1. Institute of Microengineering and Nanoelectronics, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor, Malaysia
2. Department of Physics, Allama Iqbal Open University, Islamabad-44000, Pakistan
3. Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China, Chengdu, 610054, China
4. Songshan Lake Materials Laboratory, University Innovation Park, Dongguan 523808, China
5. Solar Energy Research Institute (SERI), Universiti Kebangsaan Malaysia (The National University of Malaysia), Bangi 43600, Malaysia