Structural properties of the multilayer graphene/<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mn>4</mml:mn><mml:mi>H</mml:mi><mml:mtext>−</mml:mtext><mml:mi mathvariant="normal">Si</mml:mi><mml:mi mathvariant="normal">C</mml:mi><mml:mrow><mml:mo>(</mml:mo><mml:mn>000</mml:mn><mml:mover accent="true"><mml:mn>1</mml:mn><mml:mo stretchy="false">¯</mml:mo></mml:mover><mml:mo>)</mml:mo></mml:mrow></mml:mrow></mml:math>system as determined by surface x-ray diffraction

Hass, Joanna; Feng, Rui; Millán-Otoya, J. E.; Li, X.; Sprinkle, M.; First, Phillip N.; Heer, Walter A. de; Conrad, E. H.; Berger, Claire

doi:10.1103/physrevb.75.214109

Cited by 172 publications

(178 citation statements)

References 34 publications

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“…18), respectively. In addition, graphene on C-face SiC, which has a B30°twist angle between adjacent layers, has a 3.368 Å interlayer distance 19 . TEM characterization of the graphene layers was performed using an aberration corrected (image) Titan 80-300 TEM operated at an accelerating voltage of 80 kV.…”

Section: Resultsmentioning

confidence: 99%

Observation of the intrinsic bandgap behaviour in as-grown epitaxial twisted graphene

et al. 2015

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Twisted graphene is of particular interest due to several intriguing characteristics, such as its the Fermi velocity, van Hove singularities and electronic localization. Theoretical studies recently suggested the possible bandgap opening and tuning. Here, we report a novel approach to producing epitaxial twisted graphene on SiC (0001) and the observation of its intrinsic bandgap behaviour. The direct deposition of C 60 on pre-grown graphene layers results in few-layer twisted graphene confirmed by angular resolved photoemission spectroscopy and Raman analysis. The strong enhanced G band in Raman and sp 3 bonding characteristic in X-ray photoemission spectroscopy suggests the existence of interlayer interaction between adjacent graphene layers. The interlayer spacing between graphene layers measured by transmission electron microscopy is 0.352 ± 0.012 nm. Thermal activation behaviour and nonlinear current-voltage characteristics conclude that an intrinsic bandgap is opened in twisted graphene. Low sheet resistance (B160 O& À 1 at 10 K) and high mobility (B2,000 cm 2 V À 1 s À 1 at 10 K) are observed.

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Section: Resultsmentioning

confidence: 99%

Observation of the intrinsic bandgap behaviour in as-grown epitaxial twisted graphene

et al. 2015

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“…The TEM micrographs in Fig.1b,c include a transition layer (Layer 0), which is in direct contact with the SiC substrate, and generally is not considered graphene. 21,22 The subsequent layers above Layer 0 constitute the electrically active graphene, and give rise to its unique properties. As such, these first two upper layers are considered monolayer (Fig.…”

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confidence: 99%

Correlating Raman Spectral Signatures with Carrier Mobility in Epitaxial Graphene: A Guide to Achieving High Mobility on the Wafer Scale

et al. 2009

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We report a direct correlation between carrier mobility and Raman topography of epitaxial graphene (EG) grown on silicon carbide (SiC). We show the Hall mobility of material on the Si-face of SiC [SiC(0001)] is not only highly dependent on thickness uniformity but also on monolayer s st tr ra ai in n uniformity. Only when both thickness and strain are uniform over a significant fraction (> 40%) of the device active area does the mobility exceed 1000 cm 2 /V-s. Additionally, we achieve high mobility epitaxial graphene (18,100 cm 2 /V-s at room temperature) on the C-face of SiC [SiC(000-1)] and show that carrier mobility depends strongly on the graphene layer stacking. These findings provide a means to rapidly estimate carrier mobility and provide a guide to achieve very high mobility in epitaxial graphene. Our results suggest that ultra-high mobilities (>50,000 cm 2 /V-s) are achievable via the controlled formation of uniform, rotationally faulted epitaxial graphene.The recent success of graphene transistor operation in the giga-hertz range has solidified the potential of this material for high speed electronic applications. 1,2 Realization of graphene technologies at commercial scales, however, necessitates large-area graphene production, as well as the ability to rapidly characterize its structural and electronic quality. Graphene films can be produced by mechanical exfoliation from bulk graphite, 3,4 reduction of graphite-oxide, 5,6 chemical vapor deposition on catalytic films, 7 or via Si-sublimation from bulk SiC substrates. 8 9, -10,11, 12 The last technique currently appears to hold the most promise for large-area electronic grade graphene, and already shows tremendous potential for high-frequency device technologies. 2 Nevertheless, precise control of the graphene electronic properties (i.e. mobility) over large areas is necessary to enable graphene-based technological applications. Realization of such control will come through an intimate understanding of the process-propertyperformance relationship and the role that graphene thickness, strain, and layer stacking plays in this relationship over very large areas up to full wafers. Of the characterization techniques used for layer thickness determination, 13 ,14,15, -16,17,18, 19 Raman spectroscopy is arguably the simplest and fastest, especially for exploring monolayer EG on SiC(0001) (referred to as EG Si )and EG layer stacking on SiC(000-1) (referred to as EG c ). [15][16][17][18][19] Characterization of EG via Raman spectroscopy requires fitting the 2D Raman peak. 15,16,20 Raman spectra of EG Si fit by one or four Lorentzian functions are characteristic of monolayer or bilayer graphene, respectively. 15 Figure 1a demonstrates layer thickness evaluation for monolayer and bilayer EG Si via Lorentzian fitting of the 2D Raman spectra. To further validate these thickness measurements, cross-sectional transmission electron microscopy (TEM) was performed (Fig. 1b,c). The TEM micrographs in Fig.1b,c include a transition layer (Layer 0), which is in dire...

