1. Department of Electronics University of Barcelona E‐08028 Barcelona Spain
2. Institut für Halbleitertechnik Technische Universität Braunschweig D‐38106 Braunschweig Germany
3. Department of Advanced Materials for Energy Applications Catalonia Institute for Energy Research (IREC) E‐08930 Barcelona Spain
4. Fraunhofer Institute for Mechanics of Materials IWM D‐79108 Freiburg Germany