Physical properties evaluation of annealed ZnAl₂O₄ alloy thin films

Thin films of ZnAl₂O₄ were prepared by dip technique involving chemical solutions. Investigations on the effect of post heat treatment on the structural, optical and morphological properties of ZnAl₂O₄ thin films were studied. X-ray diffraction patterns revealed that the thin films are polycrystalline cubic structure of ZnAl₂O₄. The microstructural properties of ZnAl₂O₄ thin films were calculated and crystallite size tends to increase with increase of annealing temperatures. The texture coefficients have been evaluated and found to be greater than unity revealing high texturing of the architecture of the film. The transmittance spectra of unannealed and annealed films were plotted against UV-Vis-NIR region and found to be transmittance increases with annealing temperature. The optical band gap values were found to be in the range of 3.48 - 3.62 eV. The optical n and k constants were found to decrease with increase temperature of heat treatment. Scanning electron microscopic image revealed that the spherical shaped grains occupy the entire surface of the film and composition of the film was estimated using EDX spectra.