1. Department of Physics and Astronomy, College of Science, King Saud University 1 , Riyadh 11451, Saudi Arabia
2. 2 Future Connectivity and Advanced Sensors Institute, KACST, Riyadh, Saudi Arabia
3. 3 Biological and Environmental Sensing Research Unit, King Abdullah Institute for Nanotechnology, King Saud University, P.O. Box 2455, Riyadh 11451, Saudi Arabia