${{\mathrm{Si}}_{3}O}_{\mathit{y}}$ ( $\mathit{y}=1\mathrm{}–6$) Clusters: Models for Oxidation of Silicon Surfaces and Defect Sites in Bulk Oxide Materials

We studied the structure and bonding of a series of silicon oxide clusters, ${\mathrm{Si}}_3{\mathrm{O}}_y$ $(y=1\mathrm{}–6)$, using anion photoelectron spectroscopy and ab initio calculations. For $y=1\mathrm{}–3$ the clusters represent the sequential oxidation of ${\mathrm{Si}}_3$, and provide structural models for the oxidation of silicon surfaces. For $y=4\mathrm{}–6$, the clusters contain a central Si in a tetrahedral bonding environment, suggesting the onset of the bulklike structure. Evidence is presented that suggests the ${\mathrm{Si}}_3{\mathrm{O}}_4$ cluster $\left(D_{2d}\right)$ may provide a structural model for oxygen-deficient defect sites in bulk ${\mathrm{SiO}}_2$ materials.