1. Helmholtz‐Zentrum Dresden‐Rossendorf, Institute of Ion Beam Physics and Materials ResearchBautzner Landstrasse 40001328 DresdenGermany
2. College of Optoelectronic Engineering, Shenzhen UniversityShenzhen 518060P. R. China
3. Technische Universität Dresden01062 DresdenGermany
4. Department of Physics/Centre for Materials Science and Nanotechnology, University of OsloP.O. Box 1048 BlindernN‐0316 OsloNorway