Valley excitons in two-dimensional semiconductors

Abstract

Monolayer group-VIB transition metal dichalcogenides have recently emerged as a new class of semiconductors in the two-dimensional limit. The attractive properties include: the visible range direct band gap ideal for exploring optoelectronic applications; the intriguing physics associated with spin and valley pseudospin of carriers which implies potentials for novel electronics based on these internal degrees of freedom; the exceptionally strong Coulomb interaction due to the two-dimensional geometry and the large effective masses. The physics of excitons, the bound states of electrons and holes, has been one of the most actively studied topics on these two-dimensional semiconductors, where the excitons exhibit remarkably new features due to the strong Coulomb binding, the valley degeneracy of the band edges, and the valley dependent optical selection rules for interband transitions. Here we give a brief overview of the experimental and theoretical findings on excitons in two-dimensional transition metal dichalcogenides, with focus on the novel properties associated with their valley degrees of freedom.

Topical review, published online on National Science Review in Jan 2015

References in corpus (28)

• Two Dimensional Atomic Crystals
• Valley polarization in MoS2 monolayers by optical pumping
• Atomically thin p-n junctions with van der Waals heterointerfaces
• The Valley Hall Effect in MoS2 Transistors
• Observation of giant bandgap renormalization and excitonic effects in a monolayer transition metal dichalcogenide semiconductor
• Observation of Long-Lived Interlayer Excitons in Monolayer MoSe2-WSe2 Heterostructures
• Tightly bound excitons in monolayer WSe2
• Valley Dependent Optoelectronics from Inversion Symmetry Breaking
• Strong interlayer coupling in van der Waals heterostructures built from single-layer chalcogenides
• Optical signature of symmetry variations and spin-valley coupling in atomically thin tungsten dichalcogenides
• Probing Excitonic Dark States in Single-layer Tungsten Disulfide
• Magnetic Control of Valley Pseudospin in Monolayer WSe2
• Quasiparticle band structures and optical properties of strained monolayer MoS2 and WS2
• Valley Zeeman Effect in Elementary Optical Excitations of a Monolayer WSe2
• Breaking of valley degeneracy by magnetic field in monolayer MoSe2
• Electronic structures and theoretical modelling of two-dimensional group-VIB transition metal dichalcogenides
• Non-linear Optical Spectroscopy of Excited Exciton States for Efficient Valley Coherence Generation in WSe2 Monolayers
• High-temperature superfluidity with indirect excitons in van der Waals heterostructures
• Valley Splitting and Polarization by the Zeeman Effect in Monolayer MoSe2
• Robust optical emission polarization in MoS2 monolayers through selective valley excitation
• Ultrafast Generation of Pseudo-magnetic Field for Valley Excitons in WSe2 Monolayers
• Nonlinear Photoluminescence in Atomically Thin Layered WSe2 Arising from Diffusion-Assisted Exciton-Exciton Annihilation
• Dense network of one-dimensional mid-gap metallic modes in monolayer MoSe2 and their spatial undulations
• Temperature Dependent Valley Relaxation Dynamics in Single Layer WS2 Measured Using Ultrafast Spectroscopy
• Nonlinear valley and spin currents from Fermi pocket anisotropy in 2D crystals
• Fast Exciton Annihilation by Capture of Electrons or Holes by Defects via Auger Scattering in Monolayer Metal Dichalcogenides
• Berry Phase Effect on Exciton Transport and Bose Einstein Condensate
• Ultrafast Terahertz Probe of Transient Evolution of Charged and Neutral Phase of Photoexcited Electron-hole Gas in Monolayer Semiconductor

Cited by in corpus (107)

