Effect of post deposition annealing temperature on the properties of ZnO films prepared by RF magnetron sputtering

Highly C-axis oriented ZnO films were deposited by RF magnetron sputtering technique on unheated Si substrate with SiO₂ layer deposited using thermal oxidation. We employ thermal annealing techniques with temperature range from 350degC to 800degC to investigate quality of annealed ZnO substrates. Post deposition annealing of ZnO films at atmospheric pressure in oxygen at different temperatures were found to improve film structure such as dense structure, smooth surface, and increasing resistivity. The surface morphology dramatically changes to be smooth surfaces with increase in annealing temperature. The correlation between annealing conditions and the physical structure of the films e.g. crystalline structure and microstructure was investigated by X-ray diffraction (XRD) and atomic force microscopy (AFM). The preferred annealing condition has been found to improve ZnO film characteristics for piezoelectric applications.