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Shams-Latifi, J., Pitthan, E., Tran, T., Kaur, R. & Primetzhofer, D. (2024). Sputter-deposition of ultra-thin film stacks from EUROFER97 and tungsten: characterisation and interaction with low-energy D and He ions. Materials Research Express, 11(1), Article ID 016518.
Öppna denna publikation i ny flik eller fönster >>Sputter-deposition of ultra-thin film stacks from EUROFER97 and tungsten: characterisation and interaction with low-energy D and He ions
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2024 (Engelska)Ingår i: Materials Research Express, E-ISSN 2053-1591, Vol. 11, nr 1, artikel-id 016518Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

We have sputter-deposited stacks of ultrathin layers from EUROFER97 and tungsten on silicon substrates. Ion beam analysis techniques are used for composition characterisation and microscopy methods are employed for structural examination. The films are subsequently studied by time-of-flight low-energy ion scattering (ToF-LEIS) for primary 10 keV He+ and 8 keV D+ ions to demonstrate an approach of providing accurate and precise experimental reference electronic stopping cross-sections for fusion-relevant steels. The energy-converted ToF-LEIS spectra are compared to Monte-Carlo simulations for quantitative analysis explicitly considering the influence of plural and multiple scattering. We discuss the deduced stopping cross-sections of EUROFER97 in comparison to predictions by SRIM using Bragg's rule of stopping power additivity.

Ort, förlag, år, upplaga, sidor
Institute of Physics (IOP), 2024
Nyckelord
EUROFER97, ToF-LEIS, tungsten, electronic stopping cross-section, RBS, TEM, in situ
Nationell ämneskategori
Den kondenserade materiens fysik
Identifikatorer
urn:nbn:se:uu:diva-522874 (URN)10.1088/2053-1591/ad1f97 (DOI)001149926500001 ()
Forskningsfinansiär
Vetenskapsrådet, 2019_00191
Tillgänglig från: 2024-02-15 Skapad: 2024-02-15 Senast uppdaterad: 2024-02-15Bibliografiskt granskad
Tran, T. T., Bruce, H., Pham, N. H. & Primetzhofer, D. (2023). A contactless single-step process for simultaneous nanoscale patterning and cleaning of large-area graphene. 2D Materials, 10(2), Article ID 025017.
Öppna denna publikation i ny flik eller fönster >>A contactless single-step process for simultaneous nanoscale patterning and cleaning of large-area graphene
2023 (Engelska)Ingår i: 2D Materials, E-ISSN 2053-1583, Vol. 10, nr 2, artikel-id 025017Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

The capability to structure two-dimensional materials (2DMs) at the nanoscale with customizable patterns and over large areas is critical for a number of emerging applications, from nanoelectronics to 2D photonic metasurfaces. However, current technologies, such as photo- and electron-beam lithography, often employing masking layers, can significantly contaminate the materials. Large-area chemical vapour deposition-grown graphene is known to have non-ideal properties already due to surface contamination resulting from the transferring process. Additional contamination through the lithographic process might thus reduce the performance of any device based on the structured graphene. Here, we demonstrate a contactless chemical-free approach for simultaneous patterning and cleaning of self-supporting graphene membranes in a single step. Using energetic ions passing through a suspended mask with pre-defined nanopatterns, we deterministically structure graphene with demonstrated feature size of 15 nm, approaching the performance of small-area focused ion beam techniques and extreme ultraviolet lithography. Our approach, however, requires only a broad beam, no nanoscale beam positioning and enables large area patterning of 2DMs. Simultaneously, in regions surrounding the exposed areas, contaminations commonly observed on as-grown graphene targets, are effectively removed. This cleaning mechanism is attributed to coupling of surface diffusion and sputtering effects of adsorbed surface contaminants. For applications using 2DMs, this simultaneous patterning and cleaning mechanism may become essential for preparing the nanostructured materials with improved cleanliness and hence, quality.

