Formation of Thick Porous Anodic Alumina Films and Nanowire Arrays on Silicon Wafers and Glass

• Published in: Advanced functional materials 2003-08, Vol.13 (8), p.631-638
• Main Authors: Rabin, O., Herz, P.R., Lin, Y.-M., Akinwande, A.I., Cronin, S.B., Dresselhaus, M.S.
• Format: Article
• Language: English
• Subjects: Electrochemical deposition; Nanowires; Porous anodic alumina (PAA)
• ISSN: 1616-301X; 1616-3028
• DOI: 10.1002/adfm.200304394

A method for the fabrication of thick films of porous anodic alumina on rigid substrates is described. The anodic alumina film was generated by the anodization of an aluminum film evaporated on the substrate. The morphology of the barrier layer between the porous film and the substrate was different from that of anodic films grown on aluminum substrates. The removal of the barrier layer and the electrochemical growth of nanowires within the ordered pores were accomplished without the need to remove the anodic film from the substrate. We fabricated porous anodic alumina samples over large areas (up to 70 cm2), and deposited in them nanowire arrays of various materials. Long nanowires were obtained with lengths of at least 9 μm and aspect ratios as high as 300. Due to their mechanical robustness and the built‐in contact between the conducting substrate and the nanowires, the structures were useful for electrical transport measurements on the arrays. The method was also demonstrated on patterned and non‐planar substrates, further expanding the range of applications of these porous alumina and nanowire assemblies. Large‐area porous anodic alumina films lacking a barrier layer, and nanowire arrays of high aspect ratio nanowires (∼102) in direct contact with a conductive film, have been formed on rigid substrates. The effect of different substrates on the morphology of the film and the barrier layer was examined, and the ease of manipulation of the structures was demonstrated by patterning the films and by nanowire transport measurements.