PREPARATION AND CHARACTERAZATION OF ALUMINUM DOPED NANOCRYSTALLINE ZINC OXIDE FOR SOLAR CELLS APPLICATIONS

Abstract

Undoped transparent conducting nanocrystalline Zinc oxide (ZnO) and Aluminum doped nanocrystalline Zinc oxide (Al:ZnO) thin films with three different concentrations (0.05, 0.10 and 0.15 M) of aluminum chloride (AlCl2) have been successfully deposited on a clean commercial glass substrate using chemical bath deposition technique (CBD). The mixed aqueous solution of chemical bath consists of Zinc acetate dehydrate (Zn(CH3COO)2.2H2O) as a source of Zn+2 ions and the dopant source was aluminum chloride (AlCl2) as a source of Al-2 ions, while ammonium hydroxide was used to obtain an alkaline solution at a constant PH. The doping effects of aluminum chloride concentration (0.05, 0.10 and 0.15 M) on the optical and structural properties were investigated. The XRD patterns show that, all the prepared films are polycrystalline with prominent diffraction peak appear at (002) as a preferential orientation around 2θ=34.44º. The intensity of Al doped ZnO decreased with increasing Al concentration. While atomic force microscope results appear that, the surface roughness and the grain size of the films decreased with increasing aluminum chloride concentration. From the optical measurements, the transmittance in the visible (VIS) region and optical band gap (Eg) were found to increase with increasing Al concentration. This result is attributed to the quantum size effect as expected from the nanocrystalline nature.