Anomalous Strain Relaxation in Core-Shell Nanowire Heterostructures via Simultaneous Coherent and Incoherent Growth.
Anomalous Strain Relaxation in Core-Shell Nanowire Heterostructures via Simultaneous Coherent and Incoherent Growth.
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DOI：
10.1021/acs.nanolett.6b03681
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发表时间：
2017-01
期刊：
影响因子：
10.8
通讯作者：
R. Lewis;Lars Nicolai;H. Küpers;M. Ramsteiner;A. Trampert;L. Geelhaar
中科院分区：
文献类型：
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作者：
R. Lewis;Lars Nicolai;H. Küpers;M. Ramsteiner;A. Trampert;L. Geelhaar
纳米尺度的基板，如纳米线允许异质结构的设计冒险远远超出狭窄的晶格失配范围限制平面异质结构，由于失配应变松弛在自由表面和整个纳米结构的分区。在这项工作中，我们发现了一种新的应变弛豫过程中的GaAs/InxGa 1-xAs核壳纳米线，这是一个直接的结果，这些纳米结构的nanofaceted性质。在临界晶格失配之上，塑性弛豫土丘形成在纳米线侧壁刻面的边缘处。松弛土丘和相干壳从沉积开始同时生长，具有更高的晶格失配，越来越有利于非相干丘生长。这与Sttranski-Krastanov生长形成鲜明对比，在Sttranski-Krastanov生长中，超过临界厚度的相干层生长不再发生。这项研究强调了如何理解晶格失配的纳米异质结构的应变弛豫是必不可少的设计基于这些纳米结构的设备。
Nanoscale substrates such as nanowires allow heterostructure design to venture well beyond the narrow lattice mismatch range restricting planar heterostructures, owing to misfit strain relaxing at the free surfaces and partitioning throughout the entire nanostructure. In this work, we uncover a novel strain relaxation process in GaAs/InxGa1-xAs core-shell nanowires that is a direct result of the nanofaceted nature of these nanostructures. Above a critical lattice mismatch, plastically relaxed mounds form at the edges of the nanowire sidewall facets. The relaxed mounds and a coherent shell grow simultaneously from the beginning of the deposition with higher lattice mismatches increasingly favoring incoherent mound growth. This is in stark contrast to Stranski-Krastanov growth, where above a critical thickness coherent layer growth no longer occurs. This study highlights how understanding strain relaxation in lattice mismatched nanofaceted heterostructures is essential for designing devices based on these nanostructures.