State Key Laboratory of Integrated Optoelectronics;
College of Electronic Science and Engineering;
Jilin University;
Qianjin Street 2699;
Changchun 130012;
China;
Electron Microscopy Laboratory;
School of Physics;
Peking University;
Beijing 100871;
China;
State Key Laboratory of Crystal Materials;
Shandong University;
Jinan 250100;
China;
State Key Laboratory for Mesoscopic Physics and Frontiers Science Center for Nano-optoelectronics;
School of Physics;
Peking University;
Beijing 100871;
China;
Key Laboratory of Materials Physics of Ministry of Education;
School of Physics and Microelectronics;
Zhengzhou University;
Zhengzhou 450052;
China;