Adhesion Energy of MoS2 Thin Films on Silicon-Based Substrates Determined via the Attributes of a Single MoS2 Wrinkle.

Understanding the energetics of adhesion between two-dimensional nanomaterials and their supporting substrates is crucial for the design and fabrication of corrersponding structures with controlled interfacial effects that influence phononics, charge-carrier distribution, and electronic response. Here, we show a mechanical energy model that equates the adhesion energy of MoS2 on rigid and flat substrates (SiO2 and Si3N4) to the attributes of a single wrinkle in a MoS2 flake. The amplitude of the observed wrinkles was normalized for thickness (A/t) to select the wrinkles valid for the model. The adhesion energy values of 0.170 ± 0.033 J m-2 for MoS2 on SiO2 and 0.252 ± 0.041 J m-2 for MoS2 on Si3N4 were determined. This mechanical energy model is consistent with the model based on the local equilibrium at the contact point in the Young's equation. We also propose a method to measure the plane-strain in wrinkled MoS2. The geometrical properties (symmetry and normalized dimensions) of wrinkles and substrate effects are also discussed.