Substrate-affected lattice structural evolution in compressed monolayer ReS.

At ambient conditions, the lattice structure of supported ultrathin transition metal dichalcogenides (TMDs) can be effectively modified by a substrate. When compressed, the effect of substrate is far from settled. In this study, the effects of an Si substrate on the lattice structures of compressed monolayer and multilayer ReS2 were investigated by performing high-pressure Raman measurements and first-principle calculations. Our results revealed substrate-affected strain in compressed monolayer ReS2, which resulted in a distorted unit with S atoms sliding within a single layer. This was evidenced by the split of the Ag-5 mode above 1.7 GPa. However, unlike that of the monolayer ReS2, the Ag-5 mode of multilayer ReS2 remained symmetric up to 4.2 GPa, which can be due to weaker substrate-affected strain in compressed multilayer ReS2 when compared with that in the monolayer ReS2. The noticeably different high-pressure responses between multilayer ReS2 and monolayer ReS2 can be due to the effect of interlayer interactions, and the split of the Ag-5 mode provides a clear indication of the prominent strain in compressed supported ReS2.