Dielectric and mechanical properties of anodic films in the Ta–Ti system

Mato, S.; Alcalá, G.; Skeldon, P.; Thompson, G.E.; Mann, A.; Masheder, D.; Habazaki, H.; Shimizu, K.

doi:10.1002/sia.1549

Cited by 13 publications

(3 citation statements)

References 31 publications

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“…The change in band gap energy of "mixed oxide" with composition is also of fundamental interest [22]. Anodizing of tantalum alloys has been investigated for improving the dielectric properties of anodic Ta 2 O 5 , which is extensively used as a dielectric in the capacitor industry, as well as for increased understanding of the growth mechanism of anodic oxides [23][24][25][26][27][28][29][30][31]. Anodic Nb 2 O 5 formed on niobium is also a promising dielectric for capacitor applications due to the high dielectric constant (ε ox =42) compared with anodic Ta 2 O 5 (ε ox =27) [32,33].…”

Section: Introductionmentioning

confidence: 99%

Growth and field crystallization of anodic films on Ta–Nb alloys

Komiyama

Tsuji

Aoki

et al. 2011

J Solid State Electrochem

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The growth behavior of amorphous anodic films\ud on Ta–Nb solid solution alloys has been investigated over a\ud wide composition range at a constant current density of\ud 50 Am−2 in 0.1 mol dm−3 ammonium pentaborate\ud electrolyte. The anodic films consist of two layers,\ud comprising a thin outer Nb2O5 layer and an inner layer\ud consisting of units of Ta2O5 and Nb2O5. The outer Nb2O5\ud layer is formed as a consequence of the faster outward\ud migration of Nb5+ ions, compared with Ta5+ ions, during\ud film growth under the high electric field. Their relative\ud migration rates are independent of the alloy composition.\ud The formation ratio, density, and capacitance of the films\ud show a linear relation to the alloy composition. The\ud susceptibility of the anodic films to field crystallization\ud during anodizing at constant voltage increases with increasing\ud niobium content of the alloy

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Section: Introductionmentioning

confidence: 99%

Growth and field crystallization of anodic films on Ta–Nb alloys

Komiyama

Tsuji

Aoki

et al. 2011

J Solid State Electrochem

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“…Anodic ZrO 2 is commonly not considered for use in electrolytic capacitors because of the unacceptably high oxide formation ratio (2.5 nm V −1 ), which is substantially higher than that for Al 2 O 3 (1.3 nm V −1 ) and even Ta 2 O 5 (1.7 nm V −1 ). [ 20,26,27 ] This means that among the three oxides, a considerably thicker ZrO 2 film grows at the same applied voltage, which makes the capacitance density of ZrO 2 ‐based devices relatively smaller despite the comparable permittivities of ZrO 2 and Ta 2 O 5 . The PAA‐assisted ZrO 2 ‐Al 2 O 3 mixed anodic films are expected to grow with a reduced formation ratio, closer to that of Al 2 O 3 , similarly to the effect disclosed for the PAA‐assisted anodization of Ta.…”

Section: Introductionmentioning

confidence: 99%

The Growth, Composition, and Functional Properties of Self‐Organized Nanostructured ZrO₂‐Al₂O₃ Anodic Films for Advanced Dielectric Applications

Kamnev

Sepúlveda

Bendová

et al. 2021

Adv Elect Materials

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An aluminum‐on‐zirconium bilayer is anodized in oxalic acid solution to transform the Al layer into porous anodic alumina (PAA); this is followed by the PAA‐assisted re‐anodizing of the Zr underlayer at voltages 40–280 V. The process results in an array of amorphous ZrO2 nanocolumns, 45–330 nm long, partly filling the PAA pores and anchored to a continuous bottom oxide layer under the pores, 20–130 nm thick, comprising a ZrO1.8 spongelike sublayer superimposed on a ZrO1.5 compact sublayer. The thicknesses of the nanostructured and bottom oxides increase linearly with re‐anodizing voltage, disclosing a low film formation ratio of 1.65 nm V−1, which is impossible with anodic ZrO2. The amorphous ZrO2 nanocolumns embedded in the highly resistive amorphous PAA matrix combined with the laminated bottom oxide reveal a nearly ideal dielectric performance in a wide frequency range (10−4–104 Hz) complemented by the low leakage currents and high breakdown voltages (up to 280 V). The film permittivity may be tuned, from 11 to 20, by combining the anodizing and pore‐widening techniques. The advantageous architecture, fabrication approach, and functional properties of the films allow the design of a prototype of an emerging hybrid polymer electrolytic microcapacitor for on‐chip integration.

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“…The anodic films formed on alloys have been investigated to examine the growth mechanism and dielectric properties. 10,1826 In this study, we have examined the formation and dielectric properties of anodic films formed on Ta-W alloys. Tungsten has been selected since the permittivity of WO 3 (¾ ox = 42) is higher than that of Ta 2 O 5 (¾ ox = 27).…”

Section: Introductionmentioning

confidence: 99%

Formation and Dielectric Properties of Anodic Films Formed on Ta-W Alloys at Various Formation Voltages

et al. 2013

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Barrier-type anodic films are formed on magnetron sputtered Ta-W alloy films to various formation potentials in 0.1 mol dm −3 ammonium pentaborate electrolyte. The anodic films consist of two layers, comprising an outer thin Ta 2 O 5 layer free from tungsten species and an inner layer containing both tantalum and tungsten species. Slower migration of W 6+ ions with respect to Ta 5+ ions results in the formation of the two-layered films. Because of the absence of more soluble tungsten species in the outer layer, the anodic films grow at high current efficiency. The reciprocal of capacitance of the anodic films changes linearly with formation voltage, as a consequence of linear thickening of the anodic films with the formation potential. The capacitance is enhanced by the addition of tungsten, particularly at low formation potential. The shift of the potential, at which the anodic film growth commences, to the noble direction, contributes to the enhanced capacitance at the low formation voltages.

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Dielectric and mechanical properties of anodic films in the Ta–Ti system

Cited by 13 publications

References 31 publications

Growth and field crystallization of anodic films on Ta–Nb alloys

Growth and field crystallization of anodic films on Ta–Nb alloys

The Growth, Composition, and Functional Properties of Self‐Organized Nanostructured ZrO₂‐Al₂O₃ Anodic Films for Advanced Dielectric Applications

Formation and Dielectric Properties of Anodic Films Formed on Ta-W Alloys at Various Formation Voltages

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Dielectric and mechanical properties of anodic films in the Ta–Ti system

Cited by 13 publications

References 31 publications

Growth and field crystallization of anodic films on Ta–Nb alloys

Growth and field crystallization of anodic films on Ta–Nb alloys

The Growth, Composition, and Functional Properties of Self‐Organized Nanostructured ZrO2‐Al2O3 Anodic Films for Advanced Dielectric Applications

Formation and Dielectric Properties of Anodic Films Formed on Ta-W Alloys at Various Formation Voltages

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The Growth, Composition, and Functional Properties of Self‐Organized Nanostructured ZrO₂‐Al₂O₃ Anodic Films for Advanced Dielectric Applications