Author Affiliations

H. H. Zhu,^1,* H. S. Chen,^2,* S. Y. Li,^1,* T. Chen,² H. Cai,³ L. P. Chin,⁴ X. D. Zhang,² and A. Q. Liu^1,†

¹School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore 639798

²School of Physics, Beijing Institute of Technology, Beijing, China 100081

³Institute of Microelectronics, A*STAR (Agency for Science, Technology, and Research), Singapore 138634

⁴Department of Electrical Engineering, City University of Hong Kong, Kowloon, Hong Kong Special Administrative Region

^*These authors contributed equally to this work

^† eaqliu@ntu.edu.sg