1. École Polytechnique Fédérale de Lausanne (EPFL), Laboratoire des Matériaux Semiconducteurs (LMSC), 1015 Lausanne, Switzerland
2. Department of Applied Physics, TU Eindhoven, Den Dolech 2, 5612 AZ Eindhoven, The Netherlands
3. Philips Innovation Services Eindhoven, High Tech Campus 11, 5656 AE Eindhoven, The Netherlands
4. Kavli Institute
of Nanoscience, Delft University of Technology, 2600 GA Delft, The Netherlands