Berlin 2015 – scientific programme
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O: Fachverband Oberflächenphysik
O 66: Electronic Structure of Surfaces
O 66.7: Poster
Wednesday, March 18, 2015, 18:15–21:00, Poster A
Manipulating the surface conductivity of Bi2Se3 by Bi ad-islands — •Paul Graf, Sebastian Bauer, and Christian A. Bobisch — Faculty of Physics, Center for Nanointegration Duisburg- Essen, University of Duisburg-Essen, 47048 Duisburg, Germany
We studied the microscopic (nm-scale) electron transport on the surface of thin films of the topological insulator Bi2Se3 [1],[2] by scanning tunneling potentiometry (STP) [3] using a multiprobe STM [4]. Especially, we analyzed the impact of Bi ad-islands to the electron transport, i.e. the electrochemical potential of the Bi2Se3 film. In addition, the macroscopic (µm-scale) conductivity was determined by a two point measurement. Since the surface state of Bi2Se3 is topologically protected, small defects on the surface like the bismuth bilayer islands are predicted not to disturb the current flow through the Bi2Se3 film significantly. We find that both, the microscopic and the macroscopic conductivity of the Bi2Se3 film increases after adding bismuth bilayer islands to the surface. This effect can be explained by electron donation from the bismuth ad-islands to the Bi2Se3 film [5]. The impact of scattering of conduction electrons at the Bi ad-islands to the local surface potential will be discussed.
[1] C. L. Kane und E. J. Mele, Phys. Rev. Lett. 95, p. 146802 (2005). [2] H. Zhang et. al., Nat. Phys. 5, p. 438 (2009). [3] P. Muralt et. al., Appl. Phys. Lett. 48, p. 514 (1986). [4] A. Bannani, C. A. Bobisch and R. Möller, Rev. Sci. Instrum. 79, 083704 (2008). [5] M. Chen et. al., Appl. Phys. Lett. 101, p. 081603 (2012)