycrystalline having the characteristic peaks of cubic structure. Transmittance of the CdO films increases with increasing Sn dopant in the films, and the maximum transmittance of 84% was seen at 4% doping concentration. The above observation was confirmed by AFM study which depicts uniform and homogeneous, thin films at 2 and 4 % at Sn doping concentrations. The average bandgap energy of tin oxide was 2.30eV and this value is bigger than that of pure CdO 2.22eV. This implies that the tin doping can be used as a regulator of the bandgap of CdO films. Hall mobility, carrier density of Sn: CdO films show variation with Sn: CdO doping concentration such that carrier concentration and mobility show the maximum at 4% doping concentration. The films grown at 4% in this work is a promising candidate for solar cell applications.
Keywords: Cadmium oxide, tin, electrical, transmittance, optical band gap.