Dresden 2014 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 37: Posters: Plasmonics, Electronic Structure and Spin-Orbit Interaction, Semiconductor and Insulator Surfaces, Nanostructures

O 37.64: Poster

Dienstag, 1. April 2014, 18:30–22:00, P2

Growth of epitaxial Bi_1−xSb_x films — •Julian Koch, Philipp Kröger, Herbert Pfnür, and Christoph Tegenkamp — Leibniz Universität Hannover, Inst. für Festkörperphysik, Appelstr. 2, 30167 Hannover

The alloy Bi_1−xSb_x was the first 3D topological insulator to be discovered. Depending on the relative concentrations of Bi and Sb the surface states can be tuned between topologically trivial and nontrivial (e.g. see PRB 83, 201104(R)). The fundamental difference of these states can be probed in principle by surface transport. However, in order to identify these different regimes, control of the film quality as well as the atomic defect structure is mandatory. In-situ epitaxy is a well established concept to grow such high-quality films.

In this study this material class was epitaxially grown by co-deposition on Si(111) substrates and investigated by means of low energy electron diffraction. Films of different stoichiometry ranging from x=0.07−0.3 have been grown by co-deposition at various temperatures and correlated with their lattice constants. In order to achieve epitaxial growth of (111)-oriented Bi_1−xSb_x-films a buffer layer is necessary which has been realized by growth of 10 bilayer Bi. Growth of contiguous Bi_1−xSb_x-films with single domain structures succeeds for deposition temperatures below 400 K. At higher temperatures the film is ruptured accompanied by segregation of Sb as confirmed by XPS.