1. Institute of Microengineering and Nanoelectronics (IMEN), Universiti Kebangsaan Malaysia, UKM, Bangi 43600, Selangor, Malaysia
2. Plasma Physics Laboratory, COMSATS University Islamabad, Islamabad 45550, Pakistan
3. Department of Physics, University of Science & Technology, Bannu, 28100 KPK, Pakistan
4. Fuel Cell Institute, Universiti Kebangsaan Malaysia, Bangi 43600, Malaysia