Effect of supporting layer on growth of carbon nanotubes by thermal chemical vapor deposition

Selective growth of vertically aligned and highly dense carbon nanotubes was achieved by using thermal chemical vapor deposition via careful selection of a thin catalyst layer and an appropriate supporting layer. It was found that carbon nanotube growth was significantly enhanced when tantalum was used as the supporting layer on which a thin iron catalyst was deposited. Cross-sectional transmission electron microscopy revealed a Stranski-Krastanov mode of iron island growth on tantalum with relatively small contact angles controlled by the relative surface energies of the supporting layer, the catalyst, and their interface. The as-formed iron island morphology promoted vertical growth of carbon nanotubes. (c) 2006 American Institute of Physics.