Electronic Structures of Atomic Silicon Dimer Wires as a Function of Length

TL;DR

This study investigates the electronic structures of silicon dimer wires of varying lengths on Si(100), revealing how each additional dimer influences the electronic states within the band gap and demonstrating the stability and electronic properties of these atomic-scale wires.

Contribution

The paper provides detailed experimental and theoretical analysis of silicon dimer wires from 1 to 5 dimers, showing their stability and electronic structure evolution as a function of length.

Findings

Each dimer adds one empty state to the band gap and one filled state to the valence band.

Short wires exhibit properties similar to a 37-dimer wire.

Coupling among states creates a conduction pathway with minimal bulk coupling.

Abstract

Bare silicon dimers on hydrogen-terminated Si(100) have two dangling bonds. These are atomically localized regions of high state density near to and within the bulk silicon band gap. We studied bare silicon dimers as monomeric units. Silicon dimer wires are much more stable than wires composed of individual dangling bonds. Dimer wires composed of 1 to 5 dimers were intentionally fabricated and characterised by STM techniques combined with density functional theory to provide detailed insights into geometric and electronic structure. Structural and dynamic qualities displayed by short wires were shown to be similar to the characteristics of a relatively long 37 dimer wire. Rather than adding two states into the band gap, experiment and theory reveal that each dimer adds one empty state into the gap and one filled state into the valence bands. Coupling among these states provides a conduction pathway with small bulk coupling.