1. Leibniz-Institut für Festkörper- und Werkstoffforschung Dresden (IFW) Dresden, Institute of Complex Materials, P.O. Box 270116, D-01171 Dresden, Germany.
2. IBS Center for Integrated Nanostructure Physics, Institute for Basic Science (IBS), Daejon 305-701, Republic of Korea.
3. IFW Dresden, Institute of Solid State Research, P.O. Box 270116, D-01171 Dresden, Germany.
4. Centre of Polymer and Carbon Materials, Polish Academy of Sciences, M. Curie-Sklodowskiej 34, Zabrze 41-819, Poland.
5. Technische Universität Dresden, Institute of Materials Science, 01062 Dresden, Germany.
6. Department of Energy Science, Department of Physics, Sungkyunkwan University, Suwon 440-746, Republic of Korea.