Materials Engineering, The University of Queensland, Brisbane, QLD 4072, Australia.
Nano Lett. 2013 Feb 13;13(2):643-50. doi: 10.1021/nl304237b. Epub 2013 Jan 18.
We report a novel phase separation phenomenon observed in the growth of ternary In(x)Ga(1-x)As nanowires by metalorganic chemical vapor deposition. A spontaneous formation of core-shell nanowires is investigated by cross-sectional transmission electron microscopy, revealing the compositional complexity within the ternary nanowires. It has been found that for In(x)Ga(1-x)As nanowires high precursor flow rates generate ternary In(x)Ga(1-x)As cores with In-rich shells, while low precursor flow rates produce binary GaAs cores with ternary In(x)Ga(1-x)As shells. First-principle calculations combined with thermodynamic considerations suggest that this phenomenon is due to competitive alloying of different group-III elements with Au catalysts, and variations in elemental concentrations of group-III materials in the catalyst under different precursor flow rates. This study shows that precursor flow rates are critical factors for manipulating Au catalysts to produce nanowires of desired composition.
我们报告了在金属有机化学气相沉积生长三元 In(x)Ga(1-x)As 纳米线中观察到的一种新的相分离现象。通过横截面透射电子显微镜研究了核壳纳米线的自发形成，揭示了三元纳米线的组成复杂性。已经发现，对于 In(x)Ga(1-x)As 纳米线，高前体流速会生成富 In 的壳层的三元 In(x)Ga(1-x)As 核，而低前体流速会生成具有三元 In(x)Ga(1-x)As 壳层的二元 GaAs 核。基于第一性原理的计算结合热力学考虑表明，这种现象是由于不同的 III 族元素与 Au 催化剂的竞争合金化以及不同前体流速下催化剂中 III 族材料的元素浓度的变化所致。本研究表明，前体流速是控制 Au 催化剂以生产所需组成的纳米线的关键因素。
