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  • 1.
    Aghda, Soheil Karimi
    et al.
    Rhein Westfal TH Aachen, Germany.
    Bogdanovski, Dimitri
    Rhein Westfal TH Aachen, Germany.
    Lo, Lukas
    Sua, Heng Han
    Rhein Westfal TH Aachen, Germany.
    Patterer, Lena
    Rhein Westfal TH Aachen, Germany.
    Holzapfel, Damian M.
    Rhein Westfal TH Aachen, Germany.
    Le Febvrier, Arnaud
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Hans, Marcus
    Rhein Westfal TH Aachen, Germany.
    Primetzhofer, Daniel
    Uppsala Univ, Sweden.
    Schneider, Jochen M.
    Rhein Westfal TH Aachen, Germany.
    Valence electron concentration- and N vacancy-induced elasticity in cubic early transition metal nitrides2023In: Acta Materialia, ISSN 1359-6454, E-ISSN 1873-2453, Vol. 255, article id 119078Article in journal (Refereed)
    Abstract [en]

    Motivated by frequently reported deviations from stoichiometry in cubic transition metal nitride (TMNx) thin films, the effect of N-vacancy concentration on the elastic properties of cubic TiNx, ZrNx, VNx, NbNx, and MoNx (0.72 & LE; x & LE; 1.00) is systematically studied by density functional theory (DFT) calculations. The predictions are validated experimentally for VNx (0.77 & LE; x & LE; 0.97). The DFT results indicate that the elastic behavior of the TMNx depends on both the N-vacancy concentration and the valence electron concentration (VEC) of the transition metal: While TiNx and ZrNx exhibit vacancy-induced reductions in elastic modulus, VNx and NbNx show an increase. These trends can be rationalized by considering vacancy-induced changes in elastic anisotropy and bonding. While introduction of N-vacancies in TiNx results in a significant reduction of elastic modulus along all directions and a lower average bond strength of Ti-N, the vacancy-induced reduction in [001] direction of VNx is overcompensated by the higher stiffness along [011] and [111] directions, resulting in a higher average bond strength of V-N. To validate the predicted vacancy-induced changes in elasticity experimentally, close-to-singlecrystal VNx (0.77 & LE; x & LE; 0.97) are grown on MgO(001) substrates. As the N-content is reduced, the relaxed lattice parameter a0, as probed by X-ray diffraction, decreases from 4.128 & ANGS; to 4.096 & ANGS;. This reduction in lattice parameter is accompanied by an anomalous 11% increase in elastic modulus, as determined by nanoindentation. As the experimental data agree with the predictions, the elasticity enhancement in VNx upon N-vacancy formation can be understood based on the concomitant changes in elastic anisotropy and bonding.

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  • 2.
    Ali, Sharafat
    et al.
    Linnaeus Univ, Sweden.
    Magnusson, Roger
    Linnaeus Univ, Sweden.
    Pshyk, Oleksandr
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering. Empa Swiss Fed Labs Mat Sci & Technol, Switzerland.
    Birch, Jens
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Le Febvrier, Arnaud
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Effect of O/N content on the phase, morphology, and optical properties of titanium oxynitride thin films2023In: Journal of Materials Science, ISSN 0022-2461, E-ISSN 1573-4803, Vol. 58, p. 10975-10985Article in journal (Refereed)
    Abstract [en]

    Phase formation, morphology, and optical properties of Ti(O,N) thin films with varied oxygen-to- nitrogen ration content were investigated. The films were deposited by magnetron sputtering at 500 & DEG;C on Si(100) and c-plane sapphire substrate. A competition between a NaCl B1 structure TiN1-xOx, a rhombohedral structure Ti-2(O1-yNy)(3), and an anatase structure Ti(O1-zNz)(2) phase was observed. While the N-rich films were composed of a NaCl B1 TiN1-xOx phase, an increase of oxygen in the films yields the growth of rhombohedral Ti-2(O1-yNy)(3) phase and the oxygen-rich films are comprised of a mixture of the rhombohedral Ti-2(O1-yNy)(3) phase and anatase Ti(O1-zNz)(2) phase. The optical properties of the films were correlated to the phase composition and the observation of abrupt changes in terms of refractive index and absorption coefficient. The oxide film became relatively transparent in the visible range while the addition of nitrogen into films increases the absorption. The oxygen rich-samples have bandgap values below 3.75 eV, which is higher than the value for pure TiO2, and lower than the optical bandgap of pure TiN. The optical properties characterizations revealed the possibility of adjusting the band gap and the absorption coefficient depending on the N-content, because of the phases constituting the films combined with anionic substitution.

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  • 3.
    Alijan Farzad Lahiji, Faezeh
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Bairagi, Samiran
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Magnusson, Roger
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Sortica, Mauricio A.
    Uppsala Univ, Sweden.
    Primetzhofer, Daniel
    Uppsala Univ, Sweden.
    Ekström, Erik
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Paul, Biplab
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Le Febvrier, Arnaud
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Growth and optical properties of NiO thin films deposited by pulsed dc reactive magnetron sputtering2023In: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films, ISSN 0734-2101, E-ISSN 1520-8559, Vol. 41, no 6, article id 063402Article in journal (Refereed)
    Abstract [en]

    NiO thin films with varied oxygen contents are grown on Si(100) and c-Al2O3 at a substrate temperature of 300 degrees C using pulsed dc reactive magnetron sputtering. We characterize the structure and optical properties of NiO changes as functions of the oxygen content. NiO with the cubic structure, single phase, and predominant orientation along (111) is found on both substrates. X-ray diffraction and pole figure analysis further show that NiO on the Si(100) substrate exhibits fiber-textured growth, while twin domain epitaxy was achieved on c-Al2O3, with NiO(111) k Al2O3(0001) and NiO[1 (1) over bar0]k Al2O3[10 (1) over bar0] or NiO[(1) over bar 10]k Al2O3[2 (1) over bar(1) over bar0] epitaxial relationship. The oxygen content in NiO films did not have a significant effect on the refractive index, extinction coefficient, and absorption coefficient. This suggests that the optical properties of NiO films remained unaffected by changes in the oxygen content.

