Quantum transport length scales in silicon-based semiconducting nanowires: Surface roughness effects

We report on a theoretical study of quantum charge transport in atomistic models of silicon nanowires with surface roughness disorder, using an efficient real-space, order N Kubo-Greenwood approach and a Landauer-Buttiker Green's function method. Different transport regimes (from quasiballistic to localization) are explored depending on the length of the nanowire and the characteristics of the surface roughness profile. Quantitative estimates of the elastic mean free paths, charge mobilities, and localization lengths are provided as a function of the correlation length of the surface roughness disorder. Moreover, the limitations of the Thouless relation between the mean free path and the localization length are outlined.