1. Department of Materials Science and Engineering Inha University Incheon 22212 Republic of Korea
2. Beijing Key Lab of Nanophotonics and Ultrafine Optoelectronic Systems Center for Micro-Nanotechnology School of Physics Beijing Institute of Technology Beijing 100081 P. R. China
3. Optoelectronics Research Center School of Science Minzu University of China Beijing 100081 P. R. China
4. Research Center for Materials Science Beijing Institute of Technology Beijing 100081 P. R. China
5. MOE Key Lab of New Processing Technology for Nonferrous Metals and Materials and Guangxi Key Lab of Processing for Nonferrous Metals and Featured Materials School of Resources, Environments and Materials Guangxi University Nanning 530004 P. R. China