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“…The high mobility parameters of C-face graphene have been attributed to a weak interaction of few layer graphene (FLG) with the substrate and a decoupling between the individual sheets in the stack, i.e., C-face FLG shows a single p-band in similarity to single layer graphene (SLG). 3,4 It has been argued that a rotational disorder between the layers in the FLG stack on 4H-and 6H-SiC (000-1) leads to their decoupling. 3,4 However, other works reported that rotation of different domains occurs laterally within the same layer rather than in the adjacent layers in the stack, 6 and that C-face graphene is composed of AB-stacked sheets.…”

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confidence: 99%

“…3,4 It has been argued that a rotational disorder between the layers in the FLG stack on 4H-and 6H-SiC (000-1) leads to their decoupling. 3,4 However, other works reported that rotation of different domains occurs laterally within the same layer rather than in the adjacent layers in the stack, 6 and that C-face graphene is composed of AB-stacked sheets. 7 In contrast to the case of 4H-and 6H-SiC, C-face graphene grown on 3C-SiC is scarcely investigated.…”

mentioning

confidence: 99%

“…1,2 Consequently, C-face graphene on the hexagonal SiC polytypes has been a subject of extensive investigations with the prospect of achieving material with transport properties similar to those of exfoliated graphene. [1][2][3][4][5] C-face graphene grows typically in the form of few-layerthick regions with different numbers of graphene layers. The high mobility parameters of C-face graphene have been attributed to a weak interaction of few layer graphene (FLG) with the substrate and a decoupling between the individual sheets in the stack, i.e., C-face FLG shows a single p-band in similarity to single layer graphene (SLG).…”

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confidence: 99%

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Decoupling and ordering of multilayer graphene on C-face 3C-SiC(111)

Bouhafs

Stanishev

Zakharov

et al. 2016

Applied Physics Letters

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We show experimentally that few layer graphene (FLG) grown on the carbon terminated surface (C-face) of 3C-SiC(111) is composed of decoupled graphene sheets. Landau level spectroscopy on FLG graphene is performed using the infrared optical Hall effect. We find that Landau level transitions in the FLG exhibit polarization preserving selection rules and the transition energies obey a square-root dependence on the magnetic field strength. These results show that FLG on C-face 3C-SiC(111) behave effectively as a single layer graphene with linearly dispersing bands (Dirac cones) at the graphene K point. We estimate from the Landau level spectroscopy an upper limit of the Fermi energy of about 60 meV in the FLG, which corresponds to a carrier density below 2.5 × 1011 cm−2. Low-energy electron diffraction μ-LEED) reveals the presence of azimuthally rotated graphene domains with a typical size of ≤200 nm. μ-LEED mapping suggests that the azimuth rotation occurs between adjacent domains within the same sheet rather than vertically in the stack.

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Structural properties of the multilayer graphene/4H−SiC(0001¯)system as determined by surface x-ray diffraction

Cited by 172 publications

References 34 publications

Observation of the intrinsic bandgap behaviour in as-grown epitaxial twisted graphene

Observation of the intrinsic bandgap behaviour in as-grown epitaxial twisted graphene

Correlating Raman Spectral Signatures with Carrier Mobility in Epitaxial Graphene: A Guide to Achieving High Mobility on the Wafer Scale

Decoupling and ordering of multilayer graphene on C-face 3C-SiC(111)

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