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

Abstract

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.