Shape-dependent composition profile in epitaxial alloy quantum dots: A phase-field simulation

A phase-field microelasticity model is developed to probe the interplay between shape and composition profile in epitaxial alloy quantum dots, and special attention is focused on the competition between chemical mixing and strain energies due to lattice mismatch. Our simulation shows that the inhomogeneous stress distribution in the dot drastically depends on the dot shape and thus leads to a nonuniform composition distribution. The stress-driven composition segregation is size-dependent: the larger the height-to-width ratio of the quantum dot, the more nonuniform the stress map and the larger the composition segregation.