Ort, förlag, år, upplaga, sidor
Institute of Physics Publishing (IOPP), 2023
Nyckelord
graphene, 2D materials, nanomesh, porous, patterning, cleaning, ion irradiation
Nationell ämneskategori
Den kondenserade materiens fysik Materialkemi
Identifikatorer
urn:nbn:se:uu:diva-499894 (URN)10.1088/2053-1583/acc042 (DOI)000946099700001 ()
Forskningsfinansiär
Vetenskapsrådet, 2017-00646_9Vetenskapsrådet, 2019-00191Stiftelsen för strategisk forskning (SSF), RIF14-0053ÅForsk (Ångpanneföreningens Forskningsstiftelse), 22-313Ingegerd Berghs stiftelse
Tillgänglig från: 2023-04-11 Skapad: 2023-04-11 Senast uppdaterad: 2023-04-11Bibliografiskt granskad
Wolf, P. M., Neuss, D., Tran, T., Pitthan, E., Hans, M., Schneider, J. M. & Primetzhofer, D. (2023). An in situ ToF-LEIS characterization of the surface of Ti-based thin films under oxygen exposure and at elevated temperatures. Applied Surface Science, 638, Article ID 158076.
Öppna denna publikation i ny flik eller fönster >>An in situ ToF-LEIS characterization of the surface of Ti-based thin films under oxygen exposure and at elevated temperatures
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2023 (Engelska)Ingår i: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 638, artikel-id 158076Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

Ti-based coatings are utilized in a wide variety of applications, from biomedical implants to mechanical tools. Insight into initial stages of processes triggered by gas exposure and temperature change in the near-surface region of such coatings is essential for the understanding of their macroscopic behavior. We present an in situ time-of-flight low-energy ion scattering (ToF-LEIS) approach for the non-destructive and depth-resolved study of composition and morphology of the immediate surface region with sub-nm resolution. Ti-based coatings, with increasing compositional complexity, starting from in situ grown Ti, followed by ex situ grown Ti, TiN, and (Ti,Al) N, are studied concerning effects of exposure to oxygen and elevated temperatures. On the clean in situ deposited Ti surface, a 1.9 nm thick oxide layer is observed after exposure to 4000 Langmuir oxygen at room temperature. In contrast, for ex situ grown samples, an oxidic surface layer not removable by surface ion sputtering is found to limit effects of further oxygen exposure. TiN does not show significant changes when exposed to oxygen at 370 & DEG;C. For (Ti,Al)N, a nm-thick Al-rich surface layer is observed at annealing temperatures above 600 & DEG;C, both in ultra-high vacuum and in 1.0 x 10-3 Pa of oxygen.

Ort, förlag, år, upplaga, sidor
Elsevier BV, 2023
Nyckelord
Time-of-flight low-energy ion scattering, Surface analysis, High-resolution depth profiling, Titanium, Transition metal nitride, In situ
Nationell ämneskategori
Den kondenserade materiens fysik Materialkemi
Identifikatorer
urn:nbn:se:uu:diva-509994 (URN)10.1016/j.apsusc.2023.158076 (DOI)001047369900001 ()
Forskningsfinansiär
Vetenskapsrådet, 2020-04754_3Vetenskapsrådet, 2019-00191Stiftelsen för strategisk forskning (SSF), RIF14-0053
Tillgänglig från: 2023-08-28 Skapad: 2023-08-28 Senast uppdaterad: 2023-08-28Bibliografiskt granskad
Kretschmer, A., Bohrn, F., Hutter, H., Pitthan, E., Tran, T., Primetzhofer, D. & Mayrhofer, P. H. (2023). Analysis of (Al,Cr,Nb,Ta,Ti)-nitride and-oxynitride diffusion barriers in Cu-Si interconnects by 3D-Secondary Ion Mass Spectrometry. Materials Characterization, 197, Article ID 112676.
Öppna denna publikation i ny flik eller fönster >>Analysis of (Al,Cr,Nb,Ta,Ti)-nitride and-oxynitride diffusion barriers in Cu-Si interconnects by 3D-Secondary Ion Mass Spectrometry
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2023 (Engelska)Ingår i: Materials Characterization, ISSN 1044-5803, E-ISSN 1873-4189, Vol. 197, artikel-id 112676Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

