Explaining the anomalous orientation of epitaxial gold on sodium chloride

Abstract

It is difficult to produce parallel epitaxy of gold on cleveed sodium chloride surfaces, (001)Au | (001)NaCl, unless some substrate surface defects have been created. When such epitaxy does occur the observed orientation 〈110〉Au | 〈110〉NaCl involves a 28% misift, whereas if rotated 45° to 〈110〉Au | 〈110〉NaCl the misfit would be only 2%. A detailed calculation of cluster-surface interaction potential energies for gold clusters forming in NaCl are used to explain this observation. When clusters nucleate on the defect structures they are initiated in the poor registry orientation. Subsidiary maxima in the potential energy vs orientation curve prevent subsequent rotation to the lowest energy configuration.