Berlin 2018 – scientific programme
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O: Fachverband Oberflächenphysik
O 113: 2D materials beyond graphene: TMDCs, silicene and relatives V
O 113.5: Talk
Friday, March 16, 2018, 11:30–11:45, MA 043
Probing the band structure of quasi-freestanding monolayer MoS2 — •Clifford Murray1, Wouter Jolie1, 2, Joshua Hall1, Carsten Busse1, 2, 3, and Thomas Michely1 — 1II. Physikalisches Institut, Universität zu Köln — 2Institut für Materialphysik, Westfälische Wilhelms-Universität Münster — 3Department Physik, Universität Siegen
We epitaxially grow high-quality molybdenum disulfide (MoS2) monolayers on graphene on Ir(111), and probe its electronic structure with low temperature scanning tunnelling spectroscopy (STS).
A bandgap of 2.50 ± 0.05 eV is measured by STS, showing the freestanding nature of MoS2 on this substrate. Furthermore, by combining constant height and constant current STS modes and measuring the state-resolved tunnelling decay constant [1], we are able to disentangle the contributions of states located at various high-symmetry points, such as the spin-split valence band at the K-point. The band structure is found to be in close agreement with theoretical calculations for freestanding MoS2, further evidencing the weak coupling with its Gr/Ir(111) substrate. Additionally, the valence band is seen to undergo a stepwise bending towards twin boundary line defects in the MoS2 layer - to the best of our knowledge a phenomenon not yet reported in this material.
[1] Zhang, C. et al, Nano Lett. 15, 6494 (2015)