Tip-to-tip growth of aligned single-walled carbon nanotubes under an electric field

An electric field was applied during the chemical vapor deposition process for fabricating directional single-walled carbon nanotubes (SWNTs). The electric field significantly affected the direction of the carbon nanotubes (CNTs) synthesized on multi-layered substrate. Acetylene and hydrogen were used as carbon precursor and reducing gas, respectively. Thin Ni and Fe films were used as catalysts for CNT growth. The Ni film with a thickness ranging from 1 to 10 nm was coated on Cr layer, which was patterned on SiO2/Si substrate. The Cr layer, acting as an electrode, was etched to form a tip-to-tip pattern. The sharp edge of Cr electrode yields an enhanced electric field, which promotes the growth of SWNTs between the two tips. A theoretical analysis was proposed to model the electric field in the process, and the simulated electric field is quite consistent with the SWNT growth region around the tips.