Dresden 2003 – wissenschaftliches Programm

Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe

O: Oberflächenphysik

O 28: Adsorption an Oberfl
ächen III

O 28.9: Vortrag

Donnerstag, 27. März 2003, 13:15–13:30, FOE/ANOR

STM investigation of hydrogen diffusion on vicinal Si(001) surfaces — •M. Lawrenz, C. Schwalb, M. Dürr, and U. Höfer — Fachbereich Physik, Philipps-Universtät, D-35032 Marburg

Hydrogen diffusion on vicinal Si(001) surfaces with double atomic height steps has been imaged in a variable-temperature STM. Individual atoms were mapped in the empty-state picture where the hydrogen atoms can clearly be identified as bright features. Molecular hydrogen adsorbs dissociatively on the threefold coordinated D_B sites at room temperature. The adsorption takes place on adjacent Si atoms aligned with the dimer rows on the upper terrace. This was found to be a stable configuration up to temperatures of 550 K. At higher temperatures hydrogen starts to diffuse accross the steps and along the dimer rows. The measured hopping rate for hydrogen diffusion across the steps is 10⁻³ at 600 K. Successive scans of the same 30Å×30Å region showed that the preferential diffusion path from the step sites is towards the upper terrace.