Tailoring the dielectric screening in WS${}_2$-graphene heterostructures

Abstract

The environment contributes to the screening of Coulomb interactions in two-dimensional semiconductors. This can potentially be exploited to tailor material properties as well as for sensing applications. Here, we investigate the tuning of the band gap and the exciton binding energy in the two-dimensional semiconductor WS${}_2$ via the external dielectric screening. Embedding WS${}_2$ in van der Waals heterostructures with graphene and hBN spacers of thicknesses between one and 16 atomic layers, we experimentally determine both energies as a function of the \WS-to-graphene interlayer distance. We find that the modification to the band gap as well as the exciton binding energy are well described by a one-over-distance dependence, with a significant effect remaining at several nm distance, at which the two layers are electrically well isolated. This observation is explained by a screening arising from an image charge induced by the graphene layer. Furthermore, we find that the effectiveness of graphene to screen Coulomb interactions in nearby WS${}_2$ depends on its doping level and can therefore be controlled via the electric field effect. We determine that, at room temperature, it is modified by approximately 20\% for charge carrier densities of $2\times 10^{12}$ cm${}^{-2}$.

References in corpus (11)

• Dielectric function, screening, and plasmons in 2D graphene
• Strong interlayer coupling in van der Waals heterostructures built from single-layer chalcogenides
• Cross-sectional imaging of individual layers and buried interfaces of graphene-based heterostructures and superlattices
• Atomically thin boron nitride: a tunnelling barrier for graphene devices
• Renormalization of Molecular Electronic Levels at Metal-Molecule Interfaces
• Exciton Binding Energy of Monolayer WS2
• Evidence of high-temperature exciton condensation in 2D atomic double layers
• Probing the influence of dielectric environment on excitons in monolayer WSe2: Insight from high magnetic fields
• Observing imperfection in atomic interfaces for van der Waals heterostructures
• Dielectric permittivity, conductivity and breakdown field of hexagonal boron nitride
• Dielectric Screening by 2D Substrates

Cited by in corpus (12)

• An open-source robust machine learning platform for real-time detection and classification of 2D material flakes
• Breakdown of the static dielectric screening approximation of Coulomb interactions in atomically thin semiconductors
• Distance dependence of the energy transfer mechanism in WS${}_2$-graphene heterostructures
• Nano-optics of transition metal dichalcogenides and their van der Waals heterostructures with electron spectroscopies
• Benchmarking the integration of hexagonal boron nitride crystals and thin films into graphene-based van der Waals heterostructures
• Hyperspectral photoluminescence and reflectance microscopy of 2D materials
• MaskTerial: A Foundation Model for Automated 2D Material Flake Detection
• Excitons in epitaxially grown WS2 on Graphene: a nanometer-resolved EELS and DFT study
• $WS{e}_2$ Monolayers Grown by Molecular Beam Epitaxy on hBN
• Photoluminescence Detection of Polytype Polarization in r-MoS2 Enabled by Asymmetric Dielectric Environments
• Designable exciton mixing through layer alignment in WS${}_2$-graphene heterostructures
• Subnanometric control of coupling between WS${}_2$ monolayers with a molecular spacer