Berlin 2008 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 35: Transport: Nanoelectronics I - Quantum Dots, Wires, Point Contacts 3
TT 35.1: Vortrag
Donnerstag, 28. Februar 2008, 14:00–14:15, H 3010
Conductance of gold nanojunctions thinned by electromigration — •Regina Hoffmann1,2, Daniel Weissenberger2,3, Jacques Hawecker2,3, Dominik Stöffler1,2, and Hilbert v. Löhneysen1,2,4 — 1Physikalisches Institut, Universität Karlsruhe, 76128 Karlsruhe — 2DFG Center for Functional Nanostructures (CFN), Universität Karlsruhe, 76128 Karlsruhe — 3Laboratorium für Elektronenmikroskopie, Universität Karlsruhe, 76128 Karlsruhe — 4Forschungszentrum Karlsruhe, Institut für Festkörperphysik, 76021 Karlsruhe
Electromigration can in principle be used to fabricate arrays of nanocontacts for single-molecule junctions on the same chip, in contrast to the mechanically controllable break-junction technique. With this method, a Au nanowire prepared by electron beam lithography is heated resistively until thermally activated atoms diffuse under the influence of electromigration forces. Eventually, a nanogap is formed that can host a molecule. We report conductance histograms before a nanogap is formed that show oscillations as a function of the conductance for contacts in the ballistic regime. Obviously, heating enhances the probability of the atoms to reach equilibrium positions. The oscillations of the histogram as a function of the conductance have a period of slightly less than 1 G0. This is typical for atomic shell structures. Similar oscillations have been observed for work-hardened Au wires while annealed Au shows oscillations typical for electronic shell structures [1].
[1] I.K. Yanson et al., Phys. Rev. Lett. 95, 256806 (2005).