We report on the barrier performance of a nitride, and three oxynitrides of the system Al-Cr-Nb-Ta-Ti between Cu and Si. Different high-entropy sublattice nitrides have been tested before as diffusion barriers in this system, by depositing thin barriers on single crystalline Si substrates, followed by a thick Cu layer on top, and subsequent vacuum annealing. We investigated a reversed stacking sequence, by sputtering 15-30 nm of (Al,Cr,Nb,Ta,Ti)-O-N (between 0.5 and 63.7 at.% O) on polished polycrystalline Cu substrates, followed by 200 nm of Si. The samples were then vacuum annealed at 600, 700, 800 and 900 degrees C for 30 min. All four investigated coatings perform similar. Secondary Ion Mass Spectrometry depth profiling in high-current-bunched mode (lateral res-olution +/- 1 mu m) shows breakthrough of Si even at 600 degrees C. But 3D constructed images with Burst Alignment mode (lateral resolution of +/- 2 nm) reveal that this failure is a highly localized phenomenon, likely related to coarsening effects at the Cu grain boundaries, leading to punctuation of the diffusion barrier. Aside from this penetration, the majority of the area of each barrier coating retains its function. This in-depth analysis shows that the barrier function of the nitride and oxynitride coatings mostly stays intact up to 800 degrees C and fails completely at 900 degrees C.

Ort, förlag, år, upplaga, sidor
Elsevier, 2023
Nyckelord
Vapor deposition, Diffusion, Ceramics, Entropy
Nationell ämneskategori
Bearbetnings-, yt- och fogningsteknik
Identifikatorer
urn:nbn:se:uu:diva-500601 (URN)10.1016/j.matchar.2023.112676 (DOI)000964738000001 ()
Forskningsfinansiär
Vetenskapsrådet, 2017-00646_9Vetenskapsrådet, 2019-00191Stiftelsen för strategisk forskning (SSF), RIF14-0053
Tillgänglig från: 2023-04-20 Skapad: 2023-04-20 Senast uppdaterad: 2023-04-20Bibliografiskt granskad
Tran, T., Wong-Leung, J., Smillie, L. A., Hallen, A., Grimaldi, M. G. & Williams, J. S. (2023). High hole mobility and non-localized states in amorphous germanium. APL Materials, 11(4), Article ID 041115.
Öppna denna publikation i ny flik eller fönster >>High hole mobility and non-localized states in amorphous germanium
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2023 (Engelska)Ingår i: APL Materials, E-ISSN 2166-532X, Vol. 11, nr 4, artikel-id 041115Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

Covalent amorphous semiconductors, such as amorphous silicon (a-Si) and germanium (a-Ge), are commonly believed to have localized electronic states at the top of the valence band and the bottom of the conduction band. Electrical conductivity is thought to occur through the hopping mechanism via these localized states. The carrier mobility of these materials is usually very low, in the order of similar to 10(-3)-10(-2) cm(2)/Vs at room temperature. In this study, we show that pure high-density amorphous Ge has exceptionally high carrier mobility, in the order of similar to 100 cm(2)/Vs, and a high hole concentration of similar to 10(18) cm(-3). The temperature-dependent conductivity of the material is also very-well defined with two distinctive regions, extrinsic and intrinsic conductivity, as in crystalline Ge. These results provide direct evidence for a largely preserved band structure and non-localized states within the valence band in high-density amorphous Ge, as previously suggested by Tauc et al. from optical characterization alone.

