Superior <110>-Directed Electron Mobility to <100>-Directed Electron Mobility in Ultrathin Body (110) n-Type Metal–Oxide–Semiconductor Field-Effect Transistors

The direction dependence of electron mobility in (110) n-type metal–oxide–semiconductor field-effect transistor (MOSFET) with an extremely thin silicon-on-insulator (SOI) has been studied. It is newly found that the electron mobility in the <110> direction surpasses that in the <100> direction with SOI thickness of 3.2 nm, which is opposite to the trend observed in bulk n-type MOSFET. The physical origins of this phenomenon can be attributed to the non-parabolicity in the two-fold valley.