Figure 1

Top: Neutral ${\mathrm{O}}_2$ molecule in the triplet spin state ($S=1$), (A) diffusing through the oxide and (B) incorporating in a Si-Si bond. The incorporation leads to the formation of a threefold Si atom (III). Spin conversion to the singlet state ($S=0$) gives (C) a symmetric peroxyl linkage. Its dissociation gives (D) two neighboring Si-O-Si units. Light (black) spheres correspond to Si (O) atoms. A gray color is used for the ${\mathrm{O}}_2$ molecule. Bottom: energy profiles during the incorporation (left) and dissociation (right) processes of the oxidation reaction. For the incorporation, the energy is given with respect to the distance between the ${\mathrm{O}}_2$ molecule and the Si-Si bond at the interface. Both the triplet ($\mathrm{A}\to \mathrm{B}$, dotted line) and singlet spin states ($\mathrm{A}\to \mathrm{C}$, solid line) are considered. For the dissociation ($\mathrm{C}\to \mathrm{D}$), the energy is given with respect to the ${\mathrm{O}}_2$ bond length.Reuse & Permissions

Figure 2

Top: equilibrium configurations resulting from (A) the incorporation and (B) the dissociation of a ${\mathrm{O}}_2$ molecule at the interface in the presence of one excess electron in the simulation cell. Bottom: Respective energy profiles. Same conventions as in Fig. 1.Reuse & Permissions

Figure 3

Transition states during the oxidation reaction of a neutral ${\mathrm{O}}_2$ molecule at the $\mathrm{S}\mathrm{i}(100)\mathrm{\text{−}}\mathrm{S}\mathrm{i}{\mathrm{O}}_{\mathrm{2}}$ interface, corresponding to the case in Fig. 1. The incorporation (left) occurred via the formation of a fivefold Si atom (V) and a threefold Si atom (III). During dissociation, a threefold O atom (arrow) was observed (right). Same conventions as in Fig. 1.Reuse & Permissions