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Birch, Jens, ProfessorORCID iD iconorcid.org/0000-0002-8469-5983
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Publications (10 of 202) Show all publications
Dorri, S., Ghafoor, N., Palisaitis, J., Stendahl, S., Devishvili, A., Vorobiev, A., . . . Birch, J. (2024). Enhanced quality of single crystal CrBx/TiBy diboride superlattices by controlling boron stoichiometry during sputter deposition. Applied Surface Science, Article ID 159606.
Open this publication in new window or tab >>Enhanced quality of single crystal CrBx/TiBy diboride superlattices by controlling boron stoichiometry during sputter deposition
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2024 (English)In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, article id 159606Article in journal (Refereed) Published
Abstract [en]

Single-crystal CrB2/TiB2 diboride superlattices with well-defined layers are promising candidates for neutron optics. However, excess B in sputter-deposited TiBy using a single TiB2 target deteriorates the structural quality of CrBx/TiBy (0001) superlattices. We study the influence of co-sputtering of TiB2 + Ti on the stoichiometry and crystalline quality of 300-nm-thick TiBy single layers and CrBx/TiBy (0001) superlattices on Al2O3(0001) substrates grown by DC magnetron sputter epitaxy at growth-temperatures TS ranging from 600 to 900 °C. By controlling the relative applied powers to the TiB2 and Ti magnetrons, y could be reduced from 3.3 to 0.9. TiB2.3 grown at 750 °C exhibited epitaxial domains about 10x larger than non-co-sputtered films. Close-to-stoichiometry CrB1.7/TiB2.3 superlattices with modulation periods Λ = 6 nm grown at 750 °C showed the highest single crystal quality and best layer definition. TiB2.3 layers display rough top interfaces indicating kinetically limited growth while CrB1.7 forms flat and abrupt top interfaces indicating epitaxial growth with high adatom mobility.

Place, publisher, year, edition, pages
Elsevier, 2024
Keywords
Superlattice, Diboride, Thin film, Co-sputtering, Nanostructure
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:liu:diva-200730 (URN)10.1016/j.apsusc.2024.159606 (DOI)
Note

Funding: Swedish National Graduate School in Neutron Scattering (SwedNess), Swedish Foundation for Strategic Research (SSF) GSn15 - 0008, Swedish Government Strategic Research Area in Materials Science on Advanced Functional Materials (AFM) at Linköping University (Faculty Grant SFO Mat LiU No. 2009 00971), Center in Nanoscience and technology at LiTH CeNano, Hans Werthén Foundation (IVA), Society of Vacuum Coaters Foundation (SVCF), Swedish Research Council (VR) Grant numbers 2019-00191 (for accelerator-based ion-technological center in tandem accelerator laboratory in Uppsala University), VR and SSF for access to ARTEMI, the Swedish National Infrastructure in Advanced Electron Microscopy (2021-00171 and RIF21-0026), Knut and Alice Wallenberg Foundation for the support of the electron microscopy laboratory at Linköping University (KAW 2015.0043), VR 2021-00159 for the Swedish neutron reflectometer SuperADAM at ILL 10.5291/ILL-DATA.CRG-2964, and Plansee GmbH for providing diboride targets.

Available from: 2024-02-06 Created: 2024-02-06 Last updated: 2024-02-13Bibliographically approved
Bairagi, S., Chang, J.-C., Tarntair, F.-G., Wu, W.-Y., Gueorguiev, G. K., de Almeida, E. F., . . . Hsiao, C.-L. (2023). Formation of quaternary Zn(AlxGa1−x)2O4 epilayers driven by thermally induced interdiffusion between spinel ZnGa2O4 epilayer and Al2O3 substrate. Materials Today Advances, 20, Article ID 100422.
Open this publication in new window or tab >>Formation of quaternary Zn(AlxGa1−x)2O4 epilayers driven by thermally induced interdiffusion between spinel ZnGa2O4 epilayer and Al2O3 substrate
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2023 (English)In: Materials Today Advances, ISSN 2590-0498, Vol. 20, article id 100422Article in journal (Refereed) Published
Abstract [en]

