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BETA
Paneta, Valentina
Publications (10 of 20) Show all publications
Kokkoris, M., Androulakaki, E. G., Czyzycki, M., Erich, M., Karydas, A. G., Leani, J. J., . . . Petrovic, S. (2019). Argon ions deeply implanted in silicon studied by Rutherford/Elastic Backscattering and Grazing Incidence X-ray Fluorescence spectroscopy. Paper presented at 23rd International Conference on Ion Beam Analysis (IBA), OCT 08-13, 2017, Fudan Univ, Handan Campus, Shanghai, PEOPLES R CHINA. Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 450, 144-148
Open this publication in new window or tab >>Argon ions deeply implanted in silicon studied by Rutherford/Elastic Backscattering and Grazing Incidence X-ray Fluorescence spectroscopy
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2019 (English)In: Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, ISSN 0168-583X, E-ISSN 1872-9584, Vol. 450, p. 144-148Article in journal (Refereed) Published
Abstract [en]

Synchrotron-radiation based techniques have recently emerged as serious competitors to traditional nuclear analytical ones, not only in the characterization of various materials, but also when the depth profiling of ultra thin surface layers is concerned. The main goal of the present work was to investigate the applicability of Grazing Incidence X-Ray Fluorescence (GIXRF) and Rutherford/Elastic Backscattering Spectrometry (RBS/EBS) techniques with respect to the accurate quantitative determination of the retained doses of Ar ions deep implanted in random direction of Si [1 1 1] polished crystalline wafers. RBS/EBS measurements with protons and deuterons were taken along with GIXRF ones, the results were compared and an attempt was made to explain the occurring similarities and differences, along with the advantages and weaknesses of each applied analytical technique.

Keywords
EBS/RBS, GIXRF, Synchrotron radiation, Depth profiling
National Category
Subatomic Physics
Identifiers
urn:nbn:se:uu:diva-390988 (URN)10.1016/j.nimb.2018.08.048 (DOI)000474501400030 ()
Conference
23rd International Conference on Ion Beam Analysis (IBA), OCT 08-13, 2017, Fudan Univ, Handan Campus, Shanghai, PEOPLES R CHINA
Available from: 2019-08-19 Created: 2019-08-19 Last updated: 2019-08-19Bibliographically approved
Kalamara, A., Patronis, N., Vlastou, R., Kokkoris, M., Chasapoglou, S., Stamatopoulos, A., . . . Stamatelatos, I. E. (2019). Determination of the Ir-193(n, 2n) reaction cross section and correction methodology for the Ir-191(n, gamma) contamination. European Physical Journal A, 55(10), Article ID 187.
Open this publication in new window or tab >>Determination of the Ir-193(n, 2n) reaction cross section and correction methodology for the Ir-191(n, gamma) contamination
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2019 (English)In: European Physical Journal A, ISSN 1434-6001, E-ISSN 1434-601X, Vol. 55, no 10, article id 187Article in journal (Refereed) Published
Abstract [en]

The cross section of the Ir-193(n, 2n)Ir-192 reaction has been determined by means of the activation technique, relative to the Al-27(n, alpha) and Au-197(n, 2n) reference reactions cross sections, at neutron beam energies ranging from 10 to 21 MeV. The quasi-monoenergetic neutron beams were produced at the 5.5 MV Tandem T11/25 Accelerator Laboratory of NCSR "Demokritos" via the H-2(d, n) and H-3(d, n) reactions. The induced gamma-ray activity of the irradiated target and reference foils was measured with high resolution HPGe detectors. In order to correct for the contribution of the Ir-191(n, gamma)Ir-192 reaction, which is open to low energy parasitic neutrons, a recently developed analysis method was implemented and it is presented in great detail. Furthermore, cross section theoretical calculations were carried out using the EMPIRE and TALYS codes over a wide energy range.

