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Substrate Engineering to Control the Synthesis of Carbon Nanotubes

Krishnaswamy, Arvind

Abstract Details

2014, MS, University of Cincinnati, Engineering and Applied Science: Mechanical Engineering.
In the November of 1991, Sumio Ijima announced the discovery of Carbon Nanotubes (CNTs) to the world. Twenty two years later, researchers and scientists continue in pursuit of an elusive combination of a substrate preparation method and a metal catalyst to synthesize defect free, long CNTs. Conventional synthesis of CNT is dependent on a natural self-assembly phenomenon that occurs during the thermal Chemical Vapor Deposition (ThCVD) process. In the ThCVD, CNTs are grown from a thin film of metal catalyst deposited uniformly over the entire surface of a silicon substrate. The catalyst film breaks into small islands spaced over the substrate, and nanotubes nucleate from the islands and form a forest over the full surface of the wafer. In this thesis, instead of relying on natural growth of a nanotube forest, `substrate engineering’ is employed as a method of designing and optimizing the substrate parameters, including substrate material, patterning of the substrate with posts, lines, or holes, buffer layer type and thickness, and catalyst type, thickness and position to better control growth of the forest. Process parameters such as gas flow, diffusion, temperature, and other factors that affect nanotube nucleation must be matched to the substrate design in order to control the geometry, spacing and quality of the carbon nanotubes. The geometry and spacing of the catalyst are controlled by engineering substrates using Nano-Imprint Lithography (NIL) and Photo-Lithography techniques. A new approach was also invented in which NIL stamps are used as the substrate. Using these catalyst-coated patterned substrates, CNTs were synthesized by thermal-CVD and plasma enhanced CVD processes. The result of this substrate engineering study was to grow pattern of CNTs at desired locations on a substrate. Gas diffusion and nanotube straightness were improved in certain cases, and the patterns can be optimized for specific device applications.
Mark Schulz, Ph.D. (Committee Chair)
Vesselin Shanov, Ph.D. (Committee Member)
Kumar Vemaganti, Ph.D. (Committee Member)
141 p.

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Citations

  • Krishnaswamy, A. (2014). Substrate Engineering to Control the Synthesis of Carbon Nanotubes [Master's thesis, University of Cincinnati]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1413471369

    APA Style (7th edition)

  • Krishnaswamy, Arvind. Substrate Engineering to Control the Synthesis of Carbon Nanotubes. 2014. University of Cincinnati, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ucin1413471369.

    MLA Style (8th edition)

  • Krishnaswamy, Arvind. "Substrate Engineering to Control the Synthesis of Carbon Nanotubes." Master's thesis, University of Cincinnati, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1413471369

    Chicago Manual of Style (17th edition)