1. Nano-Optoelectronics Research Laboratory, School of Physics, Universiti Sains Malaysia, 11800-Penang, Malaysia
2. Faculty of Electrical Engineering, Universiti Teknologi MARA, 13500 Permatang Pauh, Pulau Pinang, Malaysia
3. Faculty of Electrical Engineering, Universiti Teknologi MARA, 40450 Shah Alamm, Selangor, Malaysia
4. Department of Applied Science, Universiti Teknologi MARA, 13500 Permatang Pauh, Pulau Pinang, Malaysia