Reconstruction of Gold Surface with Excessive Sulfur Source During Transition Metal Disulfide Growth

The inert gold substrate is one of the most commonly used substrates for synthesizing transition metal dichalcogenides (TMDCs), while the growth mechanism of TMDCs on gold substrates in a sulfur-rich environment is still unclear. Based on density functional theory calculations, we explored the reconstruction of the gold surface in a sulfur-rich environment, which is one of the conditions for the growth of TMDCs. We clearly revealed that both Au(100) and Au(111) surfaces tend to form metal sulfide buffer layers between TMDCs and the metallic substrate, which are the square pattern of Au4S4 on Au(100) surface and the hexagonal pattern of Au6S6 on Au(111) surface, respectively. In the sulfur-rich environment, both square and hexagonal patterns are energetically highly stable, greatly weakening the interaction between TMDCs and the substrate. Interestingly, both buffer layers inherit the symmetry of the substrate and thus have no significant effect on the growth behavior of TMDCs. This study explains many experimental puzzles and elucidates the growth behavior of 2D materials on various substrates.