Effect of calcination temperature on phase composition and optical properties of Al-ZnO nanocrystalline films

Nanocrystalline Al-ZnO films were successfully synthesized by thermal decomposition method. The method includes two stages: synthesis from the melt of organic salts and the films production. The effect of the calcination temperature varying from 600 to 800 °C on the crystallite sizes, phase composition and optical properties of the synthesized films was also investigated. X-ray diffraction (XRD) showed the formation of a hexagonal wurtzite crystal structure with a distorted lattice upon the introduction of Al 3+ ions. Based on calculations and scanning electron microscopy (SEM) images, the crystallites size increased from 18 to 28 nm with the calcination temperature increasing. Optical properties of Al-ZnO films were studied by optical transmission spectra. An increase in the calcination temperature leads to a decrease in the ZnO band gap. It was shown that the proposed method makes it possible to obtain optically transparent Al-ZnO films consisting of nanocrystallites. By varying the calcination temperature, the optical properties can be adjusted, which will significantly expand the application range of these materials.