Zinc aluminogallate, Zn(AlxGa1−x)2O4 (ZAGO), a single-phase spinel structure, offers considerable potential for high-performance electronic devices due to its expansive compositional miscibility range between aluminum (Al) and gallium (Ga). Direct growth of high-quality ZAGO epilayers however remains problematic due to the high volatility of zinc (Zn). This work highlights a novel synthesis process for high-quality epitaxial quaternary ZAGO thin films on sapphire substrates, achieved through thermal annealing of a ZnGa2O4 (ZGO) epilayer on sapphire in an ambient air setting. In-situ annealing x-ray diffraction measurements show that the incorporation of Al in the ZGO epilayer commenced at 850 °C. The Al content (x) in ZAGO epilayer gradually increased up to around 0.45 as the annealing temperature was raised to 1100 °C, which was confirmed by transmission electron microscopy (TEM) and energy dispersive x-ray spectroscopy. X-ray rocking curve measurement revealed a small full width at half maximum value of 0.72 °, indicating the crystal quality preservation of the ZAGO epilayer with a high Al content. However, an epitaxial intermediate �–(AlxGa1−x)2O3 layer (� - AGO) was formed between the ZAGO and sapphire substrate. This is believed to be a consequence of the interdiffusion of Al and Ga between the ZGO thin film and sapphire substrate. Using density functional theory, the substitution cost of Ga in sapphire was determined to be about 0.5 eV lower than substitution cost of Al in ZGO. Motivated by this energetically favorable substitution, a formation mechanism of the ZAGO and AGO layers was proposed. Spectroscopic ellipsometry studies revealed an increase in total thickness of the film from 105.07 nm (ZGO) to 147.97 nm (ZAGO/AGO) after annealing to 1100 °C, which were corroborated using TEM. Furthermore, an observed increase in the direct (indirect) optical bandgap from 5.06 eV (4.7 eV) to 5.72 eV (5.45 eV) with an increasing Al content in the ZAGO layer further underpins the formation of a quaternary ZAGO alloy with a tunable composition.

Place, publisher, year, edition, pages
Elsevier, 2023
Keywords
Zinc aluminogallate; Ellipsometry; Semiconductors; Annealing; Interdiffusion; Bandgap
National Category
Condensed Matter Physics Inorganic Chemistry
Identifiers
urn:nbn:se:liu:diva-197989 (URN)10.1016/j.mtadv.2023.100422 (DOI)001081449100001 ()
Note

Funding agencies;This research was funded by Vetenskapsrådet (2018–04198), Energimyndigheten (46658-1), and Stiftelsen Olle Engkvist Byggmästare (197–0210), STINT (MG2019-8485), and Stiftelsen för Strategisk Forskning (2009-00971). The Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linköping University (Faculty Grant SFO-Mat-LiU 2009-00971) is acknowledged for financial support. We acknowledge the support from Wafer Works Corporation, National Science and Technology Council (Taiwan) (112-2218-E-A49-024-MBK, 112-2622-8-A49-013-SB, MOST 111-2923-E-A49 -003 -MY3), and MAtek (2021-T-006).

Available from: 2023-09-20 Created: 2023-09-20 Last updated: 2023-11-03
Chang, J.-C., Tseng, E. N., Lo, Y.-L., Nayak, S. K., Lundin, D., Persson, P. O. Å., . . . Hsiao, C.-L. (2023). HiPIMS-grown AlN buffer for threading dislocation reduction in DC-magnetron sputtered GaN epifilm on sapphire substrate. Vacuum, 217, Article ID 112553.
Open this publication in new window or tab >>HiPIMS-grown AlN buffer for threading dislocation reduction in DC-magnetron sputtered GaN epifilm on sapphire substrate
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2023 (English)In: Vacuum, ISSN 0042-207X, E-ISSN 1879-2715, Vol. 217, article id 112553Article in journal (Refereed) Published
Abstract [en]

