The influence of the surface migration of gold on the growth of silicon nanowires
The influence of the surface migration of gold on the growth of silicon nanowires
复制标题
DOI：
10.1038/nature04574
复制
发表时间：
2006-03-02
期刊：
影响因子：
64.8
通讯作者：
Tromp, RM
中科院分区：
文献类型：
--
作者：
Hannon, JB;Kodambaka, S;Tromp, RM
在纳米线的兴趣继续增长，部分由纳米技术的应用（1-5）。设计纳米线特性的能力使它们在纳米电子学中特别有前途（6-9）。大多数硅纳米线使用汽液固（VLS）机制生长，其中纳米线在硅化学气相沉积期间从金/硅催化剂液滴生长（10-13）。尽管有40多年的研究，VLS增长的许多方面还没有得到很好的理解。例如，在常规图片中，催化剂液滴在生长期间不改变，并且纳米线侧壁由干净的硅刻面（10-13）组成。在这里，我们证明了这些假设是错误的Si（111）上生长的硅纳米线的条件下，所有的实验参数（表面结构，气体清洁度，和背景污染物）被仔细控制。我们发现，在生长过程中的金扩散决定的长度，形状和侧壁的纳米线的属性。来自催化剂液滴的金润湿纳米线侧壁，最终消耗液滴并终止VLS生长。金从较小的液滴扩散到较大的液滴（奥斯特瓦尔德熟化）导致纳米线直径在生长过程中发生变化。这些结果表明，硅纳米线的生长是从根本上限制了金扩散：光滑，任意长的纳米线不能生长没有消除金迁移。
Interest in nanowires continues to grow, fuelled in part by applications in nanotechnology(1-5). The ability to engineer nanowire properties makes them especially promising in nanoelectronics(6-9). Most silicon nanowires are grown using the vapour liquid - solid (VLS) mechanism, in which the nanowire grows from a gold/silicon catalyst droplet during silicon chemical vapour deposition(10-13). Despite over 40 years of study, many aspects of VLS growth are not well understood. For example, in the conventional picture the catalyst droplet does not change during growth, and the nanowire sidewalls consist of clean silicon facets(10-13). Here we demonstrate that these assumptions are false for silicon nanowires grown on Si( 111) under conditions where all of the experimental parameters ( surface structure, gas cleanliness, and background contaminants) are carefully controlled. We show that gold diffusion during growth determines the length, shape, and sidewall properties of the nanowires. Gold from the catalyst droplets wets the nanowire sidewalls, eventually consuming the droplets and terminating VLS growth. Gold diffusion from the smaller droplets to the larger ones (Ostwald ripening) leads to nanowire diameters that change during growth. These results show that the silicon nanowire growth is fundamentally limited by gold diffusion: smooth, arbitrarily long nanowires cannot be grown without eliminating gold migration.