1. Electronic Materials Research Laboratory Key Laboratory of the Ministry of Education & International Center for Dielectric Research, School of Electronic Science and Engineering, Xi’an Jiaotong University, No. 28, Xianning West Road, Xi’an 710049, Shaanxi, P. R. China
2. National Laboratory for Infrared Physics Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai 200083, P. R. China
3. State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 611731, P. R. China
4. Department of Chemistry and 4D Laboratories, Simon Fraser University, Burnaby V5A 1S6, British Columbia, Canada
5. Department of Materials Science and Engineering, University of California Los Angeles, Los Angeles 90024, California, United States