Adhesion, stiffness, and instability in atomically thin MoS2 bubbles

Abstract

We measured the work of separation of single and few-layer MoS_2 membranes from a SiO_x substrate using a mechanical blister test and found a value of 220 ± 35 mJ/m^2. Our measurements were also used to determine the 2D Young’s modulus (E_2D) of a single MoS_2 layer to be 160 ± 40 N/m. We then studied the delamination mechanics of pressurized MoS2 bubbles, demonstrating both stable and unstable transitions between the bubbles’ laminated and delaminated states as the bubbles were inflated. When they were deflated, we observed edge pinning and a snap-in transition that are not accounted for by the previously reported models. We attribute this result to adhesion hysteresis and use our results to estimate the work of adhesion of our membranes to be 42 ± 20 mJ/m^2