1. Department of Materials Science & Engineering, National Yang Ming Chiao Tung University, Hsinchu 30010, Taiwan
2. Taiwan Semiconductor Research Institute, Hsinchu 30010, Taiwan
3. Intelligent Semiconductor Nano-system Technology Research Center, National Yang Ming Chiao Tung University, 1001 Ta Hsueh Road, Hsinchu 30010, Taiwan
4. Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, California 94720, United States
5. National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan