Kinetics of surfactant-mediated epitaxial growth

A kinetic model for surfactant-mediated epitaxial growth is suggested. The surfactant atoms join kinks predominantly at steps as the latter are the energetically most favored sites on the crystal surface. The deposited atoms must displace them in order to join the crystal lattice. This gives rise to additional kinetic barriers the atoms have to overcome when they join the ascending steps. The asymmetry of incorporating atoms in ascending and descending steps is reversed and a diffusion gradient that drives the atoms to join the descending steps appears. The thermodynamic driving force for the two-dimensional–three-dimensional transformation to occur is suppressed and layer-by-layer growth takes place.