Soft Matter and Complex Systems Seminar

Different patterns are created on the surface of the growing crystals, among which the step bunches and/or step meanders are of most studied. The Ehrlich-Schwoebel effect on surface steps is considered to be one of the “usual suspects” of such patterning. A direct step barrier means it is easier to attach a particle to the step from the lower terrace than from the upper terrace. In the process of crystal growth it leads to the formation of meanders, while an inverse barrier leads to the step bunching. I will show that the cellular automata model can be used to study surface patterning process. The proper combination of a direct and inverse step barrier and the correct selection of the potential of the well between them lead to the formation of bunched step structures, followed by the formation of anti-bands, and then changes in the height of the direct step barrier lead to the growth of nanocolumns, nanowires, and nanopyramids or meanders, in the same system. The universality of surface dynamics will be further explored by differential equations describing the evolution of the surface slope. The time scaling of the bunching process resulting from these equations is further compared with the experimental results.