Ort, förlag, år, upplaga, sidor
American Institute of Physics (AIP), 2023
Nationell ämneskategori
Den kondenserade materiens fysik
Identifikatorer
urn:nbn:se:uu:diva-501321 (URN)10.1063/5.0146424 (DOI)000967579800001 ()
Tillgänglig från: 2023-05-05 Skapad: 2023-05-05 Senast uppdaterad: 2023-05-05Bibliografiskt granskad
Pitthan, E., Tran, T., Moldarev, D., Rubel, M. & Primetzhofer, D. (2023). Influence of thermal annealing and of the substrate on sputter-deposited thin films from EUROFER97 on tungsten. Nuclear Materials and Energy, 35, Article ID 101449.
Öppna denna publikation i ny flik eller fönster >>Influence of thermal annealing and of the substrate on sputter-deposited thin films from EUROFER97 on tungsten
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2023 (Engelska)Ingår i: Nuclear Materials and Energy, E-ISSN 2352-1791, Vol. 35, artikel-id 101449Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

The modification of sputter-deposited films from EUROFER97 on tungsten during and after annealing were investigated in-situ and ex-situ. The annealing resulted in a densification of the film, formation of large grains, segregation of W at the surface, and the formation of Fe-W compounds at the interfacial region. Similar structural modifications were observed also for a film annealed on a MgO substrate, with an exception to the change in composition (no increase of W concentration). Results indicate that the substrate significantly affects thermally induced modifications of re-deposited EUROFER97.

Ort, förlag, år, upplaga, sidor
Elsevier, 2023
Nationell ämneskategori
Annan materialteknik
Identifikatorer
urn:nbn:se:uu:diva-510639 (URN)10.1016/j.nme.2023.101449 (DOI)001042748700001 ()
Forskningsfinansiär
Vetenskapsrådet, 2019_00191
Tillgänglig från: 2023-09-04 Skapad: 2023-09-04 Senast uppdaterad: 2023-09-04Bibliografiskt granskad
Kaur, R., Eljamal, G., Tran, T. T., Primetzhofer, D. & Ström, P. (2023). Ion Track Formation and Nanopore Etching in Polyimide: Possibilities in the MeV Ion Energy Regime. Macromolecular materials and engineering
Öppna denna publikation i ny flik eller fönster >>Ion Track Formation and Nanopore Etching in Polyimide: Possibilities in the MeV Ion Energy Regime
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2023 (Engelska)Ingår i: Macromolecular materials and engineering, ISSN 1438-7492, E-ISSN 1439-2054Artikel i tidskrift (Refereegranskat) Epub ahead of print
Abstract [en]

Polyimide films of thickness 7.5 µm are irradiated by a wide range of ions (1H to 197Au) with energies between 1.05 and 48 MeV. Irradiated samples are then chemically etched in sodium hypochlorite solution to investigate nanopore formation due to ion track etching. A threshold in terms of electronic stopping power, Set, needs to be surpassed to preferentially etch the ion tracks. Close to Set, intermittent tracks are formed where only part of the track is etchable. The fraction of these etchable parts increases as we move away from Set, toward higher stopping powers, eventually yielding continuous etchable tracks. Both intermittent and continuous track formation thresholds are observed to be velocity-dependent, yielding a decrease of the thresholds in the present work compared to previously reported thresholds for swift heavy ions. This finding leads the authors to suggest that electrostatic ion accelerators with terminal voltages of several MV are applicable for the production of ion track membranes up to ≈10–20 µm in thickness. Suitable ions for nanopores in 7.5 µm polyimide films include 42 MeV 59Co and 48 MeV 197Au. The growth mechanism for the pores during etching is discussed, relating it to the properties of the original ion track.

