Abstract
Nanoelectrodes with nanometer separation (nanogap) are achieved by the combination of atomic force microscopy nanomachining and electromigration. By controlling the force of an atomic force microscopy (AFM) tip on a thin PMMA resist, a nanoscale groove is first created. By coating a gold film and performing a lift-off process, a gold nanowire with a width which ranges from 50 nm to 90 nm is successfully fabricated. Afterwards, by combining the photolithography with the process above, a pair of contact pads connecting a metallic nanowire is created. Then the nanowire is indented by AFM nanomachining. By measuring IV characteristic of the nanowire, the indented nanowire without splitting is assured. By externally applying a bias voltage (sweeping rate= 0.02V/sec) across the gold nanowire, the nanowire would split because of the occurrence of electromigration as the current density exceeds the critical value of 108 A/cm2. Therefore, the nanoelectrodes with the separation around 10 nm at the indented site can be realized. And the AFM nanomachining is utilized to control the site of nanowire’s split.