| Carbon nanotubes are one-dimensional molecules of carbon that have extraordinary mechanical and electrical properties. In this thesis we have studied the synthesis of carbon nanotubes and how to process carbon nanotubes into useful materials, additionally we have also studied the field emission properties of carbon nanotubes.; A pulsed laser ablation system was built and used to synthesize material containing bundles of single-walled carbon nanotubes. X-ray diffraction, Raman spectroscopy, and electron microscopy were used to structurally characterize the single-walled carbon nanotubes. The effect of changing growth parameters was studied in hopes of finding a way of tuning the structure of the as-produced nanotubes. In addition, we have used microwave plasma-enhanced chemical vapor deposition to deposit films of highly oriented multi-walled carbon nanotubes. Based on experimental observations we have developed a detailed model of how the nanotubes nucleate and grow. The plasma environment was found to be responsible for the nanotube alignment. By processing the as-grown nanotubes we have fabricated a number of potentially useful carbon nanotube-based materials, these include carbon nanotube-polymer composites, carbon-nanotube intercalation compounds, and carbon nanotube thin films.; The field emission properties of numerous carbon nanotube cathodes were evaluated. Technologically useful current densities were extracted from carbon nanotube cathodes using very low electric fields, regardless of nanotube type or orientation. In addition, it was found that very large current densities, in excess of 4 A/cm2, can be generated by carbon nanotubes. We have also shown that carbon nanotubes are very robust durable field emitters. Based on our observations, it appears that carbon nanotubes are very attractive candidates for application into a broad range of vacuum microelectronic devices, including flat panel displays and high frequency power amplifiers. |
