Interface atomic structures in alkali halides heteroepitaxy

The heteroepitaxy of KBr on a KCl 001.surface with a small misfit of 4.3% and KCl on a NaCl 001.surface with a large misfit of 11.7% are studied. The interplay between a lattice mismatch and a growth mode, and the atomic-scale mechanism of the misfit accommodation are investigated. The stable atomic configurations were calculated by minimizing the total interaction energy between the ions. For both systems, a layer growth mode is energetically more favorable than an island growth mode. For KBrrKCl 001., the pseudomorphic strained layer structure with the lateral lattice constant of a KCl substrate is more stable up to the critical thickness of 4 monolayers than the commensurate layer structure with KCl 001.. For KClrNaCl 001., the pseudomorphic strained layer structure is energetically unfavorable at all the coverages, and the grown film takes the commensurate layer structure at 1 monolayer. At 2 and 3 monolayers, the stacking fault structure with a fourfold periodicity of a substrate was investigated, and the novel structure was proposed. q1998 Elsevier Science B.V. All rights reserved.