Stoichiometric reconstruction of the Al${}_2$O${}_3$(0001) surface

Abstract

Macroscopic properties of materials stem from fundamental atomic-scale details, yet for insulators, resolving surface structures remains a challenge. The basal (0001) plane of $\alpha$-Al${}_2$O${}_3$ was imaged with noncontact atomic force microscopy with an atomically-defined tip apex. The surface forms a complex $(\sqrt{3}1\times \sqrt{3}1)R\pm 9°$ reconstruction. The lateral positions of the individual O and Al surface atoms come directly from experiment; how these connect to the underlying crystal bulk was determined based on computational modeling. Before the restructuring, the surface Al atoms assume an unfavorable, threefold planar coordination; the reconstruction allows a rehybridization with subsurface O that leads to a substantial energy gain. The reconstructed surface remains stoichiometric, Al${}_2$O${}_3$.

References in corpus (2)

• The mechanism of high-resolution STM/AFM imaging with functionalized tips
• Standardization of chemically selective atomic force microscopy for metal-oxide surfaces

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• The Unreconstructed α-Al${}_2$O${}_3$(0001) Surface is Inhomogeneous and Rough
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