1. Department of Electronics Engineering and Institute of Electronics, National Yang Ming Chiao Tung University, Hsinchu 300, Taiwan
2. Taiwan Semiconductor Research Institute, Hsinchu 300, Taiwan
3. Advanced Technology Research Center, AU Optronics Corporation, Hsinchu 300, Taiwan
4. Department of Physics, National Taiwan Normal University, Taipei 116, Taiwan
5. Department of Electrophysics, National Yang Ming Chiao Tung University, Hsinchu 300, Taiwan
6. Department of Mechanical Engineering, The University of Hong Kong, Pokfulam, Hong Kong SAR, China