Strain and Charge in Epitaxial Graphene on Silicon Carbide Studied by Raman Spectroscopy

The phonon frequencies of epitaxial graphene on silicon carbide (SiC) depend on mechanical strain and charge transfer from the substrate to the epitaxial layer. Strain and doping depend on the preparation process and on the number of graphene layers. We measured the phonon frequencies by Raman spectroscopy and compare the results between epitaxial layers fabricated by high temperature annealing and by hydrogen intercalation of the covalently bound graphene layer of the 6 p 3 6 p 3 reconstructed SiC surface. Only the latter graphene layer shows tensile strain, which can partly be explained by lattice mismatch between substrate and epitaxial graphene.

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Graphene Layers on Silicon Carbide Studied by Raman Spectroscopy

Materials Science Forum ◽

10.4028/www.scientific.net/msf.600-603.567 ◽

2008 ◽

Vol 600-603 ◽

pp. 567-570 ◽

Cited By ~ 2

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.

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Backside Monitoring of Graphene on Silicon Carbide by Raman Spectroscopy

Materials Science Forum ◽

10.4028/www.scientific.net/msf.778-780.1166 ◽

2014 ◽

Vol 778-780 ◽

pp. 1166-1169

Author(s):

Felix Fromm ◽

Martin Hundhausen ◽

Michl Kaiser ◽

Thomas Seyller

Keyword(s):

Silicon Carbide ◽

Raman Spectroscopy ◽

Raman Spectra ◽

Graphene Layer ◽

Scattered Light ◽

Epitaxial Graphene ◽

Raman Intensity ◽

Top Down ◽

Measurement Geometry

Raman spectroscopy is commonly applied for studying the properties of epitaxial graphene on silicon carbide (SiC). In principle, the Raman intensity of a single graphene layer is rather low compared to the signal of SiC. In this work we follow an approach to improve the Raman intensity of epitaxial graphene on SiC by recording Raman spectra in a top-down geometry, i.e. a geometry in which the graphene layer is probed with the excitation through the SiC substrate [1]. This technique takes advantage of the fact, that most of the Raman scattered light of the graphene is emitted into the SiC substrate. We analyze in detail the top-down measurement geometry regarding the graphene and SiC Raman intensity, as well as the influence of aberration effects caused by the refraction at the air/SiC interface.

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Pinned and unpinned epitaxial graphene layers on SiC studied by Raman spectroscopy

Journal of Applied Physics ◽

10.1063/1.4721673 ◽

2012 ◽

Vol 111 (11) ◽

pp. 114307 ◽

Cited By ~ 11

Author(s):

K. Grodecki ◽

J. A. Blaszczyk ◽

W. Strupinski ◽

A. Wysmolek ◽

R. Stępniewski ◽

...

Keyword(s):

Raman Spectroscopy ◽

Epitaxial Graphene ◽

Graphene Layers

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Deep UV Raman Spectroscopy of Epitaxial Graphenes on Vicinal 6H-SiC Substrates

Materials Science Forum ◽

10.4028/www.scientific.net/msf.645-648.611 ◽

2010 ◽

Vol 645-648 ◽

pp. 611-614

Author(s):

Susumu Kamoi ◽

Noriyuki Hasuike ◽

Kenji Kisoda ◽

Hiroshi Harima ◽

Kouhei Morita ◽

...

Keyword(s):

Graphene Layer ◽

Peak Frequency ◽

Epitaxial Graphene ◽

Intensity Increase ◽

Band Frequency ◽

Graphene Layers ◽

Exfoliated Graphene ◽

Uv Raman Spectroscopy ◽

Uv Raman ◽

Deep Ultraviolet

We report microscopic Raman scattering studies of epitaxial graphene grown on SiC substrates using a deep-ultraviolet (UV) laser excitation at 266 nm to elucidate the interaction between the graphene layer and the substrate. The samples were grown on the Si-face of vicinal 6H-SiC (0001) substrates by sublimation of Si from SiC. The G band of the epitaxial graphene layer was clearly observed without any data manipulation. Increasing the number of graphene layers, the peak frequency of the G-band decreases linearly, while the peak width and the intensity increase. The G-band frequency of the graphene layers on SiC is higher than those of exfoliated graphene, which has been ascribed to compression from the substrate.

