1 research outputs found
Shape of Heteroepitaxial Island Determined by Asymmetric Detachment
Square lattice gas models for heteroepitaxial growth are studied by means of
kinetic Monte Carlo simulations, in order to find a possible origin of
anisotropic island shape observed in growth experiments of long organic
molecules. When deposited molecules form clusters irreversibly at their
encounter during surface diffusion, islands grow in a ramified dendritic shape,
similar to DLA. Introduction of molecular detachment from edges makes islands
compact with smooth edges. Tilting of adsorbed long molecules or steps in a
vicinal substrate may induce orientation-dependence in the detachment rate of
edge molecules from an island. In simulations with orientation-dependent
detachment rates, a clear anisotropy in an island shape is observed. Shape
anisotropy on a vicinal substrate is enhanced as steps get dense, in agreement
to the experimental observation.Comment: 5 pages, 6 figure