• Excitons in atomically thin transition metal dichalcogenides
• Charged excitons in monolayer WSe${}_2$: experiment and theory
• Direct Measurement of Exciton Valley Coherence in Monolayer WSe${}_2$
• Exciton diffusion and halo effects in monolayer semiconductors
• Electronic Structure, Surface Doping, and Optical Response in Epitaxial WSe2 Thin Films
• Brightened spin-triplet interlayer excitons and optical selection rules in van der Waals heterobilayers
• Spin and valley dynamics of excitons in transition metal dichalcogenides monolayers
• Gate tunable dark trions in monolayer WSe${}_2$
• Directional Interlayer Spin-Valley Transfer in Two-Dimensional Heterostructures
• Exciton diffusion in monolayer semiconductors with suppressed disorder
• Valley pseudospin in monolayer MoSi2N4 and MoSi2As4
• Optical properties of charged excitons in two-dimensional semiconductors
• Spin-Polarized Electrons in Monolayer MoS${}_2$
• Temperature dependent excitonic effects in the optical properties of single-layer MoS${}_2$
• Intrinsic and Extrinsic Defect-related Excitons in TMDCs
• Interplay between spin proximity effect and charge-dependent exciton dynamics in MoSe${}_2$ / CrBr${}_3$ van der Waals heterostructures
• Exciton-exciton interaction in transition metal dichalcogenide monolayers and van der Waals heterostructures
• Spin-flip processes and radiative decay of dark intravalley excitons in transition metal dichalcogenide monolayers
• Multipath optical recombination of intervalley dark excitons and trions in monolayer WSe${}_2$
• On the applicability of quantum-optical concepts in strong-coupling nanophotonics
• Excitonic and valleytronic signatures of correlated states at fractional fillings of a moiré superlattice
• The valley Zeeman effect in inter- and intra-valley trions in monolayer WSe${}_2$
• Exciton optics, dynamics and transport in atomically thin semiconductors
• Intrinsic exciton states mixing and non-linear optical properties in transition metal dichalcogenide monolayers
• Nonclassical Exciton Diffusion in Monolayer WSe2
• Negative excitonic diffusion in transition metal dichalcogenides
• Phonon-assisted oscillatory exciton dynamics in monolayer MoSe2
• Valley Zeeman effect and Landau levels in Two-Dimensional Transition Metal Dichalcogenides
• Electric field and Strain-induced Band-gap Engineering and Manipulation of the Rashba Spin Splitting in Janus van der Waals Heterostructures
• Nanoscale trapping of interlayer excitons in a 2D semiconductor heterostructure
• Spatial extent of the excited exciton states in WS${}_2$ monolayers from diamagnetic shifts
• Dark trions and biexcitons in WS2 and WSe2 made bright by e-e scattering
• Valley qubit in gated MoS${}_2$ monolayer quantum dot
• Inter-valley dark trion states with spin lifetimes of 150 ns in WSe${}_2$
• Novel valley depolarization dynamics and valley Hall effect of exciton in mono- and bilayer MoS${}_2$
• Auger recombination of dark excitons in $\mathrm{W}{\mathrm{S}}_2$ and $\mathrm{WS}{\mathrm{e}}_2$ monolayers
• Interlayer Exciton Diode and Transistor
• Valley polarized relaxation and upconversion luminescence from Tamm-Plasmon Trion-Polaritons with a MoSe2 monolayer
• Autoionization and dressing of excited excitons by free carriers in monolayer WSe2
• Attractive and repulsive exciton-polariton interactions mediated by an electron gas
• Exciton valley depolarization in monolayer transition-metal dichalcogenides
• Review of Ultrafast Spectroscopy Studies of Valley Carrier Dynamics in Two Dimensional Semiconducting Transition Metal Dichalcogenides
• Exciton-polaritons in transition-metal dichalcogenides and their direct excitation via energy transfer
• Measuring valley polarization in two-dimensional materials with second-harmonic spectroscopy
• Electron recoil effect in electrically tunable MoSe2 monolayers
• Enhancement of Exciton Valley Polarization in Monolayer MoS2 Induced by Scattering
• Breakdown of the static approximation for free carrier screening of excitons in monolayer semiconductors
• Exciton-phonon relaxation bottleneck and radiative decay of thermal exciton reservoir in two-dimensional materials
• Valley Degree of Freedom in Two-Dimensional van der Waals Materials
• Band nesting and exciton spectrum in monolayer MoS${}_2$
• Chirality of Valley Excitons in Monolayer Transition-Metal Dichalcogenides
• Quantum-electrodynamical approach to the exciton spectrum in Transition-Metal Dichalcogenides
• Skew Scattering and Side Jump Drive Exciton Valley Hall Effect in Two-Dimensional Crystals
• Highly directional and coherent emission from dark excitons enabled by bound states in the continuum
