1. DTU Nanolab, National Centre for Nanofabrication and Characterization, Technical University of Denmark, DK-2800 Kongens Lyngby, Denmark
2. Department of Photonics Engineering, Technical University of Denmark, DK-4000 Roskilde, Denmark
3. Division of Solar Cell Technology, Department of Materials Science and Engineering, Uppsala University, 75236 Uppsala, Sweden
4. Department of Physics and Astronomy, Uppsala University, Box
516, 75120 Uppsala, Sweden
5. Department of Physics, University of Oslo, 0371 Oslo, Norway