Pixelated carbon nanotube forests

Carbon nanotube forests (CNTFs) were grown on a patterned substrate to form square pixelated arrays. Two-level full factorial optimization first determined the best conditions for synthesis by chemical vapor deposition catalyzed by iron (Fe) nanoparticles deposited on oxidized silicon substrates. Varied parameters included growth temperature, growth time, and acetylene-to-hydrogen gas flow rate ratio. Argon was used as a carrier gas. Unpatterned CNTF heights were grown with values from 15.3 to 185.7 microns. Reactive ion etching of the substrate in oxygen plasma dramatically improved forest growth rates. Uniform square 7 x 7 pixel arrays were produced by contact photolithography and lift-off of the deposited Fe. Each pixel was subdivided into square islands separated by gaps with different island and gap dimensions, which ranged from 4 to 50 microns and 1 to 10 microns, respectively. The results demonstrate the fabrication of thermally and electrically isolated vertically aligned CNTF islands, which have applications to batteries, sensors, infrared absorbers, and infrared or electron emitters.