The Role of Stable and Mobile Carbon Adspecies in Copper-Promoted Graphene Growth

• Published in: Journal of physical chemistry. C 2012-03, Vol.116 (9), p.5802-5809
• Main Authors: Riikonen, S, Krasheninnikov, A. V, Halonen, L, Nieminen, R. M
• Format: Article
• Language: English
• Subjects: Chemical vapor deposition (including plasma-enhanced cvd, mocvd, etc.); Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Materials science; Methods of deposition of films and coatings; film growth and epitaxy; Physics
• ISSN: 1932-7447; 1932-7455
• DOI: 10.1021/jp211818s

Early stages of carbon monolayer nucleation on the copper (111) surface are systematically studied using density-functional theory calculations in the context of chemical vapor deposition and irradiation-mediated growth of graphene. By analyzing the kinetics of carbon atoms during their agglomeration, including surface, subsurface, and surface-to-bulk migration as well as dimer formation and diffusion, we draw a qualitative picture of the first stages of graphene growth on copper. The formation and migration of dimers and graphitic fragments happens at a much faster rate than the other competing processes, such as carbon migration into copper bulk and the dissociation of dimers into carbon monomers. To explain this tendency, which is an important factor in making copper such an effective graphene catalyst, we analyze in detail the electronic structure of dimers on surfaces and suggest that dimer stabilization and mobility stem from a delicate interplay between the carbon dimer σp bonding orbitals and copper d and s electrons. Our results emphasize the role of mobile carbon dimer intermediates during the growth of graphene on Cu, Ag, and Au surfaces by chemical vapor deposition and irradiation-mediated methods, in which carbon atoms are implanted into copper foils beyond the solubility limit.