1. Key Laboratory for Micro-Nano Optoelectronic Devices of Ministry of Education, School of Physics and Electronics, Hunan University, Changsha 410082, China
2. Key Laboratory for Micro-Nano Physics and Technology of Hunan Province, College of Materials Science and Engineering and Hunan Institute of Optoelectronic Integration, Hunan University, Changsha 410082, China
3. Changsha Semiconductor Technology and Application Innovation Research Institute, College of Semiconductors (College of Integrated Circuits), Hunan University, Changsha 410082, China