Regensburg 2022 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 9: Ultrafast Electron Dynamics at Surfaces and Interfaces 2
O 9.10: Vortrag
Montag, 5. September 2022, 17:15–17:30, H3
Spatio-temporal imaging of bright and dark excitonic quasiparticles in twisted TMD heterostructures — •Jan Philipp Bange1, David Schmitt1, Wiebke Bennecke1, AbdulAziz AlMutairi2, Guiseppe Meneghini3, Daniel Steil1, R. Thomas Weitz1, Sabine Steil1, G. S. Matthijs Jansen1, Samuel Brem3, Ermin Malic3, Stephan Hofmann2, Marcel Reutzel1, and Stefan Mathias1 — 1I. Physikalisches Institut, Georg-August-Universität Göttingen, Germany — 2Department of Engineering, University of Cambridge, U.K. — 3Fachbereich Physik, Philipps-Universität Marburg, Germany
In two-dimensional van-der-Waals semiconductors, the weak Coulomb screening of charge carriers leads to exciting new material properties, such as bright and dark excitons with large binding energies. Consequently, when creating a heterostructure from two transition-metal dichalcogenide (TMD) monolayers with a type II band alignment, interlayer excitons can be formed [1]. Because dark excitons are not directly accessible with optical techniques, the spatial and lateral dynamics on the fundamental nanometer length scale remain largely unexplored. How do dark and interlayer quasiparticles form, relax and diffuse in the presence of a heterojunction, stress fields and inhomogeneities? Here, we address this question using time-resolved momentum and dark-field photoemission microscopy which enables us to study the ultrafast formation dynamics of different excitonic species in twisted WSe2/MoS2 heterostructures.
[1] Schmitt et al., arXiv2112.05011 (2021).