1. A method for obtaining flat n-graphene sheets using reverse exfoliation process
V. Huc, IPCMO, Orsay
N. Bendiab, LSP-UJF, Grenoble
T. Ebbesen, U .Pasteur, Strasbourg
C. Delacour, V. Bouchiat, Institut Néel, CNRS- Grenoble

2. Deposited Graphene layers exhibits defects : pleats and folds
Novoselov, Geim group
lowered carrier mobility and suppression of
weak localization in graphene-based devices have been
attributed to corrugation of the graphene.

3. Masa Ishigami, et al. Nano Lett. ASAP paper 11-May-2007
Meyer, J. C.; et al. On the roughness of single- and bi-layer graphene
membranes. Preprint archive, xxx.lanl.gov, cond-mat/ , 2007.
Novoselov, Geim group

4. Reverse Exfoliation Process
Epoxy glue
Freshsly cleaved
Bulk HOPG
Oxidized Silicon chip
Step 1 : Bulk HOPG Bonding (upside down)

5. Reverse Exfoliation Process
Epoxy glue
Step 1 : Bulk HOPG Bonding (upside down)
Adhesive wafer bonding
F. Niklaus et al. Appl. Phys. 99, , 2006

6. Molding of the top Graphite surface into the epoxy

7. Reverse Exfoliation Process
Step 2 : epoxy curing under screw press

8. Reverse Exfoliation Process
Bulk HOPG
Epoxy glue
Oxidized Silicon chip
Step 3 : Bulk HOPG Scalpel Cleaving

9. Step 4 : Scotch™ tape exfoliation
Bulk HOPG
Epoxy glue
Oxidized Silicon chip
Step 4 : Scotch™ tape exfoliation
K.S. Novoselov et al;, Science 306, 666 , (2004).

10. Coupe au niveau d’une bulle
Epoxy
Glue
Épaisseur
Colle = 3µm
graphene Si

11. A process reminiscent from the Smart-cut ® process
US Patent 5,882,987, published 1999
Atomic scalpel

12. A process reminiscent from the Smart-cut ® process
US Patent 5,882,987, published 1999
Bernin
Atomic scalpel

13. Image d’une fissure de contrainte (colle dans la fissure)

14. pleats defects

15. SEM zoom on Pleats defects

16. Graphene on epi SiC (GaTech U.) : same kind of pleats

18. Effective surface potential
Scanning Potential Microscopy
Effective surface potential
Sonde de Kelvin

19. Lift height = 5 nm Tip bias = 2V 6 µm Scan

20. Raman Probing
The Raman spectrum of graphite is composed of a strong band at 1582 cm-1, which has been assigned to the in-plane E2g zone centre mode (G band).
Gupta et al. Nano Lett., Vol. 6, No. 12, 2006 p.2668

21. Raman Probing
The Raman spectrum of graphite is composed of a strong band at 1582 cm-1, which has been assigned to the in-plane E2g zone centre mode (G band).
G-band clearly
downshifts with increasing n
Gupta et al. Nano Lett., Vol. 6, No. 12, 2006 p.2668

22. Raman Probing
The Raman spectrum of graphite is composed of a strong band at 1582 cm-1, which has been assigned to the in-plane E2g zone centre mode (G band).
G-band clearly downshifts
with increasing n
Gupta et al. Nano Lett., Vol. 6, No. 12, p
A. C. Ferrari, et al. Phys. Rev. Lett. 97, (2006).

23. Raman as a way to assess single graphene layers
Gupta et al. Nano Lett., Vol. 6, No. 12, 2006 p.2668

24. Raman micro-spectroscopy
MicroRaman spectra are collected using a X100 objective with a spot size of 1m using nm excitation under ambient conditions at low laser power (<1mW).

25. AFM sur Zone Raman Monocouche (2)
Marche monocouche
Colle ? Bulle

26. AFM sur Zone Raman Monocouche (2)

27. Fissure de contrainte ?
2 µm

28. Reconnection using Pd
100 µm

29. Contacts Pd/Graphene
5 µm

30. Conclusion :
Reverse exfoliation
make possible the realization of flat graphene sheets