Conductive behavior and mechanism of carbon rods during preparing porous aluminum oxide by anodization

Porous anodic aluminum oxide (AAO) films have great potential for micro and nano fabrication. Development of metallization techniques for AAO films is necessary for AAO device fabrication. In this work, a process for electroless Cu plating on AAO films was investigated. A quick Pd2+ removal process after activation improved the adhesion between plated copper (Cu) layer and AAO films. Since the Pd catalyst at the AAO top surface was effectively removed by a complex agent, the plating reaction started approximately 15–20 μm deep in the nanopores. The Cu was continuously deposited to the top of the nanopores and finally covered the AAO surface. The adhesion strength between the Cu films and AAO films measured by the 90° peeling test method was over 0.5 kN/m. Successful electroless Cu plating on AAO is an all-wet chemical batch process that does not require sophisticated fabrication facilities, and can be used as a low-cost metallization process for producing AAO microdevices.

Structural coloration using plasmonic particles has received substantial attention due to its robust, permanent, and scalable characteristics across the full color range. In this study, a plasmonic structure based on a porous anodic aluminum oxide (AAO) film coated with a metallic film was fabricated. Colors were varied by changing the refractive index, which was achieved with a convolution with nanopores of AAO film and an infiltrated liquid crystal (LC) material. LC molecules confined in the porous AAO film were uniformly aligned, and they exhibited pore-size-dependent colors because of the specific refractive index. The thermal phase transition of the LC material in the nanopores changed the effective refractive index, switching the reflected colors, and the LC-infiltrated AAO remained stable over a month. We believe LC materials can extend the use of rigid conventional plasmonic structures from simple sensor applications to multifunctional uses such as color printing, writing pens, and displays.

A new self-ordering regime for fast production of long-range ordered porous anodic aluminum oxide films

Investigation of formation processes of an anodic porous alumina film on a silicon substrate

High-temperature annealing of porous anodic aluminium oxide prepared in selenic acid electrolyte

Fabrication of Pt microporous electrodes from anodic porous alumina and immobilization of GOD into their micropores

Review on fabrication, characterization, and applications of porous anodic aluminum oxide films with tunable pore sizes for emerging technologies

Fabrication and characterization of the hierarchical AAO film and AAO-MnO2 composite as the anode foil of aluminum electrolytic capacitor

A simple method was established based on the envelope curves of the optical transmission spectrum over the wavelength range of 200 to 2500 nm at normal inc idence, which was used for the accurate determination of the optical constants o f the anodic aluminum oxide(AAO) films. The results showed that the AAO films exhibited the optical features of a semiconductor with direct band gap of about 45 eV, and the optical constants of the AAO films depended strongly on the ano dic oxidation voltage, an important technologic parameter for preparation of AAO films. With the increase of the anodic oxidation voltage, the optical constants including the refractive index, thickness and optical band gap of AAO films inc reased, and the extinction coefficient decreased. Meanwhile, the fact that the c alculated values of the thickness of AAO films were in satisfactory agreement wi th the values of measurement illuminated that the results were well self_consist ent with the experiment.

A porous anodic aluminium oxide (AAO) films were successfully fabricated on aluminium templates by using anodizing technique. The anodizing process was done in the mixed acid solution of phosphoric acid and acetic acid. The growth, morphology and chemical composition of AAO film were investigated. During the anodizing process, the growth of the oxide pores was strictly influenced by the anodizing parameters. The anodizing was done by varying the voltage at 70 V to 130 V and temperature from 5 °C to 25 °C. The electrolyte concentration was remaining constant. In this study, all the samples were characterized using scanning electron microscope (SEM) and X-ray diffraction (XRD) techniques. From this study, the optimum parameters to obtain porous AAO film with the mixture of phosphoric acid and acetic acid solution can be known.

The anodic aluminum oxide (AAO) films were prepared by anodization method from the 15 vol. % sulphuric acid solution, and prepared AAO films were heat-treated in the ranges of 25~1000°C. AAO films were characterized by EDAX, SEM and XRD techniques, respectively. The crystal phases of prepared AAO film is amorphous. The apertures of AAO film are in 25~30 nm. AAO films are amorphous when heat treatment temperatures of AAO films are below 800 °C. After the AAO film being heat-treated in the ranges of 850°C~900 °C, the heat-treated AAO film are γ-Al2O3film. When the AAO film is heat-treated at 950 °C, the part of γ-Al2O3change into α-Al2O3, and the heat-treated AAO film are mixed film of γ-Al2O3and α-Al2O3. After the AAO film being heat-treated at 1000 °C, the heat-treated AAO film is α-Al2O3film.

