1. Optoelectronics Laboratory, Helsinki University of Technology, FIN‐02150 Espoo, Finland
2. Department of Physics and Measurement Technology, Linköping University, S‐58183 Linköping, Sweden, and Outokumpu Semitronic Ab, S‐16111 Bromma, Sweden
3. Experiments Division, European Synchrotron Radiation Facility, F‐38043 Grenoble, France
4. Department of Applied Physics, University of Turku, FIN‐20500 Turku, Finland
5. Okmetic Oy, FIN‐02631 Espoo, Finland