Effect of the ratio of catalyst to carbon source on the growth of vertically aligned carbon nanotubes on nanostructured porous silicon templates

Background: The effect of the ratio of catalyst to carbon source on the growth of vertically aligned carbon nanotubes (VACNTs) has been studied. Results: Dense VACNTs were successfully synthesised on optimised nanostructured porous silicon templates using modified floated carbon source-catalyst in a two-stage hot filament thermal chemical vapour deposition system with different amounts of ferrocene as the catalyst at 800°C. The surface morphologies of the VACNTs were analysed using field emission scanning electron microscopy, and the crystallinity of the nanotubes was observed using micro-Raman spectroscopy. Conclusions: These data revealed that the amount of catalyst used significantly affected the diameter, crystallinity and growth rate of the synthesised nanotubes. The average diameter of the nanotubes ranged from ≈ 9 to 30 nm with lengths of ≈ 110 μm when 0.5 g ferrocene was used.