[1] Fac Sci, Lab Optoelectron & Phys Chem Mat, Equipe Physicochem Couches Minces, Dept Phys, Kenitra, Morocco
[2] Fac Sci, Lab Phys Mat & Rayonnement, Equipe Spect Opt Mat Solide, Dept Phys, Kenitra, Morocco
[3] Univ Nantes, Equipe Phys Solides Electron, Grp Couches Minces & Mat Nouveaux, FSTN, F-44322 Nantes 3, France