Up- and Down-Conversion between Intra- and Inter-Valley Excitons in Waveguide Coupled Monolayer WSe2
arXiv:2007.10782 · doi:10.1021/acsnano.0c04397
Abstract
The presence of two spin-split valleys in monolayer (1L) transition metal dichalcogenide (TMD) semiconductors supports versatile exciton species classified by their spin and valley quantum numbers. While the spin-0 intravalley exciton, known as the "bright" exciton, is readily observable, other types of excitons, such as the spin-1 intravalley (spin-dark) and spin-0 intervalley (momentum-dark) excitons, are more difficult to access. Here we develop a waveguide coupled 1L tungsten diselenide (WSe2) device to probe these exciton species. In particular, TM coupling to the atomic layer's out-of-plane dipole moments enabled us to not only efficiently collect, but also resonantly populate the spin-1 dark excitons, promising for developing devices with long valley lifetimes. Our work reveals several upconversion processes that bring out an intricate coupling network linking spin-0 and spin-1 intra- and inter-valley excitons, demonstrating that intervalley scattering and spin-flip are very common processes in the atomic layer. These experimental results deepen our understanding of tungsten diselenide exciton physics and illustrate that planar photonic devices are capable of harnessing versatile exciton species in TMD semiconductors.
References in corpus (34)
- Atomically thin MoS2: A new direct-gap semiconductor
- Coupled spin and valley physics in monolayers of MoS2 and other group-VI dichalcogenides
- Excitons in atomically thin transition metal dichalcogenides
- Tightly bound excitons in monolayer WSe2
- k.p theory for two-dimensional transition metal dichalcogenide semiconductors
- Three-band tight-binding model for monolayers of group-VIB transition metal dichalcogenides
- Lattice dynamics in mono- and few-layer sheets of WS2 and WSe2
- Non-linear Optical Spectroscopy of Excited Exciton States for Efficient Valley Coherence Generation in WSe2 Monolayers
- Exciton Radiative Lifetime in Transition Metal Dichalcogenide Monolayers
- Magnetic brightening and control of dark excitons in monolayer WSe2
- Valley contrasting chiral phonons in monolayer hexagonal lattices
- 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
- Helicity resolved Raman scattering of MoS2, MoSe2, WS2 and WSe2 atomic layers
- Magneto-Optics of Exciton Rydberg States in a Monolayer Semiconductor
- Charge-tuneable biexciton complexes in monolayer WSe
- Revealing the Biexciton and Trion-exciton Complexes in BN Encapsulated WSe2
- Brightening of dark excitons in monolayers of semiconducting transition metal dichalcogenides
- Exciton Dynamics in Monolayer Transition Metal Dichalcogenides
- Fine Structure and Lifetime of Dark Excitons in Transition Metal Dichalcogenide Monolayers
- Valley Phonons and Exciton Complexes in a Monolayer Semiconductor
- Coulomb-bound four- and five-particle valleytronic states in an atomically-thin semiconductor
- Enabling valley selective exciton scattering in monolayer WSe through upconversion
- Electroluminescence from multi-particle exciton complexes in transition metal dichalcogenide semiconductors
- Microsecond dark-exciton valley polarization memory in 2D heterostructures
- Gate tunable dark trions in monolayer WSe
- Momentum-Dark Intervalley Exciton in Monolayer Tungsten Diselenide Brightened via Chiral Phonon
- Spin-flip processes and radiative decay of dark intravalley excitons in transition metal dichalcogenide monolayers
- Long valley lifetime of dark excitons in single-layer WSe2
- Multipath optical recombination of intervalley dark excitons and trions in monolayer WSe
- Exciton states in monolayer MoSe2 and MoTe2 probed by upconversion spectroscopy
- Luminescent emission of excited Rydberg excitons from monolayer WSe2
- Ground and Excited Exciton Polarons in Monolayer MoSe2
- Superior valley polarization and coherence of 2s excitons in monolayer WSe2
Cited by in corpus (6)
- Magnetooptics of layered two-dimensional semiconductors and heterostructures: progress and prospects
- Enhancement of Exciton Valley Polarization in Monolayer MoS2 Induced by Scattering
- Symmetry and Control of Spin-Scattering Processes in Two-Dimensional Transition Metal Dichalcogenides
- Twisted MoSe2 Homobilayer Behaving as a Heterobilayer
- Dark exciton energy splitting in monolayer WSe2: insights from time-dependent density-functional theory
- Long-lived populations of momentum- and spin-indirect excitons in monolayer WSe