[1] Univ Agr & Environm Sci, Dept Phys, PMB 1038, Umuagwo, Imo State, Nigeria
[2] Sultan Qaboos Univ, Coll Sci, Dept Phys, Muscat, Oman
[3] Univ Agr & Environm Sci, Dept Chem, Umuagwo, Nigeria
[4] Modibbo Adama Univ, Fac Phys Sci, Dept Phys, Yola, Nigeria
[5] Bowen Univ, Dept Phys Sci, Phys programme, Iwo, Nigeria
[6] Natl Open Univ Nigeria, Dept Phys, Jabi Abuja, Nigeria
[7] Mohammed V Univ, Grp Optoelect Semicond & Nanomat, ENSAM, Rabat, Morocco
[8] Mohammed VI Polytech Univ, Inst Appl Phys, Ben Guerir, Morocco