Physical properties of spray pyrolysized nano flower ZnO thin films

Abstract Zinc Oxide thin films had been deposited on microscopic glass substrate using spray pyrolysis technique at different substrate temperatures. The X-ray diffraction pattern of the prepared films had shown the polycrystalline nature with the preferential orientation along (0 0 2) plane. SEM micrograph of the prepared films revealed the uniform distributions of the flowers shaped grains. The presence of zinc and oxygen is confirmed from the peaks at 1 keV, 8 keV and 0.44 keV using EDS analysis. The columnar arrangement of the grains with the average grain size ranging from 80 to 140 nm is observed from the AFM analysis. From the optical studies, the high transparency in the visible region with an average transmittance reaching values up to 80% is observed. The calculated values of Energy band gap Eg are found to vary from 3.06 eV to 3.26 eV with increase of substrate temperature from 325 °C to 425 °C. The rise and fall in the extinction coefficient is directly related to the absorption of light. A drastic increase of refractive index indicates the compactness of the prepared films. The photoluminescence spectra exhibited the emission peaks at 418 nm, 441 nm, 525 nm and 671 nm which were corresponding to violet, blue, green and red emission.