Figure 1

LEED images obtained at 63 eV showing the ($2\times 2$) periodicity of the surface prepared in clean oxygen atmosphere (a) and the $(\sqrt{3}\times \sqrt{3})R30°$ periodicity of the surface prepared in humid oxygen atmosphere (b). Corresponding stable structures identified by theory are shown in (c) and (d). O atoms: red, Zn atoms: gray, and H atoms: white balls.Reuse & Permissions

Figure 2

Phase diagram for the ZnO(0001)-Zn surface in equilibrium with a humid oxygen atmosphere for different temperatures. Equilibrium conditions under which water would condensate on the surface are indicated by the hashed area (upper left corner). (a) $T=0\mathrm{K}$. The geometries of the stable surface structures are shown as insets and in Figs. 1c, 1d. The oxygen atom in $n3n7+\mathrm{O}$ indicated by a gray arrow is absent in $n3n7$ (not shown). The hydrogen chemical potential ${\mu }_{\mathrm{H}}$ used to construct Fig. 3 is marked by a dot-dashed black line. (b) $T=973\mathrm{K}$. The hashed square marks characteristic conditions of the UHV experiments [10] (cf. text). (c) $T=1223\mathrm{K}$. Dot filled areas depict regions of thermodynamic stability for $(\sqrt{3}\times \sqrt{3})R30°\mathrm{O}+(2\times 1)\mathrm{H}$ and ($2\times 2$)-O at $T=723\mathrm{K}$. Parameters corresponding to our experimental setup (cf. text) are marked by black dots and arrows.Reuse & Permissions

Figure 3

Dependence of the Gibbs free energy of formation on the oxygen chemical potential ${\mu }_{\mathrm{O}}$ for ${\mu }_{\mathrm{H}}=-2\mathrm{eV}$ (see text).Reuse & Permissions