1. Department of Electronic and Information Engineering The Hong Kong Polytechnic University Hong Kong 999077 China
2. School of Microelectronics Southern University of Science and Technology Shenzhen Guangdong 518055 China
3. Department of Electronic and Computer Engineering The Hong Kong University of Science and Technology Hong Kong 999077 China
4. School of Microelectronics Engineering Research Center of Integrated Circuits for Next‐Generation Communications Ministry of Education, Southern University of Science and Technology Shenzhen Guangdong 518055 China
5. Enkris Semiconductor Suzhou Jiangsu 215028 China
6. Department of Applied Physics The Hong Kong Polytechnic University Hong Kong 999077 China