title: Surface State-Dominated Photoconduction and THz Generation in Topological Bi2Te2Se Nanowires.
abstract: Topological insulators constitute a fascinating class of quantum materials with nontrivial, gapless states on the surface and insulating bulk states. By revealing the optoelectronic dynamics in the whole range from femto- to microseconds, we demonstrate that the long surface lifetime of Bi2Te2Se nanowires allows us 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 and bulk states dynamics on the different time scales 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.
authors.affiliation: Walter Schottky Institut and Physik-Department, Technische Universität München , Am Coulombwall 4a, D-85748 Garching, Germany.
authors.forename: Paul
authors.initials: P
authors.lastname: Seifert
authors.affiliation: Max-Planck-Institut für Festkörperforschung , Heisenbergstraße 1, D-70569 Stuttgart, Germany.
authors.forename: Kristina
authors.initials: K
authors.lastname: Vaklinova
authors.affiliation: Max-Planck-Institut für Festkörperforschung , Heisenbergstraße 1, D-70569 Stuttgart, Germany.|Institut de Physique, Ecole Polytechnique Fédérale de Lausanne , CH-1015 Lausanne, Switzerland.
authors.forename: Klaus
authors.initials: K
authors.lastname: Kern
authors.affiliation: Max-Planck-Institut für Festkörperforschung , Heisenbergstraße 1, D-70569 Stuttgart, Germany.
authors.forename: Marko
authors.initials: M
authors.lastname: Burghard
authors.affiliation: Walter Schottky Institut and Physik-Department, Technische Universität München , Am Coulombwall 4a, D-85748 Garching, Germany.
authors.forename: Alexander
authors.identifier: 0000-0002-8314-4397
authors.initials: A
authors.lastname: Holleitner
keywords: Topological insulators; on-chip THz generation; surface state dynamics; ultrafast photodetector