Exciton diffusion in monolayer semiconductors with suppressed disorder

Abstract

Tightly bound excitons in monolayer semiconductors represent a versatile platform to study two-dimensional propagation of neutral quasiparticles. Their intrinsic properties, however, can be severely obscured by spatial energy fluctuations due to a high sensitivity to the immediate environment. Here, we take advantage of the encapsulation of individual layers in hexagonal boron nitride to strongly suppress environmental disorder. Diffusion of excitons is then directly monitored using time- and spatially-resolved emission microscopy at ambient conditions. We consistently find very efficient propagation with linear diffusion coefficients up to 10\,cm${}^2$/s, corresponding to room temperature effective mobilities as high as 400\,cm${}^2$/Vs as well as a correlation between rapid diffusion and short population lifetime. At elevated densities we detect distinct signatures of many-particle interactions and consequences of strongly suppressed Auger-like exciton-exciton annihilation. A combination of analytical and numerical theoretical approaches is employed to provide pathways towards comprehensive understanding of the observed linear and non-linear propagation phenomena. We emphasize the role of dark exciton states and present a mechanism for diffusion facilitated by free electron hole plasma from entropy-ionized excitons.

References in corpus (42)

• Atomically thin MoS2: A new direct-gap semiconductor
• Two Dimensional Atomic Crystals
• Boron nitride substrates for high-quality graphene electronics
• Excitons in atomically thin transition metal dichalcogenides
• A "missing" family of classical orthogonal polynomials
• Measurement of the optical dielectric function of transition metal dichalcogenide monolayers: MoS2, MoSe2, WS2 and WSe2
• k.p theory for two-dimensional transition metal dichalcogenide semiconductors
• Excitonic linewidth approaching the homogeneous limit in MoS2 based van der Waals heterostructures : accessing spin-valley dynamics
• Excitonic linewidth and coherence lifetime in monolayer transition metal dichalcogenides
• Intrinsic Transport Properties of Electrons and Holes in Monolayer Transition Metal Dichalcogenides
• Magnetic brightening and control of dark excitons in monolayer WSe2
• Electrical suppression of all nonradiative recombination pathways in monolayer semiconductors
• Exciton-exciton annihilation in MoSe2 monolayers
• In-plane Propagation of Light in Transition Metal Dichalcogenide Monolayers: Optical Selection Rules
• Revealing exciton masses and dielectric properties of monolayer semiconductors with high magnetic fields
• Valley excitons in two-dimensional semiconductors
• Charged excitons in monolayer WSe${}_2$: experiment and theory
• Exciton diffusion and halo effects in monolayer semiconductors
• Magneto-Optics of Exciton Rydberg States in a Monolayer Semiconductor
• Trion induced negative photoconductivity in monolayer MoS2
• Nonlinear Photoluminescence in Atomically Thin Layered WSe2 Arising from Diffusion-Assisted Exciton-Exciton Annihilation
• Transport Theory of Monolayer Transition-Metal Dichalcogenides through Symmetry
• Dark excitons in transition metal dichalcogenides
• Large spin-orbit splitting of deep in-gap defect states of engineered sulfur vacancies in monolayer WS2
• Excitons versus electron-hole plasma in monolayer transition metal dichalcogenide semiconductors
• Fundamental Limits of Exciton-Exciton Annihilation for Light Emission in Transition Metal Dichalcogenide Monolayers
• Phonon Sidebands in Transition Metal Dichalcogenides
• Phonon-assisted Photoluminescence from Dark Excitons in Monolayers of Transition Metal Dichalcogenides
• Indirect excitons in van der Waals heterostructures at room temperature
• Enabling valley selective exciton scattering in monolayer WSe${}_2$ through upconversion
• Exciton diffusion in WSe2 monolayers embedded in a van der Waals heterostructure
• Exciton propagation and halo formation in two-dimensional materials
• Upconverted electroluminescence via Auger scattering of interlayer excitons in van der Waals heterostructures
• Intrinsic Lifetime of Higher Excitonic States in Tungsten Diselenide Monolayers
• Exciton states in monolayer MoSe2 and MoTe2 probed by upconversion spectroscopy
• Negative excitonic diffusion in transition metal dichalcogenides
• Phonon wind and drag of excitons in monolayer semiconductors
• Band filling and cross quantum capacitance in ion gated semiconducting transition metal dichalcogenide monolayers
• Hot exciton transport in WSe2 monolayers
• Predicting the Ionization Threshold for Carriers in Excited Semiconductors
• Transient terahertz spectroscopy of excitons and unbound carriers in quasi two-dimensional electron-hole gases
• Exciton routing in the heterostructure of TMD and paraelectrics

Cited by in corpus (50)

