Formation of self-aligned carbon nanotube films by surface decomposition of silicon carbide

A simple method of producing aligned carbon nanotube films and a mechanism for their formation are described. The alignment method is based on the self-organization by surface decomposition of a SiC wafer in a vacuum at a temperature between 1500 and 1700° C. From the results of cross-sectional observations by high-resolution transmission electron microscopy and analytical electron microscopy, the following formation mechanism is proposed: SiO gas molecules are generated by surface oxidation and graphite caps of 2-5 nm in size are formed by the bubbling of SiO gas on the surface, characterized by a (0001)SiC plane. Then carbon nanotubes grow in a vertical direction, eroding the SiC crystal during the continuous oxidation.