  • 4.
    Burcea, Razvan
    et al.
    Univ Poitiers ENSMA, France.
    Barbot, Jean-Francois
    Univ Poitiers ENSMA, France.
    Renault, Pierre-Olivier
    Univ Poitiers ENSMA, France.
    Eyidi, Dominique
    Univ Poitiers ENSMA, France.
    Girardeau, Thierry
    Univ Poitiers ENSMA, France.
    Marteau, Marc
    Univ Poitiers ENSMA, France.
    Giovannelli, Fabien
    Univ Tours, France.
    Zenji, Ahmad
    Univ Bordeaux, France.
    Rampnoux, Jean-Michel
    Univ Bordeaux, France.
    Dilhaire, Stefan
    Univ Bordeaux, France.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Le Febvrier, Arnaud
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Influence of Generated Defects by Ar Implantation on the Thermoelectric Properties of ScN2022In: ACS Applied Energy Materials, E-ISSN 2574-0962, Vol. 5, no 9, p. 11025-11033Article in journal (Refereed)
    Abstract [en]

    Nowadays, making thermoelectric materials more efficient in energy conversion is still a challenge. In this work, to reduce the thermal conductivity and thus improve the overall thermoelectric performances, point and extended defects were generated in epitaxial 111-ScN thin films by implantation using argon ions. The films were investigated by structural, optical, electrical, and thermoelectric characterization methods. The results demonstrated that argon implantation leads to the formation of stable defects (up to 750 K operating temperature). These were identified as interstitial-type defect dusters and argon vacancy complexes. The insertion of these specific defects induces acceptor-type deep levels in the band gap, yielding a reduction in the free-carrier mobility. With a reduced electrical conductivity, the irradiated sample exhibited a higher Seebeck coefficient while maintaining the power factor of the film. The thermal conductivity is strongly reduced from 12 to 3 W.m(-1). K-1 at 300 K, showing the influence of defects in increasing phonon scattering. Subsequent high-temperature annealing at 1573 K leads to the progressive evolution of these defects: the initial dusters of interstitials evolved to the benefit of smaller dusters and the formation of bubbles. Thus, the number of free carriers, the resistivity, and the Seebeck coefficient are almost restored but the mobility of the carriers remains low and a 30% drop in thermal conductivity is still effective (k(total) similar to 8.5 Wm(-1).K-1). This study shows that control defect engineering with defects introduced by irradiation using noble gases in a thermoelectric coating can be an attractive method to enhance the figure of merit of thermoelectric materials.

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  • 5.
    Burcea, Razvan
    et al.
    Univ Poitiers, France.
    Bouteiller, Hugo
    Univ Poitiers, France.
    Hurand, Simon
    Univ Poitiers, France.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Barbot, Jean-Francois
    Univ Poitiers, France.
    Le Febvrier, Arnaud
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Effect of induced defects on conduction mechanisms of noble-gas-implanted ScN thin films2023In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 134, no 5, article id 055107Article in journal (Refereed)
    Abstract [en]

    Noble-gas implantation was used to introduce defects in n-type degenerate ScN thin films to tailor their transport properties. The electrical resistivity increased significantly with the damage levels created, while the electron mobility decreased regardless of the nature of the ion implanted and their doses. However, the transport property characterizations showed that two types of defects were formed during implantation, named point-like and complex-like defects depending on their temperature stability. The point-like defects changed the electrical conduction mode from metallic-like to semiconducting behavior. In the low temperature range, where both groups of defects were present, the dominant operative conduction mechanism was the variable range hopping conduction mode. Beyond a temperature of about 400 K, the point-like defects started to recover with an activation energy of 90 meV resulting in a decrease in resistivity, independent of the incident ion. The complex-like defects were, therefore, the only remaining group of defects after annealing above 700 K. These latter, thermally stable at least up to 750 K, introduced deep acceptor levels in the bandgap resulting in an increase in the electrical resistivity with higher carrier scattering while keeping the metallic-like behavior of the sample. The generation of both types of defects, as determined by resistivity measurements, appeared to occur through a similar mechanism within a single collision cascade.

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  • 6.
    Calamba, Katherine
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, Faculty of Science & Engineering. Univ Lorraine, France.
    Barrirero, Jenifer
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, Faculty of Science & Engineering. Saarland Univ, Germany.
    Joesaar, M. P. Johansson
    SECO Tools AB, Sweden.
    Bruyere, S.
    Univ Lorraine, France.
    Boyd, Robert
    Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics. Linköping University, Faculty of Science & Engineering.
    Pierson, J. F.
    Univ Lorraine, France.
    Le Febvrier, Arnaud
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Muecklich, F.
    Saarland Univ, Germany.
    Odén, Magnus
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, Faculty of Science & Engineering.
    Growth and high temperature decomposition of epitaxial metastable wurtzite (Ti1-x,Al-x)N(0001) thin films2019In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 688, article id 137414Article in journal (Refereed)
    Abstract [en]

