Effects of mismatch strain and substrate surface corrugation on morphology of supported monolayer graphene

Abstract

Graphene monolayers supported on oxide substrates have been demonstrated with superior charge mobility and thermal transport for potential device applications. Morphological corrugation can strongly influence the transport properties of the supported graphene. In this paper, we theoretically analyze the morphological stability of a graphene monolayer on an oxide substrate, subject to van der Waals interactions and in-plane mismatch strains. First, we define the equilibrium separation and the interfacial adhesion energy as the two key parameters that characterize the van der Waals interaction between a flat monolayer and a flat substrate surface. By a perturbation analysis, a critical compressive mismatch strain is predicted, beyond which the graphene monolayer undergoes strain-induced instability, forming corrugations with increasing amplitude and decreasing wavelength on a perfectly flat surface. When the substrate surface is not perfectly flat, the morphology of graphene depends on both the amplitude and the wavelength of the surface corrugation. A transition from conformal (corrugated) to non-conformal (flat) morphology is predicted. The effects of substrate surface corrugation on the equilibrium mean thickness of the supported graphene and the interfacial adhesion energy are analyzed. Furthermore, by considering both the substrate surface corrugation and the mismatch strain, it is found that, while a tensile mismatch strain reduces the corrugation amplitude of graphene, a corrugated substrate surface promotes straininduced instability under a compressive strain. These theoretical results suggest possible means to control the morphology of graphene monolayer on oxide substrates by surface patterning and strain engineering.

First principles study of van der Waals heterobilayers

“…Also, interlayer interactions in hybrid silicene/graphene nanocomposite layers induce charge carriers whose concentration is tunable by controlling the interlayer distance [7]. Interfacial phenomena such as formation of interface dipole [8], structural corrugation [9][10][11][12], charge puddles [13][14][15][16], and edge-localised dangling bond states [17,18] play important roles in typical transistor device applications. The absence of the band gap in graphene means that electrons always interact strongly with the substrate making charge tunable device properties hard to achieve.…”

Atomistic simulation and continuum modeling of graphene nanoribbons under uniaxial tension

“…When placed on a substrate, the thickness of a graphene monolayer depends on the interaction between graphene and the substrate [33], which is not an intrinsic property of graphene itself. As a result, the 2D stress in equation (10) has a unit of N m −1 , different from the conventional 3D stress (N m −2 ).…”

Theoretical investigation on the adsorption and diffusion of lithium-ion on and between graphene layers with size and defect effects

“…Nonetheless, the adsorption and equilibrium rule of Li-ion on graphene are the same. What's more, the graphene is assumed to be non-deformable and flat, and the influence of temperature and corrugation of graphene are not taken into account (Aitken and Huang, 2010;Chan and Hill, 2010;Gao and Huang, 2011). These factors will be considered in our future works.…”