1. Nano-Optoelectronics Research Laboratory, School of Physics, Universiti Sains Malaysia 11800, Pulau-Pinang, Malaysia
2. Faculty of Applied Sciences, Universiti Teknologi MARA Malaysia, 40450 Malaysia
3. Department of Applied Sciences, Universiti Teknologi MARA Pulau Pinang, 13500 Pulau Pinang, Malaysia
4. Faculty of Electrical Engineering, Universiti Teknologi MARA Pulau Pinang, 13500 Pulau Pinang, Malaysia