Liquid-like instabilities in gold nanowires fabricated by focused ion beam lithography

Observation of liquid-like instabilities is reported in Au nanowires formed by nanopatterning of Au films using focused ion beam (FIB) on different types of Si substrates including those passivated with SiO2 or Si3N4 surfaces. The onset of the instability, which can ultimately lead to break up of the FIB patterned nanowires into gold islands, occurs when the diameter of the nanowire is below a critical range, which depends on the conductivity of the substrate and the extent of native oxide present on it. We also observe the formation of Taylor cones on very narrow nanowires grown on insulating substrates at the onset of instabilities. This effect is further strong evidence of liquid behaviour and is the result of charging of the wires during FIB nanofabrication.