1. Wide Bandgap Semiconductor Technology Disciplines State Key Laboratory, School of Microelectronics, Xi'dian University, Xi'an 710071, China
2. School of Advanced Materials and Nanotechnology, Xidian University, Xi'an 710071, China
3. Xi'an Zoomview Optoelectronics Science and Technology CO., LTD, Xi'an 710071, China
4. Suzhou Institute of Nano-tech and Nano-Bionics (SINANO), Chinese Academy of Sciences, Suzhou 215132, China