Nucleation of Islands During Epitaxial Growth: Influence of a Second Species

The theory of the nucleation and growth of islands is maturing rapidly. This advance is driven by the increased availability of experimental data, as well as the need for better control over growth processes. Recently, a number of authors have studied the effects of introducing a second species onto the surface in order to influence the ultimate growth morphology. In some situations, the addition of a second species results in a signficant change (approximately a factor of 1000) in the nucleated island density. The origin of this increase in density has been linked to the anomalous diffusion induced by the presence of the additional species of atoms. In the current paper, this dependence is explored further. In particular, earlier work focused on nucleation and growth in the regime in which the second species is essentially immobile. This constraint is relaxed here, and the subsequent model studied through application of a self-consistent mean-field theory. Predictions for the total island density are presented.