Simple Preparation and Characterization of Nano-Crystalline Zinc Oxide Thin Films by Sol-Gel Method on Glass Substrate

Abstract

Nanocrystalline ZnO thin films have been fabricated by a multi-step sol-gel method using spin coating technique. Zinc acetate dihydrate, 2-methoxyethanol and monoethanolamine were used as a starting material, solvent and stabilizer, respectively. X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM) were employed to characterize struc-ture and morphologies of the as-deposited samples. The results of XRD and SEM showed that the heat treatment condi-tions, final rotational (spinning) speed, fume exhaust and precise control of concentration of reactants (precursor and solvent used) strongly affect the crystallographic orientation and morphology of the resultant ZnO films. The XRD pat-tern showed that the ZnO films formed the preferred orientation along c-axis and the grain size is 16nm for the samples. Only one peak corresponding to the (002) plane at 2θ = 34.34åppears on the diffractograms. The as-deposited films had a transparency of greater than 80% in the visible-near IR region from 400 nm -800 nm. The optical band gap ener-gy and thickness were calculated to be 3.296 eV and 266 nm respectively.