Anodically formed oxide films on niobium: Microstructural and electrical properties

Störmer, Heike; Weber, André; Fischer, V.; Ivers-Tiffée, Ellen; Gerthsen, D.

doi:10.1016/j.jeurceramsoc.2008.10.019

Cited by 43 publications

(20 citation statements)

References 22 publications

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“…[1][2][3][4][5][6] In the microelectronic industry, NO is considered as a high-permittivity dielectric instead for silicon dioxide in semiconductor devices. 7 NO is also described as a promising substitute for tantalum oxide 35 in solid-electrolyte Ta 2 O 5 /Ta capacitors, 8 due to the advantage of greater natural abundance and lower price of raw material. Despite the large number of potential applications and useful properties, the well-controlled preparation of NO films with the reproducible behavior remains a challenge.…”

Section: Introductionmentioning

confidence: 99%

Formation–structure–properties of niobium-oxide nanocolumn arrays via self-organized anodization of sputter-deposited aluminum-on-niobium layers

et al. 2014

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Nanostructured niobium oxide (NO) semiconductor is gaining increasing attention as electronic, optical, and electro-optic material. However, the preparation of stable NO nanofilms with reproducible morphology and behavior remains a challenge. 10Here we show a rapid, well-controlled, and efficient way to synthesize NO films with the self-organized columnlike nanostructured morphologies and advanced functional properties. The films are developed via the growth of a nanoporous anodic alumina layer, followed by the pore-directed 15 anodizing of the Nb underlayer. The columns may grow 30-150 nm wide, up to 900 nm long, with the aspect ratio up to 20, being anchored to a thin continuous oxide layer that separates the columns from the substrate. The as anodized films have a graded chemical composition changing from amorphous Nb 2 O 5 mixed with Al 2 O 3 , Si-, and P-containing species in the surface region to NbO 2 in the lower film layer. The post-anodizing treatments result in the controlled 20 formation of Nb 2 O 5 , NbO 2 , and NbO crystal phases, accompanied by transformation from nearly perfect dielectric to n-type semiconductor behavior of the films. The approach allows for the smooth film growth without early dielectric breakdown, stress-generated defects, or destructive dissolution at the respective interfaces, which is a unique situation in the oxide films on niobium. The functional properties of the NO films, revealed to date, allow for potential applications as nanocomposite capacitor dielectrics and active 25 layers for semiconductor gas microsensors with the sensitivity to ethanol and the response to hydrogen being among best ever reported.

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Section: Introductionmentioning

confidence: 99%

Formation–structure–properties of niobium-oxide nanocolumn arrays via self-organized anodization of sputter-deposited aluminum-on-niobium layers

et al. 2014

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“…1 Recently, this material has also been appointed as a substitute of tantalum pentoxide (ε = 27) for application in solid state capacitors. 2,3 Envisaging technological applications of Nb 2 O 5 , a deep knowledge of the conditions for each phase formation as well as their properties is absolutely necessary, since niobium pentoxide is a polymorphic material exhibiting different crystalline phases. 4,5 The main phases reported in literature for Nb 2 O 5 are T-Nb 2 O 5 , and H-Nb 2 O 5 .…”

Section: Introductionmentioning

confidence: 99%

Effect of processing method on physical properties of Nb2O5

Soares

Leite

Nico

et al. 2011

Journal of the European Ceramic Society

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“…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]. The higher permittivity of Nb 2 O 5 suggests the possibility of achieving an increased capacitance of anodic Ta 2 O 5 by incorporation of units of Nb 2 O 5 .…”

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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Anodically formed oxide films on niobium: Microstructural and electrical properties

Cited by 43 publications

References 22 publications

Formation–structure–properties of niobium-oxide nanocolumn arrays via self-organized anodization of sputter-deposited aluminum-on-niobium layers

Formation–structure–properties of niobium-oxide nanocolumn arrays via self-organized anodization of sputter-deposited aluminum-on-niobium layers

Effect of processing method on physical properties of Nb2O5

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

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