1. School of Microelectronics, Xi’an Jiaotong University, Xi’an 710049, China
2. State Key Laboratory for Mechanical Behavior of Materials and School of Materials Science and Engineering, Xi’an Jiaotong University, Xi’an 710049, China
3. State Key Discipline Laboratory of Wide Band Gap Semiconductor Technology, School of Microelectronics, Xidian University, Xi’an 710071, China
4. Frontier Institute of Science and Technology, Xi’an Jiaotong University, Xi’an 710049, China
5. Ernst Ruska Centre for Microscopy and Spectroscopy with Electrons, Forschungszentrum Jülich, D-52425 Jülich, Germany