Negative excitonic diffusion in transition metal dichalcogenides

Abstract

While exciton relaxation in transition metal dichalcogenides (TMDs) has been intensively studied, spatial exciton propagation has received only little attention - in spite of being a key process for optoelectronics and having already shown interesting unconventional behaviours (e.g. spatial halos). Here, we study the spatiotemporal dynamics in TMDs and track the way of optically excited excitons in time, momentum, and space. In particular, we investigate the temperature-dependent exciton diffusion including the remarkable exciton landscape constituted by bright and dark states. Based on a fully quantum mechanical approach, we show at low temperatures an unexpected negative transient diffusion. This phenomenon can be traced back to the existence of dark exciton states in TMDs and is a result of an interplay between spatial exciton diffusion and intervalley exciton-phonon scattering.

6 pages, 5 figures

References in corpus (7)

• Tightly bound excitons in monolayer WSe2
• k.p theory for two-dimensional transition metal dichalcogenide semiconductors
• Intrinsic Transport Properties of Electrons and Holes in Monolayer Transition Metal Dichalcogenides
• Nonlinear Photoluminescence in Atomically Thin Layered WSe2 Arising from Diffusion-Assisted Exciton-Exciton Annihilation
• Brightening of dark excitons in monolayers of semiconducting transition metal dichalcogenides
• Ultrafast transition between exciton phases in van der Waals heterostructures
• Intrinsic Lifetime of Higher Excitonic States in Tungsten Diselenide Monolayers

Cited by in corpus (19)

• Exciton diffusion in monolayer semiconductors with suppressed disorder
• Exciton optics, dynamics and transport in atomically thin semiconductors
• Nonclassical Exciton Diffusion in Monolayer WSe2
• Strain-dependent exciton diffusion in transition metal dichalcogenides
• Temporal evolution of low-temperature phonon sidebands in WSe${}_2$ monolayers
• Microscopic origin of anomalous interlayer exciton transport in van der Waals heterostructures
• Kapitza-resistance-like exciton dynamics in atomically flat MoSe${}_2$-WSe${}_2$ lateral heterojunction
• Microscopic modelling of exciton-polariton diffusion coefficients in atomically thin semiconductors
• Nonlocal Exciton-Photon Interactions in Hybrid High-Q Beam Nanocavities with Encapsulated MoS${}_2$ Monolayers
• Electrically tunable dipolar interactions between layer-hybridized excitons
• Phonon-assisted Exciton Dissociation in Transition Metal Dichalcogenides
• Negative diffusion of excitons in quasi-two-dimensional systems
• Spatiotemporal dynamics of moiré excitons in van der Waals heterostructures
• Impact of charge transfer excitons on unidirectional exciton transport in lateral TMD heterostructures
• Two dimensional semiconductors: optical and electronic properties
• Phonon-mediated exciton capture in Mo-based transition metal dichalcogenides
• Polariton transport in 2D semiconductors: Phonon-mediated transitions between ballistic, superdiffusive and exciton-limited regimes
• Impact of an electron Wigner crystal on exciton propagation
• Strain-induced exciton mobility in layered WS2 from first principles