Stability and effect of annealing on the optical properties of plasma-deposited Ta2O5 and Nb2O5 films

Masse, Jean-Philippe; Szymanowski, H.; Zabeida, O.; Amassian, Aram; Klemberg-Sapieha, J.E.; Martinů, L.

doi:10.1016/j.tsf.2006.05.047

Cited by 102 publications

(53 citation statements)

References 32 publications

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“…With increasing α, the spectra of as-deposited coatings exhibited an evolution from a typical signature of Nb-N bonds (α = 0.3) [16] to the appearance of Nb-O ones seen for α = 0.9. The diffuse bands in the range from 600 to 950 cm − 1 are attributed to Nb-O stretching vibrations, as shown in literature for Nb 2 O 5 compounds [17]. The spectrum corresponding to the intermediate duty cycle presented a transition regime.…”

Section: Chemical Composition Crystallographic Structure and Bondingsupporting

confidence: 76%

Influence of air oxidation on the properties of decorative NbOxNy coatings prepared by reactive gas pulsing

Chappé¹,

Carvalho²,

Lanceros-Méndez³

et al. 2008

Surface and Coatings Technology

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In this work the oxidation resistance of DC reactive sputtered niobium oxynitrides and its influence on the properties of the films are studied. The depositions have been carried out by DC magnetron sputtering with a reactive gas pulsing process. The nitrogen flow was kept constant and the oxygen flow was pulsed. Pulse durations of 10 s produced multilayer coatings with a period of λ = 10 nm. Three sets of films with increasing duty cycle (= on-time of high oxygen flow / pulse duration) have been deposited. The films were subsequently annealed in air at 400, 500 and 600°C, respectively. X-ray diffraction measurements showed a clear and progressive change from a roughly amorphous nature of the films to a crystalline oxidetype compound for those annealed at 600°C, which was consistent with the composition analysis. For annealing temperatures of 500 and 600°C, the coatings presented a significant reduction in hardness, approaching the values characteristic of Nb 2 O 5 -type films. Moreover, the residual stress measurements performed by using the deflection method revealed low values in all the coatings nearly independent on the annealing temperature.Color variation in the CIE − L ⁎ a ⁎ b ⁎ color space and the reflectance in the UV-visible spectrum range of these niobium oxynitrides were investigated and correlated to their chemical composition and structural features. For both properties, the variation tendencies are quite similar, showing the transition from a nitride-type alloy to an oxide-type one with increasing annealing temperature.

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Section: Chemical Composition Crystallographic Structure and Bondingsupporting

confidence: 76%

Influence of air oxidation on the properties of decorative NbOxNy coatings prepared by reactive gas pulsing

Chappé¹,

Carvalho²,

Lanceros-Méndez³

et al. 2008

Surface and Coatings Technology

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“…Activated conduction processes which can be influenced by small electric fields may happen in the band, similar to conduction on the edge of the conduction band as known in the so called Urbach tails. [76][77][78] The influence of the field is large for photon energies of 2 eV, meaning conduction processes at the edge of the band. With higher photon energies the influence of the field becomes weaker and vanishes nearly for 4 eV (see Fig.…”

Section: -63mentioning

confidence: 99%

Charge Transport Through Thin Amorphous Titanium and Tantalum Oxide Layers

Stella¹,

Kovacs²,

Diesing³

et al. 2011

J. Electrochem. Soc.

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Heterosystems of metal/insulator/gold type with titanium oxide and tantalum oxide as internal barriers are studied using internal photoemission (IPE), field induced current transport (current transients after voltage steps) and chemical reaction induced current transport (chemicurrent). IPE investigations over a broad energy range from 0.8 to 4.5 eV allow a determination of the interstitial layers band gap and the maximum height of the internal tunnel barrier. The built-in field of the heterosystem is derived by the evaluation of the slope in the photoyield versus photon energy plot. Current transients recorded after voltage steps allow the determination of the heterosystems time constants which generally have a value of some milli seconds. In titanium oxide systems additional time constants with values of several 100 s appear for bias voltages >0.5 V. These time constants are assigned to slow processes altering the height of the titanium oxide barriers. and electron sources in spin polarized tunneling. 5 In the present work we present a comparative investigation of charge transport induced by different methods through thin oxide films. Charges are driven through the oxide by: i) application of a device voltage ii) illumination of the samples with monochromatic light at variable photon energies, leading to spectra of internal photoemission, iii) non adiabatic chemical surface reactions. All three methods are combined since it is possible to derive the nature of excited carriers transport through heterosystems.6 For aluminum and tantalum oxide heterosystems it was found, that they form a high pass filter for excited electrons and holes (defect electrons). 4,6 Since the height of the internal barriers for electrons and holes can be modified by an applied bias voltage, it became possible to characterize the spectra of excited charge carriers with energies below the vacuum barrier. Bias voltages of up to 1 V could be applied to the system which had an internal barrier height of 3 eV.To increase the detection efficiency for excited electrons travelling from the surface of a metal towards the bulk, one can either decrease the thickness of the top metal film of a heterosystem or one can reduce the height of the internal barrier. But with a decrease of the internal barrier the method of applying a bias voltage for tuning this barrier might become problematic, since tunnel currents become larger with lower barrier heights. Additionally, the influence of midgap states, impurities and remanent changes of the internal barrier might become more relevant for lower barriers.8,9 These problems are adressed in the present work.A comparison of metal/insulator/metal heterojunctions is presented with potentiostatically formed titanium and tantalum oxide as interjacent insulating layer. Titanium and tantalum oxide were chosen since both have bandgaps smaller than 4.5 eV.10 For amorphous tantalum oxide values of 4.2 eV are typical 11,12 whereas crystalline samples show values of 3.9-4.5 eV.12,13 Bulk titanium oxide values are for rut...

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“…Moreover, Ta 2 O 5 films have other excellent properties of thermal and chemical stability, so they could be widely used in many fields. However, a disadvantage lies that Ta 2 O 5 films is liable to substoichiometry in the conventional electron beam evaporation deposition process, thereby annealing is performed as an important method for achieving better stoichiometry [1][2][3]. Meanwhile, annealing is also one of the effective means for altering structure and optical properties of films and the effect is different according to the annealing conditions such as temperature and time.…”

Section: Introductionmentioning

confidence: 99%

High temperature annealing effect on structure, optical property and laser-induced damage threshold of Ta2O5 films

Xiao

et al. 2008

Applied Surface Science

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Stability and effect of annealing on the optical properties of plasma-deposited Ta2O5 and Nb2O5 films

Cited by 102 publications

References 32 publications

Influence of air oxidation on the properties of decorative NbOxNy coatings prepared by reactive gas pulsing

Influence of air oxidation on the properties of decorative NbOxNy coatings prepared by reactive gas pulsing

Charge Transport Through Thin Amorphous Titanium and Tantalum Oxide Layers

High temperature annealing effect on structure, optical property and laser-induced damage threshold of Ta2O5 films

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