Growth and electronic structure of epitaxial single-layer WS₂ on Au(111)

الأصل · EN

Large-area single-layer WS₂ is grown epitaxially on Au(111) using evaporation of W atoms in a low pressure H₂S atmosphere. It is characterized by means of scanning tunneling microscopy, low-energy electron diffraction and core-level spectroscopy. Its electronic band structure is determined by angle-resolved photoemission spectroscopy. The valence band maximum at K is found to be significantly higher than at Γ. The observed dispersion around K is in good agreement with density functional theory calculations for a free-standing monolayer, whereas the bands at Γ are found to be hybridized with states originating from the Au substrate. Strong spin-orbit coupling leads to a large spin-splitting of the bands in the neighborhood of the K points, with a maximum splitting of 419(11) meV. The valence band dispersion around K is found to be highly anisotropic with spin-branch dependent effective hole masses of 0.40(02)mₑ and 0.57(09)mₑ for the upper and lower split valence band, respectively. The large size of the spin-splitting and the low effective mass of the valence band maximum make single-layer WS₂ a promising alternative to the widely studied MoS₂ for applications in electronics, spintronics and valleytronics.