Graphene Growth by Transfer-Free CVD Method Using Cobalt/Nickel Catalyst Layer

2018 ◽  
Vol 919 ◽  
pp. 207-214
Author(s):  
Petr Machac ◽  
Ondrej Hejna
Keyword(s):  
Metal Layer ◽  
Chemical Vapour ◽  
Single Layer ◽  
Dielectric Substrate ◽  
Single Layer Graphene ◽  
Nickel Layer ◽  
Mechanical And Thermal Properties ◽  
Graphene Layers ◽  
Cvd Method ◽  
Cobalt Nickel

Graphene has been long considered for application in electronics manufacturing due to its extraordinary electronic, mechanical and thermal properties. This paper focuses on the graphene preparation onto dielectric substrate using transfer-free chemical vapour deposition (CVD) method with an intermediate catalytic metal layer (cobalt, nickel). Graphene layers were formed via segregation mechanism at temperatures in the range of 850 - 1050 °C onto the metal-dielectric boundary. Evaluated Raman spectra, which reveal the number of graphene layers and their defectivity suggested, that thinner metal layer and balanced ratio of H2:CH4 yield the best results for both cobalt and nickel layer. Spectra showed low amount of defects and the average number of carbon layers between 2-3, however, single-layer graphene (SLG) samples were also prepared. Scanning electron microscopy images showed that graphene domains on larger scale are not fully continuous.

Tuning the electrical properties of exfoliated graphene layers using deep ultraviolet irradiation

2014 ◽  
Vol 2 (27) ◽  
pp. 5404-5410 ◽  
Author(s):  
M. Z. Iqbal ◽  
M. F. Khan ◽  
M. W. Iqbal ◽  
Jonghwa Eom
Keyword(s):  
Electrical Properties ◽  
Ultraviolet Irradiation ◽  
Single Layer ◽  
Single Layer Graphene ◽  
Graphene Bilayer ◽  
Graphene Layers ◽  
Exfoliated Graphene ◽  
Deep Ultraviolet ◽  
Trilayer Graphene ◽  
Unique Band

Deep ultraviolet irradiation tunes the electronic properties of mechanically exfoliated single-layer graphene, bilayer graphene, and trilayer graphene while maintaining their unique band structure and electrical properties.

Comparative study of single‐layer graphene and single‐walled carbon nanotube‐filled epoxy nanocomposites based on mechanical and thermal properties

2018 ◽  
Vol 40 (S2) ◽  
pp. E1840-E1849 ◽  
Author(s):  
Muhammad Razlan Zakaria ◽  
Muhammad Helmi Abdul Kudus ◽  
Hazizan Md Akil ◽  
Mohd Zharif Mohd Thirmizir ◽  
Muhammad Fadhirul Izwan Abdul Malik ◽  
...  
Keyword(s):  
Thermal Properties ◽  
Carbon Nanotube ◽  
Comparative Study ◽  
Single Layer ◽  
Single Layer Graphene ◽  
Mechanical And Thermal Properties ◽  
Epoxy Nanocomposites ◽  
Single Walled Carbon Nanotube ◽  
Single Walled Carbon ◽  
Layer Graphene

Zur Kristallchemie von Graphen und Graphit

2009 ◽  
Vol 66 (1) ◽  
pp. 81-83
Author(s):  
M. Trömel
Keyword(s):  
Crystal Structure ◽  
Chemical Properties ◽  
Single Layer ◽  
Single Layer Graphene ◽  
Chemical Bonds ◽  
Graphene Layers ◽  
Layer Graphene ◽  
Closest Packing ◽  
Weak Chemical ◽  
And Chemical Properties

The crystal structure of single-layer graphene in comparison to graphite is discussed with regard to its crystallographic and chemical properties. In both of these polymorphs of carbon, the atomic volume of carbon, reduced to the closest packing of atoms, is practically the same and considerably smaller than in diamond. This indicates pentavalent carbon in graphene as well as in graphite. The observed elastic corrugations of the graphene layers which probably cause their amazing rigidity seem to be due to numerous weak chemical bonds within the layers.

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.

scholarly journals Preparation of Copper Surface for the Synthesis of Single-Layer Graphene

Nanomaterials ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 1071
Author(s):  
Ivan Kondrashov ◽  
Maxim Komlenok ◽  
Pavel Pivovarov ◽  
Sergey Savin ◽  
Elena Obraztsova ◽  
...  
Keyword(s):  
Copper Foil ◽  
Single Layer ◽  
Chemical Vapor ◽  
Copper Surface ◽  
Single Layer Graphene ◽  
Graphene Layers ◽  
Layer Graphene ◽  
Additional Layer ◽  
Graphene Synthesis ◽  
Few Layer Graphene

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 additional graphene layers during synthesis arises due to the strong roughness of the initial copper foil. In this paper, various approaches are demonstrated to form a smooth copper surface before graphene synthesis to reduce the amount of few 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 foil roughness and the formation of the additional layer is demonstrated. Under optimized conditions of surface treatment, the content of the additional graphene layer 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.

