1. State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China
2. Nano Science and Technology Institute, University of Science and Technology of China, Hefei 230026, China
3. Center for High Pressure Science and Technology of Advanced Research, Shanghai 201203, China
4. School of Science, Harbin Institute of Technology, Shenzhen 518055, China
5. H. H. Wills Physics Laboratory, School of Physics, University of Bristol, Bristol BS8 1TL, UK
6. Department of Electronic Information Systems, Osaka City University, Osaka 558-8585, Japan
7. Graduate School of Engineering, Osaka Metropolitan University, Osaka 558-8585, Japan