    The structure, growth, and phase stability of (Ti1-x,Al-x)N films with high Al content were investigated. (Ti1-x,Al-x)N (x= 0.63 and 0.77) thin films were grown on MgO (111) substrates at 700 degrees C using a UHV DC magnetron sputtering system. The (Ti-0.37,Al-0.63)N film is a single crystal with a cubic NaCl (B1) structure while the (T-i0.23,Al-0.77)N film only shows epitaxial growth of the same cubic phase in the first few atomic layers. With increasing film thickness, epitaxial wurtzite (B4) forms. The thin cubic layer and the wurtzite film has an orientation relationship of c-(Ti-0.23,Al-0.77)N(111)[110]parallel to w-(Ti-0.23,Al-0.77)N(0001)[11 (2) over bar0]. Continued deposition results in a gradual break-down of the epitaxial growth. It is replaced by polycrystalline growth of wurtzite columns with a high degree of 0001 texture, separated by a Tienriched cubic phase. In the as-deposited state, c-(Ti-0.27,Al-0.63)N displays a homogeneous chemical distribution while the w-(Ti-0.23,Al-0.77)N has segregated to Al- and Ti-rich domains. Annealing at 900 degrees C resulted in the spinodal decomposition of the metastable c-(Ti-0.27,Al-0.63)N film and formation of coherent elongated c-AlN and cTi-N-rich domains with an average width of 4.5 +/- 0.2 nm while the width of the domains in the w-(Ti-0.23,Al-0.77)N film only marginally increases to 2.8 +/- 0.1 nm. The slower coarsening rate of the wurtzite structure compared to cubic is indicative of a higher thermal stability.

  • 7.
    Calamba, Katherine
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, Faculty of Science & Engineering. Univ Lorraine, France.
    Pierson, J. F.
    Univ Lorraine, France.
    Bruyere, S.
    Univ Lorraine, France.
    Le Febvrier, Arnaud
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Barrirero, Jenifer
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, Faculty of Science & Engineering. Saarland Univ, Germany.
    Muecklich, F.
    Saarland Univ, Germany.
    Boyd, Robert
    Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics. Linköping University, Faculty of Science & Engineering.
    Jöesaar Johansson, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, Faculty of Science & Engineering. SECO Tools AB, Sweden.
    Odén, Magnus
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, Faculty of Science & Engineering.
    Dislocation structure and microstrain evolution during spinodal decomposition of reactive magnetron sputtered heteroepixatial c-(Ti-0.37,Al-0.63)N/c-TiN films grown on MgO(001) and (111) substrates2019In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 125, no 10, article id 105301Article in journal (Refereed)
    Abstract [en]

    Heteroepitaxial c-(Ti-0.37,Al-0.63)N thin films were grown on MgO(001) and MgO(111) substrates using reactive magnetron sputtering. High resolution high-angle annular dark-field scanning transmission electron micrographs show coherency between the film and the substrate. In the as-deposited state, x-ray diffraction reciprocal space maps show a strained epitaxial film. Corresponding geometric phase analysis (GPA) deformation maps show a high stress in the film. At elevated temperature (900 degrees C), the films decompose to form iso-structural coherent c-Al- and c-TiN-rich domains, elongated along the elastically soft amp;lt;100amp;gt; directions. GPA analysis reveals that the c-TiN domains accommodate more dislocations than the c-AlN domains. This is because of the stronger directionality of the covalent bonds in c-AlN compared with c-TiN, making it more favorable for the dislocations to accumulate in c-TiN. The defect structure and strain generation in c-(Ti,Al)N during spinodal decomposition is affected by the chemical bonding state and elastic properties of the segregated domains.

  • 8.
    Chowdhury, Susmita
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Hjort, Victor
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Shu, Rui
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Greczynski, Grzegorz
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Le Febvrier, Arnaud
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Magnuson, Martin
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Thermoelectric properties and electronic structure of Cr(Mo,V)Nx thin films studied by synchrotron and lab-based x-ray spectroscopy2023In: Physical Review B, ISSN 2469-9950, E-ISSN 2469-9969, Vol. 108, no 20, article id 205134Article in journal (Refereed)
    Abstract [en]

    Chromium-based nitrides are used in hard, resilient coatings and show promise for thermoelectric applications due to their combination of structural, thermal, and electronic properties. Here, we investigate the electronic structures and chemical bonding correlated to the thermoelectric properties of epitaxially grown chromium-based multicomponent nitride Cr(Mo,V)Nx thin films. The small amount of N vacancies causes Cr 3d and N 2p states to appear at the Fermi level and reduces the band gap in Cr0.51N0.49. Incorporating holes by alloying of V in N-deficient CrN results in an enhanced thermoelectric power factor with marginal change in the charge transfer of Cr to N compared with Cr0.51N0.49. Further alloying of Mo, isoelectronic to Cr, increases the density of states at the Fermi level due to hybridization of the (Cr, V) 3d and Mo 4d-N 2p states in Cr(Mo,V)Nx. This hybridization and N off-stoichiometry result in more metal-like electrical resistivity and reduction in Seebeck coefficient. The N deficiency in Cr(Mo,V)Nx also depicts a critical role in reduction of the charge transfer from metal to N site compared with Cr0.51N0.49 and Cr0.50V0.03N0.47. In this paper, we envisage ways for enhancing thermoelectric properties through electronic band engineering by alloying and competing effects of N vacancies.

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  • 9.
    Du, Hao
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics. Linköping University, Faculty of Science & Engineering. Guizhou Univ, Peoples R China; Guizhou Univ, Peoples R China.
    Shu, Rui
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Boyd, Robert
    Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics. Linköping University, Faculty of Science & Engineering.
    Le Febvrier, Arnaud
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Helmersson, Ulf
    Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics. Linköping University, Faculty of Science & Engineering.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Lundin, Daniel
    Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics. Linköping University, Faculty of Science & Engineering.
    Evolution of microstructure and properties of TiNbCrAlHfN films grown by unipolar and bipolar high-power impulse magnetron co-sputtering: The role of growth temperature and ion bombardment2023In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 459, article id 129389Article in journal (Refereed)
    Abstract [en]

