Single-layerMoS2on Au(111): Band gap renormalization and substrate interaction

Abstract

The electronic structure of epitaxial single-layer MoS2 on Au(111) is investigated by angleresolved photoemission spectroscopy, scanning tunnelling spectroscopy, and first principles calculations. While the band dispersion of the supported single-layer is close to a free-standing layer in the vicinity of the valence band maximum atK and the calculated electronic band gap on Au (111) is similar to that calculated for the free-standing layer, significant modifications to the band structure are observed at other points of the two-dimensional Brillouin zone: AtΓ, the valence band maximum has a significantly higher binding energy than in the free MoS2 layer and the expected spin-degeneracy of the uppermost valence band at theM point cannot be observed. These band structure changes are reproduced by the calculations and can be explained by the detailed interaction of the out-of-plane MoS2 orbitals with the substrate.

Out‐of‐Plane Strain Induced in a Moiré Superstructure of Monolayer MoS2 and MoSe2 on Au(111)

“…Previous ARPES and density functional theory (DFT) calculation revealed that S 2p z orbitals of the lower S atoms in monolayer MoS 2 interact with d band of Au(111) surface, and strong overlap of S 2p z with Au sp band especially occurs when the lower S atoms is located on the on top position . The results mean that the S–Au interaction at the A site is significantly stronger than that at B and C sites.…”

“…STS measurements revealed that MoS 2 and MoSe 2 monolayers grown on monolayer graphene, bilayer graphene, or highly ordered pyrolytic graphite (HOPG) did not show any LDOS within the bandgap, and bandgap values of 2.15 eV or 2.40 eV (MoS 2 on HOPG), 2.2 eV (MoS 2 on monolayer graphene), and 2.18 eV (MoSe 2 on bilayer graphene) and 1.94 eV (MoSe 2 on HOPG) have been reported. Very recently, STS measurements also found that the bandgap values of MoS 2 /Au(111) become smaller than that of MoS 2 on graphene and are estimated to be 1.3 and 1.74 eV, respectively . DFT calculation also showed that the reduction of the bandgap values is attributed to be the strong interaction of lower S 2p z atoms with d band of Au surface, which causes a distortion of VBM of MoS 2 .…”

“…It was found that monolayer MoS 2 grown on a Au(111) surface produces a periodic moiré superstructure due to lattice mismatching between the MoS 2 and Au(111) lattices, and topographical analysis was inferred that the superstructure induces structural buckling in the MoS 2 layer, resulting in modulation of the electronic structure of MoS 2 . Further study used by angle‐resolved photoemission spectroscopy (ARPES), STM/STS, and first‐principles calculations was also suggested that lower sulfur atoms in the MoS 2 strongly interact with Au surface, and resultant higher binding energy shift of a valence band maximum in comparison to the free‐standing layer causes a reduction of the bandgap . However, despite of the excellent studies, there is no direct experimental evidence related to the strain generation in the TMDC layer by the metal contact.…”

Moiré structure of MoS2 on Au(111): Local structural and electronic properties

“…In contrast, the states at theK point remain largely unperturbed. This can be explained by their inplane character [15] and the fact that theK point of MoS 2 lies in a projected bulk band gap of the Au substrate [17,18].…”

Phase transition and electronic structure investigation of MoS2-reduced graphene oxide nanocomposite decorated with Au nanoparticles

“…By doing this, both the Au(111) and 2H-MoS 2 unit cell is matched with the ideal lattice constant of 1T'-MoS 2 monolayers. We should mention that this five-layer model has been adopted in previous works describing well some features observed in experiments [40,41].…”