1. Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany
2. Applied Solid State Physics (IAF), Fraunhofer Institute, Freiburg, Germany
3. Institut fuer Hochfrequenztechnik und Elektronik (IHE), Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany
4. Institute of Robust Power Semiconductor Systems, University of Stuttgart, Stuttgart, Germany