Forming Weakly Interacting Multilayers of Graphene Using Atomic Force Microscope Tip Scanning and Evidence of Competition between Inner and Outer Raman Scattering Processes Piloted by Structural Defects

摘要

We report on an alternative route based on nanomechanical folding induced by an AFM tip to obtain weakly interacting multilayer graphene (wi-MLG) from a chemical vapor deposition (CVD)-grown single-layer graphene (SLG). The tip first cuts and then pushes and folds graphene during zigzag movements. The pushed graphene has been analyzed using various Raman microscopy plots-A(D)/A(G) X E-L(4) vs Gamma(G), omega(2D) VS Gamma(2D), Gamma(2D) vs Gamma(G), omega(2D+/-) vs Gamma(2D+/-), and A(2D-)/A(2D+) vs A(2D)/A(G). We show that the SLG in-plane properties are maintained under the folding process and that a few tens of graphene layers are stacked, with a limited number of structural defects. A blue shift of about 20 cm(-1) of the 2D band is observed. The relative intensity of the 2D_ and 2D+ bands have been related to structural defects, giving evidence of their role in the inner and outer processes at play close to the Dirac cone.