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

利用沉积的纳米级金属颗粒生长纳米线是一种非常有前途的自组织纳米结构制造方法。本提案旨在利用计算固体物理学的方法，研究原子尺度上纳米线生长的基本过程。我们将研究一个广泛使用的原型系统，即在金颗粒促进的分子束外延中砷化镓和砷化铟线的生长。提出在密度泛函理论的框架内进行第一性原理计算，以获得对三相边界真空-半导体-金属-粒子起作用的表面和界面能的可靠值。此外，分子动力学模拟将用于确定与成核相关的自由能垒，动力学蒙特卡罗模拟使我们能够跟踪原子核随后的生长。了解原子成核的细节将使我们能够建立更有基础的宏观增长模型。这些是工程师用来控制纳米线中的晶体多态性和阳离子（例如，镓和铟）之间的切换，这是使这些线在半导体器件中使用所需的功能。

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.