Impact of phonon scattering in a Si GAA nanowire FET with a single donor in the channel

We study the dissipative transport of electrons through a 10 nm gate-all-around silicon nanowire transistor in the presence of a single donor atom in the channel using Non-Equilibrium Green´s Functions (NEGF) approach. Optical and acoustic phonons are considered. The 2.2×2.2 nm² nanowire cross-section is small so we expect a strong effective electron-phonon coupling. Simulations considering all phonons as elastic are included for comparison. We also compare the ballistic and dissipative transfer characteristic of a pristine nanowire transistor. Phonon scattering produces a 70 % reduction in the drain current. Our donor model accounts for the conduction electron screening of the donor and image charge polarization at the Si/SiO₂ interface in a non-perturbative way and using a Hartree approximation. The impact of scattering in the drain current is neutralized at a particular gate bias by the strong resonant tunneling current from the donor potential. The effect of the exchange-correlation potential in the local density approximation is evaluated for a pristine nanowire in the ballistic regime. The on-current of the pristine wire doubles when the exchange-correlation potential is considered as a result of the lowering of the electron energy due to the exchange correlation hole.