1. Department of Microelectronic
Science and Engineering, Faculty of Science, Ningbo University, Ningbo 315211, P. R. China
2. Department of Materials Science, Fudan University, Shanghai 200433, P. R. China
3. Department of Materials Science and Engineering, Frederick
Seitz Materials Research Laboratory, University of Illinois at Urbana−Champaign, Urbana, Illinois 61801, United States
4. State Key Laboratory of Integrated Optoelectronics, Institute of
Semiconductors, Chinese Academy of Sciences, Beijing 100083, P. R. China
5. International Center for Quantum Materials,
School of Physics, Peking University, Beijing 100871, China
6. State Key Laboratory of Functional Materials for Informatics, Shanghai
Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050, P. R. China