1. School of Microelectronics and Guangzhou Institute of Technology, Xidian University,Key Laboratory of Wide Band Gap Semiconductor Materials and Devices,Xi’an,China,710071
2. Institute of Microelectronics of Chinese Academy of Sciences,Beijing,China,100029
3. Shanghai Jiao Tong University,Department of Electronic Engineering,Shanghai,China,200240
4. Virginia Polytechnic Institute and State University,Center for Power Electronics Systems,Blacksburg,USA,24060