A Comprehensive Atomistic Analysis of Bandstructure Velocities in Si Nanowires
Date of this Version10-26-2010
A 20 band sp3d5s* spin-orbit-coupled, semi-empirical, atomistic tight-binding (TB) model is used with a semi-classical, ballistic transport model, to theoretically examine the bandstructure carrier velocity under non-degenerate conditions in silicon nanowire (NW) transistors. Infinitely long, uniform, cylindrical and rectangular NWs, of cross sectional diameters/sides ranging from 3nm to 12nm are considered. For a comprehensive analysis, n-type and p-type NWs in ,  and  transport orientations are examined. The carrier velocities of p-type  and  NWs increase by a factor of ~2X as the NWs’ diameter scales from D=12nm down to D=3nm. The velocity of n-type  NWs also increases with diameter scaling by ~50%. The velocities of n-type , and , as well as those of p-type  NWs show only minor diameter dependence. This behavior is explained through features in the electronic structure of the silicon host material.
Nanoscience and Nanotechnology