Synthesis and evaluation of the structural, microstructural, optical and magnetic properties of Zn1-xCoxO thin films grown onto glass substrate by ultrasonic spray pyrolysis

Ultrasound pyrolysis spray technique is used to prepare single-phase thin films of Zn1-xCoxO (x = 0-22 at.%). The hexagonal wurtzite structure of the films is confirmed by X-ray diffraction with an average crystallite size estimated in the range of 18-30 nm. The compound structure and stoichiometry of the films are further characterized by energy-dispersive spectroscopy (EDAX). The spectrum analysis agreement great chords between the expected and measured Co atomic content in the films indicating an effective doping. The results also reveal a high solubility of Co into ZnO solid solution at about 14 at.%. For the optical proprieties, the bandgap energy decreases due to the presence of high concentrations of localized states in the thin films. The photoluminescence spectra of all the samples exhibited a broad emission in the visible range. In addition, the magnetic properties of Zn1-xCoxO thin films are found to be strongly influenced by Co doping.