1. Department of Physics and Earth Sciences; Jacobs University gGmbH; Campus Ring 1 28759 Bremen Germany
2. Department of Life Sciences and Chemistry; Jacobs University gGmbH; Campus Ring 1 28759 Bremen Germany
3. Semiconductor Optics, Institute of Solid State Physics; University of Bremen; 28359 Bremen Germany
4. Institute of Inorganic Chemistry and Crystallography; University of Bremen; 28359 Bremen Germany