Effect of low concentration of nickel on structural and optical properties of ZnO nanofilms

For studying the effect of low doping contents of nickel on physical properties of zinc oxide, four samples of nanofilms with the low ratio Ni/Zn=0%, 0.2%, 0.4% and 0.6% on the glass slide substrates have been prepared by the spin sol-gel technique. The study of the optical and structural analyses on samples shows that initial drying temperature, final annealing temperature and doping percentage of nickel change the optical and structural properties of samples. The structural characterizations showed the zinc oxide structure without other phases or the oxide clusters of nickel and also its low doping concentrations improve the crystalline orientation of the (1 0 1) plane of zinc oxide. The formation quality of this direction was increased by increasing low amounts of nickel. The low contents of doping and also by increasing its percentage, there is increase in transparency especially in the ultraviolet region. The calculation of band gap shows a blue shift with doping nickel but decreases by a small quantity with doping more contents. Using the transmittance spectrum, the optical constants were calculated by the pointwise unconstrained minimization algorithm and fitting the data to the Cauchy formula in thin film.