Place, publisher, year, edition, pages
SPRINGER, 2019
National Category
Subatomic Physics
Identifiers
urn:nbn:se:uu:diva-396963 (URN)10.1140/epja/i2019-12879-x (DOI)000492408200001 ()
Available from: 2019-11-13 Created: 2019-11-13 Last updated: 2019-11-13Bibliographically approved
Kantre, K.-A., Paneta, V. & Primetzhofer, D. (2019). Investigation of the energy loss of I in Au at energies below the Bragg peak. Paper presented at 23rd International Conference on Ion Beam Analysis (IBA), OCT 08-13, 2017, Fudan Univ, Handan Campus, Shanghai, PEOPLES R CHINA. Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 450, 37-42
Open this publication in new window or tab >>Investigation of the energy loss of I in Au at energies below the Bragg peak
2019 (English)In: Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, ISSN 0168-583X, E-ISSN 1872-9584, Vol. 450, p. 37-42Article in journal (Refereed) Published
Abstract [en]

The energy loss of iodine in gold was investigated at energies below the Bragg peak. With the present work, the range of the available experimental data is extended to significantly lower energies, while the nuclear stopping power contribution is taken into account. Experiments were performed on thin film targets in reflection geometry. Electronic stopping cross sections were extracted by different approaches from experimental spectra. The obtained results have been compared to tabulated values from SRIM and previously published experimental data, where available. For all energies the obtained values are consistently higher than predicted by SRIM. Monte Carlo simulations (TRIM) have been performed to study path length distributions and the influence of nuclear stopping on the total energy loss. The results from the calculations indicate that the experimental geometry might be an important factor affecting the observed energy loss due to a selection of specific trajectories.

Keywords
Stopping power, Heavy ions, Iodine, Gold
National Category
Subatomic Physics
Identifiers
urn:nbn:se:uu:diva-390987 (URN)10.1016/j.nimb.2018.10.034 (DOI)000474501400007 ()
Conference
23rd International Conference on Ion Beam Analysis (IBA), OCT 08-13, 2017, Fudan Univ, Handan Campus, Shanghai, PEOPLES R CHINA
Funder
Swedish Research Council, 821-2012-5144Swedish Foundation for Strategic Research , RIF14-0053
Available from: 2019-08-19 Created: 2019-08-19 Last updated: 2019-08-19Bibliographically approved
Paneta, V., Englund, S., Suvanam, S. S., Scragg, J. J., Platzer Björkman, C. & Primetzhofer, D. (2019). Ion-beam based characterization of TiN back contact interlayers for CZTS(e), thin film solar cells. Paper presented at 23rd International Conference on Ion Beam Analysis (IBA), OCT 08-13, 2017, Fudan Univ, Handan Campus, Shanghai, PEOPLES R CHINA. Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 450, 262-266
Open this publication in new window or tab >>Ion-beam based characterization of TiN back contact interlayers for CZTS(e), thin film solar cells
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2019 (English)In: Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, ISSN 0168-583X, E-ISSN 1872-9584, Vol. 450, p. 262-266Article in journal (Refereed) Published
Abstract [en]

Time-of-Flight Elastic Recoil Detection Analysis (ToF-ERDA) and Time-of-Flight Medium-Energy Ion Scattering (ToF-MEIS) have been employed to investigate the potential of TiN thin films as intermediate layers on Mo back contact in CZTS(e) solar cells. TiN films of various thicknesses (20, 50 and 200 nm) were prepared with reactive DC magnetron sputtering and atomic layer deposition on Mo/SLG (soda-lime glass) substrates and annealed ex situ in either S or Se atmosphere. In situ annealing of the samples to different temperatures was also performed in the MEIS setup together with subsequent ToF-MEIS and ERDA analysis. The results of the sample and interlayer composition profiles, layer quality and thickness distributions are discussed in context with complementary experimental findings partially obtained previously by X-ray Photoelectron Spectroscopy (XPS), X-ray Diffraction (XRD), Scanning Electron Microscopy and Scanning Transmission Electron Microscopy- Electron Energy Loss Spectroscopy (STEM - EELS).

