The Effect of the Annealing on the Optical Properties of Zinc Oxide Thin Films Prepared by Chemical Spray Pyrolysis Technique

M. Saeed, Nada

	The Effect of the Annealing on the Optical Properties of Zinc Oxide Thin Films Prepared by Chemical Spray Pyrolysis Technique
Al-Mustansiriyah Journal of Science
Article 1, Volume 20, Issue 5, 2009, Pages 124-136
Author
Nada M. Saeed
Abstract
Zinc Oxide (ZnO) is one of an important semiconductor material for its application in a wide range of optoelectronic devices. In this paper, ZnO was prepared as thin films by using chemical spray pyrolysis technique; the films were deposited onto glass substrate at 400 °C by using aqueous zinc chloride as a spray solution of molar concentration 0.1 M/L, then annealed at 550°C. The crystallographic structure of the prepared film was analyzed with X-ray diffraction; the results shows that the film was polycrystalline in nature with preferred (002) orientation with grain size equal to 279 Å. The optical properties of the film were studied using VIS-UV spectrophotometer at wavelength within the range (300-1100) nm. The optical characterization shows that the films have an average transmittance 55% in the VIS regions and become 85% after annealing. The optical constants such as the refractive index (n), extinction coefficient (k), real and imaginary dielectric constants (εr, εi) were studied before and after annealing as a function of the photon energy at the mention wavelength, it was noted that the annealing affected on optical properties of the films. The optical energy gap was calculated to be 3.3 eV and 3.1 eV for the direct and indirect allowed transition respectively; these values are reduced after annealing.

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