Mechanism of Thin Layers Graphite Formation by C-13 Implantation and Annealing

作者：Gutierrez Gaelle; Le Normand Francois^*; Aweke Fitsum; Muller Dominique; Speisser Claude; Antoni Frederic

来源：Applied Sciences-Basel, 2014, 4(2): 180-194.

DOI：10.3390/app4020180

• carbon
• graphene
• thin layers graphite
• nickel
• nuclear reaction analysis
• Raman spectroscopy
• Raman imaging
• nucleation
• C-13 isotope

The mechanism of thin layers graphite (TLG) synthesis on a polycrystalline nickel film deposited on SiO2 (300 nm thick)/Si(100) has been investigated by C-13 implantation of four equivalent graphene monolayers and annealing at moderate temperatures (450-600 degrees C). During this process, the implanted C-13 segregates to the surface. Nuclear Reaction Analyses (NRA) are used for the first time in the topic of graphene synthesis to separate the isotopes and to determine the C-12 and C-13 concentrations at each step. Indeed, a significant part of carbon in the TLG also comes from residual C-12 carbon absorbed into the metallic matrix. Raman spectroscopy and imaging are used to determine the main location of each carbon isotope in the TLG. The Raman mappings especially emphasize the role of C-12 previously present at the surface that first diffuses along grain boundaries. They play the role of nucleation precursors. Around them the implanted C-13 or a mixture of bulk C-12-C-13 aggregate and further precipitate into graphene-like fragments. Graphenization is effective at around 600 degrees C. These results point out the importance of controlling carbon incorporation, as well as the importance of preparing a uniform nickel surface, in order to avoid heterogeneous nucleation.

• 出版日期2014-6