scholarly journals Pattern Pick and Place Method for Twisted Bi- and Multi-Layer Graphene

Materials ◽  
2019 ◽  
Vol 12 (22) ◽  
pp. 3740 ◽  
Author(s):  
Jae-Young Lim ◽  
Hyeon-Sik Jang ◽  
Hyun-Jae Yoo ◽  
Seung-il Kim ◽  
Dongmok Whang
Keyword(s):  
Graphene Layer ◽  
Twist Angle ◽  
Fabrication Method ◽  
Single Crystalline ◽  
Graphene Layers ◽  
Layer Graphene ◽  
Transmission Electron ◽  
Pick And Place ◽  
Grown Graphene ◽  
Unique Band

Twisted bi-layer graphene (tBLG) has attracted much attention because of its unique band structure and properties. The properties of tBLG vary with small differences in the interlayer twist angle, but it is difficult to accurately adjust the interlayer twist angle of tBLG with the conventional fabrication method. In this study, we introduce a facile tBLG fabrication method that directly picks up a single-crystalline graphene layer from a growth substrate and places it on another graphene layer with a pre-designed twist angle. Using this approach, we stacked single-crystalline graphene layers with controlled twist angles and thus fabricated tBLG and twisted multi-layer graphene (tMLG). The structural, optical and electrical properties depending on the twist angle and number of layers, were investigated using transmission electron microscopy (TEM), micro–Raman spectroscopy, and gate-dependent sheet resistance measurements. The obtained results show that the pick and place approach enables the direct dry transfer of the top graphene layer on the as-grown graphene to fabricate uniform tBLG and tMLG with minimal interlayer contamination and pre-defined twist angles.

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.

Low-Temperature Chemical Vapor Deposition Growth of Graphene Layers on Copper Substrate Using Camphor Precursor

2020 ◽  
Vol 20 (12) ◽  
pp. 7698-7704
Author(s):  
K. Kavitha ◽  
Akanksha R. Urade ◽  
Gurjinder Kaur ◽  
Indranil Lahiri
Keyword(s):  
Chemical Vapor Deposition ◽  
Low Temperature ◽  
Vapor Deposition ◽  
Graphene Layer ◽  
Copper Substrate ◽  
Chemical Vapor ◽  
Large Area ◽  
Chemical Vapor Deposition Growth ◽  
Graphene Layers ◽  
Grown Graphene

A two-step, low-temperature thermal chemical vapor deposition (CVD) process, which uses camphor for synthesizing continuous graphene layer on Cu substrate is reported. The growth process was performed at lower temperature (800 °C) using camphor as the source of carbon. A threezone CVD system was used for controlled heating of precursor, in order to obtain uniform graphene layer. As-grown samples were characterized by X-ray diffraction (XRD), Raman spectroscopy and transmission electron microscopy (TEM). The results show the presence of 4–5 layers of graphene. As-grown graphene transferred onto a glass substrate through a polymer-free wet-etching process, demonstrated transmittance ~91% in visible spectra. This process of synthesizing large area, 4–5 layer graphene at reduced temperature represents an energy-efficient method of producing graphene for possible applications in opto-electronic industry.

Graphene Growth on C and Si-Face of 4H-SiC – TEM and AFM Studies

2010 ◽  
Vol 645-648 ◽  
pp. 577-580 ◽  
Author(s):  
Jolanta Borysiuk ◽  
Rafał Bożek ◽  
Wlodek Strupiński ◽  
Jacek M. Baranowski
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Resolution ◽  
Graphene Layer ◽  
Graphene Growth ◽  
Graphene Layers ◽  
Prolonged Annealing ◽  
Transmission Electron ◽  
High Resolution Tem

Transmission Electron Microscopy (TEM) investigations of graphene layers synthesized on Si and C-terminated on-axis oriented 4H-SiC are presented. The high-resolution TEM (HRTEM) revealed distinctive distance differences between the first carbon graphene layer and SiC surface for both polarities. The prolonged annealing of SiC with carbon face shows, that in addition to the increase of number of graphene layers, there is also observed splitting between stack of graphene layers and the surface of SiC substrate. In addition, the density of so called “puckers” increases.

scholarly journals Synthesis and Characterization of Free-Stand Graphene/Silver Nanowire/Graphene Nano Composite as Transparent Conductive Film with Enhanced Stiffness

2020 ◽  
Vol 10 (14) ◽  
pp. 4802
Author(s):  
Chuanrui Guo ◽  
Yanxiao Li ◽  
Yanping Zhu ◽  
Chenglin Wu ◽  
Genda Chen
Keyword(s):  
Electrical Conductivity ◽  
Chemical Vapor ◽  
Optical Transmittance ◽  
Silver Nanowire ◽  
Sandwich Composite ◽  
Graphene Layers ◽  
Behavior Study ◽  
Transmission Electron ◽  
Grown Graphene ◽  
Film Stiffness

