1. Institute of Microengineering and Nanoelectronics (IMEN), Universiti Kebangsaan Malaysia (UKM), Bangi, Selangor 43600, Malaysia
2. Experimental Physics Laboratories, National Center for Physics, Shahdra Valley Road, Islamabad, 44000, Pakistan
3. Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, P. R. China