Deformation Potentials and Electron-Phonon Coupling in Silicon Nanowires

TL;DR

This paper investigates how reduced dimensionality and surface chemistry affect electron-phonon interactions in silicon nanowires, revealing significant changes in deformation potentials and resulting in notable differences in electron mobility.

Contribution

It introduces a first-principles analysis showing that reduced dimensionality alters deformation potentials and electron-phonon coupling in silicon nanowires, affecting their physical properties.

Findings

Mobility for [110] wires is 6 times larger than for [100] wires.

Surface termination has minimal impact on e-ph coupling.

Reduced dimensionality causes new coupling to breathing modes.

Abstract

The role of reduced dimensionality and of the surface on electron-phonon (e-ph) coupling in silicon nanowires is determined from first principles. Surface termination and chemistry is found to have a relatively small influence, whereas reduced dimensionality fundamentally alters the behavior of deformation potentials. As a consequence, electron coupling to "breathing modes" emerges that cannot be described by conventional treatments of e-ph coupling. The consequences for physical properties such as scattering lengths and mobilities are significant: the mobilities for [110] grown wires are 6 times larger than those for [100] wires, an effect that cannot be predicted without the form we find for Si nanowire deformation potentials.