Verification of unzipping models of electromigration in gold nanocontacts by in situhigh-resolution transmission electron microscopy

Abstract

We observed in situ the electromigration process of gold (Au) nanocontacts (NCs) byhigh-resolution transmission electron microscopy. The structural dynamics of the interiorand surfaces of the NCs were investigated at the atomic level. In particular, we directlyverified the evidence of the unzipping model of electromigration with the in situobservation of surface-edge movement. The fundamental parameters of NCs, i.e.,conductance and tensile force, were also measured during in situ lattice imaging ofelectromigration. Atoms migrating from the negative electrode accumulated at the mostconstricted regions of the NCs, leading to expansion. As a result, the NCs werecompressed by the two electrodes. We demonstrated the magnitude of the forceacting on the NCs during electromigration. The critical voltage of electromigrationwas approximately 80 mV, and the current density at the critical voltage was60 TA m − 2. We found that Au nanogaps could be fabricated by applying this bias voltage to AuNCs.