Atomistic Structural Variation via Electromigration in Molten-State Gold Nanocontacts

The atomistic structural variation in gold nanocontacts (NCs) due to applied voltage pulses was examined inside a transmission electron microscope. This examination was accompanied by simultaneous conductance measurements. The NCs melted during the passage of 4 ns long voltage pulses, with voltages in the 0.75-1.30 V range. Electromigration occurred in the molten state, and was directed from the positively-biased electrode to the negatively-biased electrode, which opposes the observed direction convention of most solid state metals. Voltage pulses higher than 1.30 V resulted in the formation of nanoscaled gaps. This study demonstrates the ability to control the external shape of NCs and to induce nanoscaled gap formation by utilizing the molten state electromigration phenomenon using voltage pulsing.