Highly Valley-Polarized Singlet and Triplet Interlayer Excitons in van der Waals Heterostructure
arXiv:1901.00200 · doi:10.1103/PhysRevB.100.041402
Abstract
Two-dimensional semiconductors feature valleytronics phenomena due to locking of the spin and momentum valley of the electrons. However, the valley polarization is intrinsically limited in monolayer crystals by the fast intervalley electron-hole exchange. Hetero-bilayer crystals have been shown to have a longer exciton lifetime and valley depolarization time. But the reported valley polarization was low; the valley selection rules and mechanisms of valley depolarization remains controversial. Here, we report singlet and brightened triplet interlayer excitons both with over 80% valley polarizations, cross- and co-polarized with the pump laser, respectively. This is achieved in WSe2/MoSe2 hetero-bilayers with precise momentum valley alignment and narrow emission linewidth. The high valley polarizations allow us to identify the band minima in a hetero-structure and con_rm unambiguously the direct band-gap exciton transition, ultrafast charge separation, strongly suppressed valley depolarization. Our results pave the way for using semiconductor heterobilayers to control valley selection rules for valleytronic applications.
References in corpus (23)
- Coupled spin and valley physics in monolayers of MoS2 and other group-VI dichalcogenides
- Control of valley polarization in monolayer MoS2 by optical helicity
- Ultrafast Charge Transfer in Atomically Thin MoS2/WS2 Heterostructures
- Excitons in atomically thin transition metal dichalcogenides
- Moiré Excitons in Van der Waals Heterostructures
- Signatures of moiré-trapped valley excitons in MoSe/WSe heterobilayers
- Breaking of valley degeneracy by magnetic field in monolayer MoSe2
- Electronic structures and theoretical modelling of two-dimensional group-VIB transition metal dichalcogenides
- Moiré excitons: from programmable quantum emitter arrays to spin-orbit coupled artificial lattices
- Valley dynamics probed through charged and neutral exciton emission in monolayer WSe2
- Long-lived direct and indirect interlayer excitons in van der Waals heterostructures
- Carrier and polarization dynamics in monolayer MoS2
- Bright excitons in monolayer transition metal dichalcogenides: from Dirac cones to Dirac saddle points
- Exciton fine structure and spin decoherence in monolayers of transition metal dichalcogenides
- Exciton Valley Dynamics probed by Kerr Rotation in WSe2 Monolayers
- Theory of optical absorption by interlayer excitons in transition metal dichalcogenide heterobilayers
- Control of interlayer excitons in two-dimensional van der Waals heterostructures
- Double Indirect Interlayer Exciton in a MoSe2/WSe2 van der Waals Heterostructure
- Polarization and time-resolved photoluminescence spectroscopy of excitons in MoSe2 monolayers
- Brightened spin-triplet interlayer excitons and optical selection rules in van der Waals heterobilayers
- Directional Interlayer Spin-Valley Transfer in Two-Dimensional Heterostructures
- Long-Lived Valley Polarization of Intra-Valley Trions in Monolayer WSe2
- Large effective mass and interaction-enhanced Zeeman splitting of -valley electrons in MoSe
Cited by in corpus (22)
- Interlayer Exciton Laser with Extended Spatial Coherence in an Atomically-Thin Heterostructure
- Twist Angle Dependent Interlayer Exciton Lifetimes in van der Waals Heterostructures
- Excitons in mesoscopically reconstructed moiré heterostructures
- Giant Valley-Zeeman Splitting from Spin-Singlet and Spin-Triplet Interlayer Excitons in WSe2/MoSe2 Heterostructure
- Moiré excitons in MoSe-WSe heterobilayers and heterotrilayers
- Moiré and beyond in transition metal dichalcogenide twisted bilayers
- Nanoscale trapping of interlayer excitons in a 2D semiconductor heterostructure
- Moiré-trapped interlayer trions in a charge-tunable WSe/MoSe heterobilayer
- Electrically controlled emission from singlet and triplet exciton species in atomically thin light emitting diodes
- Localization and interaction of interlayer excitons in MoSe/WSe heterobilayers
- Leaky exciton condensates in transition metal dichalcogenide moiré bilayers
- Spin-valley dynamics in alloy-based transition metal dichalcogenide heterobilayers
- Ultrafast Chirality-dependent Dynamics from Helicity-resolved Transient Absorption Spectroscopy
- Confined-state physics and signs of fermionization of moiré excitons in WSe/MoSe heterobilayers
- Moiré-localized interlayer exciton wavefunctions captured by imaging its electron and hole constituents
- Exciton Transport under Periodic Potential in MoSe2/WSe2 Heterostructures
- Trapping the carrier in the spin-locked MoS2 atomic valley by absorption of chiral L-cysteine
- Electrically tunable MoSe/WSe heterostructure-based quantum dot
- Topological spin-up triplet excitonic condensation in two-dimensional electron-hole systems
- Robust Interlayer Exciton Interplay in Twisted van der Waals Heterotrilayer on a Broadband Bragg Reflector up to Room Temperature
- Trimer superfluidity of antiparallel dipolar excitons in a bilayer heterostructure
- Non-local interactions and supersolidity of moiré excitons