Simulation of self-assembled compositional core-shell structures in InxGa1−xN nanowires

Abstract

We report the simulation of compositional core-shell structure formation in epitaxial InGaN nanowires (NWs) and its dependence on kinetic growth mode and epitaxial relation to substrate, based on atomistic-strain-model Monte Carlo simulations. On a lattice mismatched substrate, the layer-by-layer growth results in self-assembled core-shell structures with the core rich in the unstrained component (relative to the substrate), while the faceted growth mode leads to the strained core component, and both are distinctively different from the equilibrium composition profiles. Our simulation results explain the reason that all the existing core-shell alloy NWs grown by vapor-liquid-solid experiments have cores rich in the unstrained (or less strained) components is because they have been grown via the layer-by-layer mode and, more importantly, suggest a possible route towards controlling the NW core-shell composition by altering growth mode and/or selecting substrate.