1. Physical Chemistry I and Research Center of Micro and Nanochemistry and (Bio)Technology (Cμ), Department of Chemistry and Biology, University of Siegen, Adolf-Reichwein-Str. 2, 57076 Siegen, Germany
2. AMO GmbH, Gesellschaft für Angewandte Mikro- und Optoelektronik mbH, Otto-Blumenthal-Straße 25, 52074 Aachen, Germany
3. Chair of Electronic Devices, RWTH Aachen University, Otto-Blumenthal-Straße 2, 52074 Aachen, Germany