Growth of Vertically Aligned Carbon Nanotubes on a Continuously Moving Substrate
- Category: MEMS & BioMEMS, Nanotechnology
- Tags: brian wardle, roberto guzman de villoria
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Download as PDFVertically-aligned carbon nanotube (CNT) arrays are grown on a moving substrate, demonstrating continuous growth of nanoscale materials with long-range order. A cold-wall chamber with an oscillating moving platform (see Figure 1) is used to locally heat a silicon growth substrate coated with a Fe/Al2O3 catalyst film for CNT growth via chemical vapor deposition. The reactant gases are introduced over the substrate through a directed nozzle to attain high-yield CNT growth [1] . Aligned multi-wall carbon nanotube (MWNT) arrays (or “forests”) with heights of ≈1 mm are achieved at substrate speeds up to 2.4 mm/s. Arrays grown on moving substrates at different velocities are studied to identify potential physical limitations of repeatable and fast growth on a continuous basis. No significant differences are noted between static and moving growth as characterized by SEM (as in Figure 2) and Raman spectroscopy, although overall growth height is marginally reduced at the highest substrate velocity. CNT arrays produced on moving substrates are also found to be comparable to those produced through well-characterized batch processes consistent with a base-growth mechanism. Growth parameters required for the moving furnace are found to differ only slightly from those used in a comparable batch process; thermal uniformity appears to be the critical parameter for achieving large-area uniform array growth.
Once the parameters have been optimized, a desktop continuous will growth apparatus has been designed and implemented to grow VACNTs on silicon wafers (Figure 2), flexible sheets, and alumina fibers continuously. We have demonstrated and reported the ability to manufacture VACNT arrays in a continuous manner, significantly reducing the time spent, energy consumed, and reaction products created as compared to batch processing of these technologicallyvaluable assemblies of nanoscale materials [2] .
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- Figure 1: Moving stage system where an Fe/Al2O3-deposited silicon wafer substrate is driven by an external motor through the growth zone that is composed of two heaters (red) in a “toaster” configuration.
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- Figure 2: Detail of VACNT forest growth on a silicon wafer.
- R. Guzman de Villoria, S.L. Figueredo, A. J. Hart, S. A. Steiner III, A.H. Slocum, and B.L. Wardle, “High-yield growth of vertically aligned carbon nanotubes on a continuously moving substrate, “Nanotechnology, vol. 20, no. 40, pp. 405611-405618, 2009. [↩]
- R. Guzman de Villoria, A. J. Hart, and B.L. Wardle, “Continuous high-yield production of vertically aligned carbon nanotubes on 2D and 3D substrates,” ACS Nano, vol.5, no.6, pp. 4850–4857, 2011. [↩]