1. Institute of Solid State Physics, University of Bremen, Otto-Hahn-Allee NW1, 28359 Bremen, Germany
2. Institute of Optoelectronics, Ulm University, Albert-Einstein-Allee 45, 89081 Ulm, Germany
3. Institute of Quantum Matter/Semiconductor Physics Group, Ulm University, Albert-Einstein-Allee 45, 89081 Ulm, Germany
4. Richter Lighting Technologies GmbH, Böbinger Straße 34, 73540 Heubach, Germany
5. Wrocławskie Centrum Badań EIT+, ul. Stabłowicka 147, 54-066 Wrocław, Polska