1. Key Laboratory for
the Physics and Chemistry of Nanodevices and Department of Electronics, Peking University, Beijing 100871, China
2. Key Laboratory of Semiconductor Materials Science, Institute
of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China
3. College of Materials Science and Optoelectronic
Technology, University of Chinese Academy of Sciences, Beijing 100049, China
4. Laboratory for Condensed
Matter Physics, Chinese Academy of Sciences, Beijing 100190, China