Abstract

Carbon nanotubes are appealing materials for nanofabrication due to their unique properties and structures. However, for carbon nanotubes to be used in mass-fabricated devices, precise control of nanotube orientation and location on surfaces is critical. I have developed a technique to align single-walled carbon nanotubes (SWNTs) on surfaces from a droplet of nanotube suspension under gas flow. Fluid motion studies indicate that alignment is likely due to circulation of SWNTs in the droplet. My work provides a facile method for generating oriented nanotubes for nanodevice applications. I have also devised an approach for localizing SWNTs onto 1-pyrenemethylamine-decorated DNA on surfaces. I found that 63% of SWNTs on surfaces were anchored along DNA, and these nanotubes covered ~5% of the total DNA length. This technique was an initial demonstration of DNA-templated SWNT localization. In an improved method to localize SWNTs on DNA templates, dodecyltrimethylammonium bromide was utilized to suspend SWNTs in aqueous media and localize them on DNA electrostatically. SWNT positioning was controlled by the surface DNA arrangement, and the extent of deposition was influenced by the SWNT concentration and number of treatments. Under optimized conditions, 83% of the length of surface DNAs was covered with SWNTs, and 76% of the deposited SWNTs were on DNA. In some regions, nearly continuous SWNT assemblies were formed. This approach should be useful for the fabrication of nanotube nanowires in nanoelectronic circuits. Using my improved procedures, I have localized SWNTs on DNA templates across electrodes and measured the electrical properties of DNA-templated SWNT assemblies. When a DNA-templated SWNT was deposited on top of and bridging electrodes, the measured conductance was comparable to literature values. In contrast, SWNTs with end-on contacts to the sides of electrodes had conductances hundreds of times lower than literature values, probably due to gaps between the SWNT ends and the electrodes. This work provides a novel approach for localizing SWNTs across contacts in a controlled manner. These results may be useful in the fabrication of nanoelectronic devices such as transistors with SWNTs as active components. Moreover, this approach could be valuable in arranging SWNTs as electrical interconnects for nanoelectronics applications.

Degree

PhD

College and Department

Physical and Mathematical Sciences; Chemistry and Biochemistry

Rights

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