Regensburg 2007 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 17: Poster Session I (Nanostructures at Surfaces; Metal Substrates: Epitaxy and Growth; Methods: Scanning Probe Techniques; Phase Transitions)

O 17.50: Poster

Montag, 26. März 2007, 17:30–20:30, Poster C

Conductivity measurements using a beetle-type double-tip STM — Philipp Jaschinsky, Josef Mysliveček, Peter Coenen, Helmut Stollwerk, Gerhard Pirug, and •Bert Voigtländer — Institut für Bio- und Nanosysteme (IBN 3) und Center for Nanoelectronic Systems for Information Technology (CNI), Forschungszentrum Jülich, 52425 Jülich, Germany

We demonstrate applications of a double-tip scanning tunnelling microscope (STM) with a scanning electron microscope (SEM) in ultrahigh vacuum (UHV) environment [P. Jaschinsky et al., Rev. Sci. Instrum. 77 (2006), 093701]. This new instruments consists of two beetle type STM’s stacked into each other. The ability of this apparatus to work at the nanoscale will be shown. Since the positioning of the two tips can be controlled down to 50nm by an add-on electron column, it was possible to provide direct mechanical contact of the STM tip to nanosized GaAs/AlGaAs resonant tunnelling diodes and measure I/V curves of these diodes. Furthermore, due to the compact design, both STM’s exhibit a high stability which facilitates atomically resolved imaging with each tip. The stability allows also non-destructive electrical contacts to surfaces via the tunnelling gaps. Two-point electrical measurements via tunnelling contacts on the Si(111)-7×7 surface will be presented as function of the distance of the probe tips and compared to a model for the charge transport on this surface.