Synthesis And Characterization Of Aligned Carbon Nanotubes Prepared By CVD

Aligned carbon nanotubes (ACN) are widely studied all over the world due to its unique structure and excellent properties. Our group has developed a composite photoelectronic film made of aligned carbon nanotube and CuPc. In this paper, we investigated the aligned carbon nanotube grown on anodic aluminum oxide film (AAO) and silicon substrates. The products were characterized by TEM, SEM, AFM and Raman spectroscopy, and so on. The effects of substrate preparation and treatment on ACN growth and post-growth modifications of CAN grown on ACN were also investigated.Firstly, preparation of AAO films was studied. AAO films were anodic oxidized using oxalic acid under different voltage from 30V to 60V. Under 40V, the diameter range of AAO is 80nm~100nm and narrowly distributed. The thickness of AAO film is about 2.0 # m and the aspect ratio is beyond 15. The diameter distribution of one-step anodic oxidation is even, but the shape of the holes is not uniform while it becomes better afer second oxidation for 20min.Then aligned carbon nanotube was grown on AAO films. For one-step oxidation films, bamboo-shaped nanotubes were formed. The diamerter is even distributed and is much smaller than that of the holes. Maybe there are several nanotubes grown from one hole. For two-step oxidation films, the diameter of the prepared nanotubes is the same as that of the holes. The growth of nanotubes is very fast, so they are prone to be long and twisted out of the template. Ultrasonic was used to cut the nanotubes. At last, the nanotubes are no longer than the film thickness and they are end-opened and catalyst free.Finally, aligned carbon nanotube was prepared on silicon substrates. TEM observations were applied to investigate the detailed structure. Growth mechanism was suggested.