Analysis of carrier parameters and bandgap of electroplated Bi2Te3 films by infrared spectroscopic ellipsometry

Polycrystalline thin films have been grown on gold substrates by electrodeposition, leading to different film compositions. In particular, our conditions allow growing smooth and shiny surface films in a thickness range of nanometers to micrometers. In this article, electroplated layers were analysed by InfraRed Spectroscopic ellipsometry. The dielectric functions have been obtained from ellipsometry analyses using the Drude and Tauc-Lorentz models. We attributed the scattering distribution of the mobility with the carrier concentration to the presence of grain boundaries in the films. The energy bandgap appears to be constant whatever the carrier concentration. This result can be interpreted by bandgap shrinkage that occurs simultaneously with bandgap widening. These results were supported by additional Hall Effect Measurements. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)