Uniaxial Strain Effects on Electron Ballistic Transport in Gate-All-Around Silicon Nanowire MOSFETs

Uniaxial strain effects on electron ballistic transport in extremely scaled gate-all-around nanowire MOSFETs with both [100] and [110] orientations are investigated in this paper. Band structures of nanowires without and with strain are calculated using the empirical sp³d⁵s* tight-binding model. The top-of-the-barrier model is utilized to simulate the electron ballistic transport. It is found that uniaxial [110] strain reduces the electron transport mass, but its effect gradually decreases and becomes insignificant when the dimension of the nanowire is scaled. In addition to existing band splitting caused by quantum confinement, [100] and [110] tensile strains induce further band splitting. Hence, the impact of the strain effects depends on whether the nanowire operates in the nondegenerated or degenerated mode. Simulation results show that uniaxial strain effects are more significant in [110] nanowires. The impact of surface orientation can still be observed even in deeply scaled nanowires.