[1] Chinese Acad Sci, Key Lab Semicond Mat Sci, Beijing Key Lab Low Dimens Semicond Mat & Devices, Inst Semicond, Beijing 100083, Peoples R China
[2] Univ Chinese Acad Sci, Ctr Mat Sci & Optoelect Engn, Beijing 100049, Peoples R China
[3] Beijing Inst Technol, Sch Integrated Circuits & Elect, MIIT Key Lab Low Dimens Quantum Struct & Devices, Beijing, Peoples R China
[4] Chinese Acad Sci, Engn Res Ctr Semicond Integrated Technol, Inst Semicond, Beijing 100083, Peoples R China
[5] Tech Univ Ilmenau, Inst Phys & IMN MacroNano, Fachgebiet Angew Nanophys, D-98693 Ilmenau, Germany