Department of Physics, Brown University, Providence, RI 02912, USA.
J Phys Condens Matter. 2010 Nov 17;22(45):454114. doi: 10.1088/0953-8984/22/45/454114. Epub 2010 Oct 29.
Nanopores with one or two embedded nanoelectrodes can be fabricated by high resolution, milling-based methods. We first demonstrate how a focused ion beam, whose sputtering mechanism is well understood, can create a nanopore containing an annular electrode of an arbitrary metal, and with a regular perimeter. The inner surface of the nanopore can be insulated, and its diameter can be reduced with nanometer precision, by conformally coating a dielectric material by atomic layer deposition. We then investigate the mechanism of pore formation using a transmission electron microscope (TEM) through studies of the milling rate, and its dependence on the flux of electrons and on the atomic number of different target metals. Sputtering from the surface is identified as the dominant mechanism. Accordingly, light element conductors should be chosen to enhance the rate and resolution of TEM milling, which we demonstrate by articulating a nanopore with transverse carbon nanotube electrodes. Finally, we electrochemically verify that TEM milling preserves the quality of an annular gold electrode through cyclic voltammetry measurements performed at various stages of the fabrication.
纳米孔和一个或两个嵌入式纳米电极可以通过高分辨率、基于铣削的方法制造。我们首先演示了如何使用聚焦离子束创建一个纳米孔，其中包含一个任意金属的环形电极，并且具有规则的周长。通过原子层沉积对介电材料进行共形涂覆，可以对纳米孔的内表面进行绝缘，并以纳米级精度减小其直径。然后，我们通过研究铣削率及其对电子通量和不同目标金属原子数的依赖性，使用透射电子显微镜 (TEM) 研究了孔形成的机制。从表面溅射被确定为主要机制。因此，应该选择轻元素导体来提高 TEM 铣削的速度和分辨率，我们通过用横向碳纳米管电极阐明纳米孔来证明这一点。最后，我们通过在制造的各个阶段进行循环伏安测量，电化学验证了 TEM 铣削通过保留环形金电极的质量。
