Structural, electrical and optical studies of SILAR deposited cadmium oxide thin films: Annealing effect

Successive ionic layer adsorption and reaction (SILAR) method has been successfully employed for the deposition of cadmium oxide (CdO) thin films. The films were annealed at 623 K for 2 h in an air and changes in the structural, electrical and optical properties were studied. From the X-ray diffraction patterns, it was found that after annealing, H2O vapors from as-deposited Cd(O2)0.88(OH)0.24 were removed and pure cubic cadmium oxide was obtained. The as-deposited film consists of nanocrystalline grains of average diameter about 20–30 nm with uniform coverage of the substrate surface, whereas for the annealed film randomly oriented morphology with slight increase in the crystallite size has been observed. The electrical resistivity showed the semiconducting nature with room temperature electrical resistivity decreased from 10−2 to 10−3 Ω cm after annealing. The decrease in the band gap energy from 3.3 to 2.7 eV was observed after the annealing.