1. College of Materials Science and Engineering, Beijing University of Technology, Beijing 100124, China
2. School of Material Science and Engineering, College of Material Science & Engineering, Guilin University of Technology, Guilin 541004, China
3. Key Laboratory of Optoelectronics Technology, College of Microelectronics, Faculty of Information Technology, Beijing University of Technology, Beijing 100124, China
4. School of Science, Xi’an University of Posts and Telecommunications, Xi’an 710121, China