1. Key Laboratory for the Physics and Chemistry of Nanodevices School of Electronics Peking University Beijing 100871 China
2. Academy for Advanced Interdisciplinary Studies Peking University Beijing 100871 China
3. College of Chemistry and Molecular Engineering Peking University Beijing 100871 China
4. National Key Laboratory of Science and Technology on Micro/Nano Fabrication Institute of Microelectronics Peking University Beijing 100871 China