1. Research Center
for Applied Science, Academia Sinica, Taipei 115, Taiwan
2. Department of Physics, National Taiwan University, Sec. 4, Roosevelt Road, Taipei 106, Taiwan
3. Nano Science and Technology,
Taiwan International Graduate Program, Academia Sinica and National Taiwan University, Taipei 115, Taiwan
4. Department of Electronic and Information Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China
5. College of Engineering, Chang Gung University, Taoyuan City 333, Taiwan
6. Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu 30013, Taiwan