Nanoscale contact mechanics of the interactions at monolayer MoS₂ interfaces with Au and Si

Molybdenum disulfide (MoS₂) is a two-dimensional material that exhibits unique interfacial interactions with gold (Au) and silicon (Si). These interfaces have gained attention due to their potential to be integrated into a broad range of applications, where they involve direct contact that affects their performance. Here we investigate the nanoscale mechanical contact interaction of MoS₂ monolayers with Au and Si, using adhesion measurements and friction force microscopy. MoS₂-Au contact exhibits pronounced adhesive interaction, manifested by higher adhesion pull-off forces and energies, compared to MoS₂-Si. Influenced by the adhesive contacts, the friction forces recorded demonstrate stronger lateral interactions and stronger interfacial shear strength between MoS₂ and Au. Analysis with the Prandtl–Tomlinson model reveals that the MoS₂-Au direct interaction is also stiffer, suggesting higher elastic energy at the contact. This information on the mechanistic nature of MoS₂-Au and MoS₂-Si contacts under shear and normal loads is of potential importance in applications where such interfaces are utilized, such as in the design of coatings, sensors and mechanoelectrical devices.