Electrochemical Impedance Investigation of Anodic Alumina Barrier Layer

Benfedda, B.; Hamadou, L.; Benbrahim, N.; Kadri, A.; Chaînet, Eric; Charlot, F.

doi:10.1149/2.068208jes

Cited by 23 publications

(21 citation statements)

References 62 publications

(69 reference statements)

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“…Our results on the concentration of electron traps in porous alumina are in good agreement with the data obtained by Huang et al 27 Benfedda et al 28 for sulfuric and oxalic acid alumina films, respectively. …”

Section: Resultssupporting

confidence: 93%

Re-Anodizing Technique as a Method of Investigation of Thermally Activated Defects in Anodic Alumina Films

Vrublevsky

Jagminas

Chernyakova

2013

J. Electrochem. Soc.

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A new approach of determination of energy of shallow thermally activated traps in the anodic alumina films is suggested. The approach consists of the heat-treatment of the anodic Al 2 O 3 |Al structure at 100-350 • C (this means thermal release of electrons from the traps) and then re-anodizing of the anodic films in the barrier type electrolytes in potentiodynamic mode (refilling of electron traps during transient processes). In comparison with existing methods (thermoactivated and surface soft-X-ray absorption and photoemission spectroscopy), this method is relatively simple and can be applied to investigate electron trap levels both in semiconductor and insulator films. The algorithm of data-processing of experimental results was also proposed to obtain the parameters of thermally activated electron traps. It was applied to calculate the activation energy of electron traps that is equal to 0.147 and 0.060 eV for sulfuric and oxalic acid alumina films, respectively. The concentration of the traps was determined to be on the order of 10 19 cm −3 . The electron traps are believed to be due to the presence of coordinatively unsaturated aluminum ions, their presence was confirmed by FTIR spectroscopy. On the basis of data obtained a model is suggested for the transitions that take place in the barrier layer of the anodic alumina during heating and re-anodizing.A great number of adsorbents and catalysts are amorphous oxides. Therefore, it is important to investigate local energy states in the bandgap of the amorphous semiconductors and insulators.As is known, the films of amorphous anodic alumina with high ordered cell-porous structure is formed on the surface of aluminum when anodizing takes place in aqueous solutions of sulphuric, oxalic, phosphoric acids, and etc. 1 High reproducibility of the oxide parameters (pore diameter, cell one and pore density) are provided by self-organizing growth of the nanopore films that can be achieved by an anodizing voltage control. 2 Now porous alumina films are used for formation of metal nanowires, 3-5 arrays of carbon nanowires, 6,7 porous membranes, 8 and nanostructure magnetic materials. 9 As a result of anion incorporation into the oxide structure during anodizing of aluminum, properties of porous alumina films depend on the nature of the anodizing electrolyte. According to Lambert et al. 10 anion incorporation could be a reason for the induction of mechanical stress in the anodic oxide, which results in the origin of point defects such as electron traps. Other authors believe that the electron traps result from the defects caused by disturbance of coordination environment of aluminum ions due to acid anion incorporation or products of their oxidation in the anodic alumina. 11 In the anodic alumina layers under high strength electric field photoand electroluminescence, 12 electrical breakdown, 13,14 and switching effects in MIM-structures (metal-insulator-metal) 15 are due to the processes of capture and transfer of electrons in the electron traps. UV radiation and magnetic...

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Section: Resultssupporting

confidence: 93%

Re-Anodizing Technique as a Method of Investigation of Thermally Activated Defects in Anodic Alumina Films

Vrublevsky

Jagminas

Chernyakova

2013

J. Electrochem. Soc.

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“…Otherwise, corrosion of this barrier layer would depend on the acceptor density. Our conclusion on the n-type oxide/electrolyte interface is consistent with the conclusions of Vrublevsky [20][21][22][23] and Benfedda [24].…”

