1. Centre for Research in Nanotechnology and Science, Indian Institute of Technology Bombay, Mumbai - 400076, India
2. Department of Electrical Engineering, Indian Institute of Technology Bombay, Mumbai - 400076, India
3. Department of Electrical Engineering, Indian Institute of Technology Delhi, Hauz Khas, New Delhi, Delhi 110016, India
4. Department of Physics, Indian Institute of Technology Bombay, Mumbai - 400076, India