Radisic A, Ross F M, Searson P C
Department of Materials Science and Engineering, Johns Hopkins University, Baltimore, MA 21218, USA.
J Phys Chem B. 2006 Apr 20;110(15):7862-8. doi: 10.1021/jp057549a.
The growth kinetics for individual islands during electrodeposition of copper have been studied using in situ transmission electron microscopy. We show that for sufficiently large overpotentials, the growth kinetics approach the rate laws expected for diffusion-limited growth of hemispherical islands, characterized by two distinct regimes. At short times, the island growth exponent is 0.5 as expected for diffusion-limited growth of uncoupled hemispherical islands, while at longer times, the growth exponent approaches 1/6 as expected for planar diffusion to the growing islands. These results provide the first direct measurements of the growth of individual islands during electrochemical deposition. However, quantitative comparison with rate laws shows that the island radii are smaller than predicted and the island densities are much larger than predicted, and we suggest that this is related to adatom formation and surface diffusion, processes which are not included in conventional growth models.
利用原位透射电子显微镜研究了铜电沉积过程中单个岛状结构的生长动力学。我们发现，对于足够大的过电势，生长动力学接近半球形岛状结构扩散限制生长预期的速率定律，其特征为两个不同的阶段。在短时间内，岛状结构的生长指数为0.5，这与未耦合半球形岛状结构的扩散限制生长预期一致；而在较长时间，生长指数接近1/6，这与向生长岛状结构的平面扩散预期一致。这些结果首次直接测量了电化学沉积过程中单个岛状结构的生长。然而，与速率定律的定量比较表明，岛状结构的半径比预测值小，岛状结构的密度比预测值大得多，我们认为这与吸附原子的形成和表面扩散有关，而这些过程并未包含在传统的生长模型中。
