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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.


Related in: MedlinePlus

Density of states ρ(E) as a function of the energy Ea. For comparison, the density of states without magnetic field at EF = 100 meV is indicated by an arrow.
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Figure 6: Density of states ρ(E) as a function of the energy Ea. For comparison, the density of states without magnetic field at EF = 100 meV is indicated by an arrow.

Mentions: Following this procedure, already used in the early times after the discovery of the integer QHE [21], we find the density of states plotted in Figure 6. The formation of the Landau level is evidenced as, when Ea decreases, the density of states ρ(E) increases and becomes one order of magnitude larger than the density of states ρ0(E) without magnetic field at a comparable energy EF ~100 meV: ρ0(E) ~15 × 109 cm-2 meV-1. The shape of ρ(E) gives a rough upper bound of the half-width at half-maximum (HWHM) of the N = 1 Landau Level. We find HWHM ≤ 3 meV. This value is in good agreement with results obtained recently on EG by STM [22]. However, the extracted density is systematically larger than ρ0 over the whole investigated energy range. This observation, combined with the fact that hopping was neglected, indicates that more detailed investigations are still needed.


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)

Density of states ρ(E) as a function of the energy Ea. For comparison, the density of states without magnetic field at EF = 100 meV is indicated by an arrow.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 6: Density of states ρ(E) as a function of the energy Ea. For comparison, the density of states without magnetic field at EF = 100 meV is indicated by an arrow.
Mentions: Following this procedure, already used in the early times after the discovery of the integer QHE [21], we find the density of states plotted in Figure 6. The formation of the Landau level is evidenced as, when Ea decreases, the density of states ρ(E) increases and becomes one order of magnitude larger than the density of states ρ0(E) without magnetic field at a comparable energy EF ~100 meV: ρ0(E) ~15 × 109 cm-2 meV-1. The shape of ρ(E) gives a rough upper bound of the half-width at half-maximum (HWHM) of the N = 1 Landau Level. We find HWHM ≤ 3 meV. This value is in good agreement with results obtained recently on EG by STM [22]. However, the extracted density is systematically larger than ρ0 over the whole investigated energy range. This observation, combined with the fact that hopping was neglected, indicates that more detailed investigations are still needed.

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