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High quality MoS2 monolayers on graphene/Ir(111)

High quality MoS2 monolayers were grown by MBE on graphene/Ir(111). ARPES reveals that there is no hybridization between electronic states of graphene and MoS2. The weak MoS2-graphene interaction explains the observed photoluminescence in this system.

  Ehlen et al., 2D Mater. 6, 011006 (2019).

Angle-resolved photoemission spectroscopy (ARPES) reveals no hybridization between electronic states of graphene and MoS2 monolayer grown by molecular beam epitaxy (MBE), through coevaporation of Mo and S from pyrite, on graphene/Ir(111). The valence band (VB) maximum of MoS2 appears at the K-point of the Brillouin zone consistent with monolayer MoS2, while for bilayer MoS2 the VB maximum is at the Γ point. The splitting of the VB at the MoS2 K-point due to spin–orbit interaction is clearly seen in the high resolution scan shown in the inset of the figure. The fit to the energy distribution curve from a cut through the MoS2 K-point reveals a band splitting due to spin–orbit coupling (SOC) of 144 meV. Interestingly, graphene is more hole doped than it was before MoS2 growth, the Dirac-point binding energy ED is evaluated to be at −0.25 eV compared to −0.1 eV in the pristine case. Notably, ARPES does not show any hybridization

between MoS2 and graphene bands which supports the idea that MoS2 is weakly interacting with graphene. This can explain the observed narrow photoluminescence (PL) and the absence of the expected quenching of the PL intensity on a metallic surface.

Retrieve article
Narrow photoluminescence and Raman peaks of epitaxial MoS2 on graphene/Ir(111)
N. Ehlen, J. Hall, B.V. Senkovskiy, M. Hell, J. Li, A. Hermann, D. Smirnov, A. Fedorov, V.Yu. Voroshnin, G. Di Santo, L. Petaccia, T. Michely, and A. Grüneis,
2D Mater. 6, 011006 (2019).
doi: 10.1088/2053-1583/aaebd3

This work was selected as an Elettra Top Story.

Last Updated on Monday, 10 December 2018 09:58