1. Nano Science Laboratory, Institute Instrumentation Centre, Indian Institute of Technology Roorkee, Roorkee 247667, Uttarakhand, India
2. Centre for Nanotechnology, Indian Institute of Technology Roorkee, Roorkee 247667, Uttarakhand, India
3. Department of Electrical and Electronics Engineering, University of Petroleum and Energy Studies, Bidholi, Dehradun 248007, Uttarakhand, India