DNA Gating effect from single layer graphene

2011 ◽  
Vol 1344 ◽  
Author(s):  
Jian Lin ◽  
Desalegne Teweldebrhan ◽  
Khalid Ashraf ◽  
Guanxiong Liu ◽  
Xiaoye Jing ◽  
...  
Keyword(s):  
Dirac Point ◽  
Full Width Half Maximum ◽  
Single Layer ◽  
Single Layer Graphene ◽  
Hole Density ◽  
Voltage Measurement ◽  
Graphene Layers ◽  
Layer Graphene ◽  
Current Voltage ◽  
Gating Effect

ABSTRACTIn this letter, single stranded Deoxyribonucleic Acids (ssDNA) are found to act as negative potential gating agents that increase the hole density in single layer graphene (SLG). Current-voltage measurement of the hybrid ssDNA/graphene system indicates a shift in the Dirac point and “intrinsic” conductance after ssDNA is patterned. The effect of ssDNA is to increase the hole density in the graphene layer, which is calculated to be on the order of 1.8×1012 cm-2. This increased density is consistent with the Raman frequency shifts in the G-peak and 2D band positions and the corresponding changes in the G-peak full-width half maximum. This patterning of DNA on graphene layers could provide new avenues to modulate their electrical properties and for novel electronic devices.

scholarly journals Graphene growth from the metal/carbon/SiO2 structure

2018 ◽  
Vol 69 (3) ◽  
pp. 239-244
Author(s):  
Petr Machac ◽  
Jan Pajtai
Keyword(s):  
Transition Metal ◽  
Necessary Conditions ◽  
Single Layer ◽  
Thick Layer ◽  
Dielectric Substrate ◽  
Carbon Layer ◽  
Single Layer Graphene ◽  
Graphene Growth ◽  
Annealing Temperatures ◽  
20 Nm

Abstract The paper presents results related to graphene growth by the method of precipitation on the boundary between a transition metal (nickel or cobalt) and a dielectric (SiO2 ). The source of graphene is a thin evaporated carbon layer. Carbon in the annealing process diffunds through the transition metal and precipitates on the surface of the dielectric substrate as the structure cools down. Relatively thick layer of copper, which is evaporated over carbon as a cover, prevents carbon to diffund to the surface of the metallization. The structure of the metallization for graphene forming is then Cu/C/(transition metal)/SiO2 /Si. We consider the utilization of the diffusion barrier to be the contribution of our work to graphene formation using this method. Even though both transition metals are of similar features, the necessary conditions for growth of high- quality graphene are different. In case of nickel, long annealing times within the whole range of annealing temperatures are necessary, while in case of structures with cobalt annealing time of 20 minutes at 900°C is enough for graphene growth. By annealing the Cu(300 nm)/C(20 nm)/Ni(50 nm)/SiO2 structure at the temperature of 800 °C for 60 minutes we obtained single-layer graphene (SLG).

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.

First Principles Study of Interlayer Interaction Effect on Graphene Thermal Conductivity

2019 ◽  
Author(s):  
Yuan Dong ◽  
Chi Zhang ◽  
Chenghao Diao ◽  
Jian Lin
Keyword(s):  
Thermal Conductivity ◽  
Phonon Dispersion ◽  
Single Layer ◽  
Theoretical Aspect ◽  
Single Layer Graphene ◽  
Graphene Layers ◽  
Layer Graphene ◽  
Multiple Layer ◽  
Phonon Properties ◽  
Vdw Interaction

Abstract It is known that the interlayer van der Waals (vdW) interactions will decrease the thermal conductivity of graphene. Single layer graphene (SLG) has the highest thermal conductivities, double layer graphene (DLG) would decrease to about half of the thermal conductivity of SLG. The graphite was measured to have a thermal conductivity of about 2000 W/m-K. Some research shows that graphite differs from SLG within a factor of 2, and DLG has almost the same thermal conductivity with graphite. In theoretical aspect, how to simulate the vdW interaction between graphene layers is a long existing problem. It is only until recently that the vdW interaction is still an active topic in first principle calculations. The popular methods include the Grimme’s DFT-D, vdW-DF and vdW-DFT-R methods. The vdW-DFT-R method was further optimized to increase accuracy by Hamada and was found to predict the most accurate interlayer distance between AB-stacked graphene in our recent study. The motivation of this work is to investigate the effect of vdW interaction on the thermal conductivity of multiple layer graphene from principles. We will calculate firstly the phonon dispersion relations of multiple layer graphene with the vdW interaction included. The obtained phonon properties and force constants will be combined with the ShengBTE method to calculate the thermal conductivity. The results show how vdW interaction causes the dimensional crossover of graphene thermal conductivity.

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