1. State Key Laboratory of Functional Materials for Informatics Shanghai Institute of Microsystem and Information Technology Chinese Academy of Sciences Shanghai 200050 China
2. Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of Sciences Beijing 100049 China
3. School of Physics and Astronomy Shanghai Jiaotong University Shanghai 200240 China
4. School of Physical Science and Technology ShanghaiTech University Shanghai 201210 China