1. Center of Materials Science and Optoelectronics EngineeringCollege of Materials Science and Optoelectronic TechnologyUniversity of Chinese Academy of Sciences Beijing 100049 P. R. China
2. Helmholtz‐Center Berlin for Materials and Energy Hahn‐Meitner‐Platz 1 Berlin 14109 Germany
3. Shanghai Synchrotron Radiation FacilityShanghai Institute of Applied PhysicsChinese Academy of Sciences Shanghai 201204 P. R. China