1. Microelectronics Research UnitFaculty of Information Technology and Electrical EngineeringUniversity of Oulu FI-90014 Oulu Finland
2. CEITEC – Central European Institute of TechnologyBrno University of Technology Purkynova 123 61200 Brno Czech Republic
3. Department of PhysicsFaculty of Electrical Engineering and CommunicationBrno University of Technology Technicka 10 61600 Brno Czech Republic