Formation of Carbon Nanotubes by Catalysis of Transition Metals Obtained from Molecular Precursors

There is considerable interest to achieve a selective growth of carbon nanotubes from distinct nucleation centers on specific substrates, since they display a huge range for new applications. Transition metals can act as catalysts for the formation of carbon nanotubes. For this reasons, the influence of catalytically active metals supplied in an nanodisperse form regarding the formation of nanostructured carbon from the gas phase was studied. By this novel method, catalytically active transition metal complexes were used to generate nucleation centers on silicon substrates for the formation of carbon nanotubes. A CVD route using methane was used to supply activated carbon species from the gas phase. Since the transition metals used for this investigation are catalyzing dehydrogenation reactions, the effects of the presence of those metals on the morphology of the deposits were studied in correlation with the process parameters (pressure, substrate temperature, precursor concentration). The deposits were characterized with SEM, infrared- and raman spectroscopy.