Growth and Raman spectroscopy of thickness-controlled rotationally faulted multilayer graphene

TL;DR

This study demonstrates the controlled growth of rotationally faulted multilayer graphene on Ni foils via CVD, and uses Raman spectroscopy to analyze its structural and vibrational properties, revealing systematic behaviors related to its dimensionality.

Contribution

It introduces a method to control rf-MLG thickness by Ni foil thickness and provides detailed Raman spectral analysis of its vibrational modes.

Findings

Thickness of rf-MLG is controlled by Ni foil thickness.

Raman spectra show four distinct patterns with systematic behaviors.

In-plane and out-of-plane Raman modes are linked to the dimensionality of rf-MLG.

Abstract

We report the growth of thickness-controlled rotationally faulted multilayer graphene (rf-MLG) on Ni foils by low-pressure chemical vapor deposition and their characterization by micro-Raman spectroscopy. The surface morphology and thickness were investigated by scanning electron microscope, X-ray diffraction, and transmittance measurements. These results have revealed that the thickness of rf-MLG can be effectively controlled by the thickness of the Ni foil rather than the flow rate of CH$_4$, H$_2$, Ar. In the Raman spectroscopy measurements, we observed most Raman peaks of the graphitic materials. Raman spectra can be categorized into four patterns and show systematic behaviors. Especially, the in-plane (~1880 cm$^{-1}$, ~2035 cm$^{-1}$) and out-of-plane (~1750 cm$^{-1}$) modes are successfully analyzed to explain the dimensionality of rf-MLG as in the twisted (or rotated) bilayer graphene. In addition, it is found that the two peaks at ~1230 cm$^{-1}$ and ~2220 cm$^{-1}$ well reflect the properties of the in-plane mode. The peak intensities of the above four in-plane modes are proportional to that of 2D band, indicating that they share the common Raman resonance process.