Growth of Carbon Nanotubes Via Chemical Vapor Deposition NSF Summer Undergraduate Fellowship in Sensor Technologies

Carbon nanotubes (CNTs) are an unusual, tubular form of carbon, composed of a lattice of carbon hexagons rolled into a tube of nanometer-scale diameter. After the finding of CNTs in 1991 by Iijima on the cathode of an arc-discharge instrument, nanotechnology and nanoscience expanded tremendously. The subsequent discoveries of carbon nanotubes’ unique properties fueled research into all aspects of CNTs, from fundamental physics, to synthesis techniques, to technological applications. However, synthesis remains a challenge in almost every aspect, including control of length, diameter, and orientation. Also elusive is control of resulting nanotubes’ electric properties, which directly depend on variations in molecular structure. The other major challenge is production on a large scale, also currently far from accomplishable. Thus, we are concerned with optimizing methods to produce more consistent and higher yields. Specifically, we used chemical vapor deposition (CVD) with a focus on maximizing CNT length, alignment, and density of tubes per area. CNTs of lengths around 1mm have been achieved on silicon wafer chips, and two parameters – method of catalyst application, and catalyst concentration – have been optimized to achieve CNTs of this length. Additionally, moderate alignment of CNTs was achieved on ST-cut quartz chips and an apparent correlation between catalyst particle size and nanotube growth was found.