1. Institute of Optical and Electronic Materials, Hamburg University of Technology, Hamburg 21073, Germany
2. Department of Physics, Faculty of Science, Menoufia University, Menoufia, Egypt
3. ITMO University, 49 Kronverkskii Avenue, 197101, St. Petersburg, Russia
4. Institute of Materials Research, Helmholtz-Zentrum Geesthacht, Max-Planck-Strasse 1, Geesthacht, D-21502, Germany