1. Department of Photonics, Advanced Optoelectronic Technology
Center, National Cheng Kung University, Tainan 701, Taiwan
2. Department of Materials Science and Engineering, National Cheng Kung University, Tainan 701, Taiwan
3. Graduate Institute of Applied Science and Technology, National Taiwan University of Science and Technology, Taipei, 106, Taiwan
4. Protrustech Corporation Limited, Tainan, Taiwan
5. National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan