Theoretical prediction of new dissolution modes during metal heteroepitaxy

摘要

By means of the kinetic tight-binding Ising model we investigate the Ni/Ag dissolution modes resulting from the thermal interdiffusion between the two elements. For a thin deposit (1 ML) we show that the dissolution proceeds by the formation of encapsulted Ni precipitates covered by two pure Ag monolayers. For a thick deposit (10 ML) we find two distinct layer-by-layer modes depending on the annealing temperature. At high temperature the kinetics start with the apparition of capping Ag monolayers on a buried almost intact Ni film (surfactant-layer-by-layer mode). Below a critical temperature T_c, the dissolution proceeds without any Ag surface enrichment (layer-by-layer mode). We find that T_c decreases when the surface driving forces whcih favour the segregation of the substrate elements increase.