1. Department of Physics, The Hindu College, Krishna University, Machilipatnam, India;
2. ARL-LC, Department of Electronics & Communication Engineering, Koneru Lakshmaiah Education Foundation, Guntur, India;
3. Department of Nanotechnology, Acharya Nagarjuna University, Guntur, India;
4. Department of Physics, Andhra Loyola College, Vijayawada, India