Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark.
Nanotechnology. 2010 Mar 19;21(11):115603. doi: 10.1088/0957-4484/21/11/115603. Epub 2010 Feb 22.
GaAs nanowires were grown by molecular beam epitaxy and studied by glancing-angle x-ray diffraction during five different stages of the growth process. An entire forest of randomly positioned epitaxial nanowires was sampled simultaneously and a large variation in the Au-Ga catalyst was found. Au, AuGa, AuGa(2) and the hexagonal beta phase were all identified in several orientations and in similar amounts. The nanowires are shown to consist of regular zinc blende crystal, its twin and the hexagonal wurtzite. The evolution of the various Au-Ga catalysts and the development in the twin to the wurtzite abundance ratio indicate that the Au catalyst is saturated upon initiation of growth leading to an increased amount of wurtzite structure in the wires. A specular x-ray scan identifies the various Au-Ga alloys, three Au lattice constants and a rough interface between nanowires and catalyst. Reciprocal space maps were obtained around Au Bragg points and show the development of the Au catalyst from a distribution largely oriented with respect to the lattice to a non-uniform distribution with several well-defined lattice constants.
砷化镓纳米线通过分子束外延生长，并在生长过程的五个不同阶段通过掠入射 X 射线衍射进行研究。同时对随机定位的外延纳米线的整个森林进行采样，发现 Au-Ga 催化剂存在很大的变化。在几个方向和相似的量中都发现了 Au、AuGa、AuGa(2)和六方β相。结果表明，纳米线由规则的闪锌矿晶体、其孪晶和六方纤锌矿组成。各种 Au-Ga 催化剂的演变以及孪晶向纤锌矿丰度比的发展表明，Au 催化剂在生长开始时就达到饱和，导致纳米线中纤锌矿结构的含量增加。镜面 X 射线扫描可识别各种 Au-Ga 合金、三个 Au 晶格常数以及纳米线和催化剂之间的粗糙界面。在 Au 布拉格点周围获得了倒易空间图，并显示了 Au 催化剂从主要相对于晶格取向分布到具有几个明确定义的晶格常数的非均匀分布的发展。
