1. Institute for Integrative Nanosciences, IFW Dresden, Helmholtzstraße 20, 01069 Dresden, Germany
2. Max Planck Institute for Intelligent Systems, Heisenbergstraße 3, D-70569 Stuttgart, Germany
3. Material Systems for Nanoelectronics, Chemnitz University of Technology, Reichenhainerstraße 70, 09107 Chemnitz, Germany