• A colloquium on the variational method applied to excitons in 2D materials
• Charged exctions in two-dimensional transition-metal dichalcogenides - semiclassical calculation of Berry-curvature effects
• Control of the exciton valley dynamics in van der Waals heterostructures
• Leaky exciton condensates in transition metal dichalcogenide moiré bilayers
• Electrically tunable topological transport of moiré polaritons
• Excitonic response in TMD heterostructures from first-principles: impact of stacking, twisting, and interlayer distance
• Valley polarized current and resonant electronic transport in a non-uniform ${\mathbf{MoS}}_2$ zigzag nanoribbon
• All-optical valley switch and clock of electronic dephasing
• Chiral topological excitons in the monolayer transition metal dichalcogenides
• Non-Generic Dispersion of Excitons in the Bulk of WSe${}_2$
• Light-matter coupling and non-equilibrium dynamics of exchange-split trions in monolayer WS2
• Chiral excitonics in monolayer semiconductors on patterned dielectric
• Chiral Topological Excitons in a Chern Band Insulator
• Optical induced Spin Current in Monolayer NbSe${}_2$
• Dark-state impact on the exciton recombination of WS2 monolayers as revealed by multi-time-scale pump-and-probe spectroscopy
• Optical signatures of periodic magnetization: the moiré Zeeman effect
• Polaritons in an electron gas -- quasiparticles and Landau effective interactions
• Tunable Excitons in Rhombohedral Trilayer Graphene
• Magnetic field mixing and splitting of bright and dark excitons in monolayer MoSe2
• Effect of intravalley and intervalley electron-hole exchange on the nonlinear optical response of monolayer MoSe${}_2$
• Excitons and trions with negative effective masses in two-dimensional semiconductors
• Nonlinear optical Hall effect of few-layered NbSe2
• Anomalous magneto-optical response and chiral interface of dipolar excitons at twisted valleys
• Coupled exciton internal and center-of-mass motions in two-dimensional semiconductors by a periodic electrostatic potential
• Two dimensional semiconductors: optical and electronic properties
• Excitons and trions in CrSBr bilayers
• Cross-dimensional valley excitons from Förster coupling in arbitrarily twisted stacks of monolayer semiconductors
• Phonon-mediated exciton relaxation in two-dimensional semiconductors: selection rules and relaxation pathways
• Waveguiding valley excitons in monolayer transition metal dicalcogenides by dielectric interfaces in the substrate
• Third-order polarizability of interlayer excitons in hetero-bilayers
• Brightening odd-parity excitons in transition-metal dichalcogenides: Rashba spin-orbit interaction, skyrmions, and cavity polaritons
• Pairing of electro-magnetic bosons under spin-orbit coupling
• Tunable nonlinear excitonic optical response in biased bilayer graphene
• Twistronics and moiré superlattice physics in 2D transition metal dichalcogenides
• Non-Hermitian theory of valley excitons in two-dimensional semiconductors
• Electron-Doping Induced Semiconductor to Metal Transitions in ZrSe2 Layers via Copper Atomic Intercalation
• Tuning of exciton type by environmental screening
• Topologically-enhanced exciton transport
• Valley Gapless Semiconductor: Models and Applications
• Chiral excitonic systems in twisted bilayers from Förster coupling and unconventional excitonic Hall effects
• Signatures of valley drift in the diversified band dispersions of bright, gray, and dark excitons in MoS2 monolayers under uni-axial strains
• High-purity valley-polarized currents induced by bichromatic optical fields in two-dimensional materials
• Engineering topological exciton structures in two-dimensional semiconductors by a periodic electrostatic potential
• Fine structure of negatively charged and neutral excitons in monolayer MoS${}_2$
• Nonlinear optics in the electron-hole continuum in 2D semiconductors: two-photon transition, second harmonic generation and valley current injection
• Trion-phonon interaction in atomically thin semiconductors
• Non-local interactions and supersolidity of moiré excitons
• Gauge-invariant optical selection rules for excitons
• Hyperfine interaction in atomically thin transition metal dichalcogenides
• Valley lifetimes of conduction band electrons in monolayer WSe${}_2$
• Radiative Decay of Dark Exciton Related Emission in a Sandwiched Monolayer WSe2 Revealed by Room Temperature Micro and Nano Photoluminescence
• Interlayer Coupling Effect in van der Waals Heterostructures of Transition Metal Dichalcogenides
• Excitonic Transport and Intervalley Scattering in Exfoliated MoSe2 Monolayer Revealed by Four-Wave-Mixing Transient Grating Spectroscopy