Dresden 2020 – wissenschaftliches Programm
Die DPG-Frühjahrstagung in Dresden musste abgesagt werden! Lesen Sie mehr ...
Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe
HL: Fachverband Halbleiterphysik
HL 59: THz and MIR physics in semiconductors
HL 59.6: Vortrag
Donnerstag, 19. März 2020, 11:15–11:30, POT 151
Symmetry breaking and circular photogalvanic effect in epitaxial CdxHg1−xTe films — Stefan Hubmann1, Grigory Budkin2, •Maximilian Otteneder1, Dmitro But3, Daniel Sacré1, Ivan Yahniuk3, Kilian Diendorfer1, Vasily Bel’kov2, Dmitry Kozlov4, Nikolay Mikhailov4, Sergey Dvoretsky4, Vasily Varavin4, Vladimir Remesnik4, Sergey Tarasenko2, Wojciech Knap3, and Sergey Ganichev1 — 1Terahertz Center, University of Regensburg, Regensburg, Germany — 2Ioffe Institute, St. Petersburg, Russia — 3International Research Centre CENTERA, Institute of High Pressure Physics, Warsaw, Poland — 4Rzhanov Institute of Semiconductor Physics, Novosibirsk, Russia
We report on the observation of symmetry breaking and the circular photogalvanic effect (CPGE) in CdxHg1−xTe alloys. We demonstrate that irradiation of bulk epitaxial films with circularly polarized terahertz radiation leads to the CPGE yielding a photocurrent whose direction reverses upon switching the photon helicity. This effect is forbidden in bulk zinc-blende crystals by symmetry arguments and, therefore, its observation indicates either symmetry reduction of the bulk material or that photocurrents are excited in topological surface states formed in alloys with low cadmium concentration. Bulk states play a crucial role since the CPGE is also clearly detected in samples with non-inverted band structure and therefore we suggest that strain is a reason of the symmetry reduction. We develop a theory of the CPGE showing that it results from quantum interference of different pathways contributing to the free-carrier absorption of radiation.