Optical properties and atomic force microscopy of cds thin films prepared by chemical bath deposition and chemical spray pyrolysis methods

Nanocrystalline CdS thin films have been prepared on glass substrates by chemical bath deposition (CBD) and Chemical Spray Pyrloysis (CSP) methods. The optical properties of the films were studied by measuring their optical transmittance and reflectance spectra in the wavelength range of 300-900 nm. The optical absorption studies reveal that the electronic transition is direct with band gap value of 2.42 (eV) and 2.55 (eV) for the films deposited by (CBD) and (CSP) respectively. Other important optical constants, such as extinction coefficient and refractive index were calculated and analyzed. The morphology of the prepared films was investigated by Atomic Force Microscopy (AFM) for different regions of the samples using sampling areas of 5 μm x 5 μm and 10 μm x 10 μm. The AFM analysis showed that the samples present well defined nanosized grains in the range of 100-286 nm. It is found that the thin film deposited by (CBD) method is more homogeneous than the film deposited by (CSP) method.