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Structure of Carbonic Layer in Ohmic Contacts: Comparison of Silicon Carbide/Carbon and Carbon/Silicide Interfaces

ISRN Physical Chemistry ◽

10.1155/2013/487485 ◽

2013 ◽

Vol 2013 ◽

pp. 1-11 ◽

Cited By ~ 1

Author(s):

Paweł Borowicz ◽

Adrian Kuchuk ◽

Zbigniew Adamus ◽

Michał Borysiewicz ◽

Marek Ekielski ◽

...

Keyword(s):

Silicon Carbide ◽

Raman Spectroscopy ◽

Thermal Treatment ◽

Ohmic Contacts ◽

Carbon Film ◽

Graphene Layers ◽

Three Samples ◽

Nickel Silicon

The structure of carbonic layer in three samples composed of 4H polytype of silicon carbide and the following sequence of layers: carbon/nickel/silicon/nickel/silicon was investigated with Raman spectroscopy. Different thermal treatment of the samples led to differences in the structure of carbonic layer. Raman measurements were performed with visible excitation focused on two interfaces: silicon carbide/carbon and carbon/silicide. The results showed differences in the structure across carbon film although its thickness corresponds to 8/10 graphene layers.

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Raman Spectroscopy Imaging of Exceptional Electronic Properties in Epitaxial Graphene Grown on SiC

Nanomaterials ◽

10.3390/nano10112234 ◽

2020 ◽

Vol 10 (11) ◽

pp. 2234

Author(s):

A. Ben Gouider Trabelsi ◽

F. V. Kusmartsev ◽

A. Kusmartseva ◽

F. H. Alkallas ◽

S. AlFaify ◽

...

Keyword(s):

Graphene Layer ◽

Longitudinal Optical ◽

Epitaxial Graphene ◽

Charge Carrier Concentration ◽

Longitudinal Optical Phonon ◽

Electrical Measurements ◽

Graphene Layers ◽

Fundamental Research ◽

Application Fields ◽

High Degree

Graphene distinctive electronic and optical properties have sparked intense interest throughout the scientific community bringing innovation and progress to many sectors of academia and industry. Graphene manufacturing has rapidly evolved since its discovery in 2004. The diverse growth methods of graphene have many comparative advantages in terms of size, shape, quality and cost. Specifically, epitaxial graphene is thermally grown on a silicon carbide (SiC) substrate. This type of graphene is unique due to its coexistence with the SiC underneath which makes the process of transferring graphene layers for devices manufacturing simple and robust. Raman analysis is a sensitive technique extensively used to explore nanocarbon material properties. Indeed, this method has been widely used in graphene studies in fundamental research and application fields. We review the principal Raman scattering processes in SiC substrate and demonstrate epitaxial graphene growth. We have identified the Raman bands signature of graphene for different layers number. The method could be readily adopted to characterize structural and exceptional electrical properties for various epitaxial graphene systems. Particularly, the variation of the charge carrier concentration in epitaxial graphene of different shapes and layers number have been precisely imaged. By comparing the intensity ratio of 2D line and G line—“I2D/IG”—the density of charge across the graphene layers could be monitored. The obtained results were compared to previous electrical measurements. The substrate longitudinal optical phonon coupling “LOOPC” modes have also been examined for several epitaxial graphene layers. The LOOPC of the SiC substrate shows a precise map of the density of charge in epitaxial graphene systems for different graphene layers number. Correlations between the density of charge and particular graphene layer shape such as bubbles have been determined. All experimental probes show a high degree of consistency and efficiency. Our combined studies have revealed novel capacitor effect in diverse epitaxial graphene system. The SiC substrate self-compensates the graphene layer charge without any external doping. We have observed a new density of charge at the graphene—substrate interface. The located capacitor effects at epitaxial graphene-substrate interfaces give rise to an unexpected mini gap in graphene band structure.

