scholarly journals Identification of mono-and few-layer graphene: Raman study

2018 ◽  
Vol 3 (1) ◽  
Author(s):  
M. Boutahir ◽  
Ah Rahmani ◽  
H. Chadli ◽  
A. Rahmani
Keyword(s):  
Raman Spectra ◽  
Theoretical Work ◽  
Multilayer Graphene ◽  
Raman Analysis ◽  
Graphene Layers ◽  
Layer Graphene ◽  
Number Of Layers ◽  
Raman Study ◽  
Few Layer Graphene ◽  
Good Agreement

In this theoretical work, the Raman spectra were analyzed by considering the origin of the G peak, its shape, position and relative intensity as a function of the number of graphene layers. By using the spectral moment’s method, the Raman spectra of mono, bi and few-layers of graphene are calculated and a good agreement was found with group theory concerning the number of the Raman-active modes and the Raman measurements. Our results provide a Raman analysis to evaluate the number of layers in multilayer graphene. #Raman_spectroscopy #graphene #graphite

scholarly journals Estimation of Number of Graphene Layers Using Different Methods: A Focused Review

Materials ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 4590
Author(s):  
Vineet Kumar ◽  
Anuj Kumar ◽  
Dong-Joo Lee ◽  
Sang-Shin Park
Keyword(s):  
Electron Microscopy ◽  
Raman Spectra ◽  
Monolayer Graphene ◽  
Multilayer Graphene ◽  
Characterization Methods ◽  
Graphene Layers ◽  
Force Microscopy ◽  
Stacking Order ◽  
Transmission Electron ◽  
Few Layer Graphene

Graphene, a two-dimensional nanosheet, is composed of carbon species (sp2 hybridized carbon atoms) and is the center of attention for researchers due to its extraordinary physicochemical (e.g., optical transparency, electrical, thermal conductivity, and mechanical) properties. Graphene can be synthesized using top-down or bottom-up approaches and is used in the electronics and medical (e.g., drug delivery, tissue engineering, biosensors) fields as well as in photovoltaic systems. However, the mass production of graphene and the means of transferring monolayer graphene for commercial purposes are still under investigation. When graphene layers are stacked as flakes, they have substantial impacts on the properties of graphene-based materials, and the layering of graphene obtained using different approaches varies. The determination of number of graphene layers is very important since the properties exhibited by monolayer graphene decrease as the number of graphene layer per flake increases to 5 as few-layer graphene, 10 as multilayer graphene, and more than 10 layers, when it behaves like bulk graphite. Thus, this review summarizes graphene developments and production. In addition, the efficacies of determining the number of graphene layers using various characterization methods (e.g., transmission electron microscopy (TEM), atomic force microscopy (AFM), scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman spectra and mapping, and spin hall effect-based methods) are compared. Among these methods, TEM and Raman spectra were found to be most promising to determine number of graphene layers and their stacking order.

scholarly journals Characterizing the maximum number of layers in chemically exfoliated graphene

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Péter Szirmai ◽  
Bence G. Márkus ◽  
Julio C. Chacón-Torres ◽  
Philipp Eckerlein ◽  
Konstantin Edelthalhammer ◽  
...  
Keyword(s):  
Single Layer ◽  
Vapour Phase ◽  
Single Layer Graphene ◽  
Graphene Layers ◽  
Layer Graphene ◽  
Exfoliated Graphene ◽  
Upper Limit ◽  
Number Of Layers ◽  
Graphene Flakes ◽  
Few Layer Graphene

AbstractAn efficient route to synthesize macroscopic amounts of graphene is highly desired and bulk characterization of such samples, in terms of the number of layers, is equally important. We present a Raman spectroscopy-based method to determine the typical upper limit of the number of graphene layers in chemically exfoliated graphene. We utilize a controlled vapour-phase potassium intercalation technique and identify a lightly doped stage, where the Raman modes of undoped and doped few-layer graphene flakes coexist. The spectra can be unambiguously distinguished from alkali doped graphite, and modeling with the typical upper limit of the layers yields an upper limit of flake thickness of five layers with a significant single-layer graphene content. Complementary statistical AFM measurements on individual few-layer graphene flakes find a consistent distribution of the layer numbers.

The influence of nanoscale roughness and substrate chemistry on the frictional properties of single and few layer graphene

Nanoscale ◽  
2015 ◽  
Vol 7 (22) ◽  
pp. 10021-10029 ◽  
Author(s):  
Jessica C. Spear ◽  
James P. Custer ◽  
James D. Batteas
Keyword(s):  
Rough Surfaces ◽  
Frictional Properties ◽  
Layer Graphene ◽  
Number Of Layers ◽  
Few Layer Graphene ◽  
Nanoscale Roughness

Graphene's lack of conformity to rough surfaces impacts its frictional properties, depending on the number of layers and substrate bonding.

scholarly journals Growth of Ordered Graphene Ribbons by Sublimation Epitaxy

Crystals ◽  
2018 ◽  
Vol 8 (12) ◽  
pp. 449
Author(s):  
Shuxian Cai ◽  
Xingfang Liu ◽  
Xin Zheng ◽  
Zhonghua Liu
Keyword(s):  
Substrate Surface ◽  
Graphene Film ◽  
Graphene Ribbon ◽  
High Quality ◽  
Graphene Layers ◽  
Force Microscopy ◽  
Layer Graphene ◽  
Micro Raman Spectroscopy ◽  
Atomic Force ◽  
Few Layer Graphene

