SATURATION AND SCALING OF EPITAXIAL ISLAND DENSITIES

The aggregation or adatoms into 2D islands is studied as a function of coverage THETA and the ratio of surface diffusion rate to deposition rate R = D/F by Monte Carlo simulations or a model of epitaxial growth that permits atoms to detach from island edges at a rate determined by a pair bond energy E(N). The total island density is observed to saturate before coalescence becomes important. In this regime, the density or adatoms N1 is similar to THETA(-r)R(-omega) while the density of islands composed of s > 1 atoms N(s) is similar to THETA[s]-2g(s/[s]) where the average island size [s] is similar to THETAR(chi). The exponents r, omega, and chi vary smoothly with E(N).