1. Institute of Microelectronics and Department of Electrical Engineering, Advanced OptoelectronicTechnology Center, Center for Micro/Nano Science and Technology, National Cheng Kung University, Tainan City 701, Taiwan
2. Department of Electronic Engineering, Cheng Shiu University, Kaohsiung City 833, Taiwan
3. Central R&D Division, United Microelectronics Corporation (UMC), Tainan City 744, Taiwan