Different Regimes in the Ehrlich-Schwoebel Instability

A one-dimensional high-symmetry growing surface in presence of step-edge barriers is studied numerically and analytically, through a discrete/continuous model which neglects thermal detachment from steps. The morphology of the film at different times and/or different sizes of the sample is analyzed in the overall range of possible step-edge barriers: for a small barrier, we have a strong up-down asymmetry of the interface, and a coarsening process – with an increasing size of mounds – takes place; at high barriers no coarsening exists, and for infinite barriers the up-down symmetry is asymptotically recovered. The transition between the two regimes occurs when the so-called Schwoebel length is of order of the diffusion length.