[1] Sri Ramakrishna Mission Vidyalaya Coll Arts & Sci, Nanotechnol Lab, Dept Phys, Coimbatore 641020, Tamil Nadu, India
[2] Osmania Univ, Dept Phys, Hyderabad 500007, Andhra Pradesh, India
[3] Univ Aquila, Dept Phys, I-67100 Laquila, Italy
[4] Indian Inst Technol, Dept Phys, Thin Film Lab, New Delhi 110016, India
[5] Pondicherry Univ, Dept Phys, Pondicherry 605014, India