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

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

15 pages, 5 figures

References in corpus (13)

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Cited by in corpus (13)

• Roadmap for Photonics with 2D Materials
• Interface engineering of charge-transfer excitons in 2D lateral heterostructures
• Photoluminescence imaging of single photon emitters within nanoscale strain profiles in monolayer WSe${}_2$
• Strain control of exciton and trion spin-valley dynamics in monolayer transition metal dichalcogenides
• Synthesis of built-in highly strained monolayer MoS2 using liquid precursor chemical vapor deposition
• Two dimensional semiconductors: optical and electronic properties
• High Temperature Quantum Emission from Covalently Functionalized van der Waals Heterostructures
• Magnetic field induced polarization enhancement in the photoluminescence of MBE-grown WSe${}_2$ layers
• Emergence of non-uniform strain induced exciton species in homo- and heterobilayer transition metal dichalcogenides
• Phonon-assisted photoluminescence of bilayer MoS${}_2$ from first principles
• Strain-induced exciton mobility in layered WS2 from first principles
• Uniform Narrow Excitonic Spectrum in Large-Area Suspended WSe2 Monolayers
• Mechanical Detuning of Exciton-Phonon Resonance in WS2