Morphological regions and oblique-incidence dot formation in a model of surface sputtering

We study solid surface morphology created by off-normal ion-beam sputtering with an atomistic solid-on-solid model of sputter erosion. With respect to an earlier version of the model, we extend this model with the inclusion of lateral erosion. Using the two-dimensional structure factor, we found an upper bound μ2, in the lateral straggle μ, for clear ripple formation. Above this upper bound, for longitudinal straggle σ1.7, we found the possibility of dot formation (without sample rotation). Moreover, a temporal crossover from a hole topography to ripple topography with the same value of collision cascade parameters was found. Finally, a scaling analysis of the roughness, using the consecutive gradient approach, yields the growth exponents β=0.33 and 0.67 for two different topographic regimes. The results are discussed in the context of the continuum theory.