Carbon nanotube arrays

Carbon nanotube arrays were prepared by chemical vapor deposition (CVD) of hydrocarbon gas on various substrates. The effect of substrates on the growth, morphology and structure of carbon nanotubes were investigated. Aligned carbon nanotubes with high density and purity were achieved by CVD on bulk silica substrate. On the film-like substrates, very long carbon nanotubes of length ∼2 mm were produced, which is an order of magnitude longer (1 mm vs. 100 μm) than that described in most previous reports. High-resolution transmission electron microscopy (HRTEM) investigation illustrates that these carbon nanotubes are well graphitized and very pure. The tubes are typically consist of several to tens of concentric shells of carbon sheets with spacing about 0.34 nm. Micro-Raman spectroscopy has been carried out to detect the microstructures of CNT. The observed ratio of the integrated intensity of D and G band was found different from that of carbon nanotubes produced by arc-discharge method and pyrolytic graphite (PG). The resonance properties and higher order Raman bands are also different from other forms of carbon. With the help of the results of SEM and HRTEM the origination of the broader band structure were discussed.