1. Electronic Materials Research Laboratory, Key Laboratory of the Ministry of Education and International Center for Dielectric Research, Xi’an Jiaotong University, Xi’an 710049, China
2. School of Electronic and Information Engineering, Xi’an Jiaotong University, Xi’an 710049, China
3. College of Physics and Optoelectronic Technology, Baoji University of Arts and Sciences, Baoji 721016, China