Probing dark exciton navigation through a local strain landscape in a WSe monolayer
arXiv:2103.01064 · doi:10.1038/s41467-021-27877-2
Abstract
Monolayers of transition metal dichalcogenides (TMDs) have recently emerged as a promising optoelectronic platform. To leverage their full potential, however, it is important to understand and engineer the properties of the different exciton species that exist in these monolayers, as well as to control their transport through the material. A promising approach relies on engineering strain landscapes in atomically thin semiconductors that excitons navigate. In WSe monolayers, for example, localized strain has been used to control the emission wavelength of excitons, induce exciton funneling and conversion, and even realize single-photon sources and quantum dots. Before these phenomena can be fully leveraged for applications, including quantum information processing, the details of excitons' interaction with the strain landscape must be well understood. To address this, we have developed a cryogenic technique capable of probing the dynamics of both bright and dark excitons in nanoscale strain landscapes in TMDs. In our approach, a nanosculpted tapered optical fiber is used to simultaneously generate strain and probe the near-field optical response of WSe monolayers at 5 K. When the monolayer is pushed by the fiber, its lowest energy photoluminescence (PL) peaks red shift by as much as 390 meV, (corresponding to 20% of the bandgap of an unstrained WSe monolayer). The red-shifting peaks are polarized perpendicularly to the WSe plane and have long rising times (10 ps) and lifetimes (52 ps), indicating that they originate from nominally spin-forbidden dark excitons. Taken together, these observations indicate that dark excitons are funneled to the high-strain regions during their long lifetime and are the principal participants in drift and diffusion at cryogenic temperatures. Our work elucidates the important role that dark excitons play in locally strained WSe.
arXiv comment19 pages, 4 figures
References in corpus (26)
- Tightly bound excitons in monolayer WSe2
- Mechanical Properties of Atomically Thin Boron Nitride and the Role of Interlayer Interactions
- Excitonic linewidth approaching the homogeneous limit in MoS2 based van der Waals heterostructures : accessing spin-valley dynamics
- Large-scale quantum-emitter arrays in atomically thin semiconductors
- Band Gap Engineering with Ultralarge Biaxial Strains in Suspended Monolayer MoS2
- High-temperature superfluidity with indirect excitons in van der Waals heterostructures
- Deterministic strain-induced arrays of quantum emitters in a two-dimensional semiconductor
- Magnetic brightening and control of dark excitons in monolayer WSe2
- Valley dynamics probed through charged and neutral exciton emission in monolayer WSe2
- In-plane Propagation of Light in Transition Metal Dichalcogenide Monolayers: Optical Selection Rules
- Probing dark excitons in atomically thin semiconductors via near-field coupling to surface plasmon polaritons
- Spontaneous Coherence in a Cold Exciton Gas
- Strain-induced spatial and spectral isolation of quantum emitters in mono- and bi-layer WSe2
- Magneto-Optics of Exciton Rydberg States in a Monolayer Semiconductor
- Atomically thin mirrors made of monolayer semiconductors
- Fine Structure and Lifetime of Dark Excitons in Transition Metal Dichalcogenide Monolayers
- Generation and evolution of spin-, valley- and layer-polarized excited carriers in inversion-symmetric WSe2
- Dynamics and efficient conversion of excitons to trions in non-uniformly strained monolayer WS
- Localized inter-valley defect excitons as single-photon emitters in WSe
- Emerging Photoluminescence from the Dark-Exciton Phonon Replica in Monolayer WSe2
- Exciton diffusion in WSe2 monolayers embedded in a van der Waals heterostructure
- A fiber-coupled diamond quantum nanophotonic interface
- Gate tunable dark trions in monolayer WSe
- Dynamic exciton funneling by local strain control in a monolayer semiconductor
- Valley-selective chiral phonon replicas of dark excitons and trions in monolayer WSe2
- Theory of Strain-Induced Confinement in Transition Metal Dichalcogenide Monolayers
Cited by in corpus (8)
- Exciton optics, dynamics and transport in atomically thin semiconductors
- Interaction-driven transport of dark excitons in 2D semiconductors with phonon-mediated optical readout
- Visualization of dark excitons in semiconductor monolayers for high-sensitivity strain sensing
- Tensile strain induced brightening of momentum forbidden dark exciton in WS
- Large trion binding energy in monolayer WS via strain-enhanced electron-phonon coupling
- Curvature-enhanced localised emission from dark states in wrinkled monolayer WSe2 at room temperature
- Two dimensional semiconductors: optical and electronic properties
- Measurements of absolute bandgap deformation-potentials of optically-bright bilayer WSe