1. State Key Laboratory of Artificial Microstructure and Mesoscopic PhysicsSchool of PhysicsPeking University Beijing 100871 China
2. Frontiers Science Center for Nano‐optoelectronics & Collaborative Innovation Center of Quantum MatterPeking University Beijing 100871 China
3. State Key Laboratory for Superlattices and MicrostructuresInstitute of SemiconductorsChinese Academy of Sciences Beijing 100083 China
4. College of Materials Science and Opto‐Electronic TechnologyCollege of Physical SciencesUniversity of Chinese Academy of Sciences Beijing 100049 China