Ort, förlag, år, upplaga, sidor
Wiley-VCH Verlagsgesellschaft, 2023
Nyckelord
Ion irradiation, nanopores, polyimide, velocity-effect
Nationell ämneskategori
Materialteknik Den kondenserade materiens fysik
Identifikatorer
urn:nbn:se:uu:diva-514768 (URN)10.1002/mame.202300232 (DOI)001064894700001 ()
Forskningsfinansiär
Vetenskapsrådet, 2019‐00191
Tillgänglig från: 2023-10-23 Skapad: 2023-10-23 Senast uppdaterad: 2024-01-17Bibliografiskt granskad
Dittrich, L., Petersson, P., Moon, S., Rubel, M., Tran, T. T., Widdowson, A. & Contribuors, J. E. (2023). Retention of noble and rare isotope gases in plasma-facing components-Experience from the JET tokamak with the ITER-like wall. Fusion engineering and design, 192, Article ID 113620.
Öppna denna publikation i ny flik eller fönster >>Retention of noble and rare isotope gases in plasma-facing components-Experience from the JET tokamak with the ITER-like wall
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2023 (Engelska)Ingår i: Fusion engineering and design, ISSN 0920-3796, E-ISSN 1873-7196, Vol. 192, artikel-id 113620Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

Plasma edge cooling, ion cyclotron wall conditioning and disruption mitigation techniques involve massive gas injection (by puffs or pellets) to the torus. A certain fraction remains in plasma-facing components (PFC) due to co-deposition and implantation. An uncontrolled release/desorption of such retained species affects the stability of plasma operation. The aim of this work was to determine the lateral and depth distribution of noble (3He, 4He, Ne, Ar), seeded (N2, Ne, Ar) and tracer gases (15N, 18O) in PFC retrieved from the JET tokamak with the ITER-Like Wall (JET-ILW) after three experimental campaigns (ILW-1, ILW-2, ILW-3). Results regarding the retention of those gases are shown as well as a comparison to the deuterium retention in the studied areas. Heavy ion elastic recoil detection analysis was used, being the only technique capable of detection and quantitative assessment of all elements, especially low-Z isotopes. Helium was found on the divertor Tile 5, locally up to 44.1015 3He cm-2 and 12.1015 4He cm-2, and on the limiters as well. Neon was found in two positions on the limiters, with up to 10.1015 Ne cm-2 and the 15N tracer on Be limiters exposed to ILW-3. A correlation of N retention with the N seeding rates for each campaign has also been found.

Ort, förlag, år, upplaga, sidor
Elsevier, 2023
Nyckelord
Plasma -wall interactions, Seeded gases, Plasma -facing materials, JET tokamak, ITER-like wall
Nationell ämneskategori
Fusion, plasma och rymdfysik
Identifikatorer
urn:nbn:se:uu:diva-500307 (URN)10.1016/j.fusengdes.2023.113620 (DOI)000956841500001 ()
Forskningsfinansiär
VetenskapsrådetVetenskapsrådetStiftelsen för strategisk forskning (SSF)
Tillgänglig från: 2023-04-17 Skapad: 2023-04-17 Senast uppdaterad: 2023-04-17Bibliografiskt granskad
Pitthan, E., Petersson, P., Tran, T. T., Moldarev, D., Kaur, R., Shams-Latifi, J., . . . Primetzhofer, D. (2023). Thin films sputter-deposited from EUROFER97 in argon and deuterium atmosphere: Material properties and deuterium retention. Nuclear Materials and Energy, 34, Article ID 101375.
Öppna denna publikation i ny flik eller fönster >>Thin films sputter-deposited from EUROFER97 in argon and deuterium atmosphere: Material properties and deuterium retention
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2023 (Engelska)Ingår i: Nuclear Materials and Energy, E-ISSN 2352-1791, Vol. 34, artikel-id 101375Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

Sputter-deposited thin films (33–1160 nm) from EUROFER97 were obtained on different substrates (C, Si, W, MgO) in argon and a mix of argon and deuterium atmosphere. The composition, microstructure, and mechanical properties of the films were analyzed and compared to those of the bulk material. The films feature lower density (-10%), higher hardness (+79%), and smaller crystallites in comparison to the bulk. Despite such differences, the elemental atomic composition of the films and the bulk was very similar, as determined by ion beam analysis. Deposition in deuterium-containing atmosphere resulted in a low deuterium incorporation (0.28% of atomic content), indicating low retention of hydrogen-isotopes in the deposited material.

