GROWTH OF ALIGNED CARBON NANOTUBES ON COPPER SUBSTRATES

Since the discovery of carbon nanotubes (CNTs) in the early 1990s, there has been enormous interest in trying to synthesize and understand their growth mechanism. This is required in order to successfully integrate them into new devices and applications that exploit their remarkable physical properties, including high mechanical strength, high aspect ratio, and excellent conductivity. Depending on the alignment of CNTs, random “spaghetti-like” or preferentially aligned CNTs on suitable substrates are of interest for potential applications such as energy storage, sensing, supercapacitors, and nanoelectronic devices via a variety of chemical vapor deposition (CVD) techniques such as thermal, plasma enhanced, water assisted growth. For many of the envisioned applications, dense, aligned CNTs grown using an economically viable technique and good contact with a conductive metallic substrate such as copper is required. The primary objective of the experiments described in this dissertation is to achieve vertical growth of carbon nanotubes on copper substrates using thermal CVD. The second goal is to understand and comprehensively determine how the processing conditions can be tailored to improve the density and degree of vertical alignment of the CNTs. The final goal is to measure properties to establish feasibility of use in device structures using aligned carbon nanotubes on copper. Since copper itself is not a good catalyst for carbon nanotube growth, the technique discusses the use of sputtered thin films of nickel or Inconel deposited on copper substrates with additional catalyst supply of iron from ferrocene decomposition during the CVD growth. Thus the growth studies discussed in the dissertation includes the use of a combination of sputtered thin films and iron as catalysts on copper to promote the dense vertical growth of carbon nanotubes that is desired