Structural, optical and electrical characterization of nebulizer-sprayed ZnO nano-rods

ZnO thin films were deposited on glass substrates maintained at temperatures varying from 300 to 500 degrees C using NaOH solution. The effect of substrate temperature on the structural, surface morphology, compositional, optical and electrical properties of ZnO thin films was studied. X-ray diffraction shows that all the films are polycrystalline in nature having hexagonal structure with high preferential orientation along (002) plane. High resolution SEM studies reveal the formation of ZnO films consisting of uniformly distributed nano-rods over the entire surface of the substrates. PL measurements indicate the strong NBE emission at similar to 378 nm followed by a weak and broad visible emission around 407-489 nm. The prepared films are found to have a maximum transmittance similar to 70% and direct band gap energy 3.25 eV at 500 degrees C from the optical measurements. The complex impedance of the ZnO nano-rods shows two distinguished semicircles in which these arcs show a decrease in diameter with increase in temperature from 160 to 270 degrees C and thereafter slightly increased. (C) 2013 Elsevier Ltd. All rights reserved.