Electronic Structure, Surface Doping, and Optical Response in Epitaxial WSe2 Thin Films

Abstract

High quality WSe2 films have been grown on bilayer graphene (BLG) with layer-by-layer control of thickness using molecular beam epitaxy (MBE). The combination of angle-resolved photoemission (ARPES), scanning tunneling microscopy/spectroscopy (STM/STS), and optical absorption measurements reveal the atomic and electronic structures evolution and optical response of WSe2/BLG. We observe that a bilayer of WSe2 is a direct bandgap semiconductor, when integrated in a BLG-based heterostructure, thus shifting the direct-indirect band gap crossover to trilayer WSe2. In the monolayer limit, WSe2 shows a spin-splitting of 475 meV in the valence band at the K point, the largest value observed among all the MX2 (M = Mo, W; X = S, Se) materials. The exciton binding energy of monolayer-WSe2/BLG is found to be 0.21 eV, a value that is orders of magnitude larger than that of conventional 3D semiconductors, yet small as compared to other 2D transition metal dichalcogennides (TMDCs) semiconductors. Finally, our finding regarding the overall modification of the electronic structure by an alkali metal surface electron doping opens a route to further control the electronic properties of TMDCs.

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• Hopping Transport through Defect-induced Localized States in Molybdenum Disulfide
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Cited by in corpus (38)

• Universal mechanical exfoliation of large-area 2D crystals
• Probing the influence of dielectric environment on excitons in monolayer WSe2: Insight from high magnetic fields
• Quantum-spin-Hall insulator with a large gap: single-layer 1T' WSe${}_2$
• Observation of Topologically Protected States at Crystalline Phase Boundaries in Single-layer WSe2
• Gate controlled spin-valley locking of resident carriers in WSe2 monolayers
• Giant spin-splitting and gap renormalization driven by trions in single-layer WS${}_2$/h-BN heterostructures
• Density-Dependent Quantum Hall States and Zeeman Splitting in Monolayer and Bilayer WSe${}_2$
• Enhanced electron-phonon interaction in multi-valley materials
• In-situ exfoliation method of large-area 2D materials
• Spatially Resolved Electronic Properties of Single-Layer WS${}_2$ on Transition Metal Oxides
• Spin structure of K valleys in single-layer WS${}_2$ on Au(111)
• Spin splitting and strain in epitaxial monolayer WSe${}_2$ on graphene
• Tunable $\Gamma -K$ Valley Populations in Hole-Doped Trilayer WSe${}_2$
• Visualizing Orbital Content of Electronic Bands in Anisotropic 2D Semiconducting ReSe${}_2$
• Nanoscale patterning of quasiparticle band alignment
• Coexistence of electron whispering-gallery modes and atomic collapse states in graphene WSe2 heterostructure quantum dots
• Bound hole states associated to individual vanadium atoms incorporated into monolayer WSe${}_2$
• Growth and Thermo-driven Crystalline Phase Transition of Metastable Monolayer 1T'-WSe2 Thin Film
• Narrow photoluminescence peak of epitaxial MoS${}_2$ on graphene/Ir(111)
• Electronic Structure of Exfoliated Millimeter-Sized Monolayer WSe2 on Silicon Wafer
• Active control of excitonic strong coupling and electroluminescence in electrically driven plasmonic nanocavities
• A novel $\sqrt{19}\times \sqrt{19}$ superstructure in epitaxially grown 1T-TaTe${}_2$
• Visualizing giant ferroelectric gating effects in large-scale WSe${}_2$/BiFeO${}_3$ heterostructures
• Excitation-Dependent High-Lying Excitonic Exchange via Interlayer Energy Transfer from Lower-to-Higher Bandgap 2D Material
• Direct measurement of terahertz conductivity in a gated monolayer semiconductor
• The impact of valley profile on the mobility and Kerr rotation of transition metal dichalcogenides
• Liquid-solid surface phase transformation of fluorinated fullerene on monolayer tungsten diselenide
• Electron energy-loss spectrum and exciton band structure of ${\mathrm{WSe}}_2$ monolayer studied by ab initio Bethe-Salpeter equation calculations
• Holstein polarons, Rashba-like spin splitting and Ising superconductivity in electron-doped MoSe2
• Ultrafast Carrier Dynamics in Two-Dimensional Electron Gas-Like K-doped MoS2
• Quasiparticle gap renormalization driven by internal and external screening in a WS${}_2$ device
• Robust Coulomb Gap and Varied-temperature Study of Epitaxial 1T'-WSe${}_2$ Monolayers
• $WS{e}_2$ Monolayers Grown by Molecular Beam Epitaxy on hBN
• Transition from Optically Excited to Intrinsic Spin Polarization in WSe${}_2$
• Symmetry-breaking and spin-blockage effects on carrier dynamics in single-layer tungsten diselenide
• Non-degenerate valleys in the half-metallic ferromagnet Fe/WS${}_2$
• Vertical quantum confinement in bulk MoS${}_2$
• Epitaxy of new layered materials: 2D chalcogenides and challenges of weak van der Waals interactions