# Dresden 2014 – wissenschaftliches Programm

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# HL: Fachverband Halbleiterphysik

## HL 42: Topological insulators (organized by O)

### HL 42.10: Vortrag

### Dienstag, 1. April 2014, 12:45–13:00, GER 38

**Step wise variation of the electrochemical potential at step edges of the Bi**_{2}**Se**_{3}** surface** — •Christian A. Bobisch, Sebastian Bauer, and Rolf Möller — Faculty of Physics, Center for Nanointegration Duisburg-Essen, University of Duisburg-Essen, 47048 Duisburg, Germany

Bi_{2}Se_{3} is a 3D topological insulator (TI) whose surface states are protected from direct backscattering by time reversal symmetry [1]. However, step edges on a Bi_{2}Se_{3} surface are predicted to work as an electron scatterer for other scattering angles than 180^{∘} backscattering [2]. We studied the electron transport on the surface of a 14.5 QL (quintuple layer) thick Bi_{2}Se_{3} film grown on Si(111). By a distance dependent resistance measurement [3] in the µ *m* range, we found a metallic character of the film with a sheet conductance of 2×10^{−3}Ω^{−1} which agrees well with recent literature [4]. By scanning tunneling potentiometry (STP) [5], we simultaneously analyzed the topography and the electrochemical potential µ_{ec} under real transport conditions. We observe on the microscopic scale a potential gradient which corresponds well the macroscopic conductance. In the vicinity of step edges we find a step-like variation of µ_{ec} which is a fingerprint of electron scattering at the step edge. For the given sample the electrical conductivity of a 1 QL step could be deduced to 3800±500Ω^{−1}cm^{−1}.

[1] M. Z. Hasan et al., Rev. Mod. Phys. 82, 3045 (2010). [2] W. Jing et al., Chin Phys. B 22, 067301 (2013). [3] P. Jaschinsky et al., J. Appl. Phys. 104, 094307 (2008). [4] A. A. Taskin et al., Phys. Rev. Lett. 109, 066803 (2012). [5] P. Muralt et al., Appl. Phys. Lett. 48, 514 (1986).