Electromigration and potentiometry measurements of single-crystalline Ag nanowires underUHV conditions

Abstract

We report on in situ electromigration and potentiometry measurements on single-crystallineAg nanowires under ultra-high vacuum (UHV) conditions, using a four-probe scanningtunnelling microscope (STM). The Ag nanowires are grown in place by self-organization on a4° vicinal Si(001) surface. Two of the four available STM tips are used to contact the nanowire. Thepositioning of the tips is controlled by a scanning electron microscope (SEM). Potentiometrymeasurements on an Ag nanowire were carried out using a third tip to determine theresistance per length. During electromigration measurements current densities of up to1 × 108 A cm−2 could be achieved. We use artificially created notches in the wire to initiate electromigrationand to control the location of the electromigration process. At the position ofthe notch, electromigration sets in and is observed quasi-continuously by theSEM.