The Effect of Annealing Technique on ZnO Film Properties

Abstract

ZnO films deposited on glass substrates by ultrasonically chemical spray pyrolysis technique have been investigated to establish the effect of the annealing technique on film properties. For this purpose, films have been exposed to standard thermal annealing and microwave annealing in an air atmosphere. It has been determined that the structural, morphological, compositional, and optical properties of the ZnO films correlate with each other. X-ray diffraction analyses have been revealed the highest crystallization level and changing preferred orientations for microwave annealed films. It has been identified that the optical band gap values of the films decreased from 3.27 eV to 3.23 eV and 3.21 eV after the standard and microwave thermal annealing, respectively. Scanning electron microscope images have been revealed homogeneous morphology at plan-view images of all films. Also, it has been determined that the root-like morphology from the higher magnification scanning electron microscopy images. Thicknesses of the films have been also determined from cross-sectional scanning electron microscope images as 1.04m, 0.92m, and 0.92m for ZnO, standard thermal annealed and microwave annealed ZnO films, respectively. Also, the O/Zn ratio revealed improved stoichiometry for annealed films according to as-deposited film for investigated regions. The dependence of photoluminescence intensity on annealing technique has also been investigated in the current study.