1. Solid
State Physics and NanoLund, Lund University, Box 118, SE-221 00 Lund, Sweden
2. Department
of Mathematics, Physics and Electrical Engineering, Halmstad University, Box 823, SE-301 18 Halmstad, Sweden
3. Sol Voltaics AB, Scheelevägen 22, SE-223 63 Lund, Sweden
4. Department
of Applied Physics, Royal Institute of Technology (KTH), Science for Life Laboratory, SE-171 21 Solna, Sweden