1. State Key Laboratory of Electronic Thin Film and Integrated Devices; University of Electronic Science and Technology of China; Chengdu 610054 China
2. School of Physics; University of Electronic Science and Technology of China; Chengdu 610054 China
3. School of Applied and Chemical Engineering; Xichang College; Xichang 615053 China
4. Key Laboratory of Functional Inorganic Material Chemistry; School of Chemistry and Materials Science; Heilongjiang University; Harbin 150080 China