Effect of morphology of supporting alumina films on the synthesis of graphite-capped, vertically aligned carbon nanotube arrays
Effect of morphology of supporting alumina films on the synthesis of graphite-capped, vertically aligned carbon nanotube arrays
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DOI：
10.7567/jjap.53.065101
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发表时间：
2014-05
影响因子：
1.5
通讯作者：
Y. Matsuoka;M. Yoshimura
中科院分区：
文献类型：
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作者：
Y. Matsuoka;M. Yoshimura
我们研究了支撑氧化铝膜的厚度和粗糙度对石墨覆盖的垂直排列碳纳米管（CNT）阵列（以下简称“复合材料”）生长的影响。为了制备不同厚度的钴催化剂或氧化铝膜，我们采用了组合掩模沉积（CMD）方法。使用乙醇蒸气作为碳前体，通过在670 °C下的热化学气相沉积进行生长。随着氧化铝厚度的增加，CNT阵列和具有不连续（“中间”）和连续（“复合”）石墨顶层的那些被合成。在薄氧化铝层的情况下，催化颗粒容易通过渗透到氧化铝膜中而失活，导致CNT阵列或中间结构。粗糙的氧化铝层倾向于产生CNT或中间体，因为在倾斜沉积期间通过遮蔽效应存在非常薄的催化剂层。粗糙表面还为厚催化剂情况提供了凹陷区域，其中在催化剂层中产生突起，用作顶部石墨膜下CNT生长的核。使用赫尔曼取向因子分析CNT排列，以澄清CNT阵列的面密度。在此基础上，提出了一个复合材料的生长模型。
We investigate the effects of thickness and roughness of supporting alumina film on the growth of graphite-capped, vertically aligned carbon nanotube (CNT) arrays (hereafter, referred to as “composite”). To prepare various thicknesses of cobalt catalyst or alumina film, we employed a combinatorial masked deposition (CMD) method. The growth was carried out by thermal chemical vapor deposition at 670 °C using ethanol vapor as a carbon precursor. With the increase in alumina thickness, CNT arrays and those with discontinuous (“intermediate”) and continuous (“composite”) graphite top layers are synthesized. In the case of thin alumina layers, catalytic particles are easily deactivated through penetration into the alumina film, leading to CNT arrays or intermediate structures. Rough alumina layers tend to give CNT or intermediate, because of the existence of very thin catalyst layers by the shading effect during the oblique deposition. The rough surface also provides recessed areas for the thick catalyst case, where protrusions are created in the catalyst layers, acting as nuclei of CNT growth under the top graphite films. The CNT alignment is analyzed using a Herman’s orientation factor to clarify the areal density of CNT arrays. On the basis of the above results, we propose a growth model for the composite.