1. Graduate
Institute of Applied Science and Technology, National Taiwan University of Science and Technology, Taipei 106, Taiwan
2. Graduate
Institute of Electro-Optical Engineering and Department of Electronic
and Computer Engineering, National Taiwan University of Science and Technology, Taipei 106, Taiwan
3. Department
of Electrical Engineering, National Taiwan Ocean University, Keelung 202, Taiwan
4. Laboratoire
de Physique des Solides, University of Paris-Sud, CNRS UMR 8502, F-91405 Orsay, France