1. Department of Materials Science and Engineering National Chiao Tung University Hsinchu 30010 Taiwan
2. Department of Material Science and Engineering University of California Los Angeles CA 90095 USA
3. Department of Materials Science and Engineering National Taiwan University Taipei 10617 Taiwan
4. Institute of Nuclear Energy Research Taoyuan 32546 Taiwan
5. Department of Photonics National Chiao Tung University Hsinchu 30010 Taiwan
6. Center for Emergent Functional Matter Science National Chiao Tung University Hsinchu 30010 Taiwan