1. Institute of Plasma Physics, Chinese Academy of Sciences, P.O. Box 1126, Hefei, Anhui 230031, People's Republic of China
2. School of Nuclear Science and Technology, University of Science and Technology of China, Hefei 230026, People's Republic of China
3. Advanced Energy Research Center, Shenzhen University, Shenzhen 518060, People's Republic of China
4. Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China