    Growth temperature (Ts) and ion irradiation energy (Ei) are important factors that influence film growth as well as their properties. In this study, we investigate the evolution of crystal structure and residual stress of TiNb-CrAlHfN films under various Ts and Ei conditions, where the latter is mainly controlled by tuning the flux of sputtered Hf ions using bipolar high-power impulse magnetron (BP-HiPIMS). The results show that TiNbCrAlHfN films exhibit the typical FCC NaCl-type structure. By increasing Ts from room temperature to 600 degrees C, the film texture changes from high-surface-energy (111) to low-surface-energy (100) accompanied by a higher crystal-linity in the out-of-plane direction and a more disordered growth tilt angle to the surface plane. In addition, compressive stress decreases with increasing Ts, which is ascribed to changes in the film growth both in the early and post-coalescence stages and more tensile thermal stress at elevated Ts. In contrast, a clear texture transition window is seen under various Ei of Hf+ ions, i.e., high-surface-energy planes change to low-surface-energy planes as Ei exceeds-110 eV, while low-surface-energy planes gradually transform back to high-surface-energy planes when Ei increases from 210 to 260 eV, indicating renucleation events for Ei > 210 eV. Compressive stress in-creases with increasing Ei but is still lower than that of a reference series with DC substrate bias UDC =-100 V. The study shows that it is possible to tailor properties of FCC-structured high-entropy nitrides by varying Ts and Ei in a similar fashion to conventional transition metal nitrides using the approach of unipolar and bipolar HiPIMS co-sputtering.

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  • 10.
    Du, Hao
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics. Linköping University, Faculty of Science & Engineering. Guizhou Univ, Peoples R China; Guizhou Univ, Peoples R China.
    Shu, Rui
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Boyd, Robert
    Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics. Linköping University, Faculty of Science & Engineering.
    Le Febvrier, Arnaud
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Sortica, Mauricio A.
    Uppsala Univ, Sweden.
    Primetzhofer, Daniel
    Uppsala Univ, Sweden; Uppsala Univ, Sweden.
    Helmersson, Ulf
    Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics. Linköping University, Faculty of Science & Engineering.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Lundin, Daniel
    Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics. Linköping University, Faculty of Science & Engineering.
    Corundum-structured AlCrNbTi oxide film grown using high-energy early-arriving ion irradiation in high-power impulse magnetron sputtering2023In: Scripta Materialia, ISSN 1359-6462, E-ISSN 1872-8456, Vol. 234, article id 115578Article in journal (Refereed)
    Abstract [en]

    Multicomponent or high-entropy oxide films are of interest due to their remarkable structure and properties. Here, energetic ion irradiation is utilized for controlling the phase formation and structure of AlCrNbTi oxide at growth temperature of 500 degrees C. The ion acceleration is achieved by using a high-power impulse magnetron sputtering (HiPIMS) discharge, accompanied by a 10 & mu;s-long synchronized substrate bias (Usync), to minimize the surface charging effect and accelerate early-arriving ions, mainly Al+, O+, Ar2+, and Al2+. By increasing the magnitude of Usync from-100 V to-500 V, the film structure changes from amorphous to single-phase corundum, followed by the formation of high-number-density stacking faults (or nanotwins) at Usync =-500 V. This approach paves the way to tailor the high-temperature-phase and defect formation of oxide films at low growth temperature, with prospects for use in protective-coating and dielectric applications.

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  • 11.
    Ekström, Erik
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Elsukova, Anna
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Grasland, Justine
    IUT BloisUniv Francois Rabelais Tours, France.
    Palisaitis, Justinas
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Ramanath, Ganpati
    Rensselaer Polytech Inst, NY 12180 USA.
    Persson, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Paul, Biplab
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Eriksson, Fredrik
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Le Febvrier, Arnaud
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Epitaxial Growth of CaMnO3-y Films on LaAlO3 (112 over bar 0) by Pulsed Direct Current Reactive Magnetron Sputtering2022In: Physica Status Solidi. Rapid Research Letters, ISSN 1862-6254, E-ISSN 1862-6270, Vol. 16, no 4, article id 2100504Article in journal (Refereed)
    Abstract [en]

    CaMnO3 is a perovskite with attractive magnetic and thermoelectric properties. CaMnO3 films are usually grown by pulsed laser deposition or radio frequency magnetron sputtering from ceramic targets. Herein, epitaxial growth of CaMnO3-y (002) films on a (112 over bar 0)-oriented LaAlO3 substrate using pulsed direct current reactive magnetron sputtering is demonstrated, which is more suitable for industrial scale depositions. The CaMnO3-y shows growth with a small in-plane tilt of <approximate to 0.2 degrees toward the (200) plane of CaMnO3-y and the (1 over bar 104) with respect to the LaAlO3 (112 over bar 0) substrate. X-ray photoelectron spectroscopy of the electronic core levels shows an oxygen deficiency described by CaMnO2.58 that yields a lower Seebeck coefficient and a higher electrical resistivity when compared to stoichiometric CaMnO3. The LaAlO3 (112 over bar 0) substrate promotes tensile-strained growth of single crystals. Scanning transmission electron microscopy and electron energy loss spectroscopy reveal antiphase boundaries composed of Ca on Mn sites along and , forming stacking faults.

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  • 12.
    Ekström, Erik
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Hurand, Simon
    Univ Poitiers, France.
    Le Febvrier, Arnaud
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Elsukova, Anna
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Persson, Per O A
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Paul, Biplab
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Eriksson, Fredrik
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Sharma, Geetu
    Rensselaer Polytech Inst, NY 12180 USA.
    Voznyy, Oleksandr
    Univ Toronto Scarborough, Canada.
    Sangiovanni, Davide
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering.
    Ramanath, Ganpati
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering. Rensselaer Polytech Inst, NY 12180 USA.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Microstructure control and property switching in stress-free van der Waals epitaxial VO2 films on mica2023In: Materials & design, ISSN 0264-1275, E-ISSN 1873-4197, Vol. 229, article id 111864Article in journal (Refereed)
    Abstract [en]

