1. University of Cambridge; Cavendish Laboratory; J. J. Thomson Avenue CB3 0HE Cambridge United Kingdom
2. National Tsing Hua University; College of Engineering, Department of Materials Science and Engineering; 101, Sec. 2, KungFu Rd 300 Hsinchu Taiwan
3. Nanyang Institute of Technology; School of Electronic and Electrical Engineering; Nanyang, 473004 Henan China