Exceptional Elasticity of Microscale Constrained MoS2 Domes

The outstanding mechanical performances of two-dimensional (2D) materials make them appealing for the emerging fields of flextronics and straintronics. However, their manufacturing and integration in 2D crystal-based devices rely on a thorough knowledge of their hardness, elasticity, and interface mechanics. Here, we investigate the elasticity of highly strained monolayerthick MoS2 membranes, in the shape of micrometer-sized domes, by atomic force microscopy (AFM)-based nanoindentation experiments. A dome's crushing procedure is performed to induce a local re-adhesion of the dome's membrane to the bulk substrate under the AFM tip's load. It is worth noting that no breakage, damage, or variation in size and shape are recorded in 95% of the crushed domes upon unloading. Furthermore, such a procedure paves the way to address quantitatively the extent of the van der Waals interlayer interaction and adhesion of MoS2 by studying pullin instabilities and hysteresis of the loading-unloading cycles. The fundamental role and advantage of using a superimposed dome's constraint are also discussed.

Automated summary

The study investigates the elasticity of highly strained monolayer-thick MoS2 membranes and finds that 95% of the crushed domes do not experience breakage, damage, or changes in size and shape during unloading. The research also explores the van der Waals interlayer interaction and adhesion of MoS2 through pullin instabilities and hysteresis of loading-unloading cycles, discussing the benefits of using a superimposed dome's constraint.