1. Solid State Physics, Lund University, Box 118, S-221 00 Lund, Sweden
2. Institut d’Electronique, de Microélectronique et de Nanotechnologie, UMR CNRS 8520, Avenue Poincaré, B.P. 60069, 59652 Villeneuve d’Ascq, France
3. Department of Applied Physics, Photonics and Semiconductor Nanophysics, Eindhoven University of Technology, P.O. Box 513, NL-5600 MB Eindhoven, Netherlands
4. Department of Electrical- and Information Technology, Lund University, Box 118, 221 00, Lund, Sweden
5. Polymer & Materials Chemistry, Lund University, Box 124, S-221 00 Lund, Sweden