Berlin 2015 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 103: Transport: Poster Session
TT 103.36: Poster
Donnerstag, 19. März 2015, 15:00–18:00, Poster B
Transport measurements on epitaxial Bi1-xSbx thin films grown on Si(111) — •Julian Koch, Philipp Kröger, Herbert Pfnür, and Christoph Tegenkamp — Leibniz Universität Hannover, Inst. für Festkörperphysik, Appelstr. 2, 30167 Hannover
The alloy Bi1-xSbx is a 3D topological insulator for concentrations between x=0.04 and 0.22 [1]. Thus it has topologically protected metallic surface states and an insulating bulk at these concentrations, making it interesting for transport measurements. In this study thin films are used to reduce bulk contributions and to provide the possibility of nanostructuring. The films are grown by in-situ co-deposition on Si(111) substrates. The morphology has been controlled by means of low energy electron diffraction. Temperature dependent transport measurements for temperatures from 12 to 300 K were performed for films of different stoichiometry ranging from x=0.14−0.22 and thicknesses of 10, 20, 40 and 60 BL. Besides variable range hopping and activated bulk transport, metallic surface transport channels have been identified. At 10 BL the surface transport is strongly suppressed in accordance with measurements on Bi2Se3 [2]. Furthermore, magnetotransport measurements up to 4 T were performed in order to determine carrier concentrations, mobilities and scattering times. A 30 BL film with a concentration of x=0.18 was found to have carrier concentrations of n=1·1013 cm−2 and p=2·1013 cm−2 with mobilities of µn=2.6·102 cm2(Vs)−1 and µp=1.9·102 cm2(Vs)−1. Compared to Bi(111)-films the spin-orbit scattering rate is reduced by one order of magnitude.
[1] PRB 83, 201104(R).
[2] PRL 109, 066803