Controlled growth and characterization of two-dimensional single-walled carbon-nanotube networks for electrical applications.

We demonstrate the reproducible fabrication of single-walled carbon nanotube (SWNT) networks, via catalyzed chemical vapor deposition (cCVD). Fe nanoparticles are employed as the catalyst, with methane as the carbon-containing gas. cCVD growth under these conditions results in the formation of multiply interconnected, random, two-dimensional networks of SWNTs. Investigation of the effect of parameters such as methane flow rate and temperature on the growth process enables control over the density of the network, which controls the network conductivity. Low-density networks demonstrate p-type semiconductor behavior, whilst high-density networks exhibit semimetallic behavior. In both cases conductance is demonstrated over macroscopic length scales, up to millimeters, much longer than the individual SWNTs, despite the surface coverage being <1 %. The networks can be defined in regions of a surface by photolithography before or after growth. Controlled growth of SWNT networks thus enables the application of SWNTs as macroscale conductors with controllable, predictable, and reproducible characteristics.