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| - Rapid Growth and Flow-Mediated Nucleation of Millimeter-Scale Aligned CarbonNanotube Structures from a Thin-Film Catalyst
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| - We discuss the rapid growth of films and lithographically templated microstructures of vertically alignedsmall-diameter multiwalled carbon nanotubes (VA-MWNTs), by atmospheric-pressure thermal chemical vapordeposition (CVD) of C2H4/H2/Ar on a Fe/Al2O3 catalyst film deposited by electron beam evaporation. Thestructures grow to 1 mm height in 15 min and reach close to 2 mm in 60 min. The growth rate and finalheight of CNT microstructures grown from catalyst patterns depend strongly on the local areal density ofcatalyst, representing a reverse analogue of loading effects which occur in plasma etching processes. Abrupttransitions between areas of micrometer-thick tangled CNT films and millimeter-scale aligned CNT structuresare manipulated by changing the duration of pretreatment by H2/Ar prior to introduction of C2H4 and bychanging the configuration of the substrate sample in the furnace tube. This demonstrates that the flow profileover the sample mediates the supply of reactants to the catalyst and that pretreatment using H2 significantlyaffects the initial activity of the catalyst.
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