1. Key Laboratory of Physical Electronics and Devices of the Ministry of Education, Xi’an Jiaotong University, Xi’an, Shaanxi, China
2. School of Electronic and Information Engineering, Xi’an Jiaotong University, Xi’an, Shaanxi 710049, China
3. School of Electrical Engineering, Xi’an Jiaotong University, Xi’an, Shaanxi 710049, China