Multiwalled carbon nanotubes by chemical vapor deposition using multilayered metal catalysts

Multiwalled carbon nanotubes (MWCNTs) have been grown on various substrates by thermal chemical vapor deposition using multilayered metal catalysts. Ion beam sputtering is used to deposit various metal layers sequentially. Underlayer, of Al (2-20 nm) are shown to influence the growth characteristics with Fe or Ni used as active catalysts. The as-sputtered catalyst surface, characterized using atomic force and scanning tunneling microscopics, consists of nanometer scale (<10 nm) catalyst particles. High-resolution transmission electron microscopy and Raman analysis are used to characterize the MWCNTs. Optimization of the two layers allows growth of MWCNT towers on patterned and unpatterned substrates.