1. School of Microelectronics, Tianjin Key Laboratory of Imaging, and Sensing Microelectronic Technology, Tianjin University, Nankai District, Tianjin 300072, China
2. School of Microelectronics, Tianjin University, Nankai District, Tianjin 300072, China
3. Department of Electrical and Computer Engineering, University of Wisconsin-Madison, Madison, WI 53706, USA