Nanostructured zinc oxide thin films by spin coating technique

Abstract

Nanocrystalline zinc oxide (ZnO) thin films were deposited on glass substrates by sol-gel spin coating method. Two different sols were prepared using zinc acetate dihydrate as a precursor material dissolved in isopropyl alcohol as a solvent in the presence of two different aminoalcohols including monoethanolamine (MEA) and triethanolamine (TEA) which act as stabilisers. The molar ratio of MEA/TEA to zinc acetate was maintained at 1·0. The effect of MEA/TEA on the structural, optical, morphological and electrical properties of zinc oxide thin films has been investigated by X-ray diffraction analysis, UV-Vis-spectrophotometer, photoluminescence, scanning electron microscopy with elemental composition analysis and four-probe techniques, respectively. X-ray analysis showed that the crystallinity and the particle size decreases for zinc oxide film with TEA as the stabilising agent. Optical studies revealed that zinc oxide films, with TEA, were highly transparent and exhibited large band gap. Compared to TEA, MEA has a significant impact on the zinc oxide film morphology. The activation energy, Ea, was calculated and was found to be 0·4 and 0·2 eV for zinc oxide thin film with MEA and TEA stabilisers, respectively.