The Effect of Zinc Concentration on the Structural, Morphological and Optical Properties of CdS: Zn Nanocrystalline Prepared by Chemical Bath Deposition

Abstract

Undoped Cadmium sulfide (CdS) nanocrystalline thin film and doped Zinc are prepared by chemical bath deposition (CBD) technique. The characterization of the product was done by UV-VIS absorption, x-ray diffraction (XRD) and atomic force microscopy (AFM). The effect of zinc content on structural, morphological and several optical properties have been studied. The X-ray diffraction (XRD) analysis revealed that the films were polycrystalline and exhibited two phases cubic and hexagonal structure which increases the cubic phase and Zn ratio. Atomic force microscopy images show uniform, homogeneous and strong adherent to Undoped (CdS) nanocrystalline and doped Zinc over the entire glass substrate surface without any voids, pinholes or cracks. This reveals a continuous granular morphology for the films and therefore the average grain size changes which increase the zinc content and the band gap of the thin films which are found to be direct allowed transition. The optical characterizations of the as deposited and annealed films were carried out using UV. VIS transmittance spectroscopy in the wavelength range 300.1100 nm. The results show that in the visible region the transmittance of the films decreases as the containing of Zn increases. The reverse is the case with the absorbance as it was observed to be increased in the same region. The result also shows that the absorption coefficient, extinction coefficient, real and imaginary parts of dielectric constant are tending to increase with the increasing of Zn concentration.