Feedback controlled electromigration in four-terminal nano-junctions
Zheng-Ming Wu, Michael Steinacher, Roman Huber, Michel Calame, Sense Jan van der Molen, Christian Schonenberger
Abstract
We have developed a fast, yet highly reproducible method to fabricate metallic electrodes with nanometer separation using electromigration (EM). We employ four-terminal instead of two-terminal devices in combination with an analog feedback to maintain the voltage
U
over the junction constant. After the initialization phase (
U<0.2V),duringwhichthetemperature
T
increasesby80−150degsC,EMsetsinshrinkingthewirelocally.Thisquicklyleadstoatransitionfromthediffusivetoaquasi−ballisticregime(
0.2V < U < 0.6V). At the end of this second regime, a gap forms (U > 0.6V). Remarkably, controlled electromigration is still possible in the quasi-ballistic regime.