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

Al 2 O 3 buffer layer and Fe 2 O 3 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 Fe 2 O 3 film after heat-treatment in reduced atmosphere, and the thickness of Fe 2 O 3 film is closely related to the size of catalytic nanoparticles and the structure of VACNTs grown. For 1.2 nm-thick Fe 2 O 3 film as catalyst layer, the VACNTs have an outer diameter of ~10 nm, wall numbers of ~ 5 and height of ~ 400 m. Increasing the thickness of Fe 2 O 3 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.