    Realizing stress-free inorganic epitaxial films on weakly bonding substrates is of importance for applications that require film transfer onto surfaces that do not seed epitaxy. Film-substrate bonding is usually weakened by harnessing natural van der Waals layers (e.g., graphene) on substrate surfaces, but this is difficult to achieve in non-layered materials. Here, we demonstrate van der Waals epitaxy of stress-free films of a non-layered material VO2 on mica. The films exhibit out-of-plane 010 texture with three inplane orientations inherited from the crystallographic domains of the substrate. The lattice parameters are invariant with film thickness, indicating weak film-substrate bonding and complete interfacial stress relaxation. The out-of-plane domain size scales monotonically with film thickness, but the in-plane domain size exhibits a minimum, indicating that the nucleation of large in-plane domains supports subsequent island growth. Complementary ab initio investigations suggest that VO2 nucleation and van der Waals epitaxy involves subtle polarization effects around, and the active participation of, surface potassium atoms on the mica surface. The VO2 films show a narrow domain-size-sensitive electrical-conductiv ity-temperature hysteresis. These results offer promise for tuning the properties of stress-free van der Waals epitaxial films of non-layered materials such as VO2 through microstructure control (C) 2023 The Author(s). Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).

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  • 13.
    Ekström, Erik
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Le Febvrier, Arnaud
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Bourgeois, F.
    Univ Technol Blois, France.
    Lundqvist, Björn
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Palisaitis, Justinas
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Persson, Per O A
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Caballero-Calero, O.
    CEI UAM, Spain.
    Martin-Gonzalez, M. S.
    CEI UAM, Spain.
    Klarbring, Johan
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering.
    Simak, Sergey
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering.
    Eriksson, Fredrik
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Paul, Biplab
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    The effects of microstructure, Nb content and secondary Ruddlesden-Popper phase on thermoelectric properties in perovskite CaMn1-xNbxO3 (x=0-0.10) thin films2020In: RSC Advances, E-ISSN 2046-2069, RSC ADVANCES, Vol. 10, no 13, p. 7918-7926Article in journal (Refereed)
    Abstract [en]

    CaMn1-xNbxO3 (x = 0, 0.5, 0.6, 0.7 and 0.10) thin films have been grown by a two-step sputtering/annealing method. First, rock-salt-structured (Ca,Mn1-x,Nb-x)O thin films were deposited on 11 & x304;00 sapphire using reactive RF magnetron co-sputtering from elemental targets of Ca, Mn and Nb. The CaMn1-xNbxO3 films were then obtained by thermally induced phase transformation from rock-salt-structured (Ca,Mn1-xNbx)O to orthorhombic during post-deposition annealing at 700 degrees C for 3 h in oxygen flow. The X-ray diffraction patterns of pure CaMnO3 showed mixed orientation, while Nb-containing films were epitaxially grown in [101] out of-plane-direction. Scanning transmission electron microscopy showed a Ruddlesden-Popper (R-P) secondary phase in the films, which results in reduction of the electrical and thermal conductivity of CaMn1-xNbxO3. The electrical resistivity and Seebeck coefficient of the pure CaMnO3 film were measured to 2.7 omega cm and -270 mu V K-1 at room temperature, respectively. The electrical resistivity and Seebeck coefficient were reduced by alloying with Nb and was measured to 0.09 omega cm and -145 mu V K-1 for x = 0.05. Yielding a power factor of 21.5 mu W K-2 m(-1) near room temperature, nearly eight times higher than for pure CaMnO3 (2.8 mu W K-2 m(-1)). The power factors for alloyed samples are low compared to other studies on phase-pure material. This is due to high electrical resistivity originating from the secondary R-P phase. The thermal conductivity of the CaMn1-xNbxO3 films is low for all samples and is the lowest for x = 0.07 and 0.10, determined to 1.6 W m(-1) K-1. The low thermal conductivity is attributed to grain boundary scattering and the secondary R-P phase.

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  • 14.
    Ekström, Erik
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Le Febvrier, Arnaud
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Fournier, Daniele
    Sorbonne Univ, France.
    Lu, Jun
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Ene, Vladimir-Lucian
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, Faculty of Science & Engineering. Univ Politehn Bucuresti, Romania.
    Van Nong, Ngo
    Tech Univ Denmark, Denmark.
    Eriksson, Fredrik
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Paul, Biplab
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Formation mechanism and thermoelectric properties of CaMnO3 thin films synthesized by annealing of Ca0.5Mn0.5O films2019In: Journal of Materials Science, ISSN 0022-2461, E-ISSN 1573-4803, Vol. 54, no 11, p. 8482-8491Article in journal (Refereed)
    Abstract [en]

    A two-step synthesis approach was utilized to grow CaMnO3 on M-, R- and C-plane sapphire substrates. Radio-frequency reactive magnetron sputtering was used to grow rock-salt-structured (Ca, Mn)O followed by a 3-h annealing step at 800 degrees C in oxygen flow to form the distorted perovskite phase CaMnO3. The effect of temperature in the post-annealing step was investigated using x-ray diffraction. The phase transformation to CaMnO3 started at 450 degrees C and was completed at 550 degrees C. Films grown on R- and C-plane sapphire showed similar structure with a mixed orientation, whereas the film grown on M-plane sapphire was epitaxially grown with an out-of-plane orientation in the [202] direction. The thermoelectric characterization showed that the film grown on M-plane sapphire has about 3.5 times lower resistivity compared to the other films with a resistivity of 0.077cm at 500 degrees C. The difference in resistivity is a result from difference in crystal structure, single orientation for M-plane sapphire compared to mixed for R- and C-plane sapphire. The highest absolute Seebeck coefficient value is -350 mu VK-1 for all films and is decreasing with temperature.

