We present numerical calculations of transport properties of semiconductor nanowires based on a three-dimensional (3D) self-consistent Keldysh Green's function approach, which is able to treat quantum confinement, quasi-ballistic transport, out-of-equilibrium effects as well as the influence of elastic and inelastic scattering. We investigate the role of main scattering mechanisms responsible for mobility degradation at room temperature in ultrashort electron devices like Silicon-nanowire FETs. We consider spatial fluctuations as surface-roughness (SR) or remote-charge scattering (RCS) as main sources of elastic scattering, whereas electron-phonon (PH) interaction is assumed responsible of inelastic scattering processes. We apply these techniques to evaluate the effects of SR and RCS on the transfer characteristics and electron mobility of short-channel Silicon nanowires at room temperature and then focus on scattering-limited mobilities. Our results show that SR and RCS are mainly responsible for threshold voltage shift and sub-threshold voltage slope degradation, whereas PH scattering remains the main scattering mechanism limiting the mobility at room temperature.
