1. Department of Applied Physics, Eindhoven University of Technology, 5600 MB Eindhoven,
The Netherlands
2. Institute
of Semiconductor and
Solid State Physics, Johannes Kepler University Linz, Altenbergerstrasse 69, A-4040 Linz, Austria
3. Philips Innovation Services Eindhoven, High Tech Campus 11, 5656AE Eindhoven,
The Netherlands
4. Debye Institute, Utrecht University, Princetonplein 1, 3500TA Utrecht,
The Netherlands
5. Institut
für Festkörpertheorie
und −optik, Friedrich Schiller Universität, 07743 Jena, Germany
6. Kavli
Institute of Nanoscience, Delft University of Technology, 2600 GA Delft, The
Netherlands