Correlating Morphology and Electronic Structure of MoS₂ on Au(111)

Two-dimensional materials (2DMs) subjected to superperiodic potentials show exciting effects such as replica bands and minigaps in the electronic structure. In addition, the locally varying potential landscape can induce ordered superstructures of atoms, molecules and metallic clusters. Such superperiodic potentials can arise spontaneously in 2DMs epitaxially grown on metallic substrates, where the lattice mismatch leads to a moiré pattern. In consequence, depending on the strength of interaction, the 2DM can display a structural modulation (corrugation) which can show charge inhomogeneity and localized states.
In the present work, the morphology and electronic structure of single-layer MoS₂ epitaxially grown on Au(111) are studied by means of x-ray standing waves (XSW), scanning tunneling spectroscopy (STS) and first-principles calculations based on density functional theory (DFT). The XSW data and the DFT model indicate a nearly flat, weakly interacting layer of MoS₂ with a peak-to-peak corrugation of only 0.3 Å and a large separation of approximately 2.7 Å between the Au(111) surface and the bottom sulfur layer in the MoS₂. Still, the local probe of STS measurements shows the changes in the electronic structure along the moiré unit cell caused by the site-dependent interaction.