Optical characterization of TiO2 thin films by the combined method of spectroscopic ellipsometry and spectroscopic photometry

In this paper, results concerning the optical characterization of TiO2 thin films prepared by magnetron sputtering onto K64 glass plane-parallel plates are presented. The spectral dependences of the refractive index and extinction coefficient of these TiO2 thin films are introduced within the spectral region 230-1000 nm. For determining the values of these optical constants the method based on a combination of variable angle spectroscopic ellipsometry and spectroscopic photometry employing experimental data, of the transmittance and reflectances measured from both the sides of the films is used. For treatment of all the experimental data, the method utilizing Cauchy and Urbach formulae together with the single-wavelength method is employed. It is shown that the TiO2 films studied are homogeneous in refractive index and uniform in thickness. Moreover, the values of roughness parameters of the upper boundaries of the TiO2 films are determined. Furthermore, it is shown that the band gap value of the films corresponds to 400 nm, i.e. 3.1 eV. (c) 2005 Elsevier Ltd. All rights reserved.