STTR Phase I: Fabrication of Coaxial Nanowires/Nanocables Using Carbon Nanotubes

This Small Business Technology Transfer (STTR) Phase I project provides for the commercialization of composite alumina/tungsten/alumina (Al2O3/W/Al2O3) trilayers deposited by Atomic Layer Deposition (ALD) on carbon nanotubes (CNTs) to form coaxial nanowires/nanocables for nanoelectronic applications. Such coaxial nanostructures can be fabricated by first coating CNTs with a conformal and pinhole-free insulating nanolayer of an alumina (Al2O3) sheath to isolate and insulate the nanotubes from their surroundings. Second, a conductive W ALD film will be deposited on the insulating Al2O3 film, providing the second conducting layer. Third, a second insulating Al2O3 sheath is placed over the W layer providing for the completed coaxial nanocable. The thickness of each of the layers in the Al2O3/W/Al2O3 trilayer can be controlled to within approximately 0.1 nanometers by self-limiting ALD surface chemistry processing. This fabrication of a coaxial nanocable has already been demonstrated by the proposing research team at the microgram scale and will be scaled-up to ~ 10 grams using a scalable vibro/stirred fluidized bed reactor process. The novel CNT ALD nanowires or nanocables can be used as building blocks for future nanoscale devices, prototype power cables or "quantum wires". The potential impact extends far beyond this proposed nanocable/nanowire application. Nanoscience will only achieve true "disruptive" technology status if the individual surfaces of nanoparticles and nanotubes can be functionalized. ALD nanocoating of nanoparticles and nanotubes provides such an opportunity. It is now possible to produce nanoparticles and nanotubes with designed electrical, magnetic, optical, mechanical, rheological, or other properties. Markets for such functionalized nanoparticles and nanotubes include microelectronics, defense, hard metals, cosmetics, drug delivery, energetic materials, and polymer/ceramic nanocomposites, among others.