The Effects of Direct Source-to-Drain Tunneling and Variation in the Body Thickness on (100) and (110) Sub-10-nm Si Double-Gate Transistors

Using an atomistic quantum simulation based on sp³d⁵s* tight-binding bandstructure and ballistic nonequilibrium Green´s function, we have investigated the effects of sidewall orientation and the channel direction on transport characteristics of n-and p-type Si double-gate (DG) MOSFETs in sub-10-nm regime. Considering quantum confinement effects on average conductivity effective mass, ION-IOFF ratio of (100)/(100) devices turns out better under iso-IOFF compared with (110)/(110) devices for both n-and p-type DG MOSFETs. This is due to the effective mass tradeoff between direct source-to-drain tunneling and carrier mobility, leading to different net effects on n-and p-type DG MOSFETs. It is also shown that (100)/(100) devices have an advantage over (110)/(110) devices with respect to body thickness variation since their effective mass is less sensitive to quantum confinement effect.