Structural and optical anisotropy of nanoporous anodic aluminum oxide

Porous aluminum oxide has stimulated considerable interest as a nanostructural template, primarily because of the self-organized formation of extremely well-aligned cylindrical pores. One of the fascinating aspects is the tunability of the interpore distance and pore diameter by simple variation of the anodization parameters such as voltage and electrolyte solution composition. Apart from the application of aluminum oxide films as filtration membranes, they are frequently used to fabricate nanowires with large aspect ratios. Many different materials, such as metals, both magnetic and nonmagnetic, semiconductors, nanotubes, and even heterostructures, have been grown in the porous membranes using primarily electrodeposition. Furthermore, porous aluminum oxide membranes have also been used as humidity sensors, or as cathodes for organic light-emitting diodes.