Berlin 2015 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 66: Electronic Structure of Surfaces
O 66.6: Poster
Mittwoch, 18. März 2015, 18:15–21:00, Poster A
Elementary contributions to the resistivity of a thin Bi2Se3 film — •Sebastian Bauer, Paul Graf, and Christian A. Bobisch — Faculty of Physics, Center for Nanointegration Duisburg-Essen, University of Duisburg-Essen, 47048 Duisburg, Germany
We present scanning tunneling potentiometry (STP) measurements on a 14 QL Bi2Se3 film on Si(111) using a multiprobe STM [1]. STP gives us simultaneously microscopic information about the topography and the electrochemical potential of the topological insulator (TI) Bi2Se3 while a lateral current flows through the Bi2Se3 film. The microscopic (nm-scale) sheet conductance of the Bi2Se3 film is evaluated by STP yielding a value of 1.8 mS. This is very close to the value of our macroscopic (µm-scale) measurements (2.1 mS) also found by other groups [2]. Despite the topological protection of the Bi2Se3 surface state [3], we observe sharp voltage drops on the Bi2Se3 surface, located at Bi2Se3 step edges. The step edges contribute to the total resistance of the surface by a resistivity of 0.9 Ω·cm at each step edge of a quintuple layer, reducing the sheet conductance of the TI film [4].
[1] A. Bannani, C. A. Bobisch, and R. Möller, Rev. Sci. Instrum. 79, 083704 (2008). [2] A. Taskin et al., Phys. Rev. Lett. 109, 066803 (2012). [3] M. Hazan and C. L. Kane, Rev. Mod. Phys. 82, 3045-3067 (2010). [4] S. Bauer and C. A. Bobisch, in revision.