Dresden 2006 – wissenschaftliches Programm

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O: Oberflächenphysik

O 29: Poster session II (Nanostructures, Magnetism, Particles and clusters, Scanning probe techniques, Time-resolved spectroscopy, Structure and dynamics, Semiconductor surfaces and interfaces, Oxides and insulators, Solid-liquid interfaces)

O 29.4: Poster

Mittwoch, 29. März 2006, 14:30–17:30, P2

Preparation und characterization of molecular Ag nano contacts via electromigration — •Jedrzej Schmeidel, Gernot Gardinowski, Christoph Tegenkamp, and Herbert Pfnür — Institut für Festkörperphysik, Universität Hannover, Abteilung Oberflächen, Appelstrasse 2, 30167 Hannover, Germany

In order to obtain electrical characteristics from molecules and nanostructures, atomically well-defined and stable contacts are of high importance, which can be manufactured reproducibly, e.g. under UHV conditions to minimize further contamination.

We create nanogaps using an electromigration technique. For heat dissipation different geometries have been fabricated by using e-beam lithography on mono(PMMA)- and bi-layer(PMMA/LOR3B) photo-resist systems. The latter is used to create nano-bridges due to underetching. In a following step Ag is evaporated on H-terminated Si(100) or Si(111) surfaces at different angles, thus forming flat Ag films in between thicker Ag contacts, which are around 50nm high and laterally separated by 200nm. The evaporation is done at 80K, i.e. continuous Ag films are obtained already for 10ML in the central part. The widths of the initial structure is around 30nm. The chemistry and the structure on the mesoscopic scale is controlled by AES, SEM and AFM. In a final step, after bonding the structures, computer-controlled electromigration is performed using a high precision current source. For excluding thermal mobility and reducing the breakdown speed, the sample has been cooled down to LN₂ temperature. As revealed from I-V characteristics, gaps of around 1nm are formed.