1. Institute of Electronic Materials and Devices, Leibniz Universität Hannover, Schneiderberg 32, 30167 Hannover, Germany
2. Laboratory of Nano and Quantum Engineering (LNQE), Leibniz Universität Hannover, Schneiderberg 39, 30167 Hannover, Germany
3. Institute for Solar Energy Research Hamelin (ISFH), Am Ohrberg 1, 31860 Emmerthal, Germany
4. Institute for Solid State Physics, Leibniz Universität Hannover, Appelstraße 2, 30167 Hannover, Germany