1. Technische Universitaet Darmstadt, Institute of Materials
Science, Petersenstr.
23, 64287 Darmstadt, Germany
2. Friedrich Schiller University of Jena, Otto Schott
Institute of Materials Research, Loebdergraben 32, 07743 Jena, Germany
3. Universitaet Duisburg-Essen, Nanostructures and Technology,
Department of Engineering, 47057 Duisburg, Germany