1. a Institute of Microelectronics and Department of Electrical Engineering, Advanced Optoelectronic Technology Center, Center for Micro/Nano Science and Technology, National Cheng Kung University, No. 1, University Rd., East District, Tainan City 701, Taiwan
2. b Institute of Microelectronics and Department of Electrical Engineering, Advanced Optoelectronic Technology Center, Center for Micro/Nano Science and Technology, National Cheng Kung University, No. 1, University Rd., East District, Tainan City 701, Taiwan
3. c Medical Devices and Opto-Electronics Equipment Department, Metal Industries Research & Development Center, 3F, No. 88, Luke 5th Rd., Lujhu Township, Kaoshiung 82151, Taiwan
4. d Department of Electronics Engineering and Computer Sciences, Tung-Fang Institute of Technology, No. 110, Tung-Fung Road, Hunei Shiang, Kaohsiung County 829, Taiwan