1. Department of Physics, University School of Sciences, Gujarat University, Ahmedabad 380009, Gujarat, India
2. Applied Physics Department, Faculty of Technology and Engineering, The Maharaja Sayajirao University of Baroda, Vadodara 390001, Gujarat, India
3. Semiconductor Device Fabrication Group, CSIR - Central Electronics Engineering Research Institute Pilani, Pilani 333031, Rajasthan, India