A Comprehensive Atomistic Analysis of Bandstructure Velocities in Si Nanowires

Abstract

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 [100], [110] and [111] transport orientations are examined. The carrier velocities of p-type [110] and [111] NWs increase by a factor of ~2X as the NWs’ diameter scales from D=12nm down to D=3nm. The velocity of n-type [110] NWs also increases with diameter scaling by ~50%. The velocities of n-type [100], and [111], as well as those of p-type [100] NWs show only minor diameter dependence. This behavior is explained through features in the electronic structure of the silicon host material.

Comments

2010 14th International Workshop on Computational Electronics (IWCE), Pisa, Italy, 26-29 Oct. 2010, Pages 1-4

Keywords

nanowire, velocity, atomistic, bandstructure, sp3d5s*, tight binding, transistors, MOSFETs, variations, effective mass

Date of this Version

10-26-2010

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