Section: Defect Density and Corrosion Protection Of Aaosupporting

confidence: 92%

“…The inner region of oxide/metal interface was excess in metallic cation and n-type behavior. An opposite view was given in the works of Vrublevsky [20][21][22][23] and also Benfedda [24], who considered that negative charges such as electrons were trapped at the oxide/electrolyte interface and acted as donors for the n-type behavior. Positive charges, such as holes, were trapped at the oxide/metal interface, acting as acceptors responsible for the p-type behavior.…”

Section: Introductionmentioning

confidence: 99%

Correlation between Defect Density and Corrosion Parameter of Electrochemically Oxidized Aluminum

2019

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It has been recognized that a connection may exist between defects of oxide coating and its corrosion protection. Such a link has not been substantiated. We prepare two coatings of anodized aluminum oxide (AAO) and plasma electrolytic oxidation (PEO), and analyze them with Mott-Schottky plots and potentiodynamic polarization scans. The as-grown and annealed AAO coatings exhibit both p-type and n-type semiconductor behaviors. Polarization resistance of the AAO coating increases from (1.8 ± 1.7) × 108 to (4.3 ± 0.5) × 108 Ω·cm2, while corrosion current decreases from (6.1 ± 3.6) × 10−7 to (2.3 ± 0.9) × 10−7 A·cm−2, as annealing temperature increases from room temperature to 400 °C. The parameter analysis on AAO indicates a positive correlation between corrosion current and donor density, a negative correlation between polarization resistance and donor density. The attempt on correlating corrosion potential gives rise to considerable deviation from a linear fit. The results suggest protection of AAO hinges on its donor density, not acceptor. On the PEO coatings, only the n-type behavior is observed. Intriguingly, the donor density of PEO coating is influenced by the annealing temperature of its pre-anodized layer. The most resistant PEO coating, with pre-anodized and 400 °C annealed AAO, exhibits polarization resistance (2.1 ± 0.4) × 109 Ω·cm2 and corrosion current (1.7 ± 0.4) × 10−8 A·cm−2.

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“…31 Specific values for aluminum oxide barrier layers have recently been measured at 10 18 -10 19 cm À3 , depending on thickness. 32 Significant electronic conductivity may therefore be present, and various electronic conduction processes become thus possible. 33 These include Schottky emission (SE), Poole-Frenkel emission (PF), and Fowler-Nordheim tunneling (FN); 34 the total electronic current would therefore be j ¼ j SE þ j PF þ j FN .…”

Section: Electronic Conduction Processes In Mom Contactsmentioning

confidence: 99%

Dielectric breakdown and failure of anodic aluminum oxide films for electrowetting systems

Mibus

Jensen

et al. 2013

Journal of Applied Physics

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We study electrical properties and breakdown phenomena in metal/aluminum oxide/metal and electrolyte/aluminum oxide/metal contacts, with the aim to achieve a better understanding of failure modes and improve the performance of model electrowetting systems. Electrical conduction in anodic aluminum oxide dielectrics is dominated by the presence of electrically active trapping sites, resulting in various conduction mechanisms being dominant within distinct voltage ranges until hard breakdown occurs. Breakdown voltage depends on its polarity, due to the formation of a p-in junction within the oxide; such asymmetric behavior tends to disappear at larger oxide thickness. Electrolyte/dielectric contacts present an even more pronounced asymmetry in breakdown characteristics: a cathodic bias results in breakdown at low voltage, while under anodic bias high field ionic conduction starts before breakdown occurs. These phenomena are interpreted in terms of electrochemical reactions occurring at the surface: cathodic processes contribute to oxide dissolution and failure, while anodic processes result in additional oxide growth before breakdown. V

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Electrochemical Impedance Investigation of Anodic Alumina Barrier Layer

Cited by 23 publications

References 62 publications

Re-Anodizing Technique as a Method of Investigation of Thermally Activated Defects in Anodic Alumina Films

Re-Anodizing Technique as a Method of Investigation of Thermally Activated Defects in Anodic Alumina Films

Correlation between Defect Density and Corrosion Parameter of Electrochemically Oxidized Aluminum

Dielectric breakdown and failure of anodic aluminum oxide films for electrowetting systems

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