Evaporation and Step Edge Di usion in MBES

Using kinetic Monte{Carlo simulations of a Solid{on{Solid model we investigate the innuence of step edge diiusion (SED) and evaporation on Molecular Beam Epitaxy (MBE). Based on these investigations we propose two strategies to optimize MBE{growth. The strategies are applicable in diierent growth regimes: during layer{by{layer growth one can reduce the desorption rate using a pulsed ux. In three{dimensional (3D) growth the SED can help to grow large, smooth structures. For this purpose the ux has to be reduced with time according to a power law. The growth of high quality compound semiconductors is of great technological importance. In order to optimize growth a detailed knowledge of microscopic processes is very important. We will follow this line of thought and will report on two new approaches of growth which will be presented in more detail in a forthcoming publication. We will exploit macroscopic eeects of two distinct microscopic mechanisms. The term \microscopic" refers to events at the atomic scale: e.g. a single diiusion step of an adatom or evaporation of an atom. These are the ingredients of the computer model. This is contrasted to the term \macroscopic" for eeects which are typically measurable in experiments: e.g. the overall mass desorption, form and distribution of three{dimensional structures, or the growth rate. The model used here is the conventional solid{on{solid model on a simple cubic lattice. All simulations will start on a singular surface. The system size will be at least 300300 lattice constants with periodic boundary conditions. Even