1. Institute of Electron Devices and Circuits, Ulm University, Albert-Einstein-Allee 45, 89081 Ulm, Germany
2. Institute of Electron Microscopy, Group of Materials Science, Ulm University, Albert-Einstein-Allee 11, 89081 Ulm, Germany
3. Institute of Micro- and Nanotechnologies, Microsystems Technology Group, Technische Universität Ilmenau, Max-Planck-Ring 12, 98693 Ilmenau, Germany