1. Thin Film 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 Physics, Graphic Era (Deemed to Be University), Dehradun 248002, Uttarakhand, India