1. Electronic Materials Research Laboratory, Key Laboratory of the Ministry of Education & International Center for Dielectric Research, Xi’an Jiaotong University, Xi’an 710049, Shaanxi, China
2. Department
of Materials Science and Engineering, University of Sheffield, Sheffield S1 3JD, U.K.
3. Micro-optoelectronic
Systems Laboratories, Xi’an Technological University, Xi’an 710032, Shaanxi, China
4. National
Synchrotron Radiation Laboratory, University of Science and Technology of China, Anhui 230029, Hefei, China