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O: Fachverband Oberflächenphysik

O 113: 2D materials beyond graphene: TMDCs, silicene and relatives V

O 113.5: Vortrag

Freitag, 16. März 2018, 11:30–11:45, MA 043

Probing the band structure of quasi-freestanding monolayer MoS₂ — •Clifford Murray¹, Wouter Jolie^{1, 2}, Joshua Hall¹, Carsten Busse^{1, 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)