Communication: fully alignment-specified O2 chemisorption on vicinal Si(100).

Abstract

A fully alignment-resolved O2 sticking experiment on a single domain Si(100)-(2×1) surface is presented. This provides the first experimental evidence that the reactivity of O2 depends on both the polar and azimuthal angles of the molecular axis relative to a surface. It has been found that, in case of side-on collision, an O2 molecule perpendicular to the dimer on Si(100) is about 40% more reactive than that parallel to the dimer. Comparison of the O2 sticking on flat and vicinal Si(100) surfaces indicates that barrierless dissociation channels exist at the double layer step.