Using noise for controlled disassembly of nanoscale gold wires

Abstract

Gold wires 90 nm wide were fabricated on a 100 nm thin silicon nitride membrane using electron beam lithography. Application of a bias voltage across the wires caused them to break, due to resistive heating and electromigration, and produced a nanoscale gap in their structure. Placing the gold wires on a thin silicon nitride membrane allowed us to image the wires with transmission electron microscopy as they proceeded through the breaking process with a very high resolution. The images revealed extensive rearrangement of the metal grains and the exact shape of the final gap. A voltage-ramp algorithm using the effective conductance of the wires as the feedback parameter was developed to reproducibly generate 2 nm gaps in the wire structure. We observed that the measured relative current noise increased more than two orders of magnitude more than the resistance in the first stage of the disassembly process. The large change of the current noise makes it an attractive candidate as a parameter to be used in the control feedback loop to break the wires. Initial results for using noise to control the disassembly process are presented.