Figure 5. Density functional theory calculations of atomic interactions between MoS₂ and Si or hBN/Si surfaces.

Relative variation of the in-plane lattice constant (Δd/d) for each atomic layer due to MoS₂-substrate interactions for (a) 2 ML MoS₂ on Si (111) and (b) 1 ML MoS₂ on 4 ML hBN on Si (111). (a) The bottom MoS₂ layer interacts strongly with dangling bonds on the Si surface and gets distorted, while the structure of the top MoS₂ layer is largely unaffected due to the weak van der Waals bond between the two layers. Si–S atoms with a distance shorter than 2.6 Å are connected with bonds for illustration. (b) Inserting 4 MLs of hBN between MoS₂ and the Si substrate significantly suppresses their interaction and distortion, as evident by the small fluctuation of in-plane bond lengths of MoS₂ and the 2 × 1 surface reconstruction of Si, due to weak van der Waals bonds between adjacent layers.