1. National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, and School of Physics, Nanjing University, Nanjing 210093, China
2. National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, and School of Electronic Science and Engineering, Nanjing University, Nanjing 210093, China
3. Microfabrication and Integration Technology Center, Nanjing University, Nanjing 210093, China
4. Atom Manufacturing Institute, Nanjing 211806, China