1. Department of Materials Science and Engineering, National University of Singapore, Singapore 117575
2. Singapore Synchrotron Light Source (SSLS), National University of Singapore, 5 Research Link, Singapore 117603
3. NUSNNI-NanoCore, National University of Singapore, Singapore 117411
4. Department of Physics, National University of Singapore, 5 Research Link, Singapore 117542
5. National University of Singapore Graduate School for Integrative Sciences and Engineering (NGS), 28 Medical Drive, Singapore 117456
6. Institutes of Physical Science and Information Technology, Anhui University, Hefei 230601, People's Republic of China
7. Information Materials and Intelligent Sensing Laboratory of Anhui Province, Anhui University, Hefei 230601, People's Republic of China