Ledge-flow-controlled catalyst interface dynamics during Si nanowire growth
Ledge-flow-controlled catalyst interface dynamics during Si nanowire growth
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DOI：
10.1038/nmat2140
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发表时间：
2008-05-01
期刊：
影响因子：
41.2
通讯作者：
Robertson, John
中科院分区：
文献类型：
--
作者：
Hofmann, Stephan;Sharma, Renu;Robertson, John
自组装纳米线为电子学、光子学和生物学领域提供了精确和可扩展的原子级器件工程的前景。然而，确定性纳米线生长和掺杂剂分布和异质结构的控制受到对常用催化剂的作用，特别是其界面动力学的不完全理解的限制（1，2）。尽管在许多半导体-催化剂体系中已经证明了在低共熔温度以下纳米线的催化化学气相沉积（3-6），但是从固体催化剂的生长仍然是有争议的，并且总体机制在很大程度上没有得到解决。在这里，我们提出了一个视频速率的环境透射电子显微镜研究硅纳米线形成的钯硅化物晶体下乙硅烷曝光。Si晶核通过相分离形成，如对于液体Au - Si系统所观察到的，我们将其用作比较基准。主要的相干Pd硅化物/Si生长界面随后通过壁架的横向传播来推进，所述壁架由乙硅烷的催化解离和耦合的Pd和Si扩散驱动。我们的研究结果建立了一个原子的框架纳米线组装固体催化剂，也相关的接触形成。
Self-assembled nanowires offer the prospect of accurate and scalable device engineering at an atomistic scale for applications in electronics, photonics and biology. However, deterministic nanowire growth and the control of dopant profiles and heterostructures are limited by an incomplete understanding of the role of commonly used catalysts and specifically of their interface dynamics(1,2). Although catalytic chemical vapour deposition of nanowires below the eutectic temperature has been demonstrated in many semiconductor - catalyst systems(3-6), growth from solid catalysts is still disputed and the overall mechanism is largely unresolved. Here, we present a video-rate environmental transmission electron microscopy study of Si nanowire formation from Pd silicide crystals under disilane exposure. A Si crystal nucleus forms by phase separation, as observed for the liquid Au - Si system, which we use as a comparative benchmark. The dominant coherent Pd silicide/Si growth interface subsequently advances by lateral propagation of ledges, driven by catalytic dissociation of disilane and coupled Pd and Si diffusion. Our results establish an atomistic framework for nanowire assembly from solid catalysts, relevant also to their contact formation.