1. School of Physics and Electronic Science, Hunan University of Science and Technology, Xiangtan 411201, Hunan, China
2. Hunan Provincial Key Laboratory of Intelligent Sensors and New Sensor Materials, Xiangtan 411201, Hunan, China
3. School of Microelectronics and Physics, Hunan University of Technology and Business, Changsha 410205, China
4. School of Physics and Electronic Science, East China Normal University, Shanghai 200241, China