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

We determined the structure of epitaxial 2H-TaS2 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 moire 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 TaS2 layer remains rather flat. Significant charge transfer from Au(111) into the conduction band of the two-dimensional material is found.