1. Key Laboratory of Radio Frequency and Micro-Nano Electronics of Jiangsu Province, Nanjing University of Posts & Telecommunications, Nanjing 210023, China
2. National Laboratory of Solid State Microstructures, Nanjing University, Nanjing 210093, China
3. Jiangsu Provincial Key Laboratory of Advanced Photonic and Electronic Materials, Collaborative Innovation Center of Advanced Microstructures, School of Electronic Science and Engineering, Nanjing University, Nanjing 210093, China
4. Department of Applied Physics, Zhejiang University of Technology, Hangzhou 310023, China