1. Key Laboratory for Micro/Nano Optoelectronic Devices of Ministry of Education & Hunan Provincial Key Laboratory of Low‐Dimensional Structural Physics and Devices, School of Physics and Electronics Hunan University Changsha 410082 China
2. College of Semiconductors (Integrated Circuits) Hunan University Changsha 410082 China
3. Department of Materials Science and Engineering City University of Hong Kong Hong Kong SAR 999077 China