1. Nano and Molecular Systems Research Unit, University of Oulu, Oulu FIN-90014, Finland
2. Materials Institute and Inorganic Chemistry Department, University of Alicante, Ap. 99, E-03080 Alicante, Spain
3. Wihuri Physical Laboratory, Department of Physics and Astronomy University of Turku, Turku FIN-20014, Finland
4. Microelectronics Research Unit, Faculty of Information Technology and Electrical Engineering, University of Oulu, FI-90570 Oulu, Finland