Pixelated Carbon Nanotube Forest

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 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. Reactive ion etching of the substrate in oxygen plasma dramatically improved forest growth rates. Uniform square 7x7 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, ranging from 4 to 50 microns and 1 to 10 microns, respectively. Uniform CNTF heights were grown with controllable values from 15 to 2500 microns. The results demonstrate the fabrication of thermally and electrically isolated vertically aligned CNTF islands, which have applications to batteries, sensors, infrared absorbers, and IR or electron emitters.