Adsorption and reaction of NO on the Si(001) surface

Abstract

The interaction of the nitrous oxide (NO) molecule with the Si(001)2× 1 surface at 25-1150 °C was investigated by high-resolution photoemission using synchrotron radiation. N 1 s, O 1 s, and Si 2p core-level spectra are systematically analyzed. At room temperature, the dissociative adsorption of NO yields two distinct components for both N 1 s and O 1 s core levels indicating different adsorption species. The major N species is found to be stable up to 850 °C and is assigned to be in the N≡Si 3 configuration. These N adsorbates are thought to incorporate into the surface and subsurface Si layers. The minor adsorbate species both for N and O are unstable for an annealing above 650 °C. The core-level spectra also indicate that a further annealing at ∼950 °C converts parts of the incorporated N into the stoichiometric silicon nitride on the surface while the desorption of oxygen starts already at ∼850 °C. The Si 2p spectra for the NO-dosed surfaces could be decomposed with four oxide- or nitride-related components shifted from the bulk component by 0.8, 1.3, 2.1, and 2.9 eV, respectively. The origin of these components is discussed.