Influence of steps and defects on the dissociative adsorption of molecular hydrogen on silicon surfaces

By: M. B. Raschke and U. Höfer

Applied Physics B 68, 649 (1999)

The dissociative adsorption of molecular hydrogen on vicinal Si(001) and Si(111) surfaces was investigated by means of optical second-harmonic generation (SHG). For temperatures up to 600 K the measured initial sticking coefficients could be decomposed into contributions from step/defect and terrace sites. Whereas the presence of steps on Si(111) leads only to a moderate increase of reactivity, the sticking coefficients for step adsorption on misoriented Si(001) are many orders of magnitude higher than for terrace adsorption and reach values up to 10−4. Neither the absolute values nor the temperature dependence of adsorption on the terraces are affected by the misorientation.