1. National Laboratory of Solid-State Microstructures, Jiangsu Key Laboratory of Artificial Functional Materials, College of Engineering and Applied Sciences, Nanjing University, Nanjing 210093, China
2. Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, China
3. School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan 430074, China
4. Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan 430074, China
5. Physical Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States
6. Maryland NanoCenter, University of Maryland, College Park, Maryland 20899, United States