Morphology and dynamics of 2D Sn-Cu alloys on (100) and (111) Cusurfaces

Abstract

We have performed calculations of Sn deposition on Cu(111) and Cu(100)surfaces. The atomic interactions are described by modified embedded atommethod (MEAM) potentials. This is a modification of the embedded atom method(EAM) to include higher moments in the electron density. We find that at lowcoverages Sn deposited on Cu(111) leads to the formation of a two-dimensional(2D) alloy phase with a p((3)1/2×(3)1/2)-R 30° structurewhich is stable up to temperatures of 1200 K. For deposition of Sn on Cu(100),a coverage of one-quarter of a monolayer results in the formation of astable 2D alloy phase with a p(2×2) structure. These results are inagreement with ion-scattering experiments. It is found that on both Cu(100)and Cu(111) surfaces, the resulting alloy phases are rippled with the Sn atomsdisplaced outward from the surfaces.