1. Department of Electrical Engineering, National Sun Yat-sen University, Kaohsiung, Taiwan
2. Department of Electrophysics, National Yang Ming Chiao Tung University, Hsinchu, Taiwan
3. Department of Electrical Engineering, National Cheng Kung University, Tainan, Taiwan
4. Institute of Pioneer Semiconductor Innovation, National Yang Ming Chiao Tung University, Hsinchu, Taiwan