Berlin 2018 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 11: Topological insulators II (joint session HL/TT)
HL 11.5: Talk
Monday, March 12, 2018, 16:00–16:15, A 151
Parallel conduction channels in topological insulator thin films: Determination of conductance through bulk, interface and surface states — •Sven Just1,2, Felix Lüpke1,2, Peter Schüffelgen1,2, Tristan Heider1,2, Vasily Cherepanov1,2, Gregor Mussler1,2, Lukasz Plucinski1,2, Detlev Grützmacher1,2, Claus M. Schneider1,2, F. Stefan Tautz1,2, and Bert Voigtländer1,2 — 1JARA-FIT, Forschungszentrum Jülich, Germany — 2Peter Grünberg Institute (PGI-3, PGI-6, PGI-9), Forschungszentrum Jülich, Germany
Topological insulator (TI) thin films can exhibit multiple parallel conduction channels for current transport. Beside the topological protected surface states (TSS) on top and bottom side of the film there can be more parasitic channels, i.e. the interior (bulk) of the not perfectly insulating TI film, the interface layer and the substrate. It is a crucial task to determine and minimize the influence of these parasitic parallel channels on the total current transport for taking advantage of the special TI properties in electronic devices. By using gate-dependent surface-sensitive four-probe measurements performed with a multi-tip STM and ARPES measurements in combination with theoretical calculations of the near-surface band-bending in the TI thin film, it is possible to disentangle the contributions of the different parallel conduction channels and to determine the conductivities of the interface reconstruction and the film bulk, as well as the charge carrier densities and mobilities of the top and bottom TSS for TI materials grown by van-der-Waals epitaxy, e.g. the ternary system (Bi0.53Sb0.47)2Te3.