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Epitaxial Graphenes on Silicon Carbide

MRS Bulletin ◽

10.1557/mrs2010.552 ◽

2010 ◽

Vol 35 (4) ◽

pp. 296-305 ◽

Cited By ~ 159

Author(s):

Phillip N. First ◽

Walt A. de Heer ◽

Thomas Seyller ◽

Claire Berger ◽

Joseph A. Stroscio ◽

...

Keyword(s):

Silicon Carbide ◽

Electronic Structure ◽

Weak Coupling ◽

Materials Science ◽

Epitaxial Graphene ◽

Multilayer Graphene ◽

Wafer Scale ◽

Graphene Layers ◽

Salient Features ◽

Graphene Devices

AbstractThis article reviews the materials science of graphene grown epitaxially on the hexagonal basal planes of SiC crystals and progress toward the deterministic manufacture of graphene devices. We show that the growth of epitaxial graphene on Si-terminated SiC(0001) differs from growth on the C-terminated SiC(0001) surface, resulting in, respectively, strong and weak coupling to the substrate and to successive graphene layers. Monolayer epitaxial graphene on either surface displays the expected electronic structure and transport characteristics of graphene, but the non-graphitic stacking of multilayer graphene on SiC(0001) determines an electronic structure much different from that of graphitic multilayers on SiC(0001). This materials system is rich in subtleties, and graphene grown on the two polar faces of SiC differs in important ways, but all of the salient features of ideal graphene are found in these epitaxial graphenes, and wafer-scale fabrication of multi-GHz devices already has been achieved.

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Interface and interaction of graphene layers on SiC(0001̄) covered with TiC(111) intercalation

Physical Chemistry Chemical Physics ◽

10.1039/c7cp04443g ◽

2017 ◽

Vol 19 (39) ◽

pp. 26765-26775

Author(s):

Lu Wang ◽

Qiang Wang ◽

Jianmei Huang ◽

Wei-qi Li ◽

Guang-hui Chen ◽

...

Keyword(s):

Silicon Carbide ◽

Titanium Carbide ◽

Epitaxial Growth ◽

Graphene Layer ◽

Graphene Layers

It is important to understand the interface and interaction between the graphene layer, titanium carbide [TiC(111)] interlayer, and silicon carbide [SiC(0001̄)] substrates in epitaxial growth of graphene on silicon carbide (SiC) substrates.

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Investigation of Graphene Growth on 4H-SiC

Materials Science Forum ◽

10.4028/www.scientific.net/msf.615-617.223 ◽

2009 ◽

Vol 615-617 ◽

pp. 223-226 ◽

Cited By ~ 4

Author(s):

A. Castaing ◽

Owen J. Guy ◽

Michal Lodzinski ◽

S.P. Wilks

Keyword(s):

Photoelectron Spectroscopy ◽

Graphene Layer ◽

Bulk Material ◽

High Vacuum ◽

Epitaxial Graphene ◽

Ultra High Vacuum ◽

Graphene Growth ◽

Graphene Layers ◽

Force Microscopy ◽

Wide Range

This paper reports the investigation of epitaxial graphene growth on 4H-SiC substrates. Growth has been performed under ultra high vacuum (UHV) conditions at temperatures ranging from 1150 to 1250°C, and the formation of the graphene layer has been monitored using X-ray photoelectron spectroscopy (XPS). A gradient of 100°C in temperature was introduced across the sample in order to grow a wide range of thicknesses along the sample. Atomic force microscopy (AFM) of the surface shows that the epitaxial graphene layer follows the topography of the bulk material and introduces very little surface roughness. This paper also reports the electrical characterisation of the graphene layers.

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