Atomic structure of the Cu/Si(111) interface by high-energy core-level Auger electron diffraction

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Abstract
High-energy core-level Auger emission from adsorbed atoms on single-crystal surfaces is accompanied by diffraction and interference effects, similar to those observed in x-ray photoemission. We have used azimuthal anisotropies in the Cu(LMM) intensity at shallow polar angles and a kinematical scattering model to determine the atomic geometry of the annealed one-monolayer-thick Cu/Si(111) interface. The calculated azimuthal intensity distributions are a very sensitive function of surface geometry. Optimal agreement with experiment occurs when the ideal unreconstructed Si(111) surface is allowed to reconstruct to a planar geometry and Cu atoms are placed in hollow sites at a depth of 0.1±0.1 Å below the surface plane.