1. Institute for Microsensors, -Actuators and -Systems (IMSAS), University of Bremen, 28359 Bremen, Germany
2. Microsystems Center Bremen (MCB), 28359 Bremen, Germany
3. Institute of Inorganic Chemistry and Crystallography, University of Bremen, 28359 Bremen, Germany
4. MAPEX Center for Materials and Processes, University of Bremen, 28334 Bremen, Germany