Berlin 2015 – scientific programme

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O: Fachverband Oberflächenphysik

O 57: 2D Materials beyond Graphene: TMDCs, Slicene and Relatives

O 57.10: Talk

Wednesday, March 18, 2015, 17:30–17:45, MA 005

Growth and Characterization of Epitaxial Single-Layer MoS₂ on Au(111) — •Jill Miwa, Søren Ulstrup, Signe Sørensen, Maciej Dendzik, Antonija Grubišić Čabo, Marco Bianchi, Jeppe Vang Lauritsen, and Philip Hofmann — Dept. of Physics & Astronomy, Aarhus University, Aarhus, Denmark

We present a method for synthesizing epitaxial single-layer MoS₂ on the (111) face of Au. Using scanning tunnelling microscopy (STM) and low energy electron diffraction, the evolution of the growth is followed from nanoscale single-layer MoS₂ islands to a robust high quality epitaxial MoS₂ layer that is stable in air. We investigate the electronic structure of epitaxial single layer MoS₂ by angle resolved photoemission spectroscopy. Pristine and potassium-doped layers are studied in order to gain access to the conduction band. The potassium-doped layer is found to have a (1.39±0.05) eV direct band gap at K with the valence band top at Γ having a significantly higher binding energy than at K. A pronounced moiré superstructure of the epitaxial system observed in STM does not lead to the presence of observable replica bands or minigaps. The degeneracy of the upper valence band at K is found to be lifted by the spin-orbit interaction, leading to a splitting of (145±4) meV. Finally, it is shown that the potassium doping does not only lead to a rigid shift of the band structure but also to a distortion, giving rise to the possibility of band structure engineering in single-layers of transition metal dichalcogenides.