Ellipsometric analysis of porous anodized aluminum oxide films

We performed an ellipsometric study of porous anodized aluminum oxide (AAO) films on Si substrates. Regular cylindrical porous AAO films with flat bottom structure were formed by chemical etching and anodization. The data showed typical interference oscillations as a result of the transparent characteristics of the film throughout the visible spectral range. We applied a combined effective medium approximation model with anisotropic model to obtain optical properties of the films, which can be used as basic information applicable for more complex structures.