1. Research Center of Silicon Target and Silicon−Carbon Negative, Materials Engineering Technology, School of Materials Science & Engineering, North Minzu University, Yinchuan 750021, People’s Republic of China
2. Department of Physics, College of Science, University of Shanghai for Science and Technology, Shanghai 200093, People’s Republic of China
3. School of Materials and Chemistry, University of Shanghai for Science and Technology, Shanghai 200093, People’s Republic of China