1. Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf, 01328 Dresden, Germany
2. Technische Universität Dresden, 01062 Dresden, Germany
3. Faculty of Physics, Institute of Theoretical Physics, University of Warsaw, Pasteura 5, 02093 Warsaw, Poland
4. Institut für Halbleitertechnik, Universität Stuttgart, 70569 Stuttgart, Germany
5. Experimental Physics and Functional Materials, BTU Cottbus-Senftenberg, Erich-Weinert-Str. 1, 03046 Cottbus, Germany
6. College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, People’s Republic of China