用ECR-CVD方法制备定向碳纳米管

Synthesis and growth characteristics of well-aligned carbon nanotubes by ECR-CVD

以Fe3O4纳米粒子为催化剂,CH4和:H2为气源,采用电子回旋共振微波等离子体化学气相沉积技术(ECR-CVD)在多孔硅基底上制备出定向生长的碳纳米管.研究了气氛组成、气压、温度和反应时间对碳纳米管生长特性的影响.使用扫描电子显微镜(SEM)、透射电子显微镜(TEM)和拉曼光谱(Raman spectrum)表征了样品的形貌和结构.结果表明:气氛组成和气压影响了反应腔内离解碳的浓度,从而影响碳纳米管的成核、生长速度及定向生长;温度的变化改变催化剂的尺寸从而改变碳纳米管的直径,在过低的温度下碳纳米管不能实现定向生长;碳纳米管随着反应时间的延长而不断增长,但超过一定时间后催化剂颗粒被碳包覆而失去催化作用,生长停止.

Well-aligned carbon nanotubes (CNTs) were synthesized on porous silicon by electron cyclotron resonance chemical vapor deposition (ECR-CVD). CH4 and H2 were used as the source gases and Fe3O4 nanoparticle as the catalyst. The effects of process parameters such as gas composition, working pressure, temperature and deposition time on CNTs growing characteristics were investigated. The morphology and structure were evaluated by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Raman spectrum. The results show that the gas composition and working pressure influence the concentration of carbon radical in the chamber, which may influence growth rate, density and aligned growth of CNTs; The temperature controls the diameters of CNTs by changing the size of catalyst but CNTs can't tend to aligned growth at lower temperature; CNTs become longer and longer according to the deposition time first, but then stop growing after a certain time.