[1] Nanjing Xiaozhuang Univ, Coll Elect Engn, Nanjing 211171, Peoples R China
[2] Nanjing Univ, Collaborat Innovat Ctr Adv Microstruct, Natl Lab Solid State Microstruct, Nanjing 210093, Peoples R China
[3] Nanjing Univ, Jiangsu Prov Lab Nano Technol, Nanjing 210093, Peoples R China
[4] Nanjing Xiaozhuang Univ, Sch Environm Sci, Nanjing Key Lab Adv Funct Mat, Nanjing 211171, Peoples R China