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  • 15.
    Gangaprasad Rao, Smita
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Illgner, Pascal Manuel
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Boyd, Robert
    Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics. Linköping University, Faculty of Science & Engineering.
    Nagy, Gyula
    Uppsala Univ, Sweden.
    Djemia, Philippe
    Univ Sorbonne Paris Nord, France.
    Primetzhofer, Daniel
    Uppsala Univ, Sweden.
    Petrov, Ivan
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering. Univ Illinois, IL 61801 USA.
    Le Febvrier, Arnaud
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Low temperature epitaxial growth of Cantor-nitride thin films by magnetic field assisted magnetron sputtering2023In: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films, ISSN 0734-2101, E-ISSN 1520-8559, Vol. 41, no 5, article id 053415Article in journal (Refereed)
    Abstract [en]

    Low-temperature epitaxial growth of multicomponent alloy-based thin films remains an outstanding challenge in materials science and is important for established fundamental properties of these complex materials. Here, Cantor nitride (CrMnFeCoNi)N thin films were epitaxially grown on MgO(100) substrates at low deposition temperature by magnetic-field-assisted dc-magnetron sputtering, a technique where a magnetic field is applied to steer the dense plasma to the substrate thereby influencing the flux of Ar-ions bombarding the film during growth. Without ion bombardment, the film displayed textured growth. As the ion flux was increased, the films exhibited epitaxial growth. The epitaxial relationship between film and substrate was found to be cube on cube (001)film parallel to(001)MgO, [100]film parallel to[100]MgO. The epitaxy was retained up to a thickness of approximately similar to 100 nm after which the growth becomes textured with a 002 out-of-plane orientation. The elastic constants determined by Brillouin inelastic light scattering were found to be C-11 = 320 GPa, C-12 = 125 GPa, and C-44 = 66 GPa, from which the polycrystalline Youngs modulus was calculated as 204 GPa and Poissons ratio = 0.32, whereas available elastic properties still remained very scarce. (c) 2023 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).

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  • 16.
    Gangaprasad Rao, Smita
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Mukhamedov, Boburjon
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering.
    Nagy, Gyula
    Uppsala Univ, Sweden.
    Tseng, Eric Nestor
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Shu, Rui
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Boyd, Robert
    Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics. Linköping University, Faculty of Medicine and Health Sciences.
    Primetzhofer, Daniel
    Uppsala Univ, Sweden.
    Persson, Per O A
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Alling, Björn
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering.
    Abrikosov, Igor
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering.
    Le Febvrier, Arnaud
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Phase formation in CrFeCoNi nitride thin films2023In: Physical Review Materials, E-ISSN 2475-9953, Vol. 7, no 4, article id 055002Article in journal (Refereed)
    Abstract [en]

    As a single-phase alloy, CrFeCoNi is a face centered cubic (fcc) material related to the archetypical highentropy Cantor alloy CrFeCoNiMn. For thin films, CrFeCoNi of approximately equimolar composition tends to assume an fcc structure when grown at room temperature by magnetron sputtering. However, the single-phase solid solution state is typically not achieved for thin films grown at higher temperatures. The same holds true for Cantor alloy-based ceramics (nitrides and oxides), where phase formation is extremely sensitive to process parameters such as the amount of reactive gas. This study combines theoretical and experimental methods to understand the phase formation in nitrogen-containing CrFeCoNi thin films. Density functional theory calculations considering three competing phases (CrN, Fe-Ni and Co) show that the free energy of mixing, Delta G of (CrFeCoNi)(1-x)N-x solid solutions has a maximum at x = 0.20-0.25, and AG becomes lower when x < 0.20 and x > 0.25. Thin films of (CrFeCoNi)1-xNx (0.14 >= x <= 0.41) grown by magnetron sputtering show stabilization of the metallic fcc when x <= 0.22 and the stabilization of the NaCl B1 structure when x > 0.33, consistent with the theoretical prediction. In contrast, films with intermediate amounts of nitrogen (x = 0.22) grown at higher temperatures show segregation into multiple phases of CrN, Fe-Ni-rich and Co. These results offer an explanation for the requirement of kinetically limited growth conditions at low temperature for obtaining single-phase CrFeCoNi Cantor-like nitrogen-containing thin films and are of importance for understanding the phase-formation mechanisms in multicomponent ceramics. The results from the study further aid in making correlations between the observed mechanical properties and the crystal structure of the films.

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  • 17.
    Gangaprasad Rao, Smita
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Shu, Rui
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Boyd, Robert
    Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics. Linköping University, Faculty of Science & Engineering.
    Greczynski, Grzegorz
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Le Febvrier, Arnaud
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Phase formation and structural evolution of multicomponent (CrFeCo)Ny films2021In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 412, article id 127059Article in journal (Refereed)
    Abstract [en]

    The Cantor alloy (CoCrFeMnNi) and its variants, in bulk as well as thin films, have been extensively studied. They are known to exhibit cubic crystal structures and thermodynamic stability regardless of their complex chemical composition. Therefore, they may find use as hard, wear-resistant, corrosion and oxidation-resistant coatings. The addition of light elements, such as nitrogen, is known to help improve these properties further through processes such as amorphization and nitride compound formation. Here, we investigate the ternary CrFeCo system to study the effects of nitrogen addition. (CrFeCo)Ny multicomponent thin films are grown on silicon substrates by DC magnetron sputtering. Changes in crystal structure, morphology, mechanical and electrical properties with gradual increases of nitrogen in the film are described and discussed. Increased addition of nitrogen from 14 at.% to 28 at.% in the film leads to a transformation from an fcc to a bcc crystal structure, affects both the mechanical and electrical properties. XPS analysis shows the tendency of nitrogen to bond with Cr over other metals. The films display hardness values between 7 and 11 GPa with resistivities values ranging between 28 and 165 μΩ cm.

