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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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Magnetoresistance measurements of the best sample at different temperatures. (a) Longitudinal and transverse resistances of low p-type doped (ns = 8 × 1011 cm-2) epitaxial monolayer versus applied magnetic field B, at different temperatures. (b) Temperature dependence of the resistivity ρxx of a graphene ribbon at different magnetic field values close to the filling factor v = 3. The slope in the semilog scale gives the activation energy Ea, which is the energy difference between the Fermi energy and the mobility edge of the second (N = 1) Landau level.
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Figure 5: Magnetoresistance measurements of the best sample at different temperatures. (a) Longitudinal and transverse resistances of low p-type doped (ns = 8 × 1011 cm-2) epitaxial monolayer versus applied magnetic field B, at different temperatures. (b) Temperature dependence of the resistivity ρxx of a graphene ribbon at different magnetic field values close to the filling factor v = 3. The slope in the semilog scale gives the activation energy Ea, which is the energy difference between the Fermi energy and the mobility edge of the second (N = 1) Landau level.

Mentions: In Figure 5a, we present similar resistance measurements obtained with a lower doped sample with a hole concentration ns = 8 × 1011 cm-2 and a mobility μ ~11,000 cm2/V s. The mobility is high enough and the concentration low enough to make the N = 0 and N = 1 plateaus well resolved and stable up to 13.5 T. The experimental results of Figure 5a have been obtained in a three probes configuration with low resistance contacts (40 Ω). The Hall resistance corresponds to the symmetric part of the signal: ρxy ~(V(B)+V(-B))/2I, where the voltage V is measured between a lateral probe and the current drain. At high magnetic fields, we identify V(+B)/IG as ρxx, where G~4 is the geometric factor and I is the current.


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)

Magnetoresistance measurements of the best sample at different temperatures. (a) Longitudinal and transverse resistances of low p-type doped (ns = 8 × 1011 cm-2) epitaxial monolayer versus applied magnetic field B, at different temperatures. (b) Temperature dependence of the resistivity ρxx of a graphene ribbon at different magnetic field values close to the filling factor v = 3. The slope in the semilog scale gives the activation energy Ea, which is the energy difference between the Fermi energy and the mobility edge of the second (N = 1) Landau level.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 5: Magnetoresistance measurements of the best sample at different temperatures. (a) Longitudinal and transverse resistances of low p-type doped (ns = 8 × 1011 cm-2) epitaxial monolayer versus applied magnetic field B, at different temperatures. (b) Temperature dependence of the resistivity ρxx of a graphene ribbon at different magnetic field values close to the filling factor v = 3. The slope in the semilog scale gives the activation energy Ea, which is the energy difference between the Fermi energy and the mobility edge of the second (N = 1) Landau level.
Mentions: In Figure 5a, we present similar resistance measurements obtained with a lower doped sample with a hole concentration ns = 8 × 1011 cm-2 and a mobility μ ~11,000 cm2/V s. The mobility is high enough and the concentration low enough to make the N = 0 and N = 1 plateaus well resolved and stable up to 13.5 T. The experimental results of Figure 5a have been obtained in a three probes configuration with low resistance contacts (40 Ω). The Hall resistance corresponds to the symmetric part of the signal: ρxy ~(V(B)+V(-B))/2I, where the voltage V is measured between a lateral probe and the current drain. At high magnetic fields, we identify V(+B)/IG as ρxx, where G~4 is the geometric factor and I is the current.

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