Fabrication of Quantum-Dot structures in a ta-C/BN Multilayer system by Swift Heavy Ions
poster presentation: Monday 2010-08-23 05:00 PM - 07:00 PM in section Nanostructure synthesis and modification
Last modified: 2010-06-02
Abstract
The irradiation of tetrahedral amorphous carbon (ta-C) with swift heavy ions leads to the creation of conducting tracks of diameter below 10 nm and extending throughout the entire film thickness. Thus, the tracks form conducting nano-filaments embedded in the insulating ta-C matrix. The increased conductivity is caused by the change of the predominant sp3 hybridization of the carbon atoms into sp2-rich hybridization along the ion track [1].
In this project, we investigated the irradiation of a multilayer system of ta-C film sandwiched between two insulating layers which do not form conductive tracks (e.g., boron nitride). Each single ion projectile produces in an interrupted nano-filament representing a 10-nm wide electrical quantum dot with self-aligned contacts formed by the conductive tracks. According to calculations, the charging energy for such a small dot (0.1 eV) exceeds thermal energy at room temperature. Therefore, Coulomb-blockade effects should be present at room temperature.
We investigated ion tracks in different multilayer systems of ta-C and h-BN. The conductivity is microscopically measured by atomic force microscopy with a conductive tip. Track ensembles are characterized at different temperatures by electric measurements using macroscopic contact pads.
[1] J. Krauser, J.-H. Zollondz, A. Weidinger, and C. Trautmann, Conductivity of nanometer-sized
ion tracks in diamond-like carbon films. J. Appl. Phys. 94 (2003) 1959–1964.
Author(s) affiliation:
Anne-Katrin Nix, II. Institute of Physics, University of Göttingen, 37077 Göttingen, Germany
Johann Krauser, Hochschule Harz, University of Applied Sciences, 38855 Wernigerode, Germany
Christina Trautmann, GSI Helmholtzzentrum für Schwerionenforschung, 64291 Darmstadt, Germany
Alois Weidinger, Helmholtz-Zentrum Berlin GmbH, 14109 Berlin, Germany
Ulrich Vetter, II. Institute of Physics, University of Göttingen, 37077 Göttingen, Germany
Hans Hofsäss, II. Institute of Physics, University of Göttingen, 37077 Göttingen, Germany
*presenting author