Laboratoire de Physique Théorique
Toulouse - UMR 5152

On a first step, we demonstrate that graphene grown on the (000-1) (C-face) of SiC exhibits the presence of the ideal linear dispersion characteristic of graphene [1]. This system presents several graphene sheets rotated by different angles, giving rise to a non Bernal stacking. Such rotations break the stacking symmetry of graphite and lead to each single sheet behaving like an isolated graphene plane.

On a second step, we have focused on the electronic properties of ribbons of graphene grown on facets of the SiC(0001) surface. It is possible to take advantage of graphene grown on patterned SiC steps [2], where the edge is settled by growth instead by cutting an already existing graphene sheet. We have observed by photoemission a region with a gap opening greater than 0.5 eV in an otherwise continuous metallic graphene sheet [3]. Our morphological characterization by STM and cross sectional TEM allows to understand the origin of the band gap in mini-ribbons bordering a central extended ribbon [4]. On the nanoribbon, where our STM measurements show a well-defined edge [5], transport measurements have also shown that charge carriers travel at room temperature on a length scale greater than ten micrometers [5], which is similar to the performance of metallic carbon nanotubes, and opens a promising future for graphene electronics.

References

[1] M. Sprinkle et al., Phys. Rev. Lett. 103, 226803 (2009).
[2] M. Sprinkle et al., Nature Nanotechnology 5, 727 (2010).
[3] J. Hicks et al., Nature Physics 9, 49 (2012).
[4] I. Palacio et al., NanoLett. 15, 182 (2015).
[5] J. Baringhaus et al., Nature 506, 349 (2014).