# Forming Weakly Interacting Multi Layers of Graphene by using Atomic Force Microscope Tip Scanning and Evidence of Competition Between Inner and Outer Raman Scattering Processes Piloted by Structural Defects

## TL;DR

This paper presents a novel AFM-based method to create weakly interacting multi-layer graphene from single layers, analyzing the structural and Raman spectral changes to understand defect roles and scattering processes.

## Contribution

It introduces an AFM nanomechanical folding technique to produce multi-layer graphene and investigates the interplay of structural defects with Raman scattering processes.

## Key findings

- AFM tip induces folding of single-layer graphene into multi-layer structures.
- Folding maintains in-plane properties with limited defects.
- Structural defects influence inner and outer Raman scattering processes.

## Abstract

We report on an alternative route based on nanomechanical folding induced by AFM tip to obtain weakly interacting multi-layer graphene (wi-MLG) from a chemical vapor deposition (CVD) grown single-layer graphene (SLG). The tip first cuts, then pushes and folds graphene during zigzag movements. The pushed graphene has been analyzed using various Raman microscopy plots: $A_D /A_G \times E_L{}^4$ 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 amount 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.

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Source: https://tomesphere.com/paper/1907.10912