Optical properties of ZnO nano fiber thin films grown by spray pyrolysis of zinc acetate precursor

Good homogeneous and stoichiometric ZnO nanofiber thin films have been deposited onto cleaned glass substrate by a simple spray pyrolysis technique under atmospheric pressure using zinc acetate precursor at temperature 200 degrees C. Films of various thicknesses have been obtained by varying the deposition time, while all other deposition parameters such as spray rate, carrier gas pressure and distance between spray nozzle to substrate were kept constant. Surface morphology and optical properties of the as deposited thin films have been studied by Scanning Electron Microscopy (SEM) attached with an EDX and UV visible spectroscopy. From EDX data, atomic weight % of Zinc and Oxygen were found to be 49.22% and 49.62% respectively. The SEM micrograph of the film shows uniform deposition and scattered nano fiber around the nucleation centers. The optical band gap of the ZnO thin films was found to be in the range 3.3 to 3.4 eV and the band gap decreases with thickness of the film. Optical constants such as refractive index, extinction coefficient, real and imaginary parts of dielelectric constants were evaluated from reflectance and absorbance spectra. (c) 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim