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Title: Microwave plasma-enhanced chemical vapour deposition of carbon nanotubes and nanostructures
Author: Chuang, A. T.-H.
Awarding Body: University of Cambridge
Current Institution: University of Cambridge
Date of Award: 2008
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Microwave plasma-enhanced chemical vapour deposition (PECVD) as a scalable and low temperature synthesis technique for carbon nanostructures has been investigated in this thesis. A PECVD reactor based on ASTeX-type microwave reactors was implemented to facilitate both contact and remote plasma operations. By creating a remote plasma environment and using sandwich-like catalytic structures (Al2O3/Fe/Al2O3), densely packed and vertically aligned single-walled carbon nanotubes (SWNTs) can be synthesized consistently for temperatures between 600-650°C. Carbon species ultimately responsible for SWNT synthesis are speculated to be the more stable and long-chained species from plasma activation. Wet chemistry techniques such as cobalt colloids and iron solution are alternatives to conventional physical vapour deposition methods for catalyst preparation. Silicon micrograss and carbon fibre matrices serve as limiting cases for extreme topology for three-dimensional catalyst coating using the wet chemistry techniques. Hierarchical control of the physical and chemical texture on wetting behaviour is demonstrated by selective carbon nanotubes growth based on microscale and nanoscale surface textures. Direct synthesis of SWNTs on carbon fibres is achieved using iron solution catalyst in the remote plasma environment. Carbon nanowalls are synthesized as freestanding three-dimensional aggregates. The differentiating morphology from the surface-bound material suggests a different growth mechanism, and similarities to the formation of carbon nanohorns. The results establish a scalable production method and possible applications based on the properties such as the stable field emission and high surface area.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available