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Free keywords:
carbon nanotubes, catalysis, catalysts, chemical vapour deposition, cobalt alloys, electrical conductivity, metal-insulator boundaries, metallic thin films, nanofabrication, ohmic contacts, oxidation, silicon alloys, X-ray diffraction, X-ray photoelectron spectra
Abstract:
The growth of high density vertically aligned carbon nanotube forests on conductive CoSi2 substrate layers is characterized by in situ x-ray photoemission spectroscopy and x-ray diffraction. We use in situ silicidation to transform as loaded, low conductivity CoSi supports to highly conductive CoSi2 during nanotube growth. These cobalt silicide films are found to be stable against oxidation and carbide formation during growth and act as an excellent metallic support for growth of aligned nanotubes, resembling the growth on the insulating Fe/Al2O3 benchmark system. The good catalytic activity is attributed to interfacial reactions of the Fe catalyst particles with the underlying CoSi2 support. We obtain ohmic conduction from the support layer to the carbon nanotube forest.
