1. Research Center for Applied Sciences Academia Sinica Taipei 11529 Taiwan
2. Department of Physics National Taiwan University Taipei 10617 Taiwan
3. Institute of Electro‐Optical Science and Technology National Taiwan Normal University Taipei 11677 Taiwan
4. Department of Engineering University of Massachusetts at Boston Boston MA 02125 USA
5. Department of Opto‐Electronic Engineering National Dong Hwa University Hualien 97401 Taiwan
6. Research Institute for Electronic Science Hokkaido University Sapporo 001‐0021 Japan
7. Center for Emergent Functional Matter Science National Chiao Tung University Hsinchu 30010 Taiwan
8. Department of Material Science and Engineering National Tsing Hua University 300 Hsinchu Taiwan