Comparison Study between the Effect of (He-Ne) Laser Irradiation and Heat Treatment on the Optical Properties of Dichromium Trioxide Thin Film

H. Mohamed, G.; Kh. AL-Rawi, A.; A. Daham, N.

	Comparison Study between the Effect of (He-Ne) Laser Irradiation and Heat Treatment on the Optical Properties of Dichromium Trioxide Thin Film
Ibn Al-Haitham Journal For Pure And Applied Science
Article 1, Volume 23, Issue 3, 2010, Pages 86-94
Authors
G. H. Mohamed; A. Kh. AL-Rawi; N. A. Daham
Abstract
In this study, we investigate the effect of (He-Ne) laser irradiation for half hour and heat treatment (annealing) at 450oC for 2 hours on the optical properties of dichromium trioxide Cr2O3 thin films, prepared on glass slides by chemical spray pyrolysis at 400oC with spraying rate (1 ml /min) and (0.19±0.05) µm thickness. The optical characteristics of the prepared thin films have been investigated by UV/VIS spectrophotometer in the wavelength range (300–900)nm. Optical properties such as absorption coefficient (α), optical band gap (Eg), extinction coefficient (k), refractive index (n), and complex dielectric constants (€1&€2) were evaluated from the absorptance and transmittance spectra. All the films were found to exhibit allowed electronic transition(α >104 cm-1). The absorption edge shifted toward the longer wavelength (red shift) after irradiation, leading to decrease the optical band gap (Eg) from 3.13 eV for untreated film to 2.97eV for the irradiated film, while Eg was increased to 3.22 eV for the annealed film, indicating (blue shift). It was realized that localized states width (Et) for untreated film was increased from 0.47 eV to 0.56 eV after irradiation, and decreased to 0.41 eV after annealing.

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