TITLE:
Graphene Thin Layers Formation on Monocrystalline Ni(111)/MgO(111) by Carbon Implantation and Annealing
AUTHORS:
F. Le Normand, M. Benyahia, C. Speisser, D. Muller, F. Aweke, G. Gutierrez, J. Arabski, G. Morvan
KEYWORDS:
Graphene, Nickel, Monocrystalline Films, Ion Implantation, Raman Spectroscopy
JOURNAL NAME:
Graphene,
Vol.4 No.2,
April
8,
2015
ABSTRACT: The objectives of this study are the elaboration of graphene by 1) carbon implantation at moderate temperature (873 K) into a monodomain epitaxially-grown Ni(111) film deposited on a reusable MgO(111) substrate, followed by 2) carbon surface precipitation by thermal treatment. The growth of the nickel film by molecular beam epitaxy has been monitored by Reflection High Energy Electron Diffraction. The film morphology has been studied by Electron Back-Scattered Diffraction, Atomic Force Microscopy and Rutherford Backscattering Spectroscopy in the tunneling mode. In the optimized conditions corresponding to a germination step at 633 K followed by a step growth at 873 K and a post-annealing treatment at 1023 K monocrystalline Ni(111) //MgO(111) films are prepared, exhibiting monodomain swith high structural and orientation qualities. 13C implantation into these nickel films is subsequently achieved at 873 K with energy within 20 - 50 keV and a carbon dose equivalent to 4 monolayers of graphene (1.4 × 1016 at/cm2). Carbon diffuses mainly towards the surface, forming thin layers graphene. Compared to a Ni polycrystalline film the graphene fragments are larger and better facetted. The carbon amounts inside the nickel films at different steps, as well as the carbon amount at the surface, have been measured by Nuclear Reaction Analysis and X-ray Photoelectron Spectroscopy, respectively. The results show that, in addition to implanted 13C, some amounts of 12C is incorporated at different steps of the process and is involved in the formation of the graphene monolayers, as shown by 13C/12C Raman mappings. We finally discuss different mechanisms for carbon diffusion and surface segregation, considering the size and thickness distributions of the thin-layers graphene.