Ort, förlag, år, upplaga, sidor
Elsevier, 2023
Nyckelord
Plasma facing components, EUROFER97, Sputtering deposition, Ion beam analysis, Deuterium retention
Nationell ämneskategori
Den kondenserade materiens fysik
Forskningsämne
Fysik
Identifikatorer
urn:nbn:se:uu:diva-497118 (URN)10.1016/j.nme.2023.101375 (DOI)000990188500001 ()
Forskningsfinansiär
Europeiska kommissionen, 101052200Vetenskapsrådet, 2019-00191Stiftelsen för strategisk forskning (SSF), RIF14-0053
Tillgänglig från: 2023-02-23 Skapad: 2023-02-23 Senast uppdaterad: 2023-06-19Bibliografiskt granskad
Wolf, P. M., Pitthan, E., Zhang, Z., Lavoie, C., Tran, T. T. & Primetzhofer, D. (2022). Direct Transition from Ultrathin Orthorhombic Dinickel Silicides to Epitaxial Nickel Disilicide Revealed by In Situ Synthesis and Analysis. Small, 18(14), Article ID 2106093.
Öppna denna publikation i ny flik eller fönster >>Direct Transition from Ultrathin Orthorhombic Dinickel Silicides to Epitaxial Nickel Disilicide Revealed by In Situ Synthesis and Analysis
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2022 (Engelska)Ingår i: Small, ISSN 1613-6810, E-ISSN 1613-6829, Vol. 18, nr 14, artikel-id 2106093Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

Understanding phase transitions of ultrathin metal silicides is crucial for the development of nanoscale silicon devices. Here, the phase transition of ultrathin (3.6 nm) Ni silicides on Si(100) substrates is investigated using an in situ synthesis and characterization approach, supplemented with ex situ transmission electron microscopy and nano-beam electron diffraction. First, an ultrathin epitaxial layer and ordered structures at the interface are observed upon room-temperature deposition. At 290 °C, this structure is followed by formation of an orthorhombic δ-Ni2Si phase exhibiting long-range order and extending to the whole film thickness. An unprecedented direct transition from this δ-Ni2Si phase to the final NiSi2−x phase is observed at 290 °C, skipping the intermediate monosilicide phase. Additionally, the NiSi2−x phase is found epitaxial on the substrate. This transition process substantially differs from observations for thicker films. Furthermore, considering previous studies, the long-range ordered orthorhombic δ-Ni2Si phase is suggested to occur regardless of the initial Ni thickness. The thickness of this ordered δ-Ni2Si layer is, however, limited due to the competition of different orientations of the δ-Ni2Si crystal. Whether the formed δ-Ni2Si layer consumes all deposited nickel is expected to determine whether the monosilicide phase appears before the transition to the final NiSi2−x phase.

Ort, förlag, år, upplaga, sidor
Wiley-VCH Verlagsgesellschaft, 2022
Nyckelord
epitaxial silicide, in situ characterization, ion scattering, nickel silicide, ultrathin metal silicides
Nationell ämneskategori
Materialkemi Annan materialteknik
Identifikatorer
urn:nbn:se:uu:diva-483599 (URN)10.1002/smll.202106093 (DOI)000758571000001 ()35191181 (PubMedID)
Forskningsfinansiär
Vetenskapsrådet, 2016-03432Vetenskapsrådet, 2020-04754Vetenskapsrådet, 2017-00646_9Vetenskapsrådet, 2019-00191Stiftelsen för strategisk forskning (SSF), RIF14-0053Stiftelsen för strategisk forskning (SSF), SE13-0333
Tillgänglig från: 2022-08-31 Skapad: 2022-08-31 Senast uppdaterad: 2023-02-28Bibliografiskt granskad
Organisationer
Identifikatorer
ORCID-id: ORCID iD iconorcid.org/0000-0002-1393-1723

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