Analysis of the atomic processes in the growth of III-V-semiconductor nanowires promoted by metal particles

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The growth of nanowires with the help of deposited nanometer-sized metal particlesis a very promising route to fabricate nanostructures in a self-organized fashion. Thisproposal aims at an investigation of the elementary processes involved in nanowire growthon the atomic scale, using methods from computational solid state physics. We willinvestigate a widely used prototypical system, the growth of gallium-arsenide and indiumarsenidenanowires in molecular beam epitaxy promoted by gold particles. It is proposedto carry out first-principles calculations within the framework of density functional theoryin order to obtain reliable values of the surface and interface energies that play a role forthe triple-phase boundary vacuum-semiconductor-metal-particle. Moreover, moleculardynamics simulations will be used to determine the free energy barrier associated withnucleation, and kinetic Monte Carlo simulations enable us to follow the subsequentgrowth of the nuclei. Understanding the atomic details of nucleation will put us inposition to develop better-founded macroscopic growth models. These are intendedto be used by engineers to control the crystalline polymorphism in the nanowires andthe switching between cation species (e.g., gallium and indium) that is required forfunctionalizing these wires to be used in semiconductor devices.