Controlling folding patterns in supported graphene by adhesion, friction and strain anisotropy
Kuan Zhang (UPC), Marino Arroyo (UPC-BarcelonaTech)
Synthesis, Characterization, and Modeling of Low-Dimensional Nanomaterials
Tue 10:45 - 12:15
Salomon 202
Localized folding patterns are commonly observed in supported graphene, e.g. in CVD-grown samples. Such folds are known to affect the electronic and chemical properties of graphene. There is an increasing interest in experimentally controlling the emergence and morphology of such fold networks by tuning the transfer method and the topography of the substrate. However, the theoretical understanding of mechanisms behind folding in supported graphene remains incomplete. We systematically study the emergence and morphology of folds in supported graphene upon compressive stress with simulations relying on an atomistic- based continuum model, and with a nonlinear theoretical model. We find that localized folding in supported graphene is preceded by uniformly distributed wrinkles with very small amplitude, and show that such a wrinkle-to-fold transition is due to the nonlinearity in the van der Waals interactions between graphene and the substrate. We identify friction as a selection mechanism for the separation between folds, as the formation of far apart folds is penalized by the work of friction. Towards strain engineering of the fold networks, with potential applications in nanofluidics or nanoelectronics, we investigate how to control the position and shape of folds by tuning the adhesion and tribological properties of the interface, together with the anisotropy of the strain.