| We study the effect of a strain based spatially varying potential energy surface on the lateral and vertical self-organization of nanoscale patterns and stacked quantum dots during epitaxial growth. The computational approach is based on the level-set method in combination with an atomistic strain code. Strain changes the energy-dependence of microscopic processes during growth, and thus determines the nucleation sites and the growth of islands and dots.;In chapter 3, our results have implication for guided self-assembly of nano patterns, which is a promising new technique for many technological applications. Both kinetic as well as thermodynamic effects can lead to ordering, and we discuss the competition between these two effects.;In chapter 4, we show that strain can lead to vertical alignment as well as lateral organization. Moreover, our simulations suggest that there is an optimal thickness of the capping layer to get the best alignment and most uniform size distribution of stacked quantum dots.;In chapter 5, we discuss alloy segregation. Alloy segregation is believed to be an important factor in the growth of the wetting layer and subsequent formation of islands during heteroepitaxy. We report simulated annealing results that determine the lowest energy configuration of a strained system. Our results indicate that in addition to vertical segregation, there is also an energetic driving force for lateral segregation, and formation of sub-surface features before island formation. We believe that these sub-surface features play a crucial role in the nucleation of islands. |
