1. Department of Physics and Astronomy, University of Texas at San Antonio, San Antonio, Texas 78249, United States
2. Electronic Materials Research Laboratory and International Center for Dielectric Research, Xi’an Jiaotong University, Xi’an, Shaanxi 710049, People’s Republic of China
3. State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science & Technology of China, Chengdu, Sichuan 610054, People’s Republic of China
4. Department of Materials Science and Engineering, University of Texas at Arlington, Arlington, Texas 76019, United States
5. Department of Chemistry, University of Houston, Houston Texas 77204, United States