Self-ordered Porous Anodic Alumina Templates by a Combinatory Anodization Technique in Oxalic and Selenic Acids

• Published in: Journal of electronic materials Vol. 50; no. 8; pp. 4787 - 4796
• Main Authors: Ahmadzadeh, M., Kashi, M. Almasi, Noormohammadi, M., Ramazani, A.
• Format: Journal Article
• Language: English
• Published: New York Springer US 01-08-2021; Springer Nature B.V
• Subjects: Aluminum oxide; Anodizing; Characterization and Evaluation of Materials; Chemistry and Materials Science; Diameters; Electric fields; Electronics and Microelectronics; Emission analysis; Fast Fourier transformations; Fourier transforms; Instrumentation; Materials Science; Optical and Electronic Materials; Original Research Article; Porosity; Solid State Physics; Thickness; pore ordering; anodization time; porous anodic alumina; selenic acid; Two-step anodization
• ISSN: 0361-5235; 1543-186X
• DOI: 10.1007/s11664-021-08973-x

A combinatory two-step anodization technique is presented to prepare self-ordered porous anodic alumina (PAO) templates. The first and second anodization steps are performed in oxalic and selenic acid at 40 V and 45 V, respectively, giving rise to 13-nm-diameter PAOs with high ordering and porosity of 1.4%. The anodization time for the second step is also changed to investigate the effect of the oxide layer thickness on the pore ordering, using field-emission scanning electron microscopy and fast Fourier transform analyses. Increasing the anodization time from 20 min to 1 h considerably improved the ordering and hexagonal domain structures. Further increasing the anodization time up to 8 h continuously deteriorated the ordering of the PAOs, although the nanopore growth rate remained almost constant. The fabrication of small-diameter PAOs in selenic acid is discussed and related to the electric field concentration at the oxide–electrolyte interface at the bottom of pores.