Gallium nitride (GaN) epitaxial films on sapphire (Al2O3) substrates have been grown using reactive magnetron sputter epitaxy with a liquid Ga target. Threading dislocations density (TDD) of sputtered GaN films was reduced by using an inserted high-quality aluminum nitride (AlN) buffer layer grown by reactive high power impulse magnetron sputtering (R-HiPIMS) in a gas mixture of Ar and N2. After optimizing the Ar/N2 pressure ratio and deposition power, a high-quality AlN film exhibiting a narrow full-width at half-maximum (FWHM) value of the double-crystal x-ray rocking curve (DCXRC) of the AlN(0002) peak of 0.086° was obtained by R-HiPIMS. The mechanism giving rise the observed quality improvement is attributed to the enhancement of kinetic energy of the adatoms in the deposition process when operated in a transition mode. With the inserted HiPIMS-AlN as a buffer layer for direct current magnetron sputtering (DCMS) GaN growth, the FWHM values of GaN(0002) and (10 1‾ 1) XRC decrease from 0.321° to 0.087° and from 0.596° to 0.562°, compared to the direct growth of GaN on sapphire, respectively. An order of magnitude reduction from 2.7 × 109 cm−2 to 2.0 × 108 cm−2 of screw-type TDD calculated from the FWHM of the XRC data using the inserted HiPIMS-AlN buffer layer demonstrates the improvement of crystal quality of GaN. The result of TDD reduction using the HiPIMS-AlN buffer was also verified by weak beam dark-field (WBDF) cross-sectional transmission electron microscopy (TEM).

Place, publisher, year, edition, pages
PERGAMON-ELSEVIER SCIENCE LTD, 2023
Keywords
GaN; Magnetron sputtering; HiPIMS; Dislocations; XRCTEM
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:liu:diva-197990 (URN)10.1016/j.vacuum.2023.112553 (DOI)001072124300001 ()
Funder
Swedish Research CouncilSwedish Energy AgencyThe Swedish Foundation for International Cooperation in Research and Higher Education (STINT)Carl Tryggers foundation Olle Engkvists stiftelse
Note

Funding agencies: This research was funded by Vetenskapsrådet (grant number 2018-04198), Energimyndigheten (grant number 46658-1), Carl Tryggers Stiftelse (grant number CTS 22:2029) and Stiftelsen Olle Engkvist Byggmästare (grant number 197-0210). The Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linköping University (Faculty Grant SFO-Mat-LiU 2009-00971) is acknowledged for financial support. We acknowledge STINT foundation, Sweden, for supporting this international collaboration (grant number: MG2019-8485).

Available from: 2023-09-20 Created: 2023-09-20 Last updated: 2023-12-21
Eriksson, F., Ghafoor, N., Broekhuijsen, S., Greczynski, G., Schell, N. & Birch, J. (2023). Morphology control in Ni/Ti multilayer neutron mirrors by ion-assisted interface engineering and B4C incorporation. Optical Materials Express, 13(5), 1424-1439
Open this publication in new window or tab >>Morphology control in Ni/Ti multilayer neutron mirrors by ion-assisted interface engineering and B4C incorporation
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2023 (English)In: Optical Materials Express, ISSN 2159-3930, E-ISSN 2159-3930, Vol. 13, no 5, p. 1424-1439Article in journal (Refereed) Published
Abstract [en]

The optical contrast and minimum layer thickness of Ni/Ti broadband neutron multilayer supermirrors is usually hampered by an interface width, typically 0.7 nm, caused by nanocrystallites, interdiffusion, and/or intermixing. We explore the elimination of nanocrystallites in combination with interface smoothening by modulation of ion assistance during magnetron sputter deposition of 0.8 to 6.4 nm thick Ni and Ti layers. The amorphization is achieved through incorporation of natural B4C where B and C preferably bond to Ti. A two-stage substrate bias was applied to each layer; -30 V for the initial 1 nm followed by -100 V for the remaining part, generating multilayer mirrors with interface widths of 0.40-0.45 nm. The results predict that high performance supermirrors with m-values as high as 10 are feasible by using 11B isotope-enriched B4C combined with temporal control of the ion assistance.

