1. Department of Materials Science & Engineering; National Tsing Hua University; Hsinchu 30013 Taiwan
2. Department of Materials Science & Engineering; National Chiao Tung University; Hsinchu 30010 Taiwan
3. Department of Electrophysics; National Chiao Tung University; Hsinchu 30010 Taiwan
4. School of Materials Science and Engineering; University of New South Wales; Sydney 2052 Australia
5. Graduate Program for Science and Technology of Accelerator Light Source; National Chiao Tung University; Hsinchu 30010 Taiwan
6. National Synchrotron Radiation Research Center; Hsinchu 30076 Taiwan