Influence of Catalyst Film Thickness Deposited by Atomic Layer Deposition on Growth of Aligned Carbon Nanotubes

Al2O3 buffer layer and Fe2O3 catalyst film were deposited on Si wafer successively by atomic layer deposition (ALD). The coated Si wafer was used to grow vertically aligned carbon nanotubes (VACNTs) by water- assisted chemical vapor deposition (WACVD). Results show that catalytically active nanoparticles form in the ALD deposited Fe2O3 film after heat-treatment in reduced atmosphere, and the thickness of Fe2O3 film is closely related to the size of catalytic nanoparticles and the structure of VACNTs grown. For 1.2 nm-thick Fe2O3 film as catalyst layer, the VACNTs have an outer diameter of similar to 10 nm, wall numbers of similar to 5 and height of similar to 400 mu m. Increasing the thickness of Fe2O3 film leads to outer diameter and wall number of VACNTs increasing, but the height of which decreasing. It is also observed that VACNTs grows on the side face of Si wafer, which indicates that ALD technique can be useful for VACNTs growth on three-dimensional substrate.