Preparation and characterization of ZnO thin films deposited by sol-gel spin coating method

Abstract

ZnO thin films have been deposited onto the glass substrates by the sol-gel spin coating method at different chuck rotation rates. This method was used for the preparation of thin films of the important semiconductors II-VI. The effect of deposition parameters on the structural, optical and electrical properties of the ZnO thin films was investigated. Zinc acetate dehydrate, 2-methoxethanol and monoethanolamine (MEA) were used as a starting material, solvent and stabilizer, respectively. Thermogravimetric analysis (TGA) of the dried gel showed that weight loss continued until 300 o C. The crystal structure and orientation of the ZnO thin films were investigated by X-ray diffraction (XRD) patterns. The grain size of the films was calculated using the Scherrer formula. The optical absorbance and transmittance measurements were recorded by using a double beam spectrophotometer with an integrating sphere in the wavelength range 190-900 nm. The optical absorption studies reveal that the transition is direct band gap energy. The optical band gaps and Urbach energies of the thin films were determined. The I-V plots of the ZnO thin films were carried out in dark and under UV-illumination. The obtained ZnO thin films can be used as a photovoltaic material.