Fabrication of anodic porous alumina via anodizing in cyclic oxocarbon acids

Understanding the fast formation mechanism of hard nanoporous alumina films on aluminum in acidic solutions containing nitric acid

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> Properties of anodic aluminum oxide (AAO) film as a liquid crystal (LC) alignment material is studied. We deposit the transparent porous AAO film on glass with the diameter of the pores controlled between 17–65 nm. The liquid crystal can be aligned vertically against the substrate with the AAO film. The measured polar anchoring strength is about 1.5<formula formulatype="inline"> <tex Notation="TeX">$\,\times 10 ^{-5} {\rm J/m} ^{2}$</tex></formula>, which is comparable to that of N,N-dimethyl-N-octadecyl-3-aminopropyl -trimethoxysilyl chloride (DMOAP) layer. AAO films with smaller pore diameters exhibit higher anchoring strengths. On the other hand, the uniformity of the pore array in the AAO films does not affect the alignment quality significantly. </para>

Anodic porous alumina film, a typical self-ordered nanohole material formed by anodizing aluminum in an appropriate acidic solution, is a promising candidate for starting materials of nanofabrication of various devices. Investigations concerning the cell dimensions of porous anodic alumina films have been extensively performed after the confirmation of the classical cell model proposed by Keller et al (1). It was suggested in these studies that cell dimensions, such as pore and cell diameters and barrier layer thickness, primarily depended on the formation voltage, and that they increased linearly with increasing voltage (2). Nevertheless, the importance of current density as a controlling factor of the cell geometry was sometime claimed (3, 4). According to the classical theory of ionic conduction at the high field strength for the anodic barrier film grown on various metals (5, 6), the film thickness of each metal is inversely proportional to the logarithm of ionic current when the film is formed up to the same voltage. Thus, it is indicated that the log of current density I is proportional to the electric field strength E, i.e., the formation voltage / film thickness ratio at the barrier layer, as we reported previously (7). Concerning the anion incorporation into the film, we found that anion content was also proportional to the electric field strength E, i.e., the log of current density i (7). This principal is suggested to be applicable to porous anodic films. The purpose of the present study is the confirmation of the effect of electric field strength as a controlling factor of the cell morphology of porous anodic alumina such as pore diameter / cell diameter ratio that affects to the radius of curvature of cell base pattern and porosity. In addition, effect of electric field strength on incorporation behavior of electrolyte anions into cell wall has been studied. Obtained knowledge could help us to get further insight into self-ordering mechanism of anodic porous alumina. Although pore and cell sizes of the films formed in oxalic acid were larger than those formed in sulfuric acid even at the same voltages, the ratio of cell diameter to pore diameter (dcell / d pore) of both films is in a linear relation with the logarithm of current density (log i). The electric field strength across the barrier layer of porous films varies linearly with the logarithm of current density as in the case of barrier type films. Therefore, dcell / d pore ratio is regarded to be proportional to the electric field strength. From these results, it is deduced that pore diameter is proportional to voltage and inversely propor­tional to the square of the electric field strength, whereas barrier layer thickness and cell diameter are proportional to voltage and inversely proportional to the electric field strength. Accordingly, pore diameter is more strongly affected by current density than other cell parameters are. The content of incorporated anion in the films increases linearly with increasing log i, hence electric field strength. Therefore, it is evident that the anion incorporation is exactly governed by the electric field strength. [1] F.Keller, M.S.Hunter and D.L.Robinson, This Journal, 100, 411 (1953). [2] J.P.O'Sullivan and G.C.Wood, Proc. Roy. Soc. Lond. A.317, 511 (1970). [3] K.V.Heber, Electrochim. Acta, 23, 127 (1978). [4] S. Ono, M. Saito, M. Ishiguro and H. Asoh, J. Electrochem. Soc ., 151, B473 (2004). [5] N. Cabrera and N. F. Mott, Ret. Pror. Phys., 12, 163 (1948). [6] C. J. Dell’Oca and L. Young, J. Electrochem. Soc., 117, 1548 (1970). [7] S. Ono, F. Mizutani, M. Ue, and N. Masuko, PV 2001-22, p.1129, The Electrochemical Society Proceedings Series, Pennington, NJ (2001).