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Multidimensional characterization, Landau levels and Density of States in epitaxial graphene grown on SiC substrates.

Camara N, Jouault B, Jabakhanji B, Caboni A, Tiberj A, Consejo C, Godignon P, Camassel J - Nanoscale Res Lett (2011)

Bottom Line: Raman spectroscopy shows evidence of the almost free-standing character of these monolayer graphene sheets, which was confirmed by magneto-transport measurements.On the best samples, we find a moderate p-type doping, a high-carrier mobility and resolve the half-integer quantum Hall effect typical of high-quality graphene samples.A rough estimation of the density of states is given from temperature measurements.

View Article: PubMed Central - HTML - PubMed

Affiliation: Laboratoire Charles Coulomb, UMR 5221 CNRS-UM2, Place Eugène Bataillon, 34095 Montpellier Cedex 5, France. jouault@ges.univ-montp2.fr.

ABSTRACT
Using high-temperature annealing conditions with a graphite cap covering the C-face of, both, on axis and 8° off-axis 4H-SiC samples, large and homogeneous single epitaxial graphene layers have been grown. Raman spectroscopy shows evidence of the almost free-standing character of these monolayer graphene sheets, which was confirmed by magneto-transport measurements. On the best samples, we find a moderate p-type doping, a high-carrier mobility and resolve the half-integer quantum Hall effect typical of high-quality graphene samples. A rough estimation of the density of states is given from temperature measurements.

No MeSH data available.


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Typical magnetoresistance measurements for low doped and highly doped epitaxial graphene-based Hall Bars. (a) Longitudinal resistance of highly p-type doped epitaxial monolayer versus the magnetic field B, measured at 1.6 K. The resistance increases linearly with B with the superimposed SdH oscillations clearly resolved. Index of Landau levels (8-14) is also reported. Inset: the Landau plot indicates a phase equal to 0°, as expected for Dirac electrons. (b) Longitudinal and transverse resistance of low p-type doped epitaxial monolayer versus applied magnetic field B, at T = 1.6 K. The Hall resistance approaches the integer plateau Rxy ~12.9 kΩ at B ~13 T. The second plateau at 4 kΩ is hardly visible.
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Figure 4: Typical magnetoresistance measurements for low doped and highly doped epitaxial graphene-based Hall Bars. (a) Longitudinal resistance of highly p-type doped epitaxial monolayer versus the magnetic field B, measured at 1.6 K. The resistance increases linearly with B with the superimposed SdH oscillations clearly resolved. Index of Landau levels (8-14) is also reported. Inset: the Landau plot indicates a phase equal to 0°, as expected for Dirac electrons. (b) Longitudinal and transverse resistance of low p-type doped epitaxial monolayer versus applied magnetic field B, at T = 1.6 K. The Hall resistance approaches the integer plateau Rxy ~12.9 kΩ at B ~13 T. The second plateau at 4 kΩ is hardly visible.

Mentions: For carrier concentrations larger than 3 × 1012 cm-2, no QHE could be detected and only Shubnikov-de Haas (SdH) oscillations were found. This is shown in Figure 4 for an off-axis sample and, as usual, the plot of the inverse field at which the oscillations maxima occur versus the Landau level index shows a clear linear dependence going down to the origin. This is the usual signature of the heavily doped graphene.


Multidimensional characterization, Landau levels and Density of States in epitaxial graphene grown on SiC substrates.

Camara N, Jouault B, Jabakhanji B, Caboni A, Tiberj A, Consejo C, Godignon P, Camassel J - Nanoscale Res Lett (2011)

Typical magnetoresistance measurements for low doped and highly doped epitaxial graphene-based Hall Bars. (a) Longitudinal resistance of highly p-type doped epitaxial monolayer versus the magnetic field B, measured at 1.6 K. The resistance increases linearly with B with the superimposed SdH oscillations clearly resolved. Index of Landau levels (8-14) is also reported. Inset: the Landau plot indicates a phase equal to 0°, as expected for Dirac electrons. (b) Longitudinal and transverse resistance of low p-type doped epitaxial monolayer versus applied magnetic field B, at T = 1.6 K. The Hall resistance approaches the integer plateau Rxy ~12.9 kΩ at B ~13 T. The second plateau at 4 kΩ is hardly visible.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211189&req=5

Figure 4: Typical magnetoresistance measurements for low doped and highly doped epitaxial graphene-based Hall Bars. (a) Longitudinal resistance of highly p-type doped epitaxial monolayer versus the magnetic field B, measured at 1.6 K. The resistance increases linearly with B with the superimposed SdH oscillations clearly resolved. Index of Landau levels (8-14) is also reported. Inset: the Landau plot indicates a phase equal to 0°, as expected for Dirac electrons. (b) Longitudinal and transverse resistance of low p-type doped epitaxial monolayer versus applied magnetic field B, at T = 1.6 K. The Hall resistance approaches the integer plateau Rxy ~12.9 kΩ at B ~13 T. The second plateau at 4 kΩ is hardly visible.
Mentions: For carrier concentrations larger than 3 × 1012 cm-2, no QHE could be detected and only Shubnikov-de Haas (SdH) oscillations were found. This is shown in Figure 4 for an off-axis sample and, as usual, the plot of the inverse field at which the oscillations maxima occur versus the Landau level index shows a clear linear dependence going down to the origin. This is the usual signature of the heavily doped graphene.

Bottom Line: Raman spectroscopy shows evidence of the almost free-standing character of these monolayer graphene sheets, which was confirmed by magneto-transport measurements.On the best samples, we find a moderate p-type doping, a high-carrier mobility and resolve the half-integer quantum Hall effect typical of high-quality graphene samples.A rough estimation of the density of states is given from temperature measurements.

View Article: PubMed Central - HTML - PubMed

Affiliation: Laboratoire Charles Coulomb, UMR 5221 CNRS-UM2, Place Eugène Bataillon, 34095 Montpellier Cedex 5, France. jouault@ges.univ-montp2.fr.

ABSTRACT
Using high-temperature annealing conditions with a graphite cap covering the C-face of, both, on axis and 8° off-axis 4H-SiC samples, large and homogeneous single epitaxial graphene layers have been grown. Raman spectroscopy shows evidence of the almost free-standing character of these monolayer graphene sheets, which was confirmed by magneto-transport measurements. On the best samples, we find a moderate p-type doping, a high-carrier mobility and resolve the half-integer quantum Hall effect typical of high-quality graphene samples. A rough estimation of the density of states is given from temperature measurements.

No MeSH data available.


Related in: MedlinePlus