1. Department of Materials Science and Engineering, National Chiao Tung University, 1001 University Road, Hsinchu 30010, Taiwan
2. Material and Chemical Research Laboratories, Nanotechnology Research Center, Industrial Technology Research Institute, 195, Sec. 4, Chung Hsing Road, Chutung, Hsinchu 31040, Taiwan
3. Center for the Semiconductor Technology Research, National Chiao Tung University, Hsinchu 30010, Taiwan
4. Frontier Research Center on Fundamental and Applied Sciences of Matters, National Tsing Hua University, Hsinchu 30013, Taiwan