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O: Fachverband Oberflächenphysik

O 66: Electronic Structure of Surfaces

O 66.7: Poster

Mittwoch, 18. März 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)