1. School of Physics, Universiti Sains Malaysia, 11800 Penang, Malaysia
2. Faculty of Engineering and Built Environment, Universiti Sains Islam Malaysia, 71800, Nilai, Negeri Sembilan, Malaysia
3. Institute of Nano Optoelectronics Research and Technology (INOR), Universiti Sains Malaysia, 11800, Penang, Malaysia
4. Physics and Astronomy, Faculty of Physical Sciences and Engineering, University of Southampton, Highfield, Southampton SO17 1BJ, United Kingdom