1. Department of Physics; Cochin University of Science and Technology; Kochi Kerala 682022 India
2. Centre of Excellence in Advanced Materials; Cochin University of Science and Technology; Kochi Kerala 682022 India
3. Department of Physics; Union Christian College; Aluva India
4. Inter University Centre for Nanomaterials and Devices; Cochin University of Science and Technology; Kochi Kerala 682022 India