AVS 52nd International Symposium
    Nanometer-Scale Science and Technology Tuesday Sessions
       Session NS+EM-TuM

Paper NS+EM-TuM11
Nanometer Spaced Electrodes on Ultra Flat GaAs-AlGaAs Heterostructures for Molecular Electronics Applications

Tuesday, November 1, 2005, 11:40 am, Room 210

Session: Nanoscale Electronic Devices & Detection
Presenter: S.M. Luber, Walter Schottky Institut, TU Muenchen, Germany
Authors: S.M. Luber, Walter Schottky Institut, TU Muenchen, Germany
F. Zhang, Walter Schottky Institut, TU Muenchen, Germany
S. Strobel, Walter Schottky Institut, TU Muenchen, Germany
A. Hansen, Walter Schottky Institut, TU Muenchen, Germany
D. Schuh, Universitaet Regensburg, Germany
M. Bichler, Walter Schottky Institut, TU Muenchen, Germany
M. Tornow, Walter Schottky Institut, TU Muenchen, Germany
Correspondent: Click to Email
Current efforts in molecular electronics both aim for novel devices as well as the fundamental understanding of the electronic transport in molecular "wires". Here one of the major challenges is the preparation of well defined electrodes which allow reliably contacting and electrically investigating molecules of a given size. We pursue a novel strategy to fabricate nanometer spaced (nanogap) metal electrodes which is based on a cleavage plane of a GaAs-AlGaAs heterostructure. This allows for a precisely predetermined spacing of the electrodes. In recent studies@footnote 1@ we successfully fabricated, characterized and verified the electrical functionality of such nanogap electrodes. Using Molecular Beam Epitaxy (MBE) we embedded a thin (5-20nm) GaAs layer in between two AlGaAs layers. By cleaving the substrate and selectively etching the GaAs layer, the remaining AlGaAs layers are used as a support for deposited metal (Au) electrodes. This device is especially useful for measuring plenty of nanoscale objects in parallel, as the lateral size of the electrodes is defined by optical lithography. In our contribution we will report on a) first electrical investigations on thiolated @pi@-conjugated aromatic molecules assembled on 5nm spaced electrodes, and b) on our recent progress to reduce the lateral electrode size to a few nanometers only. Such electrode shape will allow for the contacting of merely a few or even single nanoscale objects. The downsizing is possible by the insertion of a second MBE growth step perpendicular to the first growth direction using the Cleaved Edge Overgrowth (CEO) technique. We successfully fabricated metallized electrodes of various widths (5-50nm) and various distance (15-30nm). We investigated these electrodes by AFM and SEM and made a first electrical characterization. @FootnoteText@ @footnote 1@SM Luber, S Strobel, HP Tranitz, W Wegscheider, D Schuh, and M Tornow, Nanotechnology 16 (2005), in press.