Highly site-specific adsorption of molecular hydrogen on vicinal Si(001) surfaces

By: P. Kratzer, E. Pehlke, M. Scheffler, M. B. Raschke, and U. Höfer

Physical Review Letters 81, 5596 (1998)

Experimental and theoretical results for the dissociative adsorption of H2 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 6 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.