1. Laboratory of Advanced Nano Materials and Devices Ningbo Institute of Materials Technology and Engineering Chinese Academy of Sciences Ningbo 315201 China
2. School of Microelectronics University of Science and Technology of China Hefei 230026 China
3. Institute of Materials Research and Engineering 2 Fusionopolis Way, #08‐03 Agency for Science Technology and Research Singapore 138634 Singapore
4. College of Physics and Information Engineering Fuzhou University Fuzhou 350116 China
5. Nano Science and Technology Institute University of Science and Technology of China Suzhou 215123 China
6. Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of Sciences Beijing 100049 China