[1] Chinese Acad Sci, Inst Solid State Phys, Anhui Key Lab Nanomat & Nanotechnol, Key Lab Mat Phys, Hefei 230031, Anhui, Peoples R China
[2] Chinese Acad Sci, Anhui Inst Opt & Fine Mech, Anhui Prov Key Lab Photon Devices & Mat, Hefei 230031, Anhui, Peoples R China