Stability of metal nanowires $(d \geq 15 nm)$ against electromigration

We have studied stability of metal nanowires against electromigration damage when they are subjected to high current density. Silver nanowires of diameter ranging from 15 nm to 100 nm were synthesized with electrochemical method using template route. Electromigration study was accompanied with in-situ low frequency electric resistance fluctuation or $1/f$ noise measurement in the nanowires. It was observed that nanowires with smaller diameter stayed without substantial damage even after 10 to 14 days of continuous stressing with a current of density of the order of $10^{12} A/m^2$, while those with larger diameter get damaged much sooner. Noise measurements show that for nanowires with smaller diameter, noise spectra remains almost same for the entire duration of current stressing whereas in case of nanowires of larger diameter, spectral power of noise $(S_v(f) \infty 1/f\alpha)$ as well as the frequency exponent, $\alpha$, increases as the electromigration process progresses. This is similar to that seen in metal films