• Exciton-exciton interaction in transition metal dichalcogenide monolayers and van der Waals heterostructures
• Suppressing Diffusion-Mediated Exciton Annihilation in 2D Semiconductors Using the Dielectric Environment
• Fast and anomalous exciton diffusion in two-dimensional hybrid perovskites
• Motional narrowing, ballistic transport, and trapping of room-temperature exciton polaritons in an atomically-thin semiconductor
• Exciton optics, dynamics and transport in atomically thin semiconductors
• Nonclassical Exciton Diffusion in Monolayer WSe2
• Boosting quantum yields in 2D semiconductors via proximal metal plates
• Signatures of Dimensionality and Symmetry in Exciton Bandstructure: Consequences for Time-Evolution
• Exciton lifetime and optical linewidth profile via exciton-phonon interactions: Theory and first-principles calculations for monolayer MoS${}_2$
• Complex diffusion-based kinetics of photoluminescence in semiconductor nanoplatelets
• Strain-dependent exciton diffusion in transition metal dichalcogenides
• Quantum interference effect on exciton transport in monolayer semiconductors
• Dark exciton-exciton annihilation in monolayer WSe${}_2$
• Dark-exciton driven energy funneling into dielectric inhomogeneities in two-dimensional semiconductors
• Temporal evolution of low-temperature phonon sidebands in WSe${}_2$ monolayers
• Tunable optical nonlinearity for TMD polaritons dressed by a Fermi sea
• Charged exciton kinetics in monolayer MoSe${}_2$ near ferroelectric domain walls in periodically poled LiNbO${}_3$
• Kapitza-resistance-like exciton dynamics in atomically flat MoSe${}_2$-WSe${}_2$ lateral heterojunction
• Skew Scattering and Side Jump Drive Exciton Valley Hall Effect in Two-Dimensional Crystals
• Leaky exciton condensates in transition metal dichalcogenide moiré bilayers
• Detecting, distinguishing, and spatiotemporally tracking photogenerated charge and heat at the nanoscale
• Enhancing ground state population and macroscopic coherence of room-temperature WS${}_2$ polaritons through engineered confinement
• Ultrafast photocurrent and absorption microscopy of few-layer TMD devices isolate rate-limiting dynamics driving fast and efficient photoresponse
• Microscopic modelling of exciton-polariton diffusion coefficients in atomically thin semiconductors
• Trion photoluminescence and trion stability in atomically thin semiconductors
• Zitterbewegung of moiré excitons in twisted MoS${}_2$/WSe${}_2$ hetero-bilayers
• Phonon-assisted Exciton Dissociation in Transition Metal Dichalcogenides
• Excitonic theory of doping-dependent optical response in atomically thin semiconductors
• Light-matter coupling and non-equilibrium dynamics of exchange-split trions in monolayer WS2
• Phonon-induced exciton weak localization in two-dimensional semiconductors
• Diffusion-related lifetime of indirect excitons in diamond
• Electromagnetic field assisted exciton diffusion in moiré superlattices
• Spatiotemporal dynamics of free and bound excitons in CVD-grown MoS${}_2$ monolayer
• Imaging Seebeck drift of excitons and trions in MoSe2 monolayers
• Trapping Interlayer Excitons in van der Waals Heterostructures by Potential Arrays
• Two dimensional semiconductors: optical and electronic properties
• Viscous hydrodynamics of excitons in van der Waals heterostructures
• Electron dynamics in a 2D nanobubble: A two-level system based on spatial density
• Quantized exciton-exciton annihilation in monolayer WS2 on SrTiO3 substrates with atomically flat terraces
• Phonon-mediated exciton capture in Mo-based transition metal dichalcogenides
• Phase diagram of electron-hole liquid in monolayer heterostructures based on transition metal dichalcogenides
• Wannier-Function-Based Approach to Coupled Exciton-Phonon-Photon Dynamics in Two-Dimensional Semiconductors
• Signatures of valley drift in the diversified band dispersions of bright, gray, and dark excitons in MoS2 monolayers under uni-axial strains
• Polariton transport in 2D semiconductors: Phonon-mediated transitions between ballistic, superdiffusive and exciton-limited regimes
• Limits of funneling efficiency in non-uniformly strained 2D semiconductors
• Hierarchical Disorder in Moiré Exciton Photoluminescence Probed by Spectral-Descriptor Correlations
• Microscopic Theory of Exciton-Exciton Annihilation in Two-Dimensional Semiconductors
• Trion-phonon interaction in atomically thin semiconductors
• Emergence of new optical resonances in single-layer transition metal dichalcogenides with atomic-size phase patterns
• Two-dimensional Ga${}_2$O${}_3$ glass: a large scale passivation and protection material for monolayer WS${}_2$