Influence of precursor concentration on structural, morphological and electrical properties of spray deposited ZnO thin films

Nanostructured ZnO thin films were coated on glass substrate by spray pyrolysis using Zinc acetate dihydrate as precursor. Effect of precursor concentration on structural, morphological, optical and electrical properties of the films was investigated. The crystal structure and orientation of the ZnO thin films prepared with four different precursor solution concentrations were studied and it was observed that, the prepared films are polycrystalline in nature with hexagonal wurzite structure. The peaks are indexed to (100), (002), (101), (102) and (110) planes. Grain size and texture coefficient (TC) were calculated and the grain size found to increase with an increase in precursor concentration. Presence of Zn and 0 elements was confirmed with EDAX spectra. Optical absorption measurements were carried out in the wavelength region of 380 to 800 nm and the band gap decreases as precursor concentration increases. The current-voltage characteristics were observed at room temperature and in dark. It was found that for the films deposited at four different precursor concentrations, the conductivity improves as precursor concentration increases. As trimethyl amine TMA is a good marker for food quality discrimination, sensing behavior of the films at an optimized operating temperature of 373 K, towards various concentrations of (TMA) was observed and reported. (C) 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim