1. Institut
für Anorganische Chemie, Karlsruhe Institute of Technology (KIT), Engesserstraße 15, D-76131 Karlsruhe, Germany
2. National Synchrotron
Radiation Research Center, Hsinchu 30076, Taiwan
3. Center
for Condensed Matter Sciences, National Taiwan University, Taipei 10617, Taiwan
4. Department
of Optoelectronic Engineering, National Dong Hwa University, Hualien 97401, Taiwan