OPTICAL AND ELECTRICAL PROPERTIES OF ZINC OXIDE THIN FILMS DIP-COATED OF SOL–GEL METHOD

Abstract

The transparent c-axis oriented ZnO thin films have been prepared by sol–gel method using zinc acetate as cations source, 2-mrthoxiethanol as solvent and monoethanolamine as sol stabilizer. Film deposition was performed by dip coating technique at a withdrawal rate of 10 mm/min on quartz and silicon substrates. The effect of annealing temperature in air ambient from 100 to 800°C on the structural, optical and electrical properties of the films is discussed. ZnO films annealed with higher temperature showed an extremely sharp (002) peak in the XRD patterns, indicates increased crystallization. The optical transmittance spectra of the films is found to change with annealing temperature and showed a very good transmittance (between 80 to 90%) with the films prepared at 600°C showed highest optical transparency within the visible wavelength region. The absorption edge analysis revealed that the optical band gap is found to increase with annealing temperature up to 3.5 eV at 600°C and decreased with higher temperature. Electronic transition was found to be direct transition type. The minimum electrical resistivity of 55 Ω-cm was obtained for the films annealed at 600°C.