Strongly reduced Ehrlich-Schwoebel barriers at the Cu (111) stepped surface with In and Pb surfactants

摘要

A surfactant can modify the properties of the surface and induce different mode of epitaxy growth. The atomistic mechanism is not fully understood yet. In this first-principles study, taking Cu homoepitaxy along (111) direction as an example, we show that the distribution of the surfactant atoms on the surface is the key. For In and Pb, they prefer to locate at the step edges and remain isolated. Once the growth is started, the distribution can be further modified by Cu adatoms. The uniquely decorated step edges have much lowered Ehrlich-Schwoebel (ES) barriers than that of the clean edges, thus the two dimensional growth on Cu (111) surface is promoted significantly. On the other hand, for Rh, Ir, and Au, these atoms are not favored at the step edges. The ES barriers can't be affected and these metals are not surfactants. The result is very helpful for searching of the optimal surfactants in metal homoepitaxy. (c) 2017 Elsevier B.V. All rights reserved.