Dresden 2006 – wissenschaftliches Programm

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TT: Tiefe Temperaturen

TT 26: Transport - Poster Session

TT 26.42: Poster

Mittwoch, 29. März 2006, 14:30–18:30, P1

Nanometer spaced electrodes of different metals on cleaved surfaces for molecular electronics applications — •Simone Lingitz, Sebastian Luber, Fan Zhang, Allan Hansen, Max Bichler, and Marc Tornow — Walter Schottky Institut, TU München, 85748 Garching, Germany

Current efforts in molecular electronics both aim for novel devices as well as the understanding of the electronic transport in molecules. Here one of the major challenges is the preparation of defined electrodes which allow reliably contacting and electrically investigating molecules of a given size. We pursue a novel strategy to fabricate nanometer spaced metal electrodes which is based on the cleavage plane of a GaAs-AlGaAs heterostructure.

Using Molecular Beam Epitaxy (MBE) we embedded a 5nm-GaAs layer in between two AlGaAs layers. By cleaving the substrate and selectively etching the GaAs layer, the remaining AlGaAs layers act as a support for deposited metal electrodes. We also used an inverse template structure (AlGaAs layer within GaAs) to profit from the unsurpassed selectivity of HF based etchants. In both approaches the electrode distance is precisely predetermined and various electrode metals can be used. This provides a platform to investigate the alignment of molecular and metal energy levels. In our contribution we will report on electrical investigations on thiolated @∖pi@-conjugated aromatic molecules assembled on 5nm spaced gold electrodes. Here the current-voltage characteristics show an exponential like increase in current at voltages above approx. 0.3V. We compare this to similar investigations on platinum electrodes.