1. State Key Laboratory of Luminescence and ApplicationsChangchun Institute of Optics, Fine Mechanics and PhysicsChinese Academy of Sciences Changchun 130033 China
2. School of Physics and EngineeringZhengzhou University Zhengzhou 450052 China
3. CRHEA (Centre de Recherche sur l'Hétéro‐Epitaxie et ses Applications)CNRS – Université Côte d'Azurrue Bernard GregorySophia Antipolis Valbonne 06560 France
4. State Key Lab for Mesoscopic PhysicsSchool of PhysicsPeking University Beijing 100871 China