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  • 18.
    Gangaprasad Rao, Smita
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Shu, Rui
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Boyd, Robert
    Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics. Linköping University, Faculty of Science & Engineering.
    Le Febvrier, Arnaud
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Plasma diagnostics and film growth of multicomponent nitride thin films with magnetic-field-assisted-dc magnetron sputtering2022In: Vacuum, ISSN 0042-207X, E-ISSN 1879-2715, Vol. 204, article id 111331Article in journal (Refereed)
    Abstract [en]

    During direct current magnetron sputtering (dcMS) of thin films, the ion energy and flux are complex parameters that influence thin film growth and can be exploited to tailor their properties. The ion energy is generally controlled by the bias voltage applied at the substrate. The ion flux density however is controlled by more complex mechanisms. In this study, we look into magnetic-field-assisted dcMs, where a magnetic field applied in the deposition chamber by use of a solenoid coil at the substrate position, influences the energetic bombardment by Ar ions during deposition. Using this technique, CrFeCoNi multicomponent nitride thin films were grown on Si(100) substrates by varying the bias voltage and magnetic field systematically. Plasma diagnostics were performed by a Langmuir wire probe and a flat probe. On interpreting the data from the current-voltage curves it was confirmed that the ion flux at the substrate increased with increasing coil magnetic field with ion energies corresponding to the applied bias. The increased ion flux assisted by the magnetic field produced by the solenoid coil aids in the stabilization of NaCl B1 crystal structure without introducing Ar ion implantation.

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  • 19.
    Gangaprasad Rao, Smita
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Shu, Rui
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Boyd, Robert
    Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics. Linköping University, Faculty of Science & Engineering.
    Le Febvrier, Arnaud
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    The effects of copper addition on phase composition in (CrFeCo)1-yNy multicomponent thin films2022In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 572, article id 151315Article in journal (Refereed)
    Abstract [en]

    The Cantor alloy CrFeCoMnNi is generally fcc structured, but moderate changes in the composition can have a large influence on the phase formation. The aim of this study was to understand the changes brought on in lownitrogen-containing (CrFeCo)1-yNy thin films with y = 0.19 on the addition of copper, an interesting metal in terms of atomic size and nitride formation enthalpy. (CrFeCoCux)1-yNy films were grown by reactive magnetron sputtering. The amount of copper in the films was increased from x = 0 to x = 0.15 to study competitive phase formation. Without Cu, two-phase fcc + bcc films were obtained. The addition of Cu was found to stabilize the bcc structure despite the fact that Cu as a pure metal is fcc. Nanoindentation tests showed slight increase in hardness with initial Cu addition from 11 GPa to 13.7 +/- 0.2 GPa. The occurrence of pile up as opposed to cracking is an indication of the films ductility.

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  • 20.
    Gangaprasad Rao, Smita
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Shu, Rui
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Wang, Ji
    Ningbo Univ, Peoples R China.
    Chai, Jianlong
    Inst Modern Phys, Peoples R China.
    Zhu, Yabin
    Inst Modern Phys, Peoples R China.
    Le Febvrier, Arnaud
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Mechanical properties of Xe-ion-irradiated high-entropy-alloy-based multilayers2024In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 124, no 6, article id 061906Article in journal (Refereed)
    Abstract [en]

    In this Letter, we investigate the mechanical stability of HEA-based multilayers after Xe-ion irradiation. CrFeCoNi/TiNbZrTa metallic and nitride thin films with a bilayer thickness of 30 nm were grown by reactive dc-magnetron sputtering on Al2O3(0001) substrates for irradiation studies and on Si(100) substrates for other characterizations. The films were subjected to 3-MeV Xe-ion irradiation at room temperature (RT) and at 500 degrees C. The crystal structure and mechanical properties of the films before and after irradiation were studied by x-ray diffraction and nanoindentation. Before irradiation, both the metallic and nitride multilayers displayed a lower hardness (7 and 20 GPa, respectively). Annealing at 500 degrees C for 150 min increased the hardness of the multilayer samples, but it also induced intermixing of elements between the sublayers of the metallic multilayer. Irradiation hardening was observed only in the metallic multilayer at room temperature. When comparing the effects of irradiation damage vs the effects of annealing on the mechanical properties, it was observed that annealing the multilayers had a more pronounced effect.

  • 21.
    Gangaprasad Rao, Smita
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Shu, Rui
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Wang, Siyang
    Imperial Coll London, England.
    Boyd, Robert
    Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics. Linköping University, Faculty of Science & Engineering.
    Giuliani, Finn
    Imperial Coll London, England.
    Le Febvrier, Arnaud
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Thin film growth and mechanical properties of CrFeCoNi/TiNbZrTa multilayers2022In: Materials & design, ISSN 0264-1275, E-ISSN 1873-4197, Vol. 224, article id 111388Article in journal (Refereed)
    Abstract [en]

    Multilayers of high entropy alloys (HEA) are picking up interest due to the possibility of altering material properties by tuning crystallinity, thickness, and interfaces of the layers. This study investigates the growth mechanism and mechanical properties of CrFeCoNi/TiNbZrTa multilayers grown by magnetron sputtering. Multilayers of bilayer thickness (A) from 5 nm to 50 nm were grown on Si(1 0 0) substrates. Images taken by transmission electron microscopy and energy-dispersive X-ray spectroscopy mapping revealed that the layers were well defined with no occurrence of elemental mixing. Multilayers with A < 20 nm exhibited an amorphous structure. As A increased, the CrFeCoNi layer displayed a higher crystallinity in comparison to the amorphous TiNbZrTa layer. The mechanical properties were influenced by the crystallinity of the layers and stresses in the film. The film with A = 20 nm had the highest hardness of approximately 12.5 GPa owing grain refinement of the CrFeCoNi layer. An increase of A >= 30 nm resulted in a drop in the hardness due to the increase in crystal domains of the CrFeCoNi layer. Micropillar compression induced shear in the material rather than fracture, along with elemental intermixing in the core of the deformed region of the compressed micropillar.

