Distance control of electromigration-induced silver nanogaps.

Abstract

Electromigration (EM) in Ag nanocontacts (NCs) was observed in situ on an atomic scale using simultaneous measurements of electrical conductance and mechanical stress. The in situ observations showed that the critical bias voltage of EM was 45 mV. As the bias voltage was increased to 100-200 mV, the NCs broke and gaps with distances of 1.3 +/- 0.8 nm were obtained for NCs having widths smaller than 6 nm. When the bias voltage was further increased to 200-300 mV, the gaps expanded to more than 3 nm, regardless of the NC width. It was found that the nanogap distance could be controlled to fit specific molecular sizes by appropriately selecting the bias voltage and NC width.