Quantum confinement point of view for mobility and stress responses on (100) and (110) SingleGate and double-gate nMOSFETs

Impact of quantum confinement on electron mobility and its stress responses for (100) and (110)-orientated single-gate (SG) and double-gate (DG) nMOSFETs is studied. Unstrained electron mobility in (110) DG nMOSFETs is found to be significantly higher than that of (110) SG devices. This paper discusses another physical explanation to the experimentally observed higher electron mobility in (110) FinFET sidewall channels as compared to that observed in planar (110) devices. It is also found that the electron mobility increases faster under uniaxial tensile stress for (110) devices than for (100) ones. The higher mobility in (110) DG devices is attributed to the lighter confinement effective mass of Δ4 valleys and the non-parabolicity of Δ2 valleys along the <110> directions. With high enough tensile strain, DG nMOSFETs with (110) surface orientation are expected to outperform these on (100).