title: Intrinsic conduction through topological surface states of insulating Bi2Te3 epitaxial thin films.
abstract: Topological insulators represent a novel state of matter with surface charge carriers having a massless Dirac dispersion and locked helical spin polarization. Many exciting experiments have been proposed by theory, yet their execution has been hampered by the extrinsic conductivity associated with the unavoidable presence of defects in Bi2Te3 and Bi2Se3 bulk single crystals, as well as impurities on their surfaces. Here we present the preparation of Bi2Te3 thin films that are insulating in the bulk and the four-point probe measurement of the conductivity of the Dirac states on surfaces that are intrinsically clean. The total amount of charge carriers in the experiment is of the order of 10(12) cm(-2) only, and mobilities up to 4,600 cm(2)/Vs have been observed. These values are achieved by carrying out the preparation, structural characterization, angle-resolved and X-ray photoemission analysis, and temperature-dependent four-point probe conductivity measurement all in situ under ultra-high-vacuum conditions. This experimental approach opens the way to prepare devices that can exploit the intrinsic topological properties of the Dirac surface states.
authors.affiliation: Max Planck Institute for Chemical Physics of Solids, Dresden 01187, Germany; and katharina.hoefer@cpfs.mpg.de.
authors.forename: Katharina
authors.initials: K
authors.lastname: Hoefer
authors.affiliation: Max Planck Institute for Chemical Physics of Solids, Dresden 01187, Germany; and.
authors.forename: Christoph
authors.initials: C
authors.lastname: Becker
authors.affiliation: Max Planck Institute for Chemical Physics of Solids, Dresden 01187, Germany; and.
authors.forename: Diana
authors.initials: D
authors.lastname: Rata
authors.affiliation: Max Planck Institute for Chemical Physics of Solids, Dresden 01187, Germany; and University of British Columbia, Vancouver, BC, Canada V6T 1Z4.
authors.forename: Jesse
authors.initials: J
authors.lastname: Swanson
authors.affiliation: Max Planck Institute for Chemical Physics of Solids, Dresden 01187, Germany; and.
authors.forename: Peter
authors.initials: P
authors.lastname: Thalmeier
authors.affiliation: Max Planck Institute for Chemical Physics of Solids, Dresden 01187, Germany; and.
authors.forename: L H
authors.initials: LH
authors.lastname: Tjeng
keywords: Dirac electrons; in situ four-point conductance; molecular beam epitaxy; thin films; topological insulator