1 College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China.
2 Key Laboratory of Materials Processing and Mold (Ministry of Education), Zhengzhou University, Zhengzhou 450002, China.
3 College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China; CAS Center for Excellence in Nanoscience, Beijing Key Laboratory of Micro-nano Energy and Sensor, Beijing Institute of Nanoenergy and Nanosystems, Chinese Academy of Sciences, Beijing 100083, China; School of Nanoscience and Technology, University of Chinese Academy of Sciences, Beijing 100049, China. Electronic address: cfpan@binn.cas.cn.