Effect of annealing temperature on structural, morphological and optical properties of zno nanorod thin films prepared by hydrothermal method

Abstract

The hydrothermal process is considered as one of the simplest and cheapest methods applied to prepare zinc oxide nanorods (ZnO-NRs) to be arranged on glass substrates. Each glass substrate was pre-coated by ZnO seed layer. The grown nanostructures were annealed in air at temperatures of 200, 250 and 400 °C. The effect of annealing process on structural, optical and morphological properties has been studied. The X-ray diffraction (XRD) tests confirmed that all synthesized samples are polycrystalline structures that possess hexagonal shapes and preferable orientation plane of (002), along with c-axis coordination which is also evident from FE-SEM image. The intensity of (002) peak was most prominent at 250 °C. Due to the increase in crystals size with annealing temperature at 250 °C, the full width at half maximum (FWHM) has been decreased. The energy dispersive spectroscopy test (EDS) showed that the Zn:O atomic ratio for all samples was nearly stoichiometric. The atomic force microscopy (AFM) image show that the root mean square (RMS) decreases when the temperature increases up to 400 °C. The optical transparency and band gap of (ZnO-NRs) decreased with the increase of annealing temperature.