Kinetics of axial composition evolution in multi-component alloy nanowires

The axial composition profiles in two-component alloy semiconductor nanowires are theoretically studied based on a comprehensive transient growth model which accounts for both surface diffusion and direct impingement of atoms to catalyst. The composition variation derives from the different growth rates contributed by each component. Our simulations reveal that the component with larger (smaller) diffusivity will segregate near the bottom (top) of the nanowire. In the presence (absence) of direct deposition on nanowire sidewalls, the steady state alloy composition is determined by the ratio of effective diffusion lengths (impingement rates to the catalyst).