Scaling of island densities in submonolayer growth of binary alloys.

We study the nucleation kinetics of binary alloys formed by codeposition of A and B atoms onto a planar substrate with fluxes F(alpha) (alpha=A, B). Based on a generalization of mean-field rate equations, we derive scaling relations for the dependence of the number density of stable islands on the ratios D(alpha)/F(alpha), where D(alpha) are the diffusion coefficients of two types of adatoms. Novel scaling laws are predicted for different situations of cluster stabilities with respect to their size and composition. The predictions are validated by kinetic Monte Carlo simulations and can be tested in experiments.