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

Abstract

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.