Lattice Kinetic Modeling of the Anisotropic Growth of Two-Dimensional Islands on Barite (001) Surface

In
this paper, we present simulations of two-dimensional islands
on the barite (001) face. These simulations were performed with MMonCa,
a computer code based on the kinetic Monte Carlo technique. Our results
are in excellent agreement with previous in situ atomic
force microscopy (AFM) observations. Indeed, MMonCa is able to precisely
reproduce both the thickness and the characteristic fan shape of barite
(001) two-dimensional islands, which is defined by two straight steps
parallel to the ⟨120⟩ directions and a curved step connecting
them. In addition, MMonCa also simulates the orientation reversal
of islands in successive growth monolayers. Fundamental for the adequate
reproduction of the shape of barite (001) islands is the introduction
of an anisotropy factor for the incorporation of growth units into
crystallographically nonequivalent step edges. The results presented
in this paper demonstrate that the consideration of simple crystallographic
and geometrical constraints can be enough to provide a consistent
explanation for the development of complex nanotopographies during
the growth of crystals.