Synthesis of uniformly distributed carbon nanotubes on a large area of Si substrates by thermal chemical vapor deposition

Abstract

We have synthesized carbon nanotubes by thermal chemical vapor deposition of ${\mathrm{C}}_2{\mathrm{H}}_2$ on transition metal-coated silicon substrates. Multiwalled carbon nanotubes are uniformly synthesized on a large area of the plain Si substrates, different from previously reported porous Si substrates. It is observed that surface modification of transition metals deposited on substrates by either etching with dipping in a HF solution and/or ${\mathrm{NH}}_3$ pretreatment is a crucial step for the nanotube growth prior to the reaction of ${\mathrm{C}}_2{\mathrm{H}}_2$ gas. We will demonstrate that the diameters of carbon nanotubes can be controlled by applying the different transition metals.