Sayed Sayed Y, Wang Feng, Malac Marek, Meldrum Al, Egerton Ray F, Buriak Jillian M
National Institute for Nanotechnology, National Research Council, 11421 Saskatchewan Drive, Edmonton T6G 2M9, Canada.
ACS Nano. 2009 Sep 22;3(9):2809-17. doi: 10.1021/nn900685a.
This work focuses on the synthesis and interfacial characterization of gold nanostructures on silicon surfaces, including Si(111), Si(100), and Si nanowires. The synthetic approach uses galvanic displacement, a type of electroless deposition that takes place in an efficient manner under aqueous, room-temperature conditions. The case of gold-on-silicon has been widely studied and used for several applications and yet, a number of important, fundamental questions remain as to the nature of the interface. Some studies are suggestive of heteroepitaxial growth of gold on the silicon surface, whereas others point to the existence of a silicon-gold intermetallic sandwiched between the metallic gold and the underlying silicon substrate. Through detailed high resolution transmission electron microscopy (TEM), combined with selected area electron diffraction (SAED) and nanobeam diffraction (NBD), heteroepitaxial gold that is grown by galvanic displacement is confirmed on both Si(100) and Si(111), as well as silicon nanowires. The coincident site lattice (CSL) of gold-on-silicon results in a very small 0.2% lattice mismatch due to the coincidence of four gold lattices to three of silicon. The presence of gold-silicon intermetallics is suggested by the appearance of additional spots in the electron diffraction data. The gold-silicon interfaces appear heterogeneous with distinct areas of heteroepitaxial gold on silicon, and others, less well-defined, where intermetallics may reside. The high resolution cross-sectional TEM images reveal a roughened silicon interface under these aqueous galvanic displacement conditions, which most likely promotes nucleation of metallic gold islands that merge over time: a Volmer-Weber growth mechanism in the initial stages.
这项工作聚焦于硅表面（包括Si(111)、Si(100)和硅纳米线）上金纳米结构的合成及界面表征。合成方法采用无电沉积中的一种——电偶置换，该过程在水相室温条件下高效发生。硅上镀金的情况已得到广泛研究并用于多种应用，但关于界面的性质仍存在一些重要的基本问题。一些研究表明金在硅表面外延生长，而另一些研究则指出在金属金和下层硅衬底之间存在硅 - 金金属间化合物。通过详细的高分辨率透射电子显微镜（TEM），结合选区电子衍射（SAED）和纳米束衍射（NBD），证实了通过电偶置换生长的外延金在Si(100)、Si(111)以及硅纳米线上均存在。硅上金的重合点阵（CSL）由于四个金晶格与三个硅晶格重合，导致晶格失配非常小，仅为0.2%。电子衍射数据中出现的额外斑点表明存在金 - 硅金属间化合物。金 - 硅界面呈现出异质性，在硅上有明显的外延金区域，还有一些不太明确的区域，可能存在金属间化合物。高分辨率横截面TEM图像显示，在这些水相电偶置换条件下，硅界面变得粗糙，这很可能促进了金属金岛的成核，随着时间推移这些金岛会合并：这是初始阶段的伏尔默 - 韦伯生长机制。