Place, publisher, year, edition, pages
Optica Publishing Group, 2023
Keywords
Ion beam analysis; Ion beams; Magnetic fields; Optical components; X ray diffraction; X ray mirrors
National Category
Accelerator Physics and Instrumentation
Identifiers
urn:nbn:se:liu:diva-193550 (URN)10.1364/OME.476713 (DOI)000994009100005 ()
Note

Funding: Stiftelsen för Strategisk Forskning; Vetenskapsrådet.

Available from: 2023-05-05 Created: 2023-05-05 Last updated: 2023-06-14Bibliographically approved
Alves Machado Filho, M., Hsiao, C.-L., dos Santos, R. B., Hultman, L., Birch, J. & Gueorguiev, G. K. (2023). Self-Induced Core–Shell InAlN Nanorods: Formation and Stability Unraveled by Ab Initio Simulations. ACS Nanoscience Au, 3(1), 84-93
Open this publication in new window or tab >>Self-Induced Core–Shell InAlN Nanorods: Formation and Stability Unraveled by Ab Initio Simulations
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2023 (English)In: ACS Nanoscience Au, E-ISSN 2694-2496, Vol. 3, no 1, p. 84-93Article in journal (Refereed) Published
Abstract [en]

By addressing precursor prevalence and energetics using the DFT-based synthetic growth concept (SGC), the formation mechanism of self-induced InAlN core–shell nanorods (NRs) synthesized by reactive magnetron sputter epitaxy (MSE) is explored. The characteristics of In- and Al-containing precursor species are evaluated considering the thermal conditions at a typical NR growth temperature of around 700 °C. The cohesive and dissociation energies of In-containing precursors are consistently lower than those of their Al-containing counterparts, indicating that In-containing precursors are more weakly bonded and more prone to dissociation. Therefore, In-containing species are expected to exhibit lower abundance in the NR growth environment. At increased growth temperatures, the depletion of In-based precursors is even more pronounced. A distinctive imbalance in the incorporation of Al- and In-containing precursor species (namely, AlN/AlN+, AlN2/AlN2+, Al2N2/Al2N2+, and Al2/Al2+ vs InN/InN+, InN2/InN2+, In2N2/In2N2+, and In2/In2+) is found at the growing edge of the NR side surfaces, which correlates well with the experimentally obtained core–shell structure as well as with the distinctive In-rich core and vice versa for the Al-rich shell. The performed modeling indicates that the formation of the core–shell structure is substantially driven by the precursors’ abundance and their preferential bonding onto the growing edge of the nanoclusters/islands initiated by phase separation from the beginning of the NR growth. The cohesive energies and the band gaps of the NRs show decreasing trends with an increment in the In concentration of the NRs’ core and with an increment in the overall thickness (diameter) of the NRs. These results reveal the energy and electronic reasons behind the limited growth (up to ∼25% of In atoms of all metal atoms, i.e., InxAl1–xN, x ∼ 0.25) in the NR core and may be qualitatively perceived as a limiting factor for the thickness of the grown NRs (typically <50 nm).

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2023
Keywords
self-induced InAlN core−shell nanorods; synthetic growth concept; DFT; reactive magnetron sputter epitaxy; precursor species; nucleation and structural evolution of nanostructures; immiscible systems at nanoscale
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:liu:diva-197988 (URN)10.1021/acsnanoscienceau.2c00041 (DOI)001091274000001 ()37101465 (PubMedID)
Funder
Swedish Research Council, 2018-04198Swedish Research Council, 2018-05973Swedish Research Council, SNIC 2022/23-137Swedish Research Council, SNIC 2022/5-135Swedish Energy Agency, 46658-1Linköpings universitet, 2009-00971
Note

