Developing Cu pore-filling percentage in hard anodized anodic aluminum oxide templates with large diameters

• Published in: Materials chemistry and physics Vol. 260; p. 124109
• Main Authors: Hosseinabadi, Z., Ramazani, A., Almasi Kashi, M.
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 15-02-2021; Elsevier BV
• Subjects: Aluminum; Aluminum oxide; Arrays; Barrier layers; Cu nanowire arrays; Emission analysis; Hard anodized AAO; High aspect ratio; Investigations; Large pore diameter; Nanotechnology devices; Nanowires; Pore-filling percentage; Pulsed electrochemical deposition; Cu solution concentration; Pulsed electrochemical deposition; anodic aluminum oxide; Pore-filling percentage; pore diameter; Large pore diameter; Cu nanowire arrays; Nanowires; Hard anodized AAO; high aspect ratio
• ISSN: 0254-0584; 1879-3312
• DOI: 10.1016/j.matchemphys.2020.124109

This study aims to overcome a major challenge that is reaching high pore-filling percentage (FP) in the fabrication of high aspect ratio (HAR) nanowires (NWs) grown electrochemically in large diameter porous templates. By ultrathinning the barrier layer of hard anodized anodic aluminum oxide (AAO) templates with large pore diameters (Dp) of 110 and 180 nm, while also filling its branched sections with FeCoNi, the development of Cu FP was investigated for different Cu solution concentration (MCu = 0.05–0.3 M) in the fabrication of HAR Cu NW arrays using a pulsed electrochemical deposition technique under optimized parameters. At Dp = 180 nm, field-emission scanning electron microscopic investigations revealed that, increasing MCu increases the corresponding FP up to 62%, resulting in highly uniform NW arrays. Structural properties were investigated by X-ray diffraction analysis, indicating that different phase percentages of Cu and Cu2O are formed depending on Dp of AAO and MCu. The resulting HAR Cu NWs were also released from the hard templates to obtain free-standing NW arrays with a length of 70 μm, which may find potential use for large-scale nanodevice applications.
By ultrathinning the alumina barrier layer and filling the branched sections of nanopores with FeCoNi material, it is possible to achieve a high porefilling percentage of 62%. This leads to the formation of high uniformity and free-standing Cu nanowire arrays with a length of 70 μm and a large diameter of 180 nm in steady-state electrochemical deposition. [Display omitted]
•FP of hard anodized AAO templates was investigated in the fabrication of Cu NW arrays.•AAO barrier layer was ultrathinned and its branched sections were filled with FeCoNi.•Electrochemical deposition was optimized through changing Cu electrolyte concentration.•High FP of 62% was obtained for 70 μm thick AAO template with a large diameter of 180 nm.•Highly crystalline HAR NWs comprised different fractions of Cu and Cu2O phases.