Coarsening kinetics of heteroepitaxial islands in nucleationless Stranski-Krastanov growth

A large-scale three-dimensional computer investigation of coarsening kinetics of heteroepitaxial islands during nucleationless Stranski-Krastanov growth is conducted. Both surface diffusion and condensation are considered. It is found that island formation and coarsening kinetics are strongly influenced by the growth rate and growth mode. Under the nucleationless growth mode, unusual coarsening kinetics, i.e., the superlinear increase in the mean island volume with respect to time, and the higher-than-linear-rate decrease in the areal density of islands with respect to time described by Floro et al. [Phys. Rev. Lett. 84, 701 (2000)], is observed. It is proposed that unusual coarsening kinetics is attributed to the island volume distribution at the beginning of coarsening. The standard mean-field theory considering the island volume distribution at the beginning of coarsening reproduces the observed behavior.