1. Institute of Microstructure Technology, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
2. Light Technology Institute, Karlsruhe Institute of Technology, Engesserstrasse 13, 76131 Karlsruhe, Germany
3. TNO Partner in Solliance, Department of Solar Technology and Applications, High Tech Campus 21, NL-5656 AE Eindhoven, The Netherlands