ZnO thin film deposition by laser ablation of Zn target in oxygen reactive atmosphere

ZnO thin films were deposited by laser ablation of Zn target in oxygen reactive atmosphere. The films are crystalline, their c-axis is perpendicular to the substrate surface, they exhibit high optical transmission (95% in the visible range, with a step transition at 380 nm), a band gap value of 3.2 eV and a high piezoelectric coefficient. A YAG laser (lambda = 1.06 mu m, tau(FWHM) = 10 nS, 0.3 J/pulse), was used as laser source. The material was collected on different substrates: Si wafers, sapphire, Coming glass plates. The influence of the process parameters on the physical properties of the deposited films was studied. The target-collector distance was varied in the range 4-8 cm, the oxygen pressure was set between 10(-3) mbar and 10(-1) mbar, the collectors were heated at different temperatures between 20 and 350 degrees C. Cross-section scanning electron microscopy, optical transmission spectra, X-ray diffraction and electroacoustic studies were performed to characterize the deposited films.