1. Institute of Electronic Devices; University of Wuppertal; Rainer-Gruenter-Str. 21 42119 Wuppertal Germany
2. Electronic Materials and Nanoelectronics; Ruhr-Universität Bochum; Universitätsstr. 150 44801 Bochum Germany
3. Chair of Large Area Optoelectronics; University of Wuppertal; Rainer-Gruenter-Str. 21 Wuppertal 42119 Germany