Anodizing process of Al films on Si substrates for forming alumina templates with short-distance ordered 25 nm nanopores

Porous alumina templates with short-distance ordered 25 nm nanopores were fabricated by controlling anodizing progress of Al films on Si substrates in sulfuric acid solution. The ordering of nanopore arrangement with a hexagonal symmetry was found to be closely related to thickness of the deposited Al film, growth temperature, applied voltage, and solution concentration. These parameters were explored in detail and proper experimental conditions were obtained to be 0.44 μm, 5 °C, 20 V, and 15 wt.% for the formation of a relatively ordered nanopore array. Anodizing progress of the Al film was monitored through the current-time (I-t) curve. Infrared transmittance spectral characterization and microstructural observations disclose that a SiO ₂ island array has been formed on the surface of Si substrate under our experimental conditions. This kind of SiO₂ island array can be expected to have applications in nanoelectronics and optoelectronics. © 2005 Elsevier B.V. All rights reserved.