Mimicking Nanometer Atomic Processes on a Micrometer Scale via Electrophoretic Deposition
Mimicking Nanometer Atomic Processes on a Micrometer Scale via Electrophoretic Deposition
复制标题
通过电泳沉积在微米尺度上模拟纳米原子过程
DOI：
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发表时间：
2000
期刊：
影响因子：
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通讯作者：
T. Umegaki
中科院分区：
文献类型：
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作者：
P. Sarkar;D. De;K. Yamashita;P. Nicholson;T. Umegaki
本文研究了在硅片上电泳沉积微米级（直径≤ 0.5 μm）SiO_2胶体膜时，亚单层膜的形成过程与沉积时间的关系。通过分子束外延（MBE）的原子膜生长（10000倍小的规模）的二氧化硅单层的成核和生长的过程进行了比较，并首次观察到两个生长过程之间的惊人的相似性。同样，在通过MBE的原子生长过程中，二氧化硅颗粒在EPD期间的整个成核、生长和聚集过程可以大致分为两个区域。在低的表面覆盖率时，二氧化硅颗粒沉积在集群外，随机扩散，并坚持接触他们的集群，在这个区域的增长机制如下扩散限制聚集（DLA）和二维集群的分形维数被发现是接近1.65。后来，随着团簇尺寸的增长，团簇内颗粒的沉积变得重要，团簇变得越来越紧凑，导致致密、紧密堆积和均匀的单层。这个区域被称为一个固结区，并已观察到的分形维数从1.65向2的变化，随着表面覆盖度的增加。
The process of submonolayer formation during the electrophoretic deposition (EPD) of colloidal films of micrometer-sized (diameter ∼ 0.5 μm) silica particles on a silicon wafer has been observed as a function of deposition time. The process of nucleation and growth of the silica monolayer is compared with that of atomic film growth (10000 times smaller scale) via molecular-beam epitaxy (MBE), and for the first time, a striking similarity between the two growth processes is observed. Likewise in the atomic growth process via MBE, the entire nucleation, growth, and aggregation process during EPD of silica particles can be broadly classified into two regions. At low surface coverage when silica particles are deposited outside of clusters, diffuse randomly, and stick to a cluster on touching them, the mechanism of growth in this region follows diffusion-limited aggregation (DLA) and the fractal dimension of the two-dimensional clusters is found to be close to 1.65. Later on, as the clusters grow in size, deposition of particles inside the clusters become important and clusters become more and more compact, resulting in a dense, close-packed, and homogeneous monolayer. This region is termed a consolidation region, and a change in fractal dimension from 1.65 toward 2 with increasing surface coverage has been observed.