Shi Ping, Bohn Paul W
Department of Chemical and Biomolecular Engineering, University of Notre Dame, Notre Dame, Indiana 46556, USA.
ACS Nano. 2008 Aug;2(8):1581-8. doi: 10.1021/nn8002955.
Metallic atom-scale junctions (ASJs) constitute the natural limit of nanowires, in which the limiting region of conduction is only a few atoms wide. They are of interest because they exhibit ballistic conduction and their conductance is extraordinarily sensitive to molecular adsorption. However, identifying robust and regenerable mechanisms for their production is a challenge. Gold ASJs have been fabricated electrochemically on silicon using an iodide-containing medium to control the kinetics. Extremely slow electrodeposition or electrodissolution rates were achieved and used to reliably produce ASJs with limiting conductance <5 G(0). Starting from a photolithographically fabricated, Si(3)N(4)-protected micrometer-scale Au bridge between two contact electrodes, a nanometer-scale gap was prepared by focused ion beam milling. The opposing Au faces of this construct were then used in an open-circuit working electrode configuration to produce Au ASJs, either directly or by first overgrowing a thicker Au nanowire and electrothinning it back to an ASJ. Gold ASJs produced by either approach exhibit good stabilityin some cases being stable over hours at 300 Kand quantized conductance properties. The influence of deposition/dissolution potential and supporting electrolyte on the stability of ASJs are considered.
金属原子尺度结（ASJs）构成了纳米线的自然极限，其中传导的限制区域只有几个原子宽。它们之所以受到关注，是因为它们表现出弹道传导，并且其电导对分子吸附异常敏感。然而，确定其制造的稳健且可再生的机制是一项挑战。已使用含碘介质在硅上通过电化学方法制造金ASJs，以控制动力学。实现了极慢的电沉积或电溶解速率，并用于可靠地生产极限电导<5G(0)的ASJs。从通过光刻制造的、位于两个接触电极之间的Si(3)N(4)保护的微米级金桥开始，通过聚焦离子束铣削制备纳米级间隙。然后将该结构相对的金面用于开路工作电极配置，以直接或通过首先生长更厚的金纳米线并将其电减薄回ASJ来生产金ASJs。通过这两种方法生产的金ASJs在某些情况下表现出良好的稳定性，在300K下数小时内稳定，并具有量子化电导特性。考虑了沉积/溶解电位和支持电解质对ASJs稳定性的影响。
