Structure of monolayer 2H−TaS2 on Au(111)

Abstract

We determined the structure of epitaxial $2H\text{\ensuremath{-}}\mathrm{Ta}{\mathrm{S}}_{2}$ on Au(111) using the method of x-ray standing waves (XSW), supported by density functional theory (DFT) calculations and scanning tunneling microscopy (STM). The lattice mismatch between substrate and overlayer gives rise to a moir\'e superstructure, which modulates the structural and electronic properties. For a specific registry (S atoms directly above Au substrate atoms), local covalentlike bonds form, whereas globally weak van der Waals bonding prevails. Still, the $\mathrm{Ta}{\mathrm{S}}_{2}$ layer remains rather flat. Significant charge transfer from Au(111) into the conduction band of the two-dimensional material is found.