Optical and Electrical Properties of Chemically Deposited ZnO Thin Films.

Good homogenous ZnO thin film was prepared by the chemical bath deposition (CBD) technique using aqueous solution of zinc sulphate (ZnSO4) as a starting material and triethanolamine (TEA) was employed as a complexing agent. The film was characterized for optical and electrical properties. From the results obtained, the film was found to have high transmittance in the wavelength range of 400-1100nm and low transmittance near fundamental absorption. The absorbance of the ZnO film was found to be low in the VIS/NIR regions and high in the UV region. The extinction coefficient of the film suggests that, there is absorption of light at the grain boundary. The X-ray diffraction (XRD) analysis of the film reveals that the ZnO film has hexagonal structure with orientation of C–axis. The Scanning Electron Microscope (SEM) micrograph of the ZnO film illustrates the formation of such-micrometer crystallites over the surface with holes indicating large porosity and agglomeration of small crystallites in certain regions. The decrease in electrical resistance of the ZnO film was found to be related to the increase in Carrier Concentration