INFLUENCE OF SURFACE STRESS ON THE EQUILIBRIUM SHAPE OF STRAINED QUANTUM DOTS

The equilibrium shapes of InAs quantum dots (i.e., dislocation-free, s trained islands with sizes greater than or equal to 10 000 atoms) grow n on a GaAs (001) substrate are studied using a hybrid approach that c ombines density functional theory (DFT) calculations of microscopic pa rameters, surface energies, and surface stresses with elasticity theor y for the long-range strain fields and strain relaxations. In particul ar we report DFT calculations of the surface stresses and analyze the influence of the strain on the surface energies of the various facets of the quantum dot. The surface stresses have been neglected in previo us studies. Furthermore, the influence of edge energies on the island shapes is briefly discussed. From the knowledge of the equilibrium sha pe of these islands, we address the question whether experimentally ob served quantum dots correspond to thermal equilibrium structures or if they are a result of growth kinetics.