Optical response of monolayer, few-layer and bulk tungsten disulfide

Abstract

We present a comprehensive optical study of thin films of tungsten disulfide (WS${}_2$) with layer thicknesses ranging from mono- to octalayer and in the bulk limit. It is shown that the optical band-gap absorption of monolayer WS${}_2$ is governed by competing resonances arising from one neutral and two distinct negatively charged excitons whose contributions to the overall absorption of light vary as a function of temperature and carrier concentration. The photoluminescence response of monolayer WS${}_2$ is found to be largely dominated by disorder/impurity- and/or phonon-assisted recombination processes. The indirect band-gap luminescence in multilayer WS${}_2$ turns out to be a phonon-mediated process whose energy evolution with the number of layers surprisingly follows a simple model of a two-dimensional confinement. The energy position of the direct band-gap response (A and B resonances) is only weakly dependent on the layer thickness, which underlines an approximate compensation of the effect of the reduction of the exciton binding energy by the shrinkage of the apparent band gap. The A-exciton absorption-type spectra in multilayer WS${}_2$ display a non-trivial fine structure which results from the specific hybridization of the electronic states in the vicinity of the K-point of the Brillouin zone. The effects of temperature on the absorption-like and photoluminescence spectra of various WS${}_2$ layers are also quantified.

13 pages, 13 figures, electronic supporting information

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Cited by in corpus (21)

• Strong light-matter interaction with self-hybridized bound states in the continuum in monolithic van der Waals metasurfaces
• Excitonic complexes in $n$-doped WS${}_2$ monolayer
• Layer degree of freedom for excitons in transition metal dichalcogenides
• Stacking-dependent exciton multiplicity in WSe${}_2$ bilayers
• Phonon-assisted exciton and trion conversion efficiency in transition metal Dichalcogenides
• Exciton-polaritons in multilayer WSe${}_2$ in a planar microcavity
• Controlling valley splitting and Polarization of dark- and bi-excitons in monolayer WS${}_2$ by a tilted magnetic field
• The optical response of artificially twisted MoS${}_2$ bilayers
• Impacts of dielectric screening on the luminescence of monolayer WSe${}_2$
• Anisotropic complex refractive indices of atomically thin materials: determination of the optical constants of few-layer black phosphorus
• Excitons and trions in WSSe monolayers
• Indium selenides for next-generation low-power computing devices
• Analogy and dissimilarity of excitons in monolayer and bilayer of MoSe${}_2$
• Raman scattering excitation in monolayers of semiconducting transition metal dichalcogenides
• Flattening conduction and valence bands for interlayer excitons in a moiré MoS${}_2$/WSe${}_2$ heterobilayer
• Symmetric Domain Segmentation in WS2 Flakes: Correlating spatially resolved photoluminescence, conductance with valley polarization
• Extremely high excitonic $g$-factors in 2D crystals by alloy-induced admixing of band states
• Optical response of WSe${}_2$-based vertical tunneling junction
• Rydberg series of intralayer K-excitons in WSe${}_2$ multilayers
• Valley Emission and Upconversion in Isotopically Engineered Monolayer WS${}_2$ under Resonant Excitation
• Electrically modulated light-emitting diodes driven by resonant and antiresonant tunneling between Cr${}_2$Ge${}_2$Te${}_6$ electrodes