Computer simulation of nucleation on (001) Kossel crystal surface with and without diffusion

The Monte Carlo technique was applied to nucleation-controlled growth of a (001) Kossel crystal surface, either with or without surface diffusion. The sizes of critical nucleus, n0, and of supercritical cluster, n+, have been obtained at different temperatures and supersaturations. With the inclusion of diffusion, both sizes are reduced, and this explains why the nucleation dip of nucleation growth is shortened. However, n+n0≈2, as predicted by the theory of Burton, Carbrera and Frank, only in the absence of diffusion. Also, when diffusion operates the kink site density along steps is no longer independent of supersaturation. It is concluded that surface diffusion brings the system further away from thermodynamic equilibrium.