Controlled low-temperature growth of carbon nanofibres by plasma deposition

Vertically aligned carbon nanofibres were grown at temperatures as low as 120degreesC by plasma-enhanced chemical vapour deposition (PECVD). A systematic study of the temperature dependence of the growth rate found an activation energy of 0.23 eV, much less than that for thermal chemical vapour deposition (1.2-1.5 eV). This suggests that growth occurs by surface diffusion of carbon on nickel. Vertically aligned carbon nanofibres were grown by PECVD on to flexible plastic substrates. We show that individual lines and dots of free-standing 20-50 nm diameter nanotubes can be grown on to chromium-covered polyimide foil. The scalable deposition method allows large-area coverage without damaging or bending the sensitive substrate material. Field-emission cathodes were made for the purpose of demonstration.