Strain fingerprinting of exciton valley character in 2D semiconductors
Intervalley excitons with electron and hole wavefunctions residing in different valleys determine the long-range transport and dynamics observed in many semiconductors. However, these excitons with vanishing oscillator strength do not directly couple to light and, hence, remain largely unstudied. Here, we develop a simple nanomechanical technique to control the energy hierarchy of valleys via their contrasting response to mechanical strain. We use our technique to discover previously inaccessible intervalley excitons associated with K, Γ, or Q valleys in prototypical 2D semiconductors WSe<sub>2</sub> and WS<sub>2</sub>. We also demonstrate a new brightening mechanism, rendering an otherwise "dark" intervalley exciton visible via strain-controlled hybridization with an intravalley exciton. Moreover, we classify various localized excitons from their distinct strain response and achieve large tuning of their energy. Overall, our valley engineering approach establishes a new way to identify intervalley excitons and control their interactions in a diverse class of 2D systems.
Authors
- Pablo Hernández López (ORCID: https://orcid.org/0000-0002-8064-2198)
- Joakim Hagel (ORCID: https://orcid.org/0000-0002-3858-4174)
- Cornelius Gahl (ORCID: https://orcid.org/0000-0002-9833-8581)
- Christoph Schattauer (ORCID: https://orcid.org/0000-0001-7618-0923)
- Florian Libisch (ORCID: https://orcid.org/0000-0001-5641-9458)
- Bianca Höfer (ORCID: https://orcid.org/0000-0003-0719-1033)
- Abhijeet M. Kumar (ORCID: https://orcid.org/0000-0003-3645-6061)
- Douglas J. Bock
- Sebastian Heeg (ORCID: https://orcid.org/0000-0002-6485-3083)
- Ermin Malić (ORCID: https://orcid.org/0000-0003-1434-9003)
- Roberto Rosati (ORCID: https://orcid.org/0000-0002-2514-3425)
- Jan Kirchhof (ORCID: https://orcid.org/0000-0001-8576-4787)
- Denis Yagodkin (ORCID: https://orcid.org/0000-0002-9135-8918)
- Kirill I. Bolotin (ORCID: https://orcid.org/0000-0003-1821-3429)
- Kenneth Burfeindt
- Sarah Tobisch
Institutions
- TU Wien (AT)
- Philipps University of Marburg (DE)
- Humboldt-Universität zu Berlin (DE)
- Chalmers University of Technology (SE)
- Freie Universität Berlin (DE)
- Delft University of Technology (NL)
Publication Details
- Journal
- Nature Communications
- Published
- 2024-08-30
- DOI
- https://doi.org/10.1038/s41467-024-51195-y
- Citations
- 27
- Primary Topic
- 2D Materials and Applications
- Type
- article
- Field-Weighted Citation Impact
- 3.16
Funders
- Deutsche Forschungsgemeinschaft
- Bundesministerium für Bildung und Forschung
- Austrian Science Fund