1. Department of Electrical Engineering and College of Semiconductor and Advanced Technology Research, National Sun Yat-sen University, Kaohsiung, Taiwan
2. Department of Electrophysics, National Yang Ming Chiao Tung University, Taiwan
3. Department of Electrical Engineering, National Cheng Kung University, Tainan, Taiwan
4. Department of Electrical Engineering, National Sun Yat-sen University, Kaohsiung, Taiwan