1. National Engineering Research Center for Technology and Equipment of Environmental Deposition, Lanzhou Jiaotong University, Lanzhou 730070, China
2. Key Laboratory of Opt-Electronic Technology and Intelligent Control of Ministry of Education, Lanzhou Jiaotong University, Lanzhou 730070, China
3. School of Materials Science and Engineering, Lanzhou Jiaotong University, Lanzhou 730070, China