Physical properties of spray deposited Ni-doped zinc oxide thin films

Transparent thin films of nickel doped zinc oxide were deposited on to corning glass substrates via chemical spray pyrolysis using zinc acetate and nickel nitrate as precursors. Structural, morphological, optical, electrical, dielectrical and impedance properties of the films as a function of nickel doping concentration as well as inter-particle interactions by complex impedance spectroscopy were investigated. The deposited films are polycrystalline with a hexagonal (wurtzite) crystal structure along (002) preferential orientation. The films are highly transparent in the visible region with a transmittance higher than 86%, and have an optical band gap ranging from 3.23 to 3.19 eV depending on the nickel doping concentration. The high electrical conductivity of doped films is explained on the basis of the presence of oxygen vacancies. Decrease of electrical conductivity due to nickel doping is explained on the basis of compensation of oxygen vacancies. The dielectric constant and loss tangent as a function of frequency are reported. Interparticle interactions in the deposited films are studied by complex impendence spectroscopy.