Surface characterization of nanoporous aluminium oxide films synthesized by single-step DC and AC anodization

Nanoporous alumina films were synthesized on commercial grade aluminum substrates using single-step anodization technique in 0.3 M phosphoric acid at room temperature. Effect of applied voltage (100-130 V) on surface characteristics of anodized aluminum oxide (AAO) film was investigated. Surface topography parameters and regularity ratio of nanopores arrangement were characterized using power spectral density (PSD) and fast Fourier transform (FFT) profiles. While DC anodization suffered from filament-like cavities at 130 V owing to thermally enhanced dissolution of oxide, AC anodization produced localized flower-like morphology for all the applied voltages. The intensity of localized flower-like morphology was increased monotonically with applied voltage. Evolution of flower-like morphology was discussed on the basis of Pashchanka-Schneider model.