Evolution of Graphene Growth on Ni and Cu by Carbon Isotope Labeling

• Published in: Nano letters Vol. 9; no. 12; pp. 4268 - 4272
• Main Authors: Li, Xuesong, Cai, Weiwei, Colombo, Luigi, Ruoff, Rodney S
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 09.12.2009
• Subjects: Carbon Isotopes - analysis; Chemical vapor deposition (including plasma-enhanced cvd, mocvd, etc.); Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Copper - chemistry; Cross-disciplinary physics: materials science; rheology; Crystallization - methods; Exact sciences and technology; Fullerenes and related materials; Fullerenes and related materials; diamonds, graphite; Graphite - chemistry; Infrared and raman spectra and scattering; Isotope Labeling - methods; Macromolecular Substances - chemistry; Materials science; Materials Testing - methods; Methods of deposition of films and coatings; film growth and epitaxy; Molecular Conformation; Nanostructures - chemistry; Nanostructures - ultrastructure; Nanotechnology - methods; Nickel - chemistry; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Particle Size; Physics; Solid surfaces and solid-solid interfaces; Specific materials; Spectrum Analysis, Raman - methods; Surface Properties; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); Raman spectra; Chemical precipitation; Growth rate; Segregation; Hydrocarbons; Grain orientation; Raman spectroscopy; Carbon; Precipitates; Precursor; CVD; Metallic thin films; Spatial distribution; Adsorption; Graphene; Graphite; Growth mechanism; Nickel; Copper
• ISSN: 1530-6984; 1530-6992
• DOI: 10.1021/nl902515k

Large-area graphene growth is required for the development and production of electronic devices. Recently, chemical vapor deposition (CVD) of hydrocarbons has shown some promise in growing large-area graphene or few-layer graphene films on metal substrates such as Ni and Cu. It has been proposed that CVD growth of graphene on Ni occurs by a C segregation or precipitation process whereas graphene on Cu grows by a surface adsorption process. Here we used carbon isotope labeling in conjunction with Raman spectroscopic mapping to track carbon during the growth process. The data clearly show that at high temperatures sequentially introduced isotopic carbon diffuses into the Ni first, mixes, and then segregates and precipitates at the surface of Ni forming graphene and/or graphite with a uniform mixture of 12C and 13C as determined by the peak position of the Raman G-band peak. On the other hand, graphene growth on Cu is clearly by surface adsorption where the spatial distribution of 12C and 13C follows the precursor time sequence and the linear growth rate ranges from about 1 to as high as 6 μm/min depending upon Cu grain orientation. This data is critical in guiding the graphene growth process as we try to achieve the highest quality graphene for electronic devices.