Berlin 2024 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 18: 2D Materials and Heterostructures: Emerging Materials and Phenomena
HL 18.9: Vortrag
Dienstag, 19. März 2024, 11:45–12:00, EW 201
Strain fingerprinting of exciton valley character in 2D semiconductors — •Abhijeet Kumar1, Denis Yagodkin1, Roberto Rosati2, Douglas J. Bock1, Christoph Schattauer3, Sarah Tobisch3, Joakim Hagel4, Bianca Höfer1, Jan N. Kirchhof1, Pablo H. López5, Kenneth Burfeindt1, Sebastian Heeg5, Cornelius Gahl1, Florian Libisch3, Ermin Malic2, and Kirill I. Bolotin1 — 1Free Universität Berlin, Germany — 2Philipps-Universität Marburg, Germany — 3TU Wien, Austria — 4Chalmers University of Technology, Sweden — 5Humboldt-Universität Berlin, Germany
Momentum-indirect excitons define optoelectronic properties of many 2D semiconductors, but are challenging to detect due to their weak coupling to light. The identification of the excitons’ valley character is further limited by complexities associated with momentum-selective probes. Here, we study the photoluminescence of controllably strained 2D materials at cryogenic temperatures and find that indirect excitons i) exhibit valley-specific energy shifts, enabling their valley fingerprinting, and ii) hybridize with bright excitons, becoming directly accessible to optical spectroscopy methods. This approach allows us to identify multiple previously inaccessible excitons with wavefunctions residing in K, Γ, or Q valleys in the momentum space, as well as various types of defect-related excitons. Overall, our approach is well-suited to unravel and tune intervalley excitons in various 2D systems.
Keywords: TMDC; Excitons; Strain engineering; dark excitons; WSe2