Plasma-Enhanced CVD Growth of Single-Wall Carbon Nanotubes Using Dendrimer-Stabilized Fe Nanoparticles
P.B. Amama, M.R. Maschmann, T.S. Fisher and T.D. Sands
Purdue University, US
single-wall carbon nanotubes, plasma-enhanced CVD, dendrimer, Fe nanoparticles
A fourth-generation (G4) poly(amidoamine) (PAMAM) dendrimer (G4-NH2) has been used as a “nanotemplate” to deliver nearly monodispersed catalyst nanoparticles to Si/SiO2, Si/Ti, sapphire and porous anodic alumina (PAA) substrates. Fe2O3 nanoparticles obtained after calcination of the immobilized Fe3+/G4-NH2 composite served as catalytic “seeds” for the growth of single-walled carbon nanotubes (SWNTs) by microwave plasma-enhanced CVD (PECVD). In order to surmount the difficulty associated with SWNT growth in the PECVD, reaction conditions that promote the stabilization of Fe nanoparticles, resulting in enhanced SWNT selectivity and quality, have been identified. In particular, in situ annealing of Fe catalyst supported on SiO2/Si, Ti/Si and sapphire in an N2 atmosphere was found to improve SWNT selectivity and quality. H2-prereduction at 900 °C for ~5 min was also found to enhance SWNT selectivity, albeit of lower quality for sapphire-supported catalyst. The application of DC bias voltage (200 V) during SWNT growth was shown to be very effective in removing amorphous carbon impurities completely while enhancing graphitization, SWNT selectivity, and vertical alignment. The results of this study would promote the use of naked Fe nanoparticles supported on different substrates for the growth of high-quality SWNTs by PECVD.
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Nanotech 2006 Conference Program Abstract