Elaboration of highly ordered nanoporous alumina by two-step anodization: influence of experimental parameters on porous layer structure

摘要

Highly ordered nanoporous alumina film has been widely investigated especially since the discovery of two-step anodizing process by Masuda and Fukada in 1995 because of their possible applications in nanotechnology. Coloring, template for nanotubes and nanowire, optic and electronic nanodevices can be quoted. The geometry of these films is characterized by closed packed arrays of columnar hexagonal cells each containing a central pore. Theoretically and ideally, the cell size and the pore size are respectively comprised between 25 and 500 nm and between 10 and 300 nm. Both of them depend on the anodizing parameters. The depth of the channel is the depth of the porous layer and can reach one hundred micrometers. Practically some effort must be done concerning the study of experimental parameters influence on the porous layer structure. The aim of our work is to progress in the exhaustive study of the influence of experimental parameters. Voltage, electrolyte nature and concentration, temperature, anodizing duration, nature of the substrate and anion role have been investigated. Our aim is to be able to choose experimental parameters to obtain ordered film whatever the chosen film depth, cell size and pore size. In fact, it is well known for some geometry, a 100 nm interpore distance for instance, but less known for 150 nm for instance.