1. School of Microelectronics, Southern University of Science and Technology, Shenzhen, China
2. Department of Applied Physics, The Hong Kong Polytechnic University, Hong Kong, China
3. Department of Electrical and Electronic Engineering, and the School of Biomedical Sciences, The University of Hong Kong, Hong Kong, China
4. School of Microelectronics, and the Engineering Research Center of Integrated Circuits for Next-Generation Communications, Ministry of Education, Southern University of Science and Technology, Shenzhen, China