[1] Tsinghua Univ, Inst Microelect, Tsinghua Natl Lab Informat Sci & Technol TNList, Beijing 100084, Peoples R China
[2] McGill Univ, Elect & Comp Engn, Montreal, PQ H3A 2T8, Canada
[3] Aalto Univ, Sch Sci & Technol, Dept Micro & Nanosci, Espoo, Finland
[4] Univ Elect Sci & Technol China, State Key Lab Elect Thin Films & Integreted Dev, Chengdu 610054, Peoples R China