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O: Fachverband Oberflächenphysik

O 68: Nanostructures at Surfaces: 1D, 2D Structures and Networks

O 68.5: Poster

Mittwoch, 9. März 2016, 18:15–20:30, Poster A

Electromigration to create nanoscale gaps for molecular electronics — •Atasi Chatterjee, Frederik Edler, Christoph Tegenkamp, and Herbert Pfnür — Leibniz Universität Hannover, Institut für Festkörperphysik, 30167, Hannover, Germany

The fundamental size limitations of today's silicon based technologies can be solved by the bottom up approach,if stable and reproducible nanometer spaced electrodes can be generated, and single (organic) molecules can be reproducibly attached to them in well-defined geometries. Therefore,fabrication of reliable contacts in order to investigate the functionalities of the molecules is a primary challenge. Electromigration, which was earlier well known as a failure mechanism of integrated circuit metallizations subjected to high current densities, now serves as one of the most promising methods of fabricating metallic nanogaps. We create flat ultrathin silver nanocontacts at the centre via electro-migration of lithographically prepared silver nanowires on a silicon substrate. A thin adhesion layer of Cr is used for Ag contact pads to avoid contact problems with STM tips. Electromigration is performed in a 4-tip SEM/STM chamber where two tips are used to contact the structure and a software controlled process is used to reach the tunneling regime at a preset tunneling resistance.Ultrathin and laterally open contact structures allow direct access for the STM tips for local control, in-situ observation and characterization of the gap. By detailed investigations of the dependence on current density and temperature, we try to explore the underlying physical mechanisms that form electromigrated gaps.