原子层沉积工艺制备催化薄膜厚度对生长碳纳米管阵列的影响

通过原子层沉积(ALD)工艺在硅基底依次沉积氧化铝缓冲层薄膜和氧化铁催化薄膜, 然后利用管式炉进行水辅助化学气相沉积(WACVD)生长垂直碳纳米管阵列(VACNTs)。结果表明: ALD工艺制备的氧化铁薄膜经还原气氛热处理可形成碳纳米管阵列生长所需的纳米催化颗粒; 氧化铁薄膜厚度与纳米催化颗粒大小以及生长出的碳纳米管阵列的结构密切相关。当氧化铁薄膜厚度为1.2 nm时, 生长出的碳纳米管阵列管外径约为10 nm, 管壁层数约为5层, 阵列高度约为400 μm。增大氧化铁薄膜的厚度, 生长出的碳纳米管阵列外径和管壁数增加, 阵列高度降低。实验还在硅基底侧面观察到了VACNTs, 表明ALD工艺可在三维结构上制备催化薄膜用于生长VACNTs。

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 ~10 nm, wall numbers of ~ 5 and height of ~ 400 μm. 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.