Structural and optical properties of electrodeposited ZnO thin films

Zinc oxide thin films were electrodeposited on different substrates. Electrodeposition was performed with hydrogen peroxide, as hydroxide ions source, at − 1.5 V versus mercurial sulfate electrode during one hour, and a temperature maintained at 70 °C. The resulting thin films have a good crystallinity and a high c-axis orientation, and the unit cell parameters determined by X-ray diffraction experiment are a = 0.326 nm and c = 0.523 nm, respectively. Microstructure studies using scanning electron microscopy and atomic force microscopy show a good homogeneity of the film and a roughness around 22 nm. Optical properties were studied with Raman spectroscopy and photoluminescence spectroscopy. Optical properties of the films revealed a low defect emission in photoluminescence spectra. The E2 vibration mode for ZnO was observed near 439 cm− 1, indicating that the as-deposited films were under compressive stress. Oscillations were observed in the photoluminescence spectra, from which the refractive index of ZnO thin films was extracted, that is ~ 1.90.