State Key Laboratory for Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences , 500 Yutian Road, Shanghai 200083, China.
Nano Lett. 2017 Dec 13;17(12):7824-7830. doi: 10.1021/acs.nanolett.7b04039. Epub 2017 Nov 10.
Understanding the compositional distribution of ternary nanowires is essential to build the connection between nanowire structures and their potential applications. In this study, we grew epitaxial ternary InGaAs nanowires with high In concentration on GaAs {111} substrates. Our detailed electron microscopy characterizations suggest that the grown ternary InGaAs nanowires have an extraordinary core-shell structure with In-rich cores and Ga-enriched shells, in which both nanowire cores and shells showed compositional gradient. It was found that In-rich nanowire cores are formed due to the Ga-limited growth environment, caused by the competition with the spontaneous InGaAs planar layer growth on the substrate that consumes more Ga than the nominal Ga concentration during the growth. Moreover, the composition gradient in the nanowires cores and shells is a result of strain relaxation between them. Our optoelectronic property measurements from prototype nanowire devices show a remarkable photoresponsivity under the near-infrared illumination. This study provides a new approach for designing and realizing complex nanowire heterostructures for high-efficiency nanowire-based systems and devices.
了解三元纳米线的组成分布对于建立纳米线结构与其潜在应用之间的联系至关重要。在这项研究中，我们在 GaAs{111}衬底上生长了具有高铟浓度的外延三元 InGaAs 纳米线。我们详细的电子显微镜表征表明，所生长的三元 InGaAs 纳米线具有非凡的核壳结构，其中含有富铟核和富镓壳，在这种核壳结构中，纳米线的核和壳都表现出组成梯度。研究发现，由于与衬底上自发的 InGaAs 平面层生长竞争，导致 Ga 受限生长环境，从而形成富铟纳米线核，在生长过程中，该平面层生长消耗的 Ga 比名义 Ga 浓度多。此外，纳米线核和壳之间的组成梯度是它们之间应变松弛的结果。我们从原型纳米线器件的光电性能测量中发现，在近红外光照射下，器件具有显著的光响应性。这项研究为设计和实现高效纳米线基系统和器件的复杂纳米线异质结构提供了一种新方法。
