1. Information Materials and Intelligent Sensing Laboratory of Anhui Province, Institutes of Physical Science and Information Technology, Anhui University 1 , Hefei 230601, People's Republic of China
2. Institute of Materials Research and Engineering (IMRE), Agency for Science, Technology and Research (A*STAR) 2 , 2 Fusionopolis Way, Innovis #08-03, Singapore 138634, Singapore
3. Department of Physics, National University of Singapore 3 , Singapore 117575, Singapore
4. Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University 4 , Singapore 637371, Singapore
5. School of Electrical and Electronic Engineering, Nanyang Technological University 5 , Singapore 639798, Singapore
6. Hefei National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China 6 , Hefei 230026, People's Republic of China
7. Stony Brook Institute at Anhui University, Anhui University 7 , Hefei 230039, People's Republic of China