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arXiv 2102.01978cond-mat.mtrl-scicond-mat.mes-hall
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InAs/InP/GaAsSb核-双壳纳米线的生长和应变弛豫机制

Growth and Strain Relaxation Mechanisms of InAs/InP/GaAsSb Core-Dual-Shell Nanowires

Omer Arif, Valentina Zannier, Ang Li, Francesca Rossi, Daniele Ercolani, Fabio Beltram, Lucia Sorba

摘要:

纳米线异质结构中的核/壳几何结构和带隙工程的组合可以用于实现具有新颖的传输和光学性质的系统。在这里,我们报告了通过无催化剂化学束外延在Si(111)衬底上生长InAs/InP/GaAsSb核双壳纳米线的情况。通过扫描和透射电子显微镜和能量色散X-射线光谱法进行了详细的形态,结构和成分分析的纳米线作为生长参数的函数。此外,结合扫描透射电镜-莫尔技术和几何相分析,我们研究了该系统中的残余应变和弛豫机制。我们发现,只有当标称厚度大于1 nm时,InP壳面才沿所有结晶方向发育良好,这表明了岛状生长模式。此外,晶体学分析表明,InP和GaAsSb壳几乎相干生长的InAs核心沿112方向和弹性压缩沿110方向。当InP壳层厚度大于8 nm时,界面处出现位错和粗糙化。该研究为基于这些核-双壳纳米线的高质量器件的制造提供了有用的一般指导。

英文摘要:

The combination of core/shell geometry and band gap engineering in nanowire heterostructures can be employed to realize systems with novel transport and optical properties. Here, we report on the growth of InAs/InP/GaAsSb core-dual-shell nanowires by catalyst-free chemical beam epitaxy on Si(111) substrates. Detailed morphological, structural, and compositional analyses of the nanowires as a function of growth parameters were carried out by scanning and transmission electron microscopy and by energy-dispersive X-ray spectroscopy. Furthermore, by combining the scanning transmission electron microscopy-Moire technique with geometric phase analysis, we studied the residual strain and the relaxation mechanisms in this system. We found that InP shell facets are well-developed along all the crystallographic directions only when the nominal thickness is above 1 nm, suggesting an island-growth mode. Moreover, the crystallographic analysis indicates that both InP and GaAsSb shells grow almost coherently to the InAs core along the 112 direction and elastically compressed along the 110 direction. For InP shell thickness above 8 nm, some dislocations and roughening occur at the interfaces. This study provides useful general guidelines for the fabrication of high-quality devices based on these core-dual-shell nanowires.

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