A comprehensive analysis of the CVD growth of boron nitride nanotubes
A comprehensive analysis of the CVD growth of boron nitride nanotubes
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DOI：
10.1088/0957-4484/23/21/215601
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发表时间：
2012-06-01
期刊：
影响因子：
3.5
通讯作者：
Golberg, Dmitri
中科院分区：
文献类型：
--
作者：
Pakdel, Amir;Zhi, Chunyi;Golberg, Dmitri
在卧式电炉中通过催化化学气相沉积（CVD）方法在硅/二氧化硅（Si/SiO2）衬底上生长氮化硼纳米管（BNNT）薄膜。系统研究了生长温度和催化剂浓度对薄膜形貌和单个 BNNT 结构的影响。在 1200 和 1300 摄氏度下生长的 BNNT 薄膜由随机方向的均匀分散的单独管组成，平均外径分别类似于 30 nm 和类似于 60 nm。与此同时，在 1400 摄氏度下生长的薄膜由呈花状形态的 BNNT 束组成，其中包括平均直径接近 100 nm 的粗管，周围环绕着直径低至接近 10 nm 的非常细的管。此外，低催化剂浓度导致形成由缠结的卷曲管组成的BNNT薄膜，而高催化剂含量导致形成非常厚的管，直径高达350 nm，呈半直立的花状形态。广泛的透射电子显微镜 (TEM) 研究揭示了 BNNT 的直径依赖性生长机制；即，具有封闭端的细管和粗管分别通过基部生长和尖端生长机制生长。然而，高催化剂浓度促进了充满催化剂的 BNNT 的形成，该 BNNT 通过碱基生长机制进行开放式生长。
Boron nitride nanotube (BNNT) films were grown on silicon/silicon dioxide (Si/SiO2) substrates by a catalytic chemical vapor deposition (CVD) method in a horizontal electric furnace. The effects of growth temperature and catalyst concentration on the morphology of the films and the structure of individual BNNTs were systematically investigated. The BNNT films grown at 1200 and 1300 degrees C consisted of a homogeneous dispersion of separate tubes in random directions with average outer diameters of similar to 30 and similar to 60 nm, respectively. Meanwhile, the films grown at 1400 degrees C comprised of BNNT bundles in a flower-like morphology, which included thick tubes with average diameters of similar to 100 nm surrounded by very thin ones with diameters down to similar to 10 nm. In addition, low catalyst concentration led to the formation of BNNT films composed of entangled curly tubes, while high catalyst content resulted in very thick tubes with diameters up to similar to 350 nm in a semierect flower-like morphology. Extensive transmission electron microscopy (TEM) investigations revealed the diameter-dependent growth mechanisms for BNNTs; namely, thin and thick tubes with closed ends grew by base-growth and tip-growth mechanisms, respectively. However, high catalyst concentration motivated the formation of filled-with-catalyst BNNTs, which grew open-ended with a base-growth mechanism.