[1] Lanzhou Univ, Sch Phys Sci & Technol, Inst Microelect, Lanzhou 730000, Gansu, Peoples R China
[2] Lanzhou Univ, Sch Phys Sci & Technol, Key Lab Magnetism & Magnet Mat MOE, Lanzhou 730000, Gansu, Peoples R China
[3] Xidian Univ, Sch Microelect, State Key Discipline Lab Wide Bandgap Semicond Te, Xian 710071, Peoples R China
[4] Wuhan Univ, Elect Informat Sch, Wuhan 430072, Peoples R China