Keywords
ToF-ERDA, ToF-MEIS, TiN, Annealing, CZTS(e), Thin film solar cell, Interlayer
National Category
Materials Chemistry Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-390990 (URN)10.1016/j.nimb.2018.06.020 (DOI)000474501400054 ()
Conference
23rd International Conference on Ion Beam Analysis (IBA), OCT 08-13, 2017, Fudan Univ, Handan Campus, Shanghai, PEOPLES R CHINA
Funder
Swedish Research Council, 821-2012-5144Swedish Foundation for Strategic Research , RIF14-0053
Available from: 2019-08-19 Created: 2019-08-19 Last updated: 2020-01-31Bibliographically approved
Zhou, Y., Bergsåker, H., Bykov, I., Petersson, P., Paneta, V., Possnert, G. & Romanelli, F. (2019). Micro ion beam analysis for the erosion of beryllium marker tiles in a tokamak limiter. Paper presented at 23rd International Conference on Ion Beam Analysis (IBA), OCT 08-13, 2017, Fudan Univ, Handan Campus, Shanghai, PEOPLES R CHINA. Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 450, 200-204
Open this publication in new window or tab >>Micro ion beam analysis for the erosion of beryllium marker tiles in a tokamak limiter
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2019 (English)In: Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, ISSN 0168-583X, E-ISSN 1872-9584, Vol. 450, p. 200-204Article in journal (Refereed) Published
Abstract [en]

Beryllium limiter marker tiles were exposed to plasma in the Joint European Torus to diagnose the erosion of main chamber wall materials. A limiter marker tile consists of a beryllium coating layer (7-9 mu m) on the top of bulk beryllium, with a nickel interlayer (2-3 mu m) between them. The thickness variation of the beryllium coating layer, after exposure to plasma, could indicate the erosion measured by ion beam analysis with backscattering spectrometry. However, interpretations from broad beam backscattering spectra were limited by the non-uniform surface structures. Therefore, micro-ion beam analysis (mu-IBA) with 3 MeV proton beam for Elastic back scattering spectrometry (EBS) and PIXE was used to scan samples. The spot size was in the range of 3-10 mu m. Scanned areas were analysed with scanning electron microscopy (SEM) as well. Combining results from mu-IBA and SEM, we obtained local spectra from carefully chosen areas on which the surface structures were relatively uniform. Local spectra suggested that the scanned area (approximate to 600 mu m x 1200 mu m) contained regions with serious erosion with only 2-3 mu m coating beryllium left, regions with intact marker tile, and droplets with 90% beryllium. The nonuniform erosion, droplets mainly formed by beryllium, and the possible mixture of beryllium and nickel were the major reasons that confused interpretation from broad beam EBS.

Keywords
Microbeam, Limiter, Beryllium marker tile, Joint European Torus (JET), Plasma-facing components (PFC)
National Category
Fusion, Plasma and Space Physics
Identifiers
urn:nbn:se:uu:diva-390989 (URN)10.1016/j.nimb.2018.08.028 (DOI)000474501400041 ()
Conference
23rd International Conference on Ion Beam Analysis (IBA), OCT 08-13, 2017, Fudan Univ, Handan Campus, Shanghai, PEOPLES R CHINA
Note

JET contributors.

Available from: 2019-08-19 Created: 2019-08-19 Last updated: 2019-08-19Bibliographically approved
Sortica, M. A., Paneta, V., Bruckner, B., Lohmann, S., Nyberg, T., Bauer, P. & Primetzhofer, D. (2019). On the Z(1)-dependence of electronic stopping in TiN. Scientific Reports, 9, Article ID 176.
Open this publication in new window or tab >>On the Z(1)-dependence of electronic stopping in TiN
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2019 (English)In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 9, article id 176Article in journal (Refereed) Published
Abstract [en]

We present a thorough experimental study of electronic stopping of H, He, B, N, Ne and Al ions in TiN with the aim to learn about the energy loss mechanisms of slow ions. The energy loss was measured by means of time-of-flight medium-energy ion scattering. Thin films of TiN on silicon with a delta-layer of W at the TiN/Si interface were used as targets. We compare our results to non-linear density functional theory calculations, examining electron-hole pair excitations by screened ions in a free electron gas in the static limit, with a density equivalent to the expected value for TiN. These calculations predict oscillations in the electronic stopping power for increasing atomic number Z(1) of the projectile. An increasing discrepancy between our experimental results and predictions by theory for increasing Z(1) was observed. This observation can be attributed to contributions from energy loss channels different from electron-hole pair excitation in binary Coulomb collisions.

