Shaping single atomic junctions in ultra-thin Ag structures by electromigration

By characterizing and manipulating the conductive properties of single Ag nano-grain boundaries with electromigration—originally considered only as a detrimental effect for metallic nanostructures—we show that atomic point contacts can be generated at well-defined locations with extreme reliability in ultra-thin (5 nm) and ultra-small (minimum width 16 nm) Ag nanostructures, deposited on hydrogen terminated low-doped Si(100) samples. Single contacts were always obtained once the smallest constriction of the structures was below the average grain size of the Ag films and competing thermal migration was suppressed. These ultra-thin and laterally open structures on Si provide complete accessibility for local characterisation of the molecular junction.