Carbon Nanotube Pattern Formation—Precise Routing on Silicon Oxide Using Nanoscale Catalyst Breadboards

A method for directly routing single-walled carbon nanotubes on silicon dioxide is presented. The lack of a preferred direction on the amorphous oxide film was overcome by placing nanoscale catalyst particles on the surface in the form of a grid or breadboard. Colloidal lithography was used to create an ordered nanoscale array of uniformly distributed Fe/Mo catalyst particles to serve as the breadboard. Following chemical vapor deposition at 900 °C with a methane/hydrogen gas mixture, intricate nanotube patterns that corresponded to the underlying breadboard were formed. Most patterns were found to consist of individual tubes or few-tube bundles. A “lift-and-drop” model was used to describe the nanotube pattern formation process whereby a combination of gas flow and van der Waals interactions allows tube growth to be precisely guided onto the breadboards without requiring an external impetus. These results indicate a potential path to carbon nanotube integration on standard oxide films for future deep nanoscale electronics.