1. a Department of Optoelectronic Engineering, Far East University, No. 49, Zhonghua Rd., Xinshi Dist., Tainan City 74448, Taiwan
2. b Department of Materials Engineering, National Pingtung University of Science and Technology, No. 1, Shuefu Rd., Neipu Township, Pingtung County 91201, Taiwan
3. c Department of Materials Engineering, National Pingtung University of Science and Technology, No. 1, Shuefu Rd., Neipu Township, Pingtung County 91201, Taiwan