Single-layer MoS$_2$ on Au(111): band gap renormalization and substrate interaction

TL;DR

This study investigates how the substrate Au(111) influences the electronic band structure of single-layer MoS$_2$, revealing both preserved features near the valence band maximum and significant modifications elsewhere due to substrate interaction.

Contribution

It provides detailed experimental and theoretical analysis of substrate-induced band structure modifications in single-layer MoS$_2$ on Au(111).

Findings

Band dispersion near $ar{K}$ resembles free-standing MoS$_2$.

Significant valence band shifts at $ar{ ext{Gamma}}$ and $ar{ ext{M}}$ points.

Interactions with the substrate alter out-of-plane orbitals and band degeneracies.

Abstract

The electronic structure of epitaxial single-layer MoS$_2$ on Au(111) is investigated by angle-resolved 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 at $\bar{K}$ 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: At $\bar{\Gamma}$, the valence band maximum has a significantly higher binding energy than in the free MoS$_2$ layer and the expected spin-degeneracy of the uppermost valence band at the $\bar{M}$ 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 MoS$_2$ orbitals with the substrate.