1. School of Materials Science and Engineering
2. Tsinghua University
3. Beijing
4. P. R. China
5. Tsinghua-Foxconn Nanotechnology Research Center
6. Qian Xuesen Laboratory of Space Technology
7. China Academy of Space Technology
8. Beijing 100094
9. State Key Laboratory of Low Dimensional Quantum Physics
10. Department of Physics
11. Beijing 100084
12. Department of Mechanical Engineering