Control of growth orientation for carbon nanotubes

Abstract

Laterally aligned carbon nanotubes were synthesized on substrates over iron nanoparticles using chemical vapor deposition. In addition, aligned carbon nanotubes grown vertically and with tilt angle to the substrates were produced, which means that it is possible to grow aligned carbon nanotubes at any angle relative to the substrate. The growth direction of the carbon nanotubes was controlled by a magnetic field that is applied in the process of adhering catalyst particles on silicon oxide substrates from dispersion. The ferromagnetic property of the iron nanoparticles fixes them in a defined orientation under magnetic field, which results in aligned growth of the carbon nanotubes. These results indicate that carbon nanotubes preferentially grow from certain facets of the catalyst particles, suggesting a crucial clue in investigating the growth mechanism of carbon nanotubes. The laterally aligned carbon nanotubes could make it possible to integrate them in nanoelectronic devices, such as a channel for field-effect transistors.