Real-space investigation of hydrogen dissociation at step sites of vicinalSi(001) surfaces - art. no. 121315

Ha adsorption on vicinal silicon (001) surfaces with double atomic height D -B steps has been investigated using scanning tunneling microscopy. At room temperature, the only observable reaction is dissociative adsorption at st ep sites. This process leads to H adsorption at pairs of adjacent step atom s aligned with the dimer rows of the upper terrace. The sticking probabilit y is found to increase at sites next to those already occupied by adsorbed H, as manifested in a strongly nonstatistical distribution of occupied pair s of dangling bonds. At elevated surface temperature, dissociative adsorpti on is also observed to occur at the complementary pairs of step atoms.