[1] Bahauddin Zakariya Univ, Dept Phys, Multan 60800, Pakistan
[2] State Key Lab Elect Thin Films & Integrated Devic, Chengdu 610054, Peoples R China
[3] Univ Agr Faisalabad, Dept Phys, Faisalabad 38040, Pakistan
[4] Univ Engn & Technol, Dept Phys, Lahore 54890, Pakistan
[5] COMSATS Inst Informat Technol, Dept Phys, Islamabad 44000, Pakistan