Growth of Carbon Nanotubes on Anodic Aluminum Oxide Templates: Fabrication of a Tube-in-Tube and Linearly Joined Tube

We have fabricated multiwalled carbon nanotubes (CNTs) with flowing acetylene, using a well-ordered porous anodic aluminum oxide (AAO) nanotemplate with or without deposition of Co in the pores as a catalyst. Without deposition of Co, the tubes were made in the pores having the shape of the pores by catalysis with the alumina of the AAO templates. With deposition of Co, both alumina and Co could work as a catalyst. By widening the pores after Co deposition, tubes grow out from the pores, by forming a tube-in-tube, which could be used for electrochemical energy storage. Since the alumina of the AAO templates works as a catalyst, one can fabricate special shapes of CNTs by designing the pores of AAO templates. We have succeeded for the first time to fabricate linearly joined CNTs by using AAO templates prepared by using pore widening and multianodization techniques. The electronic properties of the linearly joined CNTs will be affected critically by the junctions that contain five- and seven-membered carbon ring defects and could be controlled by changing the ratio of the two diameters of them. A schematic to fabricate FET (field-effect transistor) using the linearly joined CNTs fabricated on AAO templates has been suggested.