1. Center for Hybrid Nanostructures (CHyN) Universität Hamburg Luruper Chaussee 149 22761 Hamburg Germany
2. Faculty of Engineering Laboratory of Semiconductor Materials Institute of Materials École Polytechnique Fédérale de Lausanne (EPFL) Lausanne 1015 Switzerland
3. Faculty of Basic Sciences Institute of Physics École Polytechnique Fédérale de Lausanne (EPFL) Lausanne 1015 Switzerland
4. Material Science and Engineering College of Engineering University of Wisconsin‐Madison Madison WI 53706 USA