Controlled growth of carbon nanotube architectures and devices

Carbon nanotubes with their extraordinary physical and electrical properties show much promise of finding practical applications. Because of their small size and limited ability for processing it is necessary to grow nanotubes in configurations and architectures that are already suited for their application. Several techniques for growing specific nanotube architectures have been achieved. Self-oriented arrays of vertically aligned multi-walled nanotubes (MWNT) have been grown using chemical vapor deposition (CVD), which exhibit high current density field emission properties. Use of MWNT as non-wearing high resolution tips for nanolithography is also demonstrated.; Extensive networks of single-walled nanotubes (SWNT) have been grown using the substrate to guide in what directions the nanotubes orient themselves. Full wafer scale growth of nanotube electronic devices has been achieved, along with a general method for adapting nanotube growth conditions to any scale. A more complete explanation of the nanotube growth mechanism is gained from the advances in nanotube synthesis.; Chemical sensors based on individual SWNT are demonstrated. Upon exposure to gaseous molecules such as NO₂ or NH₃, the electrical resistance of a semiconducting SWNT is found to dramatically increase or decrease respectively. The nanotube sensors exhibit a fast response and a substantially higher sensitivity than that of existing solid-state sensors at room temperature. The interactions between molecular species and SWNTs and the mechanisms of molecular sensing with nanotube molecular wires are illuminated. Probing the photoelectrical properties of single-walled carbon nanotubes (SWNTs) led to the discovery of photoinduced molecular desorption phenomena in nanotube molecular wires. A method has been developed for the immediate desorption of adsorbed molecules from carbon nanotubes using illumination.; Suspended carbon nanotube arrays are grown on pre-fabricated molybdenum electrodes that are compatible with the growth process. This allows for nanotubes to be electrically addressed directly after the growth process, and for electrical investigation of intricate nanotube architectures that would not survive further processing.