1. State Key Discipline Laboratory of Wide Band Gap Semiconductor Technology, School of Microelectronics, Xidian University, No.2 South TaiBai Road, Xi'an 710071, China
2. China Electronic Product Reliability and Environmental Testing Research Institute, No. 110 Dongguanzhuang Road, Guangzhou 510610, China
3. School of Aerospace Science and Technology, Xidian University, No.2 South TaiBai Road, Xi'an 710071, China