1. Department of Materials Science and Engineering National Chung Hsing University Taichung 40227 Taiwan
2. Center for Condensed Matter Sciences National Taiwan University Taipei 10617 Taiwan
3. Department of Materials Engineering Ming Chi University of Technology New Taipei 24301 Taiwan
4. Institute and Department of Electrophysics National Chiao Tung University Hsinchu 30010 Taiwan
5. National Synchrotron Radiation Research Center Hsinchu 30010 Taiwan
6. Department of Electronics Engineering Institute of Electronics National Chiao Tung University Hsinchu 30010 Taiwan
7. Center for Atomic Initiative for New Materials National Taiwan University Taipei 10617 Taiwan