Atomic versus molecular reactivity at the gas-solid interface: The adsorption and reaction of atomic oxygen on the Si(100) surface

The reaction of atomic oxygen with the Si(100) surface has been examined by employing supersonic beam techniques. Atomic oxygen adsorbs with unit probability on the clean Si(100) surface. The rate of oxidation decreases rapidly with increasing coverage up to ∼3–4 monolayers, followed by a regime that exhibits a weaker dependence on coverage. At surface temperatures above ∼1000 K, atomic oxygen reacts with the substrate to produce SiO(g). The kinetics of this reaction depends on the nature of the gas-phase reactant: A single stable surface intermediate is formed from O(g), whereas two intermediates are implicated from ${\mathrm{O}}_2$(g).