[1] Univ Ibn Tofail, Fac Sci, Dept Phys, Lab Optoelect & Phys Chim Mat Unite Rech Associee, BP 133, Kenitra 14000, Morocco
[2] Univ Angers, UMR CNRS 6200, Lab MOLTECH Anjou, F-49045 Angers 01, France
[3] Univ Reims, UTAP LMET, UPRES EA 2061,, UFR Sci, F-51685 Reims 2, France