Highly site-specific H2 adsorption on vicinal Si(001) surfaces

TL;DR

This study combines experimental and theoretical approaches to investigate H2 dissociative adsorption on vicinal Si(001) surfaces, revealing significantly higher sticking probabilities at step sites and elucidating the underlying adsorption pathways and barriers.

Contribution

It provides new insights into site-specific H2 adsorption mechanisms on vicinal Si(001), highlighting the role of step sites and rehybridization effects.

Findings

Sticking probabilities at step sites exceed terrace probabilities by up to six orders of magnitude.

Density functional theory shows lowered barriers for step adsorption due to rehybridization.

Direct adsorption pathways for monohydride formation are identified.

Abstract

Experimental and theoretical results for the dissociative adsorption of H_2 on vicinal Si(001) surfaces are presented. Using optical second-harmonic generation, sticking probabilities at the step sites are found to exceed those on the terraces by up to six orders of magnitude. Density functional theory calculations indicate the presence of direct adsorption pathways for monohydride formation but with a dramatically lowered barrier for step adsorption due to an efficient rehybridization of dangling orbitals.