Stress-driven oxidation chemistry of wet silicon surfaces

TL;DR

This study uses first principles molecular dynamics to explore how wet conditions and tensile strain influence oxidation and crack propagation in silicon surfaces, revealing water dissociation and reactive site formation.

Contribution

It demonstrates the role of tensile strain and water dissociation in silicon oxidation and crack growth, providing molecular insights into environmentally-driven failure mechanisms.

Findings

Water dissociates on oxidized silicon surfaces, creating reactive sites.

Tensile strain enhances water dissociation and oxidation reactions.

Reactive sites may facilitate crack propagation in wet silicon environments.

Abstract

The formation of a hydroxylated native oxide layer on Si(001) under wet conditions is studied by means of first principles molecular dynamics simulations. Water molecules are found to adsorb and dissociate on the oxidised surface leading to rupture of Si-O bonds and producing reactive sites for attack by dissolved dioxygen or hydrogen peroxide molecules. Tensile strain is found to enhance the driving force for the dissociative adsorption of water, suggesting that similar reactions could be responsible for environmentally-driven sub-critical crack propagation in silicon.