1. Laboratoire LASTID, Faculté des Sciences, Université Ibn Tofail, 14000 Kénitra , Morocco
2. Laboratoire LN2E, Faculté des Sciences, Université Cadi Ayyad, 40000 Marrakech, Morocco
3. Institute for Solid State Physics and Optics, Wigner Research Centre for Physics, Hungarian Academy of Sciences, Budapest, P.O.Box 49, Hungary
4. Faculty of Engineering and Information Technology, University of Pécs, 7624 Pécs, Hungary
5. I3N and Physics Department, University of Aveiro, 3810-193 Aveiro, Portugal