Ultrahigh density modulation of aligned single-walled carbon nanotube arrays
SWNT density, chemical vapor deposition, periodic growth, growth mechanism
ABSTRACT Controlling the densities of aligned single-walled carbon nanotube arrays (SWNTs) on ST-cut quartz is a critical step in various applications of these materials. However the growth mechanism for tuning SWNT density using the chemical vapor deposition (CVD) method is still not well understood, preventing the development of efficient ways to obtain the desired results. Here we report a general “periodic” approach that achieves ultrahigh density modulation of SWNT arrays on ST-cut quartz substrates—with densities increased by up to ~60 times compared with conventional methods using the same catalyst densities—by varying the CH4 gas “off” time. This approach is applicable to a wide range of initial catalyst densities, substrates, catalyst types and growth conditions. We propose a general mechanism for the catalyst size-dependent nucleation of SWNTs associated with different free carbon concentrations, which explains all the observations. Moreover, the validity of the model is supported by systematic experiments involving the variation of key parameters in the “periodic” CVD approach.
Tsinghua University Press
Bin Wu,Dechao Geng,Yunlong Guo,Liping Huang,Jianyi Chen,Yunzhou Xue,Gui Yu,Yunqi Liu,Hisashi Kajiura,Yongming Li, Ultrahigh density modulation of aligned single-walled carbon nanotube arrays. NanoRes.2011, 4(10): 931–937