XPS investigation of monatomic and cluster argon ion sputtering of tantalum pentoxide

Simpson, Robin; White, R. G.; Watts, John F.; Baker, Mark

doi:10.1016/j.apsusc.2017.02.006

Cited by 225 publications

(119 citation statements)

References 26 publications

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“…Starting with the Ta 4f core level for the three films without sputtering (0 min, black spectra) we observe that there is a spin-orbit doublet corresponding to the levels 4f 7/2 and 4f 5/2 . The binding energy for the doublets is around (27.8±0.1) eV with spin-orbit splitting of (1.9±0.1) eV in agreement with those reported for Ta 5+ in stoichiometric amorphous Ta 2 O 5 films 36,46,47 , suggesting that at the surface Ta 2 O 5 forms. This is expected because during annealing the film surface is in an oxygen rich environment that favours surface oxidation much better than in deeper layers.…”

Section: B Morphology and Grain Sizesupporting

confidence: 88%

“…Here we wish to extend the study in Ta 2 O 5 films to find out how their chemical properties are modified by ion bombardment. In the past, several researchers have used Ta 2 O 5 films (in some cases a standard BCR-261T) in XPS depth profile experiments to study several aspects of the samples such as film composition, chemical properties, and etch rate for different ion guns, ion energies and/or irradiation fluences [32][33][34][35][36] . From these studies, it is generally believed that, as the ion bombardment progresses, there is a preferential sputtering of oxygen to be caused by the low atomic number of oxygen that leads to the generation of several oxidation states of tantalum.…”

Section: Introductionmentioning

confidence: 99%

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Effect of ion bombardment on the chemical properties of crystalline tantalum pentoxide films

Pérez

Sosa

Perera

et al. 2019

Vacuum

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The effect of argon ion bombardment on the chemical properties of crystalline Ta2O5 films grown on Si(100) substrates by radio frequency magnetron sputtering was investigated by X-ray photoelectron spectroscopy. All samples were irradiated for several time intervals [(0.5, 3, 6, 9) min] and the Ta 4f and O 1s core levels were measured each time. Upon analysis at the surface of the films, we observe the Ta 4f spectrum characteristic of Ta2O5. Irradiated samples exhibit the formation of Ta suboxides with oxidation states Ta 1+ , Ta 2+ , Ta 3+ , Ta 4+ , and Ta 5+ . Exposing the films, after ion bombardment, to ambient for some days stimulates the amorphous phase of Ta2O5 at the surface suggesting that the suboxides of Ta are unstable. Using a sputtering simulation we discuss that these suboxides are largely generated during ion bombardment that greatly reduces the oxygen to tantalum ratio as the irradiation time increases. The computer simulation indicates that this is due to the high sputtering yield of oxygen.

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Section: B Morphology and Grain Sizesupporting

confidence: 88%

Section: Introductionmentioning

confidence: 99%

Effect of ion bombardment on the chemical properties of crystalline tantalum pentoxide films

Pérez

Sosa

Perera

et al. 2019

Vacuum

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“…Ta 4f 7/2 and 4f 5/2 peaks of NTO or NTO F appear at 25.7 or 26.3 eV and 27.6 or 29.0 eV, respectively, indicating the existence of Ta species in the form of Ta 5+ in agreement with literature data . The doublet with line splitting of 1.9 eV is notable for the 4f 5/2 and 4f 7/2 components in Ta 2 O 5 . In contrast, the corresponding O 1 s XPS core level spectra of NNO or NTO powders and NNO F or NNO F (film) were clearly different.…”

Section: Resultssupporting

confidence: 89%

“…Any particular niobate or tantalate can be characterized by a set of binding energies (BE) related to maximums of Nb 3d or Ta 4f and O 1s lines. However, a significant scattering exists in binding energy values reported in the literature Nb 3d 3/2 (210 eV) and Nb 3d 5/2 (207 eV) or Ta 4f 5/2 (28 eV) and Ta 4f 7/2 (26 eV) components even for such stable compounds as Nb 2 O 5 or Ta 2 O 5 . The binding energy differences Δ(O―Nb) = B E (O 1s) − B E (Nb 3d 5/2 ) and Δ(O―Ta) = B E (O 1s) − B E (Ta 4f 7/2 ) are suitable parameters to characterize average Nb―O bonding in niobates (322.2‐323.6 eV) and Ta―O bonding in tantalates (502.7‐504.4 eV) …”

Section: Introductionmentioning

confidence: 97%

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X‐ray photoelectron spectroscopy study of neodymium niobate and tantalate precursors and thin films

Bruncková

Kolev

Kaňuchová

2018

Surface & Interface Analysis

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Neodymium niobate NdNbO4 (NNO) and tantalate NdTaO4 (NTO) thin films (~100 nm) were prepared by sol‐gel/spin‐coating process on Al2O3 substrate with LaNbO4/PbZrO3 interlayer and annealing at 1000°C. Surface chemistry was investigated by X‐ray photoelectron spectroscopy (XPS). The core‐level XPS studies of sol‐gel NNO and NTO were performed for the first time. The binding energy differences Δ(O―Nb) and Δ(O―Ta) were used to characterize average energies of Nb―O bonding in NNO (322.9 eV) and Ta―O bonding in NTO (504.2 eV). The XPS demonstrated single valence state of Nd (Nd3+) in precursors. Nd concentration (at. %) decreases from 22% in precursors to 7% in films considering the substrate contains C, Al, Si, Pb, and Zr elements (37%) at Nb or Ta (5%) and O (51%). The X‐ray diffraction analyses verified formation of the monoclinic (M‐NdNbO4 or M′‐NdTaO4), orthorhombic (O‐NdNbO4) and tetragonal (T‐NdTaO4) phases in precursors and films. Single valence state of Nd3+ was confirmed in these films designed for the application in environmental electrolytic thin film devices.

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On the Surface Property–Oxidation Relationship in Refractory High‐Entropy Alloys

Nazarahari,

Ozdemir,

Barienti

et al. 2024

Adv Eng Mater

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In this study, oxidation behavior in as‐cast polycrystalline HfNbTaTi3, HfNbTaTiZr, HfMoTaTiZr, and NbMoTaTiZr refractory high‐entropy alloys (RHEAs), and the amorphous form of NbMoTaTiZr RHEA, is investigated. Herein, the surfaces of samples undergoing static oxidation experiments at 700, 800, and 900 °C using scanning electron microscopy, energy‐dispersive X‐Ray spectroscopy, X‐Ray photoelectron spectroscopy, and X‐Ray diffraction are explored. In the corresponding findings, the presence of three different oxidation behaviors in the studied RHEAs is shown: formation of a non‐protective scale, powderization and pesting of the sample, and a distinct amorphous oxidation behavior compared to its polycrystalline counterpart. Notably, Nb appears to induce a detrimental effect on the oxidation properties of samples due to the high ratio of volume change between the oxide and the metal. In the current findings, it is also evidenced that Mo can cause catastrophic failure in RHEAs that lack a protective oxide layer. Overall, the results constitute a step forward in enhancing the understanding of oxidation behavior in RHEAs and developing novel oxidation‐resistant RHEAs.

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XPS investigation of monatomic and cluster argon ion sputtering of tantalum pentoxide

Cited by 225 publications

References 26 publications

Effect of ion bombardment on the chemical properties of crystalline tantalum pentoxide films

Effect of ion bombardment on the chemical properties of crystalline tantalum pentoxide films

X‐ray photoelectron spectroscopy study of neodymium niobate and tantalate precursors and thin films

On the Surface Property–Oxidation Relationship in Refractory High‐Entropy Alloys

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