Reactive scattering of O+ on oxidized Si(001)

Thin silicon oxide films are grown on Si(001) through ion-beam oxidation (I BO), using hyperthermal O+ ions. Within a steady-state oxidation regime, sc attering of O+ from these thin films yields both positive (Si+, SiO+) and n egative (O-, O-) ion products. The emergence of O- and O-2(-) is investigat ed through isotopic labeling and angle-, mass- and energy-resolved detectio n. The O- signal comprises direct scattering and surface recoil components. Two distinct O-2(-) formation mechanisms are operative, with different dep endencies on incident O+ energy at low O+ energies, O-2(-) is created exclu sively by abstraction of a surface oxygen atom by an incident oxygen; where as for higher O+ energies, a second channel involving a recoil abstracting a surface atom contributes. These studies represent the first investigation of the scattered reaction products formed during silicon IBO. (C) 2001 Pub lished by Elsevier Science B.V.