LAUSR

We investigate the relationship between temperature and electron wind force in electromigration (EM) of ultrathin gold nanowires by monitoring power and current density at breakdown under a generalized AC bias (AC with a DC offset). Based on model calculations, our driving frequency of 10 MHz is low enough to maintain steady state self-heating behavior of our wires but high enough that the direction of the wind force switches quickly relative to the time-scale of atomic motion through the junction. The maximum and time-average of the squared current density (which dictate the temperature) both exhibit a minimum in DC offset (which dictates the wind force). This is explained by wind force driven annealing of the wire under long-range atomic displacements. Our hypothesis is supported by observations of changing device resistance on the voltage ramp prior to EM onset and by subsequent SEM inspection of electromigrated devices. The frequency dependence of pure AC EM breaking is also presented and interpreted in terms of the effectiveness of damage healing upon current reversal and the degree of wind force driven annealing.We investigate the relationship between temperature and electron wind force in electromigration (EM) of ultrathin gold nanowires by monitoring power and current density at breakdown under a generalized AC bias (AC with a DC offset). Based on model calculations, our driving frequency of 10 MHz is low enough to maintain steady state self-heating behavior of our wires but high enough that the direction of the wind force switches quickly relative to the time-scale of atomic motion through the junction. The maximum and time-average of the squared current density (which dictate the temperature) both exhibit a minimum in DC offset (which dictates the wind force). This is explained by wind force driven annealing of the wire under long-range atomic displacements. Our hypothesis is supported by observations of changing device resistance on the voltage ramp prior to EM onset and by subsequent SEM inspection of electromigrated devices. The frequency dependence of pure AC EM breaking is also presented and interpreted ...