Dong Lifeng, Jiao Jun, Foxley Sean, Tuggle David W, Mosher Catherine L, Grathoff Georg H
Physics Department, Portland State University, Portland, Oregon 97207-0751, USA.
J Nanosci Nanotechnol. 2002 Apr;2(2):155-60. doi: 10.1166/jnn.2002.083.
Well-aligned carbon nanotubes with controllable properties were grown on porous silicon substrates by thermal chemical vapor deposition. The morphologies of the carbon nanotubes were varied with the introduction of H2 during the catalyst activation and/or carbon nanotube growth processes. It was found that H2 promotes the growth of carbon nanotubes while preventing the formation of spherical amorphous carbon particles. Without the introduction of H2 during the C2H2 thermal decomposition, aligned carbon nanotubes mixed with spherical carbon particles were formed on the substrate. However, with the introduction of H2, pure carbon nanotubes were synthesized. These nanotubes also had uniform diameters of 10-20 nm, which is much smaller than nanotubes synthesized without H2. The average growth rate of nanotubes was also affected by the introduction of hydrogen into the reaction chamber during nanotube growth. With the addition of hydrogen, the average growth rate changed from 78 nm/s to 145 nm/s. A possible growth mechanism, including the effect of a high ratio of H2 to C2H2, is suggested for the growth of these well-aligned carbon nanotubes with uniform diameters.
通过热化学气相沉积法在多孔硅衬底上生长出了具有可控特性且排列良好的碳纳米管。在催化剂活化和/或碳纳米管生长过程中引入氢气时，碳纳米管的形态会发生变化。研究发现，氢气促进了碳纳米管的生长，同时防止了球形非晶碳颗粒的形成。在乙炔热分解过程中不引入氢气时，衬底上会形成排列的碳纳米管与球形碳颗粒的混合物。然而，引入氢气后，则合成出了纯碳纳米管。这些纳米管的直径也很均匀，为10 - 20纳米，这比不使用氢气合成的纳米管要小得多。在纳米管生长过程中向反应室中引入氢气也会影响纳米管的平均生长速率。加入氢气后，平均生长速率从78纳米/秒变为145纳米/秒。针对这些直径均匀且排列良好的碳纳米管的生长，提出了一种可能的生长机制，包括高氢气与乙炔比例的影响。
