Determination and analysis of optical constants for Ga2Se3 films near absorption edge

Ga2Se3 has been prepared in bulk and thin film forms. The composition of films has been checked using energy dispersive X-ray spectroscopy technique. X-ray diffraction measurements have shown that Ga2Se3 films evaporated at room temperature substrates were amorphous. The transmittance (T) of Ga2Se3 thin films has been measured over the wavelength range (400-900 nm). The optical constants, the refractive index (n) and the absorption index (k) have been determined from the analysis of the transmittance data. Analysis of the refractive index (n) yields the values of the long wavelength dielectric constant (epsilon(o)), the average oscillator wavelength (lambda(o)) average oscillator strength (S-o), average oscillator energy E-o, the refractive index dispersion parameter (E-o/S-o) and the dispersion energy (E-d). Analysis of absorption index (k) yields both direct and indirect allowed transitions with optical energy gaps of 2.65 and 2.056 eV, respectively. The effect of annealing at different temperatures on optical constants is also investigated. (C) 2002 Elsevier Science B.V. All rights reserved.