Regensburg 2016 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 56: 2D Materials: Growth

HL 56.1: Vortrag

Mittwoch, 9. März 2016, 10:30–10:45, S053

Growth and electronic structure of epitaxial single-layer WS₂ on Au(111) — •Maciej Dendzik, Matteo Michiardi, Charlotte Sanders, Marco Bianchi, Jill A. Miwa, Signe S. Grønborg, Jeppe V. Lauritsen, Albert Bruix, Bjørk Hammer, and Philip Hofmann — Department of Physics and Astronomy, Interdisciplinary Nanoscience Center, Aarhus University, 8000 Aarhus C, Denmark

Single-layer WS₂ is a promising alternative to the widely studied MoS₂, because of the larger size of the spin-splitting and the lower effective mass of the valence band maximum. Here we present a detailed study of the electronic structure of the large-area single-layer WS₂ grown epitaxially on Au(111) using evaporation of W atoms in a low pressure H₂S atmosphere. The growth process is characterized by means of scanning tunneling microscopy, low-energy electron diffraction and core-level spectroscopy. The electronic band structure of the single-layer WS₂ 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)m_e and 0.57(09)m_e for the upper and lower split valence band, respectively.