Characterizations of bismuth telluride films from Mott-Schottky plot and spectroscopic ellipsometry

Capacitance measurement results (via the so-called Mott-Schottky plot) and Infrared spectroscopic ellipsometry (IRSE) analysis have been carried out in order to study semiconducting properties of electroplated thin films of bismuth telluride (Bi2Te3) without any electrical contact. Electrochemical impedance measurements at 10 kHz exhibited that films characterized n-type semiconductors, depending upon potentials applied above and below the flat-band potential. By IRSE study, the energy band gap Eg was found to be about 0.11 eV independent of the film composition and the electrical resistivity of about 30 mu.Omega.m. By combining IRSE and capacitance measurement results, dielectric constant epsilon and carrier concentration of the samples were calculated without any assumptions. Copyright (C) 2008 John Wiley & Sons, Ltd.