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Journal of Nanomaterials
Volume 2010, Article ID 906204, 7 pages
http://dx.doi.org/10.1155/2010/906204
Research Article

Regrowth of Carbon Nanotubes Array on Al Layer Coated Substrate

1Graduate School of Engineering, Toyota Technological Institute, 2-12-1 Hisakata, Tempaku, Nagoya 468-8511, Japan
2Department of Chemistry, Institute for Advanced Research, Nagoya University, Furo-cho, Chikusa, Nagoya 464 8602, Japan
3Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa, Nagoya 464 8603, Japan

Received 5 June 2009; Revised 9 November 2009; Accepted 8 January 2010

Academic Editor: Do Kim

Copyright © 2010 Chien-Chao Chiu et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Carbon nanotube (CNT) arrays have been synthesized by a repeated growth method using a custom-fabricated plasma-enhanced thermal chemical vapor deposition (PE-thermal CVD) apparatus. The initial catalyst is a layered structure prepared by depositing 10 nm of Al followed by 3 nm of Fe on an oxidized silicon substrate. Following CNT growth, the CNT arrays are removed using an ultrasonic cleaner, and another CNT array is grown on the remaining Fe-Al bimetalic nanoparticles without the addition of more catalyst. Annealing the catalytic substrate in air between growth cycles results in the removal of residual amorphous carbon along with the CNTs, and oxidation of the Fe-Al nanoparticles. The diameter of CNTs is reduced with repeated growth-annealing cycles, an effect of which is attributed to the diminishing size of the catalytically active nanoparticles with each cycle. After two growth cycles, SWNTs with the extraordinarily narrow diameter of 0.86 nm are synthesized. The ratio derived from the Raman spectrum of these of the SWNT arrays shows the remarkably low value of 0.22.