Soliton effects in dangling-bond wires on Si(001)

TL;DR

This paper investigates soliton effects in dangling-bond wires on Si(001) using tight binding calculations, revealing stable solitons with distinct types influencing electronic properties and intra-gap states.

Contribution

It provides the first detailed electronic structure analysis of solitons in dangling-bond wires, identifying two soliton types and their impact on bandgap states.

Findings

Solitons are stable in even-length dangling-bond wires.

Two types of solitons significantly affect bandgap edge energetics.

Intra-gap states are localized on soliton atoms, between 0.1 eV and 0.2 eV from band edges.

Abstract

Dangling bond wires on Si(001) are prototypical one dimensional wires, which are expected to show polaronic and solitonic effects. We present electronic structure calculations, using the tight binding model, of solitons in dangling-bond wires, and demonstrate that these defects are stable in even-length wires, although approximately 0.1 eV higher in energy than a perfect wire. We also note that in contrast to conjugated polymer systems, there are two types of soliton and that the type of soliton has strong effects on the energetics of the bandgap edges, with formation of intra-gap states between 0.1 eV and 0.2 eV from the band edges. These intra-gap states are localised on the atoms comprising the soliton.