Electrochemical Nucleation of SiOx Nanoparticles into the Pore Bottoms of an Anodic Aluminum Oxide

Abstract

Utilizing the wafer-scale anodization of a thermally evaporated Ti layer onto a Si substrate, SiOx nanoparticles could be electrochemically nucleated into the pore bottoms of an anodic aluminum oxide. The formation of a Si-containing Ti layer (Ti1-xSix, x < 0.1) was identified between the Al and the silicon substrate by thermal diffusion of Si during the evaporation. Upon prolonged anodization of similar to 1 h after alumina barrier layer touched the Si-containing Ti layer, pyramid-shaped TiOx nanopillars formed underneath the pore bottoms as a result of a curvature inversion of the barrier oxide with Ti migration. These TiOx nanopillars were observed to act as a diffusion route of silicon from the Si-containing Ti layer. Only one SiOx nanoparticle (similar to 8 +/- 5 nm) for each pore was generally precipitated without Ti contamination. This finding suggests a new route which can make SiOx nanoparticles confined within an anodic aluminum oxide template.