. . . . . . . . . .    ANM 2010     3rd International Conference on Advanced Nano Materials     12-15 September 2010 - Agadir, Morocco Back    Abstract ANMM279 USING NANOSCALE SURFACE TOPOGRAPHY TO CONTROL PORE SIZE AND ORDER IN ANODIC ALUMINUM OXIDE A. Apolinario 1, D. C. Leitao 1,2, C. T. Sousa 1, J. Ventura 1, J. B. Sousa 1, M. Vazquez 2, J. P. Araujo 1 1 IFIMUP and IN - Institute of Nanoscience and Nanotechnology, Departamento de Fisica, Faculdade de Ciencias, Universidade do Porto, Rua do Campo Alegre, 687, 4169-007 Porto, Portugal 2 Instituto de Ciencia de Materiales de Madrid, CSIC, Campus Cantoblanco 28049 Madrid, Spain . In the last twenty years, anodic aluminum oxide (AAO) membranes emerged as an extremely popular template-based method for the fabrication of a wide range of nanostructures. For many technological applications, such as high density magnetic media, photonic crystals or pattern-transfer masks, the ordering and organization of the nanopores is a crucial factor and a high degree of regularity and uniformity is required. This work stresses the usefulness of electropolishing as a tool to control and tune the initial aluminum (Al) surface at the nanoscale, leading to significant improvements in the AAO hexagonal-domain size and pore dimension uniformity. Such an effective control of the AAO properties was achieved by simply changing the electropolishing time (tEP). With increasing tEP besides the reduced surface roughness (Rsuf), AFM characterization also revealed dimple-nanopatterns on the treated Al. The effect of such landscapes on the AAO-surface after first and second anodizations was studied in detail. SEM images of the first anodization surfaces showed an AAO with well defined pores but no organized structure, whilst after the second anodization hexagonal patterns were already visible. Quantitative Fast Fourier Transform analysis of SEM images allowed us to infer directly the periodicity of the porous structure, enabling an easy and straightforward way to evaluate the lattice constant and its long/short range-order. In addition, from statistical analysis an increase of nanopore average diameters (<Dpore>) with tEP was observed; an increasing sharpness of Dpore Gaussian distribution which translates in the decrease of the corresponding standard deviation (σpore) was also obtained. Our results clearly established a quantitative dependence of the spatial-order parameter (γ) and σpore on Rsuf, showing that tailoring of the nanoscale topography upon EP results in AAO with improved order (higher γ) and uniformity (lower σpore), thus  reflecting a close correlation between the Al surface and AAO properties. . © nanoAC . . . . . . . . . .

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