Funding: Swedish Government Strategic Research Area in Materials Science on Advanced Functional Materials (AFM) at Linkoping University [2009-00971]; Swedish Research Council (Vetenskapsradet) [2018-04198]; Swedish Energy Agency (Energimyndigheten) [46658-1]; Brazilian Research agency CNPq; Brazilian Research agency CAPES; Swedish Research Council [2018-05973]

Available from: 2023-09-20 Created: 2023-09-20 Last updated: 2023-11-15Bibliographically approved
Nyman, J., Junaid, M., Sarius, N., Birch, J., Kahl, S. & Högberg, H. (2023). Substrate bias effects on cathodic arc deposited Cr coatings. Results in Materials, 19, Article ID 100450.
Open this publication in new window or tab >>Substrate bias effects on cathodic arc deposited Cr coatings
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2023 (English)In: Results in Materials, ISSN 2590-048X, Vol. 19, article id 100450Article in journal (Refereed) Published
Abstract [en]

We investigate the effects of substrate bias on cathodic arc deposition of Cr coatings without external substrate heating at four different substrate bias levels, floating, −30, −50, and −70 V. After 10 min of deposition, the substrate temperature reaches 180, 210, 230, and 260 °C for floating potential, −30, −50, and −70 V, respectively. Time-of-flight energy elastic recoil detection analysis shows that all grown coatings are of high purity, with no coating containing more than 0.2 at.% of C and/or O. Increasing the substrate bias also reduces the number of macroparticles, steers the texture from preferred [110]- to [100]-orientation and induces a residual compressive stress of ∼450 MPa in the coatings. The hardness of the coatings remains at a constant 7.5 GPa irrespective of the substrate bias. The four-point probe resistivity of the grown coatings is 15–17 μΩcm regardless of substrate bias, close to the 12.9 μΩcm of bulk Cr.

Keywords
Chromium coatings, Cathodic arc deposition, Substrate bias, Stress, Hardness
National Category
Manufacturing, Surface and Joining Technology
Identifiers
urn:nbn:se:liu:diva-198779 (URN)10.1016/j.rinma.2023.100450 (DOI)
Note

Funding agencies: The research leading to these results has received funding from the Swedish Foundation for Strategic Research (SSF) and contract ID17-0055. The authors acknowledge Arnaud Le Febvrier and Claudia Schnitter for assistance with the pole figure measurements. Support from the Swedish research council VR-RFI (#2017–00646_9) for the Accelerator based ion-technological center, and from the Swedish Foundation for Strategic Research (contract RIF14-0053) for the tandem accelerator laboratory in Uppsala is gratefully acknowledged. H.H. acknowledges financial support from the Swedish Government Strategic Research Area in Materials Science on Advanced Functional Materials at Linkoping University (Faculty Grant SFO-Mat-LiU No. 2009–00971).

Available from: 2023-10-27 Created: 2023-10-27 Last updated: 2023-10-27Bibliographically approved
Broekhuijsen, S., Ghafoor, N., Vorobiev, A., Birch, J. & Eriksson, F. (2023). Synthesis and characterization of 11B4C containing Ni/Ti multilayers using combined neutron and X-ray reflectometry. Optical Materials Express, 13(4), 1140-1149
Open this publication in new window or tab >>Synthesis and characterization of 11B4C containing Ni/Ti multilayers using combined neutron and X-ray reflectometry
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2023 (English)In: Optical Materials Express, ISSN 2159-3930, E-ISSN 2159-3930, Vol. 13, no 4, p. 1140-1149Article in journal (Refereed) Published
Abstract [en]

The performance of multilayers in optical components, such as those used in neutron scattering instruments, is crucially dependent on the achievable interface width. We have shown how the interface width of Ni/Ti multilayers can be improved using the incorporation of B4C to inhibit the formation of nanocrystals and limit interdiffusion and intermetallic reactions at the interfaces. A modulated ion-assistance scheme was used to prevent intermixing and roughness accumulation throughout the layer stack. In this work we investigate the incorporation of low-neutron-absorbing 11B4C for Ni/Ti neutron multilayers. Combined fitting of neutron reflectivity and X-ray reflectivity measurements shows an elimination of accumulated roughness for the 11B4C containing multilayers with a mean interface width of 4.5 Å, resulting in an increase in reflectivity at the first Bragg peak by a factor of 2.3 and 1.5 for neutron and X-ray measurements, respectively.

