[1] Peking Univ, State Key Lab Mesoscop Phys, Beijing 100871, Peoples R China
[2] Peking Univ, Dept Phys, Beijing 100871, Peoples R China
[3] New Display Device & Syst Integrat Collaborat Inn, Fuzhou 350002, Peoples R China
[4] Xi An Jiao Tong Univ, Key Lab Photon Technol Informat, Minist Educ,Sch Elect & Informat Engn, Dept Elect Sci & Technol,Key Lab Phys Elect & Dev, Xian 710049, Peoples R China