1. National Key Laboratory of Science and Technology on Micro/Nano Fabrication, Department of Micro/Nano Electronics, Shanghai Jiao Tong University, Shanghai 200240, China
2. Department of Optical Engineering, School of Physics, Hefei University of Technology, Hefei 230601, China
3. Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117583
4. School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore 639798
5. Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Científicas, Campus de Cantoblanco, Madrid 28049, Spain
6. School of Optoelectronic Engineering and Instrumentation Science, Dalian University of Technology, Dalian 116024, China
7. Department of Photonics, National Cheng Kung University, Tainan 70101, Taiwan
8. Department of Electrical Engineering, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, China
9. School of Physics, Harbin Institute of Technology, Harbin 150001, China
10. School of Optoelectronic Science and Engineering, University of Electronic Science and Technology of China, Chengdu 610054, China
11. School of Electronic and Optical Engineering, Nanjing University of Science and Technology, Jiangsu 210094, China
12. CNR Nanotec─Institute of Nanotechnology, S.S. Cosenza, Rende, CS 87036, Italy
13. Department of Physics, University of Calabria, Ponte P. Bucci 31C, Rende, CS 87036, Italy
14. Department of Physics, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China