SYNTHESIS AND CHARACTERIZATION OF NANOSTRUCTURED ZINC OXIDE THIN FILMS USING AQUEOUS CHEMICAL METHOD

SYNTHESIS AND CHARACTERIZATION OF NANOSTRUCTURED ZINC OXIDE THIN FILMS USING AQUEOUS CHEMICAL METHOD

ABSTRACT

In this work, we report on the synthesis of Zinc Oxide (ZnO), by a cost effective and low temperature aqueous chemical method on conducting glass substrates. The grown nanostructures have been characterized by X-ray diffraction analysis (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), optical absorption techniques and Raman spectroscopy. Resistivity of the films was studied with I-V data for the ZnO samples.  SEM images show the formation of flower, bud, star, spindle and blades-like morphologies at different deposition time ranging from 15 to 40 minutes. The AFM analysis reveals that the films are dominated by voids with regard to surface topography. The XRD results showed that all films crystallized under hexagonal wurtzite structure and presented a preferential orientation along the c-axis with the maximum crystallite size of 86.33 nm. The average transmittance of all the films increase in the visible region from 32 -75% in a long wavelength domain from 300 – 1100nm. The extinction coefficient decreases with an increase in wavelength and the band gap energy increases from 3.24 to 3.98eV due to increase in phonon energy. In addition to the vibrational modes from ZnO, the Raman spectra are dominated by the longitudinal optics (LO) between 480 – 580cm-o1. The resistivity of the films decreases as deposition time increases, this shows that ZnO thin films is a good conductor.