Place, publisher, year, edition, pages
Optica Publishing Group, 2023
Keywords
Condensed matter; Ion beam analysis; Optical components; Reflectivity; Synchrotron radiation; X ray mirrors
National Category
Accelerator Physics and Instrumentation
Identifiers
urn:nbn:se:liu:diva-193551 (URN)10.1364/OME.481049 (DOI)
Available from: 2023-05-05 Created: 2023-05-05 Last updated: 2023-05-09Bibliographically approved
Chang, J.-C., Birch, J., Kostov Gueorguiev, G., Bakhit, B., Greczynski, G., Eriksson, F., . . . Hsiao, C.-L. (2022). Domain epitaxial growth of Ta3N5 film on c-plane sapphire substrate. Surface & Coatings Technology, 443, Article ID 128581.
Open this publication in new window or tab >>Domain epitaxial growth of Ta3N5 film on c-plane sapphire substrate
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2022 (English)In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 443, article id 128581Article in journal (Refereed) Published
Abstract [en]

Tritantalum pentanitride (Ta3N5) semiconductor is a promising material for photoelectrolysis of water with high efficiency. Ta3N5 is a metastable phase in the complex system of TaN binary compounds. Growing stabilized single-crystal Ta3N5 films is correspondingly challenging. Here, we demonstrate the growth of a nearly single-crystal Ta3N5 film with epitaxial domains on c-plane sapphire substrate, Al2O3(0001), by magnetron sputter epitaxy. Introduction of a small amount ~2% of O2 into the reactive sputtering gas mixed with N2 and Ar facilitates the formation of a Ta3N5 phase in the film dominated by metallic TaN. In addition, we indicate that a single-phase polycrystalline Ta3N5 film can be obtained with the assistance of a Ta2O5 seed layer. With controlling thickness of the seed layer smaller than 10 nm and annealing at 1000 °C, a crystalline β phase Ta2O5 was formed, which promotes the domain epitaxial growth of Ta3N5 films on Al2O3(0001). The mechanism behind the stabilization of the orthorhombic Ta3N5 structure resides in its stacking with the ultrathin seed layer of orthorhombic β-Ta2O5, which is energetically beneficial and reduces the lattice mismatch with the substrate.

Place, publisher, year, edition, pages
Elsevier, 2022
Keywords
Ta3N5, Sputtering, MSE, XRD, XPS, Water splitting, Single crystal
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:liu:diva-188556 (URN)10.1016/j.surfcoat.2022.128581 (DOI)000868328000003 ()
Note

Funding: Swedish Research Council [2018-04198, 2021-00357]; Swedish Energy Agency [46658-1]; Stiftelsen Olle Engkvist Byggmastare [197-0210]; Linkoping University Library; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University [SFO-Mat-LiU 2009-00971]

Available from: 2022-09-16 Created: 2022-09-16 Last updated: 2023-12-21Bibliographically approved
Lai, C.-C., Boyd, R., Svensson, P.-O., Höglund, C., Robinson, L., Birch, J. & Hall-Wilton, R. (2022). Effect of substrate roughness and material selection on the microstructure of sputtering deposited boron carbide thin films. Surface & Coatings Technology, 433, Article ID 128160.
Open this publication in new window or tab >>Effect of substrate roughness and material selection on the microstructure of sputtering deposited boron carbide thin films
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2022 (English)In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 433, article id 128160Article in journal (Refereed) Published
Abstract [en]

