Epitaxial graphene on SiC

Staff: Pierre Mallet, Jean-Yves Veuillen

Our objective is to study at the subnanometer scale the morphology and the electronic properties of graphene films only a few (1-4) layers thick. Our experimental tool is scanning tunnelling microscopy and spectroscopy (STM/STS), using an home made variable temperature microscope in UHV conditions.

Variable temperature STM in UHV

Home made variable temperature STM in the UHV chamber.

Samples are elaborated in-situ by sublimating Si from SiC wafers in the adjacent preparation chamber and characterized by standard surface science techniques (LEED and Auger spectroscopy). This work is part of a project involving other groups of the Néel Institute (and beyond) which aims at investigating the physical properties of this promising material (epitaxial graphene on SiC).

Atomic resolution on a graphene monolayer: honeycomb pattern.

Atomic resolution on a graphene monolayer: honeycomb pattern.

We have prepared samples with graphene coverage between one and two layers on the average. We have shown that we can discriminate graphene single and multi-layers (with AB stacking) from the atomic contrast in STM images.

Mono (M) et bilayer (B) graphene epitaxially grown on 6H-SiC(0001).

Mono (M) et bilayer (B) graphene epitaxially grown on 6H-SiC(0001).

Our study also reveals point defects generating intervalley scattering as well as the presence of a significant density of interface states in the vicinity of the Fermi level on the substrate surface.

Electron diffusion by a point defect on bilayer graphene (circle).

Electron diffusion by a point defect on bilayer graphene (circle).


Publications :

- "Electron states of mono- and bilayer graphene on SiC probed by scanning-tunneling microscopy", P. Mallet, F. Varchon, C. Naud, L. Magaud, C. Berger, and J.-Y. Veuillen, Phys. Rev. B 76, 041403(R) (2007)

- "Electronic structure of epitaxial graphene layers on SiC: Effect of the substrate", F. Varchon, R. Feng, J. Hass, X. Li, B. Ngoc Nguyen, C. Naud, P. Mallet, J.-Y. Veuillen, C. Berger, E. H. Conrad, and L. Magaud, Phys. Rev. Lett. 99, 126805 (2007)

- "Rotational disorder in few-layer graphene films on 6H-SiC(000-1): A scanning tunneling microscopy study", F. Varchon, P. Mallet, L. Magaud, and J.-Y. Veuillen, Phys. Rev. B 77, 165415 (2008)

Collaborations :

- Néel Institute : Group « Théorie et simulation numérique des propriétés électroniques » (MCMF) : atomic and electronic structure. Group « Cohérence quantique » (Nano) : electronic transport.

- The Georgia Institute of Technology (GATECH), Atlanta, Georgia, USA : transport and X-ray diffraction.

- Soleil : Antarès beamline (High resolution ARPES).

Fundings :

- ANR « Blanc » (2007).
- Projet Cible Région Rhône-Alpes (2007).
- ACI « Jeunes chercheurs » 2004-2007.


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