1. Microelectronics Research Unit, Faculty of Information Technology and Electrical Engineering, University of Oulu, P.O. Box 4500, FI-90014 Oulu, Finland
2. VTT Finland, P.O. Box 1100, FI-90571 Oulu, Finland
3. Sensor and Actuator Systems, Department of Physics, Chemistry and Biology, Linköping University, SE-58183 Linköping, Sweden
4. Department of Material Science and NanoEngineering, Rice University, Houston, Texas 77005, USA
5. Department of Materials Science and Engineering, University of California, Los Angeles, California 90095, USA
6. Department of Physics, Southern Illinois University, Carbondale, Illinois 62901, USA