Motivated by the recent electron microscopy studies indicating the presence of oxygen at the silicon nitride/rare-earth oxide interfaces, results from an extensive set of first-principles calculations are presented for the preferred bonding sites and configurations of O on the $\beta {\text{-Si}}_3{\text{N}}_4$ $\left(10\overline{1}0\right)$ surface as a function of coverage and surface stoichiometry. Most of the energetically favorable oxygenated $\beta {\text{-Si}}_3{\text{N}}_4$ $\left(10\overline{1}0\right)$ surfaces are predicted to exhibit reconstructions and nonstoichiometry as O replaces N to achieve bridging configurations between two Si atoms. The structural stability of most of the low-energy structures is driven by tendency of the surface atoms to saturate their dangling bonds while preserving close-to-ideal coordination and bond angles. The implications of these first-principles results in light of the recent experimental studies and previous computational studies on the bare surface are discussed.

• Received 27 August 2008

DOI:https://doi.org/10.1103/PhysRevB.78.165322