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TT: Fachverband Tiefe Temperaturen

TT 67: Topological Insulators II (joint session DS, HL, MA, O, TT, organized by HL)

TT 67.5: Vortrag

Donnerstag, 23. März 2017, 16:15–16:30, POT 251

Surface state-dominated photoconduction and THz-generation in topological Bi₂Te₂Se-nanowires — •Marinus Kundinger¹, Paul Seifert¹, Kristina Vaklinova², Klaus Kern^2,3, Marko Burghard², and Alexander Holleitner¹ — ¹Walter Schottky Institut and Physics-Department, Technical University of Munich, Am Coulombwall 4a, D-85748 Garching, Germany — ²Max-Planck-Institut für Festkörperforschung, Heisenbergstraße 1, D-70569 Stuttgart, Germany — ³Institut de Physique, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland

Topological insulators constitute a fascinating class of quantum materials with non-trivial, gapless states on the surface and trivial, insulating bulk states. In revealing the optoelectronic dynamics in the whole range from femto- to microseconds, we demonstrate that the long surface lifetime of Bi₂Te₂Se-nanowires allows to access the surface states by a pulsed photoconduction scheme and that there is a prevailing bolometric response of the surface states. The interplay of the surface state dynamics on the different timescales gives rise to a surprising physical property of Bi₂Te₂Se-nanowires: their pulsed photoconductance changes polarity as a function of laser power. Moreover, we show that single Bi₂Te₂Se-nanowires can be used as THz-generators for on-chip high-frequency circuits at room temperature. Our results open the avenue for single Bi₂Te₂Se-nanowires as active modules in optoelectronic high-frequency and THz-circuits.

We acknowledge financial support by the DFG priority program SPP 1666 ’topological insulators’.