Bi表面活性剂引导下InAs纳米结构在GaAs纳米线侧壁上的自组装
Self-assembly of InAs nanostructures on the sidewalls of GaAs nanowires directed by a Bi surfactant
摘要：
表面能在三维（3D）纳米结构的自组装中起主导作用。在这封信中，我们表明，使用表面活性剂来修改表面能可以提供一种手段，外部控制纳米结构的自组装，使新的分层纳米结构的合成。我们探索了Bi作为表面活性剂在GaAs纳米线{1-10}侧壁面上生长InAs。表面Bi的存在下诱导形成的InAs 3D岛屿的过程类似的Stranski-Krastanov机制，这不会发生在没有Bi在这些表面上。InAs 3D岛在临界壳厚度以上的{1-10}面的拐角处成核，然后沿着<110>纳米线侧壁的平面中的方向伸长。利用这种生长机制，我们实现了一系列新颖的层次纳米结构，从InAs量子点上的单个{1-10}纳米线方面的锯齿形纳米环完全包围纳米线核心。光致发光光谱和阴极发光谱线扫描表明，小的表面诱导的InAs三维岛的行为作为光学活性量子点。这项工作说明了如何表面活性剂可以提供一个前所未有的水平的外部控制纳米结构的自组装。
英文摘要：
Surface energies play a dominant role in the self-assembly of three dimensional (3D) nanostructures. In this letter, we show that using surfactants to modify surface energies can provide a means to externally control nanostructure self-assembly, enabling the synthesis of novel hierarchical nanostructures. We explore Bi as a surfactant in the growth of InAs on the {1-10} sidewall facets of GaAs nanowires. The presence of surface Bi induces the formation of InAs 3D islands by a process resembling the Stranski-Krastanov mechanism, which does not occur in the absence of Bi on these surfaces. The InAs 3D islands nucleate at the corners of the {1-10} facets above a critical shell thickness and then elongate along <110> directions in the plane of the nanowire sidewalls. Exploiting this growth mechanism, we realize a series of novel hierarchical nanostructures, ranging from InAs quantum dots on single {1-10} nanowire facets to zig-zag shaped nanorings completely encircling nanowire cores. Photoluminescence spectroscopy and cathodoluminescence spectral line scans reveal that small surfactant-induced InAs 3D islands behave as optically active quantum dots. This work illustrates how surfactants can provide an unprecedented level of external control over nanostructure self-assembly.
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