Growth of three-dimensional SiC clusters on Si modelled by KMC

The formation of silicon carbide nanoclusters on silicon substrates by MBE deposition of carbon provides a variety of applications, such as antidot structures, nanowire heterostructures, wave guides and arrays of tips for cold cathode emission. The SiC growth on Si is unusual for semiconductor systems with large lattice mismatch due to the formation of a Si1−xCx solid solution along with the formation of two-dimensional 3C-SiC, and a subsequent step transforming the two-dimensional (2D) clusters into three-dimensional (3D) clusters for overall stress minimization. At the same time there are strong experimental evidences that under some experimental conditions 2D clusters could exist even at relatively high coverages. To study the transition from the 2D to the 3D cluster during SiC nucleation and growth the kinetic Monte Carlo method was used. Silicon and carbon atoms are allowed to exchange between the fixed sites of the 3D lattice with the symmetry of the diamond lattice (to simulate the growth of the 3C-SiC polytype mainly observed in growth experiments). The fitting parameters were estimated by means of molecular dynamics simulation as well as by comparing the data obtained with the experimental TEM results. Formation of a three-dimensional clusters and pits in the surface is demonstrated.