Limits...
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

SEM images of a monolayer graphene islands grown on the C-face of an 8° off-axis 4H-SiC substrate. (a, b) Images of the largest homogeneous SLEG islands, (c) early growth, (d) zoomed image with visible wrinkles, (e, f) example of starting nucleation point by a surface defect with step bunching clearly visible in (f).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC3211189&req=5

Figure 1: SEM images of a monolayer graphene islands grown on the C-face of an 8° off-axis 4H-SiC substrate. (a, b) Images of the largest homogeneous SLEG islands, (c) early growth, (d) zoomed image with visible wrinkles, (e, f) example of starting nucleation point by a surface defect with step bunching clearly visible in (f).

Mentions: To produce SLEG, in both cases of on axis and 8° off-axis SiC substrates, we used the recipes of Ref.[12]. On the on-axis material, this produces long, self-ordered, graphene ribbons which are typically 5 μm wide and several 100 μm long. This has been described at length in the work of Ref.[16]. On the off-axis substrates, this resulted also on SLEG islands but the morphology is completely different This is shown in Figure 1. Instead of narrow ribbons, after 30 min graphitisation at 1700°C, large SLEG islands can be obtained which can reach 300 μm long and 50 μm wide for the biggest ones. See Figure 1a and 1b. They can have a trapezoidal or triangular shape, see Figure 1a-c and 1f and, usually, nucleate from a defect on the surface. See Figure 1e and 1f. This may be either an unintentional particle remaining on the surface, a crystallographic defect such as a threading dislocation or a simple scratch made by a diamond tip. Whatever the origin, the growth starts from one nucleating centre and expands in a two-dimension carpet-like way. All resulting triangles are then self-oriented, with the longest side following the (11-20) plane direction.


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)

SEM images of a monolayer graphene islands grown on the C-face of an 8° off-axis 4H-SiC substrate. (a, b) Images of the largest homogeneous SLEG islands, (c) early growth, (d) zoomed image with visible wrinkles, (e, f) example of starting nucleation point by a surface defect with step bunching clearly visible in (f).
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 1: SEM images of a monolayer graphene islands grown on the C-face of an 8° off-axis 4H-SiC substrate. (a, b) Images of the largest homogeneous SLEG islands, (c) early growth, (d) zoomed image with visible wrinkles, (e, f) example of starting nucleation point by a surface defect with step bunching clearly visible in (f).
Mentions: To produce SLEG, in both cases of on axis and 8° off-axis SiC substrates, we used the recipes of Ref.[12]. On the on-axis material, this produces long, self-ordered, graphene ribbons which are typically 5 μm wide and several 100 μm long. This has been described at length in the work of Ref.[16]. On the off-axis substrates, this resulted also on SLEG islands but the morphology is completely different This is shown in Figure 1. Instead of narrow ribbons, after 30 min graphitisation at 1700°C, large SLEG islands can be obtained which can reach 300 μm long and 50 μm wide for the biggest ones. See Figure 1a and 1b. They can have a trapezoidal or triangular shape, see Figure 1a-c and 1f and, usually, nucleate from a defect on the surface. See Figure 1e and 1f. This may be either an unintentional particle remaining on the surface, a crystallographic defect such as a threading dislocation or a simple scratch made by a diamond tip. Whatever the origin, the growth starts from one nucleating centre and expands in a two-dimension carpet-like way. All resulting triangles are then self-oriented, with the longest side following the (11-20) plane direction.

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