Characteristics of Nickel-doped Zinc Oxide thin films prepared by sol–gel method

Abstract

Transparent and conductive high preferential c-axis oriented Ni-doped ZnO (NZO) thin films as a function of Ni content have been prepared by sol–gel method using zinc acetate and nickel acetate as starting material, anhydrous ethanol and 2-methodxyethanol as solvent. The NZO thin films with a dopant ratio (0.2, and 0.4 mol%) have a preferred orientation in the (002) direction. However, when the Ni doping ratio exceeds 0.6 mol%, films possessed a non-textured polycrystalline structure. The electric and optical properties of the Ni doped ZnO films were found to be strongly dependent on the Ni contents. The lowest resistivity value was 4.8×10−4 Ω cm, which was obtained in the 0.2 mol% Ni-doped ZnO thin film. The improvement of the electrical and optical properties of NZO films may be related to the both increase in the concentration of oxygen vacancies and free carries of Ni ions. The average optical transmittance values of the 0.2 mol% Ni-doped NZO thin films were more than 91.2% in the visible range.