Dresden 2017 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 63: Focus Session: Charge Transport at Surfaces and Nanostructures with Multi-probe Techniques
O 63.1: Poster
Dienstag, 21. März 2017, 18:30–20:30, P2-OG3
Multiprobe measurements on a stepped Bi2Se3 surface — •Sebastian Bauer, Mandana Soleimani-Esfahani, Stephanie Hoepken, and Christian A. Bobisch — Faculty of Physics, Center for Nanointegration Duisburg-Essen (CENIDE), University of Duisburg-Essen, Lotharstraße 1-21, 47057 Duisburg
Bi2Se3 is a well-known representative of the new material class of 3D topological insulators (TI). TIs have a spinpolarized surface state for which direct backscattering of electrons is forbidden. Therefore, they are discussed for future spintronic devices [1]. We present a detailed multiprobe analysis of a 15 QL thick stepped Bi2Se3 film which was grown in situ on an inclined Si(111) surface. Scanning tunneling potentiometry [2] gives us a direct view into the nanoscale electron transport on the Bi2Se3 surface. While a lateral current flows along the surface, an STM tip records simultaneously the local electrochemical potential and the topography on the Bi2Se3 surface. We found that beside surface steps [3], also grain boundaries scatter the conducting electrons in the film. An additional rotational four point probe measurement shows an electronic anisotropy of the sheet conductivity due to the anisotropic arrangement of the Bi2Se3 steps on the surface. The computed step conductivity of about 1000 S/cm confirms former STP results [4] and reveals the contribution of step edges as electron scatterer.
[1] M. Z. Hasan, C. L. Kane, Rev. Mod. Phys. 82, 3045 (2010). [2] C. A. Bobisch and R. Möller, CHIMIA 66, 23-30 (2012). [3] S. Bauer, C. A. Bobisch, Nat. Com. 7, 11381 (2016). [4] T. Kanagawa et al., Phys. Rev. Lett. 91, 036805 (2003).