1. College of Physical Science and Technology/Microelectronics Industry Research Institute, Yangzhou University, 225002 Yangzhou, China
2. School of Electronics Science and Engineering/National Laboratory of Solid State Microstructures, Nanjing University, 210093 Nanjing, China
3. Cell R&D Center, JA Solar Holdings Co. Ltd, Yangzhou, 225000, China
4. School of Microelectronics/School of Integrated Circuit, Nantong University, Nantong, 226019, China