Fath Allah Rabie, Ben Teresa, González David
Dpto. Ciencia de los Materiales e Ingeniería Metalúrgica y Q.I.,Facultad de Ciencias,Apdo. 40,11510 Puerto Real,Cádiz,Spain.
Microsc Microanal. 2014 Aug;20(4):1254-61. doi: 10.1017/S1431927614000634. Epub 2014 Apr 3.
A study by electron microscopy techniques of the structural and compositional properties of Al x Ga1-x N/GaN nanowire (NW) heterostructures on Si(111) is presented. Al x Ga1-x N depositions grown without catalyst by plasma-assisted molecular beam epitaxy were designed to form NWs in the range of 0.20<x<0.40 with different lengths and growth temperatures. The NWs exhibit a well-defined core-shell radial structure with a complex chemical distribution along and across the growth direction that finally affects the NW morphology. All the wires have an initial stage with a maximum Al content in the core slightly above the GaN/Al x Ga1-x N interface, which initially decreases exponentially with the NW height depending on the nominal Al content and the growth temperature. In longer NWs, this trend changes and evolves increasing both the Al/Ga ratio and the core diameter as well as sharpening the shell. Adatom surface kinetic differences and the geometrical shadow effect during the growth are the probable drivers of this behavior.
本文介绍了一项利用电子显微镜技术对硅（111）上的AlxGa1-xN/GaN纳米线（NW）异质结构的结构和组成特性进行的研究。通过等离子体辅助分子束外延在无催化剂的情况下生长AlxGa1-xN沉积物，旨在形成长度和生长温度不同的0.20<x<0.40范围内的纳米线。纳米线呈现出明确的核壳径向结构，沿生长方向和垂直于生长方向具有复杂的化学分布，最终影响纳米线的形态。所有纳米线在初始阶段，其核心中的最大铝含量略高于GaN/AlxGa1-xN界面，该含量最初会根据标称铝含量和生长温度随纳米线高度呈指数下降。在较长的纳米线中，这种趋势会发生变化并演变，同时增加铝/镓比率和核心直径，并使壳层变锐。生长过程中的吸附原子表面动力学差异和几何阴影效应可能是这种行为的驱动因素。
