1. Institute of Solid State Electronics, TU-Wien, Floragasse 7, A-1040 Vienna, Austria
2. Institute of Solid State Physics, TU-Wien, Wiedner Hauptstrasse 8/052, A-1040 Vienna,
Austria
3. Institute of Materials
Science
and Technology, University of Jena, Löbdergraben
32, D-07743 Jena, Germany
4. Institute of Solid State Physics, University of Jena, Max-Wien-Platz 1, D-07743 Jena,
Germany
5. Spawnt Research GmbH, Entwicklungszentrum Wolfen, Kunstseidenstrasse
6, D-06766 Bitterfeld-Wolfen/Goethe-University Frankfurt a.M., Max-von-Laue-Strasse
7, 60438 Frankfurt am Main, Germany