Important physical parameters of Bi2O3 thin films found by applying several models for optical data

Different optical parameters for thin solid films can be computed as functions of wavelength from the optical transmission and reflection spectra. Subsequently, several models can be tested on the obtained data, in order to check their validity with respect to the materials under study. Moreover, these models offer the possibility to estimate essential physical parameters. Such models are tested within this article for the refraction index and for the real part of the complex dielectric constant, for bismuth trioxide thin films deposited on glass substrates maintained at three different temperatures. Also, the model proposed by Tauc is applied for the absorption spectrum of the same films, in order to determine the type of electronic transition and to estimate the optical energy bandgap. It will be noticed that the optical parameters vary rather significantly with changing substrate temperature, while the structure of the films, as studied by means of X-ray diffractometry is almost insensitive to this change of deposition parameter. (C) 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim