1 State Key Laboratory for Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China
2 Key Laboratory of Interface Science and Engineering in Advanced Materials of Ministry of Education, Research Center of Advanced Materials, Science and Technology, Taiyuan University of Technology, Taiyuan 030024, China
3 College of Materials Science and Opto-electronic Technology, University of Chinese Academy of Sciences, Beijing 100029, China
1 College of Electronic and Optical Engineering, College of Microelectronics, Nanjing University of Posts and Telecommunications, Nanjing 210023, China
2 State Key Laboratory of Transient Optics and Photonics, Xi’an Institute of Optics and Precision Mechanics, Chinese Academy of Sciences (CAS), Xi’an 710119, China