Im Jiwoon, Lee Minbaek, Myung Sung, Huang Ling, Rao Saleem G, Lee Dong Joon, Koh Juntae, Hong Seunghun
School of Physics and NANO Systems Institute, Seoul National University, Seoul 151-747, Korea.
Nanotechnology. 2006 Jul 28;17(14):3569-73. doi: 10.1088/0957-4484/17/14/035. Epub 2006 Jun 26.
Self-assembled monolayer (SAM) patterns on electrodes are often utilized to guide the assembly of single-walled carbon nanotubes (SWCNTs) onto the electrodes to form desired device structures. In this case, the SWCNTs are in contact with the electrodes through the SAM which comprises molecular wires. Presumably, it is desirable to use conjugated molecular wires for a low contact resistance because they have been reported as a better electric conductor than non-conjugated ones. However, until now, the directed-assembly of SWCNTs has been driven mostly via molecular wires with alkane backbones which are known to be relatively poor conductors. Herein, we report large-scale directed-assembly of SWCNTs utilizing SAM patterns comprising conjugated molecular wires. We achieved highly selective adsorption and precision alignment of SWCNTs utilizing polar SAM patterns comprising conjugated molecular wires, while SAM patterns with non-polar terminal groups efficiently prevented adsorption of SWCNTs. Furthermore, we developed a process for assembling a SWCNT across two electrodes coated with conjugated molecular wires, and the electrical conduction through the SWCNT was measured via a conducting atomic force microscope. This result could be an important guideline for large-scale directed-assembly of SWCNT-based devices in the future.
电极上的自组装单分子层（SAM）图案常被用于引导单壁碳纳米管（SWCNT）在电极上组装，以形成所需的器件结构。在这种情况下，SWCNT通过包含分子线的SAM与电极接触。据推测，使用共轭分子线以实现低接触电阻是很理想的，因为据报道共轭分子线比非共轭分子线是更好的电导体。然而，到目前为止，SWCNT的定向组装主要是通过具有烷烃主链的分子线来驱动的，而烷烃主链已知是相对较差的导体。在此，我们报道了利用包含共轭分子线的SAM图案进行SWCNT的大规模定向组装。我们利用包含共轭分子线的极性SAM图案实现了SWCNT的高度选择性吸附和精确排列，而具有非极性端基的SAM图案有效地阻止了SWCNT的吸附。此外，我们开发了一种在两个涂覆有共轭分子线电极之间组装SWCNT的工艺，并通过导电原子力显微镜测量了通过SWCNT的导电情况。这一结果可能是未来基于SWCNT的器件大规模定向组装的重要指导原则。
