Regensburg 2019 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 24: Molecular Electronics and Photonics
TT 24.4: Vortrag
Dienstag, 2. April 2019, 10:15–10:30, H22
Conductance switching by CO adsorption in Ag point contacts — Atasi Chatterjee1, Frederik Edler1,2, Christoph Tegenkamp1,2, and •Herbert Pfnür1 — 1Institut für Festkörperphysik, Leibniz Universität Hannover, Germany — 2Institut für Physik, TU Chemnitz, Germany
We demonstrate 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, grown on hydrogen terminated low-doped Si (100) samples using the process of electro-migration at 100K inside a 4-tip SEM/STM UHV chamber. 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. Conductance histograms exhibit characteristic conductance values that were assigned to the different metastable configurations prior to atomic point contact formation. In-situ chemisorption of CO strongly altered the conductance from 0.9 G0< σ < 1.3 G0 to a stable value close to 0.1 G0, suggesting adsorption of single CO molecules within the contact. In the presence of CO, current versus voltage curves showed a slightly rectifying behavior indicating preferential binding of CO to one side of the electrode. Furthermore, time resolved current measurements at 100 K demonstrate voltage-induced bi-stable conductance at 0.08 and 0.14 G0 with stability of the 0.14 G0 value below 0.1 V and of the lower conductance above 0.25 V, whereas at intermediate voltages switching between these values was observed.