Place, publisher, year, edition, pages
NATURE PUBLISHING GROUP, 2019
National Category
Condensed Matter Physics Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-375865 (URN)10.1038/s41598-018-36765-7 (DOI)000455951300024 ()30655585 (PubMedID)
Funder
Swedish Foundation for Strategic Research , RIF14-0053
Available from: 2019-02-04 Created: 2019-02-04 Last updated: 2020-01-08Bibliographically approved
Lohmann, S., Sortica, M. A., Paneta, V. & Primetzhofer, D. (2018). Analysis of photon emission induced by light and heavy ions in time-of-flight medium energy ion scattering. Paper presented at 15th International Conference on Particle Induced X-ray Emission (PIXE), APR 02-07, 2017, Split, CROATIA. Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 417, 75-80
Open this publication in new window or tab >>Analysis of photon emission induced by light and heavy ions in time-of-flight medium energy ion scattering
2018 (English)In: Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, ISSN 0168-583X, E-ISSN 1872-9584, Vol. 417, p. 75-80Article in journal (Refereed) Published
Abstract [en]

We present a systematic analysis of the photon emission observed due to impact of pulsed keV ion beams in time-of-flight medium energy ion scattering (ToF-MEIS) experiments. Hereby, hydrogen, helium and neon ions served as projectiles and thin gold and titanium nitride films on different substrates were employed as target materials. The present experimental evidence indicates that a significant fraction of the photons has energies of around 10 eV, i.e. on the order of typical valence and conduction band transitions in solids. Furthermore, the scaling properties of the photon emission with respect to several experimental parameters were studied. A dependence of the photon yield on the projectile velocity was observed in all experiments. The photon yield exhibits a dependence on the film thickness and the scattering angle, which can be explained by photon production along the path of the incident ion through the material. Additionally, a strong dependence on the projectile type was found with the photon emission being higher for heavier projectiles. This difference is larger than the respective difference in electronic stopping cross section. The photon yield shows a strong material dependence, and according to a comparison of SiO2 and Si seems to be subject to matrix effects. (C) 2017 Elsevier B.V. All rights reserved.

Place, publisher, year, edition, pages
ELSEVIER SCIENCE BV, 2018
Keywords
Photons, Deep UV, TOF-MEIS, Au
National Category
Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:uu:diva-348917 (URN)10.1016/j.nimb.2017.08.005 (DOI)000426030500014 ()
Conference
15th International Conference on Particle Induced X-ray Emission (PIXE), APR 02-07, 2017, Split, CROATIA
Funder
Swedish Foundation for Strategic Research , RIF14-0053Swedish Research Council, 821-2012-5144
Available from: 2018-04-25 Created: 2018-04-25 Last updated: 2018-05-22Bibliographically approved
Riedl, H., Glechner, T., Wojcik, T., Koutna, N., Kolozsvari, S., Paneta, V., . . . Mayrhofer, P. H. (2018). Influence of carbon deficiency on phase formation of super-hard TaCy thin films. Scripta Materialia, 149, 150-154
Open this publication in new window or tab >>Influence of carbon deficiency on phase formation of super-hard TaCy thin films
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2018 (English)In: Scripta Materialia, ISSN 1359-6462, E-ISSN 1872-8456, Vol. 149, p. 150-154Article in journal (Refereed) Published
Abstract [en]

Using nonreactive sputter deposition allows the preparation of single-phase fcc structured TaCy thin films over a wide compositional range with y between 0.63 and 1.04. Among this composition range, the C-deficient TaC0.78 exhibits the highest as deposited hardness of 43.4 +/- 0.65 GPa combined with the highest thermal stability. Even after vacuum annealing to 2400 degrees C, no vacancy-ordered or faulted Ta-C based phases can be detected. The stabilization of carbon deficient fcc structured TaCy near y of about 0.75, revealed the decisive character of vacancy engineered thin films materials for ultra-high temperature applications. (C) 2018 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Place, publisher, year, edition, pages
PERGAMON-ELSEVIER SCIENCE LTD, 2018
Keywords
Ta-C, Thin films, Carbon vacancies, UHTC, Density Functional Theory (DFT)
National Category
Materials Chemistry Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:uu:diva-352582 (URN)10.1016/j.scriptamat.2018.02.030 (DOI)000429390500033 ()
Funder
Swedish Foundation for Strategic Research
Available from: 2018-08-07 Created: 2018-08-07 Last updated: 2018-08-07Bibliographically approved
Dalbauer, V., Ramm, J., Kolozsvari, S., Paneta, V., Koller, C. M. & Mayrhofer, P. H. (2018). On the phase formation of cathodic arc evaporated Al1-xCrx-based intermetallic coatings and substoichiometric oxides. Surface & Coatings Technology, 352, 392-398
Open this publication in new window or tab >>On the phase formation of cathodic arc evaporated Al1-xCrx-based intermetallic coatings and substoichiometric oxides
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2018 (English)In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 352, p. 392-398Article in journal (Refereed) Published
Abstract [en]

