Exciton Dynamics in Monolayer Transition Metal Dichalcogenides

Abstract

Since the discovery of semiconducting monolayer transition metal dichalcogenides, a variety of experimental and theoretical studies have been carried out seeking to understand the intrinsic exciton population decay and valley relaxation dynamics. Reports of the exciton decay time range from hundreds of femtoseconds to ten nanoseconds, while the valley depolarization time can exceed one nanosecond. At present, however, a consensus on the microscopic mechanisms governing exciton radiative and non-radiative recombination is lacking. The strong exciton oscillator strength resulting in up to 20% absorption for a single monolayer points to ultrafast radiative recombination. However, the low quantum yield and large variance in the reported lifetimes suggest that non-radiative Auger-type processes obscure the intrinsic exciton radiative lifetime. In either case, the electron-hole exchange interaction plays an important role in the exciton spin and valley dynamics. In this article, we review the experiments and theory that have led to these conclusions and comment on future experiments that could complement our current understanding.

References in corpus (50)

• Atomically thin MoS2: A new direct-gap semiconductor
• Two Dimensional Atomic Crystals
• Coupled spin and valley physics in monolayers of MoS2 and other group-VI dichalcogenides
• Control of valley polarization in monolayer MoS2 by optical helicity
• Valley polarization in MoS2 monolayers by optical pumping
• Observation of tightly bound trions in monolayer MoS2
• Emerging Device Applications for Semiconducting Two-Dimensional Transition Metal Dichalcogenides
• MoS_2 as an ideal material for valleytronics: valley-selective circular dichroism and valley Hall effect
• Exciton Binding Energy and Nonhydrogenic Rydberg Series in Monolayer WS2
• Grains and grain boundaries in highly crystalline monolayer molybdenum disulfide
• 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
• Optical Spectrum of MoS${}_2$: Many-body Effects and Diversity of Exciton States
• Extraordinary room-temperature photoluminescence in WS2 monolayers
• Electrical Control of Two-Dimensional Neutral and Charged Excitons in a Monolayer Semiconductor
• Optical Generation of Excitonic Valley Coherence in Monolayer WSe2
• Tightly bound excitons in monolayer WSe2
• Strong light-matter coupling in two-dimensional atomic crystals
• Probing Excitonic Dark States in Single-layer Tungsten Disulfide
• Three-band tight-binding model for monolayers of group-VIB transition metal dichalcogenides
• Theory of Neutral and Charged Excitons in Monolayer Transition Metal Dichalcogenides
• Low-temperature photocarrier dynamics in monolayer MoS2
• Exciton Binding Energy of Monolayer WS2
• Ultrafast Dynamics of Defect-Assisted Electron-Hole Recombination in Monolayer MoS2
• Non-linear Optical Spectroscopy of Excited Exciton States for Efficient Valley Coherence Generation in WSe2 Monolayers
• Intrinsic Exciton Linewidth in Monolayer Transition Metal Dichalcogenides
• Direct imaging of the band profile in single layer $Mo{S}_2$ on graphite: quasiparticle energy gap, metallic edge states and edge band bending
• Probing excitonic states in ultraclean suspended two-dimensional semiconductors by photocurrent spectroscopy
• Valley dynamics probed through charged and neutral exciton emission in monolayer WSe2
• Carrier and polarization dynamics in monolayer MoS2
• Exciton-exciton annihilation in MoSe2 monolayers
• Spin-Layer Locking Effects in Optical Orientation of Exciton Spin in Bilayer WSe2
• Bright excitons in monolayer transition metal dichalcogenides: from Dirac cones to Dirac saddle points
• Valley depolarization due to inter- and intra-valley electron-hole exchange interactions in monolayer MoS${}_2$
• Direct Measurement of Exciton Valley Coherence in Monolayer WSe${}_2$
• Exciton fine structure and spin decoherence in monolayers of transition metal dichalcogenides
• Exciton Valley Dynamics probed by Kerr Rotation in WSe2 Monolayers
• Nonlinear Photoluminescence in Atomically Thin Layered WSe2 Arising from Diffusion-Assisted Exciton-Exciton Annihilation
• Dramatic reduction of surface recombination by in-situ surface passivation of silicon nanowires
• Trion Formation Dynamics in Monolayer Transition Metal Dichalcogenides
• Valley Carrier Dynamics in Monolayer Molybdenum Disulphide from Helicity Resolved Ultrafast Pump-probe Spectroscopy
• Surface Recombination Limited Lifetimes of Photoexcited Carriers in Few-Layer Transition Metal Dichalcogenide MoS2
• Intervalley biexcitons and many-body effects in monolayer MoS2
• Fundamental Limits of Exciton-Exciton Annihilation for Light Emission in Transition Metal Dichalcogenide Monolayers
• Polarization and time-resolved photoluminescence spectroscopy of excitons in MoSe2 monolayers
• Spin and valley dynamics of excitons in transition metal dichalcogenides monolayers
• Coherent Electronic Coupling in Atomically Thin MoSe2
• Temperature Dependent Valley Relaxation Dynamics in Single Layer WS2 Measured Using Ultrafast Spectroscopy
• Fast Exciton Annihilation by Capture of Electrons or Holes by Defects via Auger Scattering in Monolayer Metal Dichalcogenides
• Population pulsation resonances of excitons in monolayer MoSe2 with sub 1 μeV linewidth