As-grown graphene via chemical vapor deposition (CVD) has potential defects, cracks, and disordered grain boundaries induced by the synthesis and transfer process. Graphene/silver nanowire/graphene (Gr/AgNW/Gr) sandwich composite has been proposed to overcome these drawbacks significantly as the AgNW network can provide extra connections on graphene layers to enhance the stiffness and electrical conductivity. However, the existing substrate (polyethylene terephthalate (PET), glass, silicon, and so on) for composite production limits its application and mechanics behavior study. In this work, a vacuum annealing method is proposed and validated to synthesize the free-stand Gr/AgNW/Gr nanocomposite film on transmission electron microscopy (TEM) grids. AgNW average spacing, optical transmittance, and electrical conductivity are characterized and correlated with different AgNW concentrations. Atomic force microscope (AFM) indentation on the free-stand composite indicates that the AgNW network can increase the composite film stiffness by approximately 460% with the AgNW concentration higher than 0.6 mg/mL. Raman spectroscopy shows the existence of a graphene layer and the disturbance of the AgNW network. The proposed method provides a robust way to synthesize free-stand Gr/AgNW/Gr nanocomposite and the characterization results can be utilized to optimize the nanocomposite design for future applications.

TEM Investigations of Graphene on 4H-SiC(0001)

2009 ◽  
Vol 615-617 ◽  
pp. 207-210
Author(s):  
Jolanta Borysiuk ◽  
Wlodek Strupiński ◽  
Rafał Bożek ◽  
Andrzej Wysmolek ◽  
Jacek M. Baranowski
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Silicon Carbide ◽  
Carbon Layer ◽  
Covalent Bonds ◽  
Axis Orientation ◽  
Graphene Layers ◽  
Layer Graphene ◽  
Transmission Electron ◽  
High Resolution Tem

Transmission Electron Microscopy (TEM) investigations of graphene layers on Si terminated 4H-SiC(0001) are presented. The graphene layers have been grown in a standard method using decomposition of silicon carbide. Two kind of graphene layers have been investigated: 1) grown on substrates with on-axis orientation, 2) grown on substrates with 4° and 8° off-axis orientation in respect of c-axis of SiC. In the case of 0° orientation the high resolution TEM micrographs revealed that a thin layer graphene is present: 1-3 monolayers were obtained. It was found that the first carbon layer was about 2Å from the SiC surface. This result indicates that a strong covalent bonds between carbon layer and silicon atoms on the SiC surface exist. The subsequent graphene layers have been found spaced by 3.4 Å - similar as in the graphite. That indicates a weak van der Waals bonding between subsequent carbon layers. In the case of 4° and 8° off-axis orientation a thicker layer of about 5-6 monolayers of graphene were obtained. Relative spacings of graphene layers were the same as in the case of on-axis orientation.

Twist-angle-dependent thermal conduction in single-crystalline bilayer graphene

2021 ◽  
Vol 118 (19) ◽  
pp. 193104
Author(s):  
Shuo Han ◽  
Xianhua Nie ◽  
Shangzhi Gu ◽  
Wenyu Liu ◽  
Luchen Chen ◽  
...  
Keyword(s):  
Thermal Conduction ◽  
Twist Angle ◽  
Bilayer Graphene ◽  
Single Crystalline

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.

scholarly journals Exploring the Capability of HAADF-STEM Techniques to Characterize Graphene Distribution in Nanocomposites by Simulations

2018 ◽  
Vol 2018 ◽  
pp. 1-12
Author(s):  
N. Baladés ◽  
D. L. Sales ◽  
M. Herrera ◽  
A. M. Raya ◽  
J. C. Hernández-Garrido ◽  
...  
Keyword(s):  
Electron Tomography ◽  
Carbon Matrix ◽  
Reconstruction Algorithm ◽  
Dark Field ◽  
Graphene Layers ◽  
Transmission Electron ◽  
Dispersion Degree ◽  
Scanning Transmission ◽  
The Matrix ◽  
Annular Dark Field

This paper explores the capability of scanning transmission electron microscopy (STEM) techniques in determining the dispersion degree of graphene layers within the carbon matrix by using simulated high-angle annular dark-field (HAADF) images. Results ensure that unmarked graphene layers are only detectable if their orientation is parallel to the microscope beam. Additionally, gold-marked graphene layers allow evaluating the dispersion degree in structural composites. Moreover, electron tomography has been demonstrated to provide truthfully 3D distribution of the graphene sheets inside the matrix when an appropriate reconstruction algorithm and 2D projections including channelling effect are used.

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.

scholarly journals Coupling of waveguide mode and graphene plasmons

2021 ◽  
Vol 255 ◽  
pp. 07002
Author(s):  
Jiří Petráček ◽  
Jiří Čtyroký ◽  
Vladimír Kuzmiak ◽  
Pavel Kwiecien ◽  
Ivan Richter
Keyword(s):  
Low Power ◽  
Graphene Layer ◽  
Waveguide Mode ◽  
Chemical Potential ◽  
Temperature Sensing ◽  
Graphene Layers ◽  
Optical Wavelength ◽  
Electro Optic ◽  
Photonic Waveguides ◽  
Graphene Plasmons

Photonic waveguides with graphene layers have been recently studied for their potential as fast and low-power electro-optic modulators with small footprints. We show that in the optical wavelength range of 1.55 μm, surface plasmons supported by the graphene layer with the chemical potential exceeding ~0.5 eV can couple with the waveguide mode and affect its propagation. This effect might be possibly utilized in technical applications as a very low-power amplitude modulation, temperature sensing, etc.

Sign in / Sign up

Export Citation Format

Share Document