High-yield synthesis of conductive carbon nanotube tips for multiprobe scanning tunneling microscope
High-yield synthesis of conductive carbon nanotube tips for multiprobe scanning tunneling microscope
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DOI：
10.1063/1.2432253
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发表时间：
2007-01-01
影响因子：
1.6
通讯作者：
Mori, H.
中科院分区：
文献类型：
--
作者：
Konishi, H.;Murata, Y.;Mori, H.
我们建立了一种用于多探针扫描隧道显微镜 (STM) 的高产量导电碳纳米管 (CNT) 尖端的制造工艺。首先，通过介电泳方法将 CNT 附着在支撑 W 尖端的顶端，其次，通过碳氢化合物的电子束沉积和随后的加热来增强 CNT 和 W 尖端之间的粘附力，最后通过脉冲激光沉积在其上完全涂覆薄金属层。在空气中长途运输后，超过 90% 的 CNT 尖端完好无损，表明 CNT 尖端的实际耐用性。即使与另一个金属尖端反复接触 100 次以上，碳纳米管尖端的形状也没有改变，这证明了其机械坚固性。我们利用多探针 STM 中的四端子方法利用 CNT 尖端进行电子传输测量，其中尖端的 PtIr 涂层 CNT 部分表现出具有 1.8 k Omega/μ m 低电阻率的扩散传输。 CNT 和支撑 W 尖端之间的接触电阻估计小于 0.7 k Omega。我们证实，尽管 PtIr 层在 CNT 上剥离并聚集成颗粒，但过电流通过后，PtIr 薄层仍保留在 CNT-W 结部分，这可能是由于电迁移或热激活扩散过程所致。这些结果表明，按照我们的配方制造的 CNT 尖端具有足以进行多探针 STM 测量的高可靠性和再现性。 (c) 2007 年美国物理研究所。
We have established a fabrication process for conductive carbon nanotube (CNT) tips for multiprobe scanning tunneling microscope (STM) with high yield. This was achieved, first, by attaching a CNT at the apex of a supporting W tip by a dielectrophoresis method, second, by reinforcing the adhesion between the CNT and the W tip by electron beam deposition of hydrocarbon and subsequent heating, and finally by wholly coating it with a thin metal layer by pulsed laser deposition. More than 90% of the CNT tips survived after long-distance transportation in air, indicating the practical durability of the CNT tips. The shape of the CNT tip did not change even after making contact with another metal tip more than 100 times repeatedly, which evidenced its mechanical robustness. We exploited the CNT tips for the electronic transport measurement by a four-terminal method in a multiprobe STM, in which the PtIr-coated CNT portion of the tip exhibited diffusive transport with a low resistivity of 1.8 k Omega/mu m. The contact resistance at the junction between the CNT and the supporting W tip was estimated to be less than 0.7 k Omega. We confirmed that the PtIr thin layer remained at the CNT-W junction portion after excess current passed through, although the PtIr layer was peeled off on the CNT to aggregate into particles, which was likely due to electromigration or a thermally activated diffusion process. These results indicate that the CNT tips fabricated by our recipe possess high reliability and reproducibility sufficient for multiprobe STM measurements. (c) 2007 American Institute of Physics.