General Nano LLC — Department of Defense STTR Phase I: Success growing long carbon nanotube arrays rests on the preparation of the catalytic subs

Description

Success growing long carbon nanotube arrays rests on the preparation of the catalytic substrate. Current best practices use a sputtering, oxidization, evaporation and annealing process to form catalyst particles. This natural self-assembly method is not the best approach. It creates substrates with too many variations, causing nanotubes to grow at different rates, lengths, and diameters, and causing defects and preventing nanotube arrays from achieving their growth potential. Proposed is a new nanomanufacturing approach - Substrate Engineering. In this approach, the catalytic substrate is designed to produce carbon nanotube arrays with a desired morphology. Van der Waals force engineering is used to optimize the geometry of catalyst wells. Chirality control will be attempted by matching catalyst well size to the diameter of armchair nanotubes. Novel techniques will be used to fabricate the substrate. Nanoimprint lithography will pattern the alumina buffer layer on the substrate with catalyst wells the same size throughout the substrate. Laser drilled holes in thin substrates will enable a new base flow chemical vapor deposition method to be used in conjunction with the patterned catalyst. Combinatorial studies using different mold patterns will determine the diameter, depth, and spacing of wells that produce long, high-quality nanotube arrays. It is anticipate that nanotube arrays produced from engineered substrates will permit advanced devices with the energy and power to outperform incumbent materials.