Cited by in corpus (50)

• Hundredfold Enhancement of Light Emission via Defect Control in Monolayer Transition-Metal Dichalcogenides
• Twist Angle Dependent Interlayer Exciton Lifetimes in van der Waals Heterostructures
• The ultrafast onset of exciton formation in 2D semiconductors
• Directional Interlayer Spin-Valley Transfer in Two-Dimensional Heterostructures
• Long-Lived Valley Polarization of Intra-Valley Trions in Monolayer WSe2
• Coherent and Incoherent Coupling Dynamics between Neutral and Charged Excitons in Monolayer MoSe2
• Ultrafast dynamics in monolayer TMDCs: the interplay of dark excitons, phonons and intervalley Coulomb exchange
• Intrinsic exciton states mixing and non-linear optical properties in transition metal dichalcogenide monolayers
• Valley Trion Dynamics in Monolayer MoSe${}_2$
• Microscopic Origin of the Valley Hall Effect in Transition Metal Dichalcogenides Revealed by Wavelength Dependent Mapping
• Femtosecond valley polarization and topological resonances in transition metal dichalcogenides
• Phonon wind and drag of excitons in monolayer semiconductors
• Trion Valley Coherence in Monolayer Semiconductors
• The interplay between excitons and trions in a monolayer of MoSe${}_2$
• Inverse Funnel Effect of Excitons in Strained Black Phosphorus
• Momentum-Resolved Exciton Coupling and Valley Polarization Dynamics in Monolayer WS${}_2$
• Review of Ultrafast Spectroscopy Studies of Valley Carrier Dynamics in Two Dimensional Semiconducting Transition Metal Dichalcogenides
• Harnessing Exciton-Exciton Annihilation in Two-Dimensional Semiconductors
• Nonlinear optics in 2D materials: from classical to quantum
• Strain control of exciton and trion spin-valley dynamics in monolayer transition metal dichalcogenides
• Theory of topological exciton insulators and condensates in flat Chern bands
• Defect Passivation of 2D Semiconductors by Fixating Chemisorbed Oxygen Molecules via h-BN Encapsulations
• Resonantly excited exciton dynamics in two-dimensional MoSe${}_2$ monolayers
• Up- and Down-Conversion between Intra- and Inter-Valley Excitons in Waveguide Coupled Monolayer WSe2
• Ultrafast photocurrent and absorption microscopy of few-layer TMD devices isolate rate-limiting dynamics driving fast and efficient photoresponse
• Optical Emission from Light-like and Particle-like Excitons in Monolayer Transition Metal Dichalcogenides
• Nonlinear exciton drift in piezoelectric two-dimensional materials
• Theory of the Coherent Response of Magneto-Excitons and Magneto-Biexcitons in Monolayer Transition Metal Dichalcogenides
• Gate-tunable trion switch for excitonic device applications
• Pump-triple sum-frequency-probe spectroscopy of transition metal dichalcogenides
• Single-molecule-resolution ultrafast near-field optical microscopy via plasmon lifetime extension
• Photonics in Flatland: Challenges and Opportunities for Nanophotonics with 2D Semiconductors
• Investigation of indirect excitons in bulk $2H$-MoS${}_2$ using transmission electron energy-loss spectroscopy
• The Importance of Pure Dephasing in the Optical Response of Excitons in High-quality van der Waals Heterostructures
• Photoluminescence kinetics of dark and bright excitons in atomically thin MoS${}_2$
• Dynamic screening of quasiparticles in WS${}_2$ monolayers
• Phonon-assisted Auger decay of excitons in doped transition metal dichalcogenide monolayers
• Nonexponential photoluminescence dynamics in an inhomogeneous ensemble of excitons in WSe${}_2$ monolayers
• Engineering Purcell factor anisotropy for dark and bright excitons in two dimensional semiconductors
• Spin/Valley pumping of resident electrons in WSe2 and WS2 monolayers
• Temperature-dependent Optical and Polaritonic Properties of hBN-encapsulated Monolayer TMDs
• Localized Gradual Photomediated Brightness and Lifetime Increase of Superacid Treated Monolayer MoS${}_2$
• Long-lived Nonlinear Oscillatory States in Interacting Relativistic Bose-Einstein Condensates
• Fine structure of negatively charged and neutral excitons in monolayer MoS${}_2$
• Variational and field-theoretical approach to exciton-exciton interactions and biexcitons in semiconductors
• Femtosecond-Nanometer Visualization of Exciton Dynamics in MoSe${}_2$
• Coherence and density dynamics of excitons in a single-layer MoS${}_2$ reaching the homogeneous limit
• Dynamics of resonantly excited excitons in MoSe${}_2$ and WS${}_2$ single-layers monitored with four-wave mixing
• Two-dimensional Ga${}_2$O${}_3$ glass: a large scale passivation and protection material for monolayer WS${}_2$
• Tracking the photoinduced dynamics of a dark excitonic state in single-layer WS${}_2$ via resonant Autler-Townes splitting