Growth kinetics of disk-shaped copper islands in electrochemical deposition.
Growth kinetics of disk-shaped copper islands in electrochemical deposition.
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DOI：
10.1103/physreve.79.051601
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发表时间：
2009-05
期刊：
影响因子：
--
通讯作者：
Lian Guo;Shouliang Zhang;P. Searson
中科院分区：
文献类型：
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作者：
Lian Guo;Shouliang Zhang;P. Searson
在电结晶中，独立决定岛屿的形状和晶体取向的能力仍然是一个重大的挑战。其主要原因是底物、成核和表面化学之间复杂的相互作用尚未完全了解。本文报道了铜在氧化钌上的岛生长动力学。小的成核过电位导致横向生长增强和六边形圆盘状岛的形成。非晶衬底允许原子核获得热力学上有利的取向，即111表面法向。岛屿生长在横向和纵向上都遵循幂律动力学。在较短的时间内，两个生长指数等于1/2，而在较长的时间内，横向生长减慢，而垂直生长加快。我们提出了一种生长机制，其中圆盘状岛屿的横向生长是由氧化钌表面上的Cu附着原子附着到岛屿周边而开始的，而垂直生长是由顶部平台上的二维成核开始的，然后是横向阶梯传播。这些结果表明了电沉积中增强横向生长的三个标准：(i)衬底导致小的成核过电位，（ii）衬底上的快速吸附原子表面扩散以促进横向生长，以及（iii）优先阴离子吸附以稳定基面。
The ability to independently dictate the shape and crystal orientation of islands in electrocrystallization remains a significant challenge. The main reason for this is that the complex interplay between the substrate, nucleation, and surface chemistry is not fully understood. Here we report on the kinetics of island growth for copper on ruthenium oxide. The small nucleation overpotential leads to enhanced lateral growth and the formation of hexagonal disk-shaped islands. The amorphous substrate allows the nuclei to achieve the thermodynamically favorable orientation, i.e., a 111 surface normal. Island growth follows power law kinetics in both lateral and vertical directions. At shorter times, the two growth exponents are equal to 1/2 whereas at longer times lateral growth slows down while vertical growth speeds up. We propose a growth mechanism, wherein the lateral growth of disk-shaped islands is initiated by attachment of Cu adatoms on the ruthenium oxide surface onto the island periphery while vertical growth is initiated by two-dimensional nucleation on the top terrace and followed by lateral step propagation. These results indicate three criteria for enhanced lateral growth in electrodeposition: (i) a substrate that leads to a small nucleation overpotential, (ii) fast adatom surface diffusion on substrate to promote lateral growth, and (iii) preferential anion adsorption to stabilize the basal plane.