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arXiv · 2207.11037

Strain control of hybridization between dark and localized excitons in a 2D semiconductor

Pablo Hernández López·Sebastian Heeg·Christoph Schattauer·Sviatoslav Kovalchuk·Abhijeet Kumar·Douglas J. Bock·Jan N. Kirchhof·Bianca Hoefer·Kyrylo Greben·Florian Libisch·Kirill I. Bolotin
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Abstract

Mechanical strain is a powerful tuning knob for excitons, Coulomb-bound electron-hole complexes dominating optical properties of two-dimensional semiconductors. While the strain response of bright free excitons is broadly understood, the behavior of dark free excitons (long-lived excitations that generally do not couple to light due to spin and momentum conservation) or localized excitons related to defects remains mostly unexplored. Here, we develop a technique capable of straining pristine suspended WSe2 kept at cryogenic temperatures up to 3\% to study the strain behavior of these fragile many-body states. We find that under the application of strain, dark and localized excitons in monolayer WSe2 - a prototypical 2D semiconductor - are brought into energetic resonance, forming a new hybrid state that inherits the properties of the constituent species. The characteristics of the hybridized state, including an order-of-magnitude enhanced light/matter coupling, avoided-crossing energy shifts, and strain tunability of many-body interactions, are all supported by first-principles calculations. The hybridized exciton reported here may play a critical role in the operation of single quantum emitters based on WSe2. Furthermore, the techniques we developed may be used to fingerprint unidentified excitonic states

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Pablo Hernández López, Sebastian Heeg, Christoph Schattauer, Sviatoslav Kovalchuk, Abhijeet Kumar, Douglas J. Bock, Jan N. Kirchhof, Bianca Hoefer, Kyrylo Greben, Florian Libisch, Kirill I. Bolotin. 2022-07-22. Strain control of hybridization between dark and localized excitons in a 2D semiconductor. https://doi.org/10.1038/s41467-022-35352-9

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