Growth of mm-long carbon nanotubes by grid-inserted plasma-enhanced chemical vapor deposition

Vertically aligned long multi-walled carbon nanotubes (MWNTs) have been successfully grown by grid-inserted plasma-enhanced chemical vapor deposition (PECVD). A thin Fe (1 nm)/Ti (1 nm) double-layer catalyst was effective in growing the long MWNTs. The length of the MWNTs increased to I mm for the growth time of 120 min without growth termination. A thick Fe catalyst or thick Ti underlayer resulted in a low growth rate. Transmission electron microscopy, energy-dispersive X-ray analysis and thermo-gravimetric analysis (TGA) measurements suggest that the MWNTs were grown in a root growth mode. Moreover, the TGA measurements suggest that MWNTs of high quality/purity were successfully grown by grid-inserted PECVD with a double-layer catalyst.