Mimicking nanometer atomic processes on a micrometer scale via electrophoretic deposition

The process of submonolayer formation during the electrophoretic deposition (EPD) of colloidal films of micrometer-sized (diameter approximate to 0.5 mu m) silica particles on a silicon wafer has been observed as a function o f deposition time. The process of nucleation and growth of the silica monol ayer is compared with that of atomic film growth (10000 times smaller scale ) via molecular-beam epitaxy (MBE), and for the first time, a striking simi larity between the two growth processes is observed, Likewise in the atomic growth process via MBE, the entire nucleation, growth, and aggregation pro cess during EPD of silica particles can be broadly classified into two regi ons, At low surface coverage when silica particles are deposited outside of clusters, diffuse randomly, and stick to a cluster on touching them, the m echanism of growth in this region follows diffusion-limited aggregation (DL A) 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 parti cles inside the clusters become important and clusters become more and more compact, resulting in a dense, close-packed, and homogeneous monolayer, Th is region is termed a consolidation region, and a change in fractal dimensi on from 1.65 toward 2 with increasing surface coverage has been observed.