Ballistic Conductance in Oxidized Si Nanowires

TL;DR

This study investigates how local oxidation affects hole transport in silicon nanowires using density functional theory, revealing that certain oxidation configurations do not significantly impair electrical conduction, especially in [110] orientations.

Contribution

It demonstrates that oxidation-induced bonds do not greatly reduce hole mobility in [110] silicon nanowires, providing insights for nanoelectronic device design.

Findings

Oxygen bridging bonds do not significantly degrade hole transport.

Mean free paths are comparable to or longer than nanowire lengths.

[110] oriented nanowires have better hole mobility than [100] orientations.

Abstract

The influence of local oxidation in silicon nanowires on hole transport, and hence the effect of varying the oxidation state of silicon atoms at the wire surface, is studied using density functional theory in conjunction with a Green's function scattering method. For silicon nanowires with growth direction along [110] and diameters of a few nanometers, it is found that the introduction of oxygen bridging and back bonds does not significantly degrade hole transport for voltages up to several hundred millivolts relative to the valence band edge. As a result, the mean free paths are comparable to or longer than the wire lengths envisioned for transistor and other nanoelectronics applications. Transport along [100]-oriented nanowires is less favorable, thus providing an advantage in terms of hole mobilities for [110] nanowire orientations, as preferentially produced in some growth methods.