The phase evolution of Al1-xCrx-based intermetallic coatings and corresponding substoichiometric oxides grown by cathodic arc evaporation was investigated in order to obtain a better understanding of the relation between oxygen flow rate, Al and Cr content, and structural evolution of the coatings deposited. When using 20 sccm Ar, or 50 sccm O-2, or 100 sccm O-2 per active source (p.a.s.) the cathode reaction zone consists of various intermetallic Al-Cr-compounds, which are in good agreement with the binary Al-Cr phase diagram. This is generally also reflected in the phase composition of the metallic and substoichiometric oxide coatings. The Al-rich compositions, Al0.75Cr0.25 and Al0.70Cr0.30, show a strong tendency for the formation of gamma(1)-Al8Cr5 phases. Mostly, the coating compositions of the metallic constituents of the synthesised intermetallic and substoichiometric oxide coatings deviate from the elemental compositions of the cathode, show enrichment in Cr. This deviation is more pronounced for Cr-rich cathodes using low O-2 flow rates during deposition. The dense columnar structure of the intermetallic coatings (hardness values between 2.5 and 10.2 GPa) turns into a nano-composite-like morphology for depositions with 50 and 100 sccm O-2 p.a.s., which in turn leads to a significant hardness increase up to similar to 24 GPa. Among all coatings investigated, the Cr-rich compositions have higher hardness and denser morphology than the Al-rich layers.

Place, publisher, year, edition, pages
ELSEVIER SCIENCE SA, 2018
Keywords
AlCr intermetallics, (Al, Cr)(2)O-3, Oxides, Alumina, Cathodic arc evaporation
National Category
Manufacturing, Surface and Joining Technology
Identifiers
urn:nbn:se:uu:diva-368439 (URN)10.1016/j.surfcoat.2018.08.038 (DOI)000447106400041 ()
Available from: 2018-12-07 Created: 2018-12-07 Last updated: 2018-12-07Bibliographically approved
Moraes, V., Fuger, C., Paneta, V., Primetzhofer, D., Polcik, P., Bolvardi, H., . . . Mayrhofer, P. H. (2018). Substoichiometry and tantalum dependent thermal stability of alpha-structured W-Ta-B thin films. Scripta Materialia, 155, 5-10
Open this publication in new window or tab >>Substoichiometry and tantalum dependent thermal stability of alpha-structured W-Ta-B thin films
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2018 (English)In: Scripta Materialia, ISSN 1359-6462, E-ISSN 1872-8456, Vol. 155, p. 5-10Article in journal (Refereed) Published
Abstract [en]

Physical vapor deposited (PVD) WB2 thin films crystallize in the alpha-AIB(2)-prototype structure rather than in their thermodynamically stable (omega-W2B5-z-prototype structure. Contrary to the majority of alpha-AlB2-type transition metal diborides (TMB2), alpha-WB2 exhibits a more ductile character. Combining density functional theory and sophisticated experiments, we show that the stability of alpha-WB2 thin films is basically influenced by point defects such as vacancies present in PVD materials. With the help of alpha-TaB2 (one of the most ductile TMB2 with high preference for alpha-AlB2-type), the thermally driven decomposition and phase transformation of alpha-W1-xTaxB2-z to the omega-W2B5-z-type can be shifted to temperatures above 1200 degrees C.

Keywords
W-Ta-B, Thin films, Boron vacancies, Density functional theory (DFT), UHTC
National Category
Inorganic Chemistry
Identifiers
urn:nbn:se:uu:diva-363093 (URN)10.1016/j.scriptamat.2018.06.005 (DOI)000440958000002 ()
Available from: 2018-10-16 Created: 2018-10-16 Last updated: 2018-10-16Bibliographically approved
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