AVS 52nd International Symposium
    Nanometer-Scale Science and Technology Tuesday Sessions
       Session NS-TuP

Paper NS-TuP17
Synthesis of Aligned Carbon Nanotubes by CVD Using Ball-Shaped Microwave Plasma

Tuesday, November 1, 2005, 4:00 pm, Room Exhibit Hall C&D

Session: Nanometer Scale Science and Technology Poster Session
Presenter: Y. Oshiro, Kyoto Institute of Technology, Japan
Authors: Y. Oshiro, Kyoto Institute of Technology, Japan
S. Nishino, Kyoto Institute of Technology, Japan
Y. Hayashi, Kyoto Institute of Technology, Japan
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Aligned carbon nanotubes (CNTs) have been successfully synthesized by plasma-enhanced chemical vapor deposition using ball-shaped microwave plasma in a quartz bell jar. CNTs are expected to be used as field electron emitters for a display or an X-ray source, because they have the characters of high aspect ratio, small radius of tip curvature and mechanical strength, which are required for long-lived emitters with intensive electric field at their tips even at low applied voltage. Ball-shaped microwave plasma, which is generated non-contact with a quartz bell jar, has been used for aligned CNTs growth because of high purity CNT synthesis. In the plasma, CNTs are expected to grow in an environment with few impurity inclusion by the sputtering of the wall of a quartz bell jar. 10% methane diluted in hydrogen was introduced in the bell jar chamber and the pressure was kept at 2000 Pa during the growth of CNTs. Microwave power of 450W was induced for the generation of ball-shaped microwave plasma. For the growth of vertically aligned CNTs, we placed a DC cathode plate parallel to a grounded electrode , which plays a role of an end plate for microwave propagation, to apply a uniform and intensive electric field on a substrate. Iron substrates were set on the cathode plate, to which negative bias of 300V was induced. Aligned carbon fibers of 30 nm in diameter and 800 nm in length were observed by scanning electron microscopy. These carbon fibers should be CNTs formed by tip growth, because they were hollow and had cone-shaped particles at their tips, which are generally observed to be those of iron catalytic metal in the tip-growth mode of CNTs.