Amorphous boron carbide (B4C) thin films are by far the most popular form for the neutron converting layers in the 10B-based neutron detectors, which are a rising trend in detector technologies in response to the increasing scarcity and price of 3He, the standard material for neutron detection. The microstructure of the B4C films is closely related to the important properties, e.g. density and adhesion, for the converting layers, which eventually affect the detection efficiency and the long-term stability of the detectors. To study the influence from substrates of different roughness and materials, the B4C films were deposited on polished Si substrates with Al, Ti, and Cu buffer layers and unpolished Si, Al, Ti, and Cu substrates by direct current magnetron sputtering at a substrate temperature of 623 K. The tapered columnar grains and nodular defects, generally observed in SEM images, indicated a strong shadowing effect where voids were introduced around the grains. The change in the grain size did not show a direct dependence to the substrate roughness, acquired from the surface profile, nor to the mass density of the films, obtained from reflectivity patterns. However, films with non-uniform size of columnar grains were deposited on substrates with high skewness, leading to a drop of mass density from ∼95% down to ∼70% of tabulated bulk density. On the other hand, similar microstructures and mass density were obtained from the films deposited on Al, Ti, and Cu of different roughness and good adhesion were observed from cross-cut adhesion tests, showing the reliability of sputtering deposited B4C films on common structural materials in neutron detectors.

Place, publisher, year, edition, pages
Lausanne, Switzerland: Elsevier, 2022
Keywords
Boron carbide; Thin films; Magnetron sputtering; Microstructure; Surface roughness
National Category
Manufacturing, Surface and Joining Technology
Identifiers
urn:nbn:se:liu:diva-184745 (URN)10.1016/j.surfcoat.2022.128160 (DOI)000782695200001 ()2-s2.0-85123888908 (Scopus ID)
Available from: 2022-05-10 Created: 2022-05-10 Last updated: 2022-06-02Bibliographically approved
Nayak, S. K., Singh, C. K., Dahlqvist, M., Rosén, J., Eklund, P. & Birch, J. (2022). First-principles study on the superconductivity of doped zirconium diborides. Physical Review Materials, 6(4), Article ID 044805.
Open this publication in new window or tab >>First-principles study on the superconductivity of doped zirconium diborides
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2022 (English)In: Physical Review Materials, E-ISSN 2475-9953, Vol. 6, no 4, article id 044805Article in journal (Refereed) Published
Abstract [en]

Recent experiments [Barbero et al. Phys. Rev. B 95, 094505 (2017)] have established that bulk superconductivity (Tc ∼ 8.3-8.7 K) can be induced in AlB2-type ZrB2 and HfB2, highly covalent refractory ceramics, by vanadium (V) doping. These AlB2-structured phases provide an alternative to earlier diamon-like or diamond-based superconducting and superhard materials. However, the underlying mechanism for doping-induced superconductivity in these materials is yet to be addressed. In this paper, we have used first-principles calculations to probe electronic structure, lattice dynamics, and electron-phonon coupling (EPC) in V-doped ZrB2 and consequently examine the origin of the superconductivity. We find that, while doping-induced stress weakens the EPC, the concurrently induced charges strengthen it. The calculated critical transition temperature (Tc) in electron (and V)-doped ZrB2 is at least one order of magnitude lower than experiments, despite considering the weakest possible Coulomb repulsion between electrons in the Cooper pair, hinting a complex origin of superconductivity in it.

Place, publisher, year, edition, pages
College Park, MD, United States: American Physical Society, 2022
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:liu:diva-185624 (URN)10.1103/PhysRevMaterials.6.044805 (DOI)000798279000001 ()2-s2.0-85129754900 (Scopus ID)
Note

Funding Agencies: Swedish Research Council [2018-05973]; Knut and Alice Wallenberg (KAW) Foundation; Wallenberg Academy Fellows program [2020.0196, 2018.0146, 2019.0433, 2015.0043]

Available from: 2022-06-10 Created: 2022-06-10 Last updated: 2022-08-02Bibliographically approved
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ORCID iD: ORCID iD iconorcid.org/0000-0002-8469-5983

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