Catalyst-Free Growth of Ordered Single-Walled Carbon Nanotube Networks

We report the catalyst-free horizontal growth of carbon nanotubes on the Si face of hexagonal silicon carbide (6H-SiC) at temperatures above 1500°C. These nanotubes are single walled with a very narrow distribution of diameters. Nanotubes tend to follow the atomic structure of the surface, leading to preferential orientation and the development of ordered networks of tubes. Manipulation of nanotubes using atomic force microscopy indicates that the tubes move on the surface at high temperature and are stabilized in the directions parallel and perpendicular to the step edges.