Ordered graphene ribbons were grown on the surface of 4° off-axis 4H-SiC wafers by sublimation epitaxy, and characterized by using scanning electron microscopy (SEM), atomic force microscopy (AFM) and micro-Raman spectroscopy (μ-Raman). SEM showed that there were gray and dark ribbons on the substrate surface, and AFM further revealed that these ordered graphene ribbons had clear stepped morphologies due to surface step-bunching. It was shown by μ-Raman that the numbers of graphene layers of these two types of regions were different. The gray region was composed of mono- or bilayer ordered graphene ribbon, while the dark region was of tri- or few-layer ribbon. Meanwhile, ribbons were all homogeneous and had a width up to 40 μm and a length up to 1000 μm, without micro defects such as grain boundaries, ridges, or mono- and few-layer graphene mixtures. The results of this study are useful for optimized growth of high-quality graphene film on silicon carbide crystal.

Graphene Layers on Silicon Carbide Studied by Raman Spectroscopy

2008 ◽  
Vol 600-603 ◽  
pp. 567-570 ◽  
Author(s):  
Jonas Röhrl ◽  
Martin Hundhausen ◽  
Konstantin V. Emtsev ◽  
Thomas Seyller ◽  
Lothar Ley
Keyword(s):  
Silicon Carbide ◽  
Raman Spectroscopy ◽  
Light Scattering ◽  
Graphene Layer ◽  
Monolayer Graphene ◽  
Spectroscopy Study ◽  
Graphene Layers ◽  
Layer Graphene ◽  
Micro Raman Spectroscopy ◽  
Few Layer Graphene

We present a micro-Raman spectroscopy study on single- and few layer graphene (FLG) grown on the silicon terminated surface of 6H-silicon carbide (SiC). On the basis of the 2D-line (light scattering from two phonons close to the K-point in the Brillouin zone) we distinguish graphene mono- from bilayers or few layer graphene. Monolayers have a 2D-line consisting of only one component, whereas more than one component is observed for thicker graphene layers. Compared to the graphite the monolayer graphene lines are shifted to higher frequencies. We tentatively ascribe the corresponding phonon hardening to strain in the first graphene layer.

Raman Spectroscopy as a Tool to Address Individual Graphene Layers in Few-Layer Graphene

2012 ◽  
Vol 116 (35) ◽  
pp. 19046-19050 ◽  
Author(s):  
Martin Kalbac ◽  
Jing Kong ◽  
Mildred S. Dresselhaus
Keyword(s):  
Raman Spectroscopy ◽  
Graphene Layers ◽  
Layer Graphene ◽  
Few Layer Graphene

Direct growth of etch pit-free GaN crystals on few-layer graphene

RSC Advances ◽  
2015 ◽  
Vol 5 (2) ◽  
pp. 1343-1349 ◽  
Author(s):  
Seung Jin Chae ◽  
Yong Hwan Kim ◽  
Tae Hoon Seo ◽  
Dinh Loc Duong ◽  
Seung Mi Lee ◽  
...  
Keyword(s):  
Vapour Deposition ◽  
Chemical Vapour ◽  
Organic Chemical ◽  
High Quality ◽  
Graphene Layers ◽  
Layer Graphene ◽  
Etch Pit ◽  
Direct Growth ◽  
Metal Organic ◽  
Few Layer Graphene

We report high-quality GaN crystals grown directly on graphene layers without a buffer layer by metal–organic chemical vapour deposition.

scholarly journals Influence of Different Copper Treatment on the Formation of Single-Layer Graphene by CVD Method

2020 ◽  
Vol 4 (1) ◽  
pp. 14
Author(s):  
Ivan Kondrashov ◽  
Maxim Komlenok ◽  
Pavel Pivovarov ◽  
Sergei Savin ◽  
Elena Obraztsova ◽  
...  
Keyword(s):  
Copper Foil ◽  
Single Layer ◽  
Chemical Vapor ◽  
Copper Surface ◽  
Single Layer Graphene ◽  
Graphene Layers ◽  
Layer Graphene ◽  
Graphene Synthesis ◽  
Number Of Layers ◽  
Optimized Conditions

Chemical vapor deposition synthesis of graphene on copper foil from methane is the most promising technology for industrial production. However, an important problem of the formation of the second and subsequent graphene layers during synthesis arises due to the strong roughness of the initial copper foil. Here we demonstrate the various approaches to prepare a smooth copper surface before graphene synthesis to reduce the formation of multi-layer graphene islands. Six methods of surface processing of copper foils are studied, and the decrease of the roughness from 250 to as low as 80 nm is achieved. The correlation between roughness and the formation of multi-layer graphene is demonstrated. Under optimized conditions of surface treatment, the content of the multi-layer graphene islands drops from 9% to 2.1%. The quality and the number of layers of synthesized graphene are analyzed by Raman spectroscopy, scanning electron microscopy, and measurements of charge mobility.

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