1. School of Opto-electronic and Communication Engineering, Xiamen University of Technology, Xiamen 361024, China
2. Fujian Provincial Key Laboratory of Nanomaterials, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002, China
3. Department of Materials Science and Engineering, Da-Yeh University, Changhua 51591, Taiwan
4. Fujian Key Laboratory of Optoelectronic Technology and Devices, Xiamen University of Technology, Xiamen 361024, China