* Corresponding authors

^a Department of Materials Science and Engineering, National Yang Ming Chiao Tung University, Hsinchu 30010, Taiwan
E-mail: khwei@mail.nctu.edu.tw

^b Department of Material Science and Engineering, University of California, Los Angeles, CA 90095, USA

^c Department of Electrophysics, National Yang Ming Chiao Tung University, Hsinchu 30010, Taiwan

^d Center for Emergent Functional Matter Science, National Yang Ming Chiao Tung University, Hsinchu 30010, Taiwan