1. Key Laboratory of Microelectronic Devices and Integrated Technology; Institute of Microelectronics of Chinese Academy of Sciences; Beijing 100029 China
2. University of Chinese Academy of Sciences; Beijing 100049 China
3. CAS Key Laboratory of Standardization and Measurement for Nanotechnology; CAS Center for Excellence in Nanoscience National Centre for Nanoscience and Technology; No. 11 Beiyitiao Zhongguancun Beijing 100190 China
4. Key Laboratory of Wide Band Gap Semiconductor Technology; School of Advanced Materials and Nanotechnology; Xidian University; Xi'an 710071 China
5. School of Information Science and Engineering; Shandong University; Shandong 250100 China