Dong Lifeng, Chirayos Vachara, Bush Jocelyn, Jiao Jun, Dubin Valery M, Chebian Ramanan V, Ono Yoshi, Conley John F, Ulrich Bruce D
Department of Physics, Portland State University, Portland, Oregon 97207-0751, USA.
J Phys Chem B. 2005 Jul 14;109(27):13148-53. doi: 10.1021/jp051803h.
We present a floating-potential dielectrophoresis method used for the first time to achieve controlled alignment of an individual semiconducting or metallic single-walled carbon nanotube (SWCNT) between two electrical contacts with high repeatability. This result is significantly different from previous reports, in which bundles of SWCNTs were aligned between electrode arrays by a conventional dielectrophoresis process where the results were only collected from the control electrode regions. In this study, our alignment focus is not only on the regions of the control electrodes but also on those of the floating electrodes. Our results indicate that bundles of carbon nanotubes along with impurities were first moved into the region between two control electrodes while individual nanotubes without impurities were straightened and aligned between two floating electrodes. The measurements for the back-gated nanotube transistors made by this method displayed an on-off ratio and transconductance of 10(5) and 0.3 microS, respectively. These output and transport properties are comparable with those of nanotube transistors made by other methods. Most importantly, the findings in this study show an effective way to separate individual nanotubes from bundles and impurities and advance the processes for site-selective fabrication of single-SWCNT transistors and related electrical devices.
我们首次展示了一种浮动电位介电泳方法，该方法能够以高重复性实现单个半导体或金属单壁碳纳米管（SWCNT）在两个电触点之间的可控排列。这一结果与之前的报道有显著不同，在之前的报道中，SWCNT束是通过传统介电泳过程在电极阵列之间排列的，且结果仅从控制电极区域收集。在本研究中，我们的排列重点不仅在于控制电极区域，还在于浮动电极区域。我们的结果表明，带有杂质的碳纳米管束首先被移动到两个控制电极之间的区域，而无杂质的单个纳米管则被拉直并排列在两个浮动电极之间。用这种方法制作的背栅纳米管晶体管的测量结果显示，其开/关比和跨导分别为10⁵和0.3微西门子。这些输出和传输特性与通过其他方法制作的纳米管晶体管相当。最重要的是，本研究中的发现展示了一种从束和杂质中分离单个纳米管的有效方法，并推进了单SWCNT晶体管及相关电子器件的位点选择性制造工艺。
