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O: Fachverband Oberflächenphysik

O 36: Poster Session II (Metals; Nanostructures at surfaces; Surface or interface magnetism; Spin-Orbit Interaction at Surfaces; Electron and spin dynamics; Surface dynamics; Methods; Theory and computation of electronic structure)

O 36.64: Poster

Dienstag, 15. März 2011, 18:30–22:00, P4

The resistance of single atomic steps in ultrathin Pb nanowires on Si(557) — Jan Rönspies, •Lisa Kühnemund, Svend Wiessell, and Herbert Pfnür — Leibniz-Universität Hannover, Inst. f. Festkörperphysik

We studied the local electronic transport properties of a monolayer thick Pb wire by local potentiometry with the tip of a tunneling microscope. 50-nm-wide wires on bare Si(557) were generated by direct writing with an electron beam in an ultrathin film of SiO₂ using the process of electron-beam-induced selective stimulated thermal desorption of oxygen (EBSTD) in combination with a shadow mask technique and macroscopic TiSi₂ contacts. The resistivity of this wire agrees well with expectations derived from anisotropic monolayer thick Pb films on Si(557). Although small Pb clusters nucleated during annealing and desorption of excess Pb, they had a negligible effect on the local resistive properties of the wire. Steps in the substrate of atomic height apparently do not interrupt the conducting path, but due to local scattering at step edge states increase the local resistivity by more than one order of magnitude. Furthermore, a systematic study of the resistance as a function of the lateral width of the wires revealed an effective conducting width, which is about 3 nm smaller on both sides than the geometrically determined width. In addition, we found deviations from Ohm’s law at widths below 20 nm.