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  • 22.
    Gharavi, Mohammad Amin
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Gambino, Davide
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering.
    Le Febvrier, Arnaud
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Eriksson, Fredrik
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Armiento, Rickard
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering.
    Alling, Björn
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    High thermoelectric power factor of pure and vanadium-alloyed chromium nitride thin films2021In: Materials Today Communications, ISSN 2352-4928, Vol. 28, article id 102493Article in journal (Refereed)
    Abstract [en]

    Chromium-nitride based materials have shown unexpected promise as thermo-electric materials for, e.g., wasteheat harvesting. Here, CrN and (Cr,V)N thin films were deposited by reactive magnetron sputtering. Thermoelectric measurements of pure CrN thin films show a low electrical resistivity between 1.2 and 1.5 x 10(-3) Omega cm and very high values of the Seebeck coefficient and thermoelectric power factor, in the range between 370-430 mu V/K and 9-11 x 10(-3) W/mK(2), respectively. Alloying of CrN films with small amounts (less than 15 %) of vanadium results in cubic (Cr,V)N thin films. Vanadium decreases the electrical resistivity and yields powerfactor values in the same range as pure CrN. Density functional theory calculations of sub-stoichiometric CrN1-delta and (Cr,V)N1-delta show that nitrogen vacancies and vanadium substitution both cause n-type conductivity and features in the band structure typically correlated with a high Seebeck coefficient. The results suggest that slight variations in nitrogen and vanadium content affect the power factor and offers a means of tailoring the power factor and thermoelectric figure of merit.

  • 23.
    Gharavi, Mohammad Amin
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Greczynski, Grzegorz
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Eriksson, Fredrik
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Lu, Jun
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Balke, B.
    Univ Stuttgart, Germany.
    Fournier, D.
    Sorbonne Univ, France.
    Le Febvrier, Arnaud
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Pallier, Camille
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Synthesis and characterization of single-phase epitaxial Cr2N thin films by reactive magnetron sputtering2019In: Journal of Materials Science, ISSN 0022-2461, E-ISSN 1573-4803, Vol. 54, no 2, p. 1434-1442Article in journal (Refereed)
    Abstract [en]

    Cr2N is commonly found as a minority phase or inclusion in stainless steel, CrN-based hard coatings, etc. However, studies on phase-pure material for characterization of fundamental properties are limited. Here, Cr2N thin films were deposited by reactive magnetron sputtering onto (0001) sapphire substrates. X-ray diffraction and pole figure texture analysis show Cr2N (0001) epitaxial growth. Scanning electron microscopy imaging shows a smooth surface, while transmission electron microscopy and X-ray reflectivity show a uniform and dense film with a density of 6.6gcm(-3), which is comparable to theoretical bulk values. Annealing the films in air at 400 degrees C for 96h shows little signs of oxidation. Nano-indentation shows an elastic-plastic behavior with H=18.9GPa and E-r=265GPa. The moderate thermal conductivity is 12Wm(-1)K(-1), and the electrical resistivity is 70cm. This combination of properties means that Cr2N may be of interest in applications such as protective coatings, diffusion barriers, capping layers and contact materials.

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  • 24.
    Gharavi, Mohammad Amin
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Kerdsongpanya, Sit
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering. Rensselaer Polytech Inst, NY 12180 USA.
    Schmidt, Susann
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Eriksson, Fredrik
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Nong, N. V
    Tech Univ Denmark, Denmark.
    Lu, Jun
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Balke, B.
    Johannes Gutenberg Univ Mainz, Germany.
    Fournier, D.
    UPMC Univ Paris 06, France.
    Belliard, L.
    UPMC Univ Paris 06, France.
    Le Febvrier, Arnaud
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Pallier, Camille
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Microstructure and thermoelectric properties of CrN and CrN/Cr2N thin films2018In: Journal of Physics D: Applied Physics, ISSN 0022-3727, E-ISSN 1361-6463, Vol. 51, no 35, article id 355302Article in journal (Refereed)
    Abstract [en]

    CrN thin films with an N/Cr ratio of 95% were deposited by reactive magnetron sputtering onto (0001) sapphire substrates. X-ray diffraction and pole figure texture analysis show CrN (111) epitaxial growth in a twin domain fashion. By changing the nitrogen versus argon gas flow mixture and the deposition temperature, thin films with different surface morphologies ranging from grainy rough textures to flat and smooth films were prepared. These parameters can also affect the CrN(x )system, with the film compound changing between semiconducting CrN and metallic Cr2N through the regulation of the nitrogen content of the gas flow and the deposition temperature at a constant deposition pressure. Thermoelectric measurements (electrical resistivity and Seebeck coefficient), scanning electron microscopy, and transmission electron microscopy imaging confirm the changing electrical resistivity between 0.75 and 300 m omega cm, the changing Seebeck coefficient values between 140 and 230 mu VK-1, and the differences in surface morphology and microstructure as higher temperatures result in lower electrical resistivity while gas flow mixtures with higher nitrogen content result in single phase cubic CrN.

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  • 25.
    Gharavi, Mohammad Amin
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Le Febvrier, Arnaud
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Lu, Jun
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Greczynski, Grzegorz
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Alling, Björn
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering.
    Armiento, Rickard
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Phase Transformation and Superstructure Formation in (Ti-0.5, Mg-0.5)N Thin Films through High-Temperature Annealing2021In: Coatings, ISSN 2079-6412, Vol. 11, no 1, article id 89Article in journal (Refereed)
    Abstract [en]

    (Ti-0.5, Mg-0.5)N thin films were synthesized by reactive dc magnetron sputtering from elemental targets onto c-cut sapphire substrates. Characterization by theta-2 theta X-ray diffraction and pole figure measurements shows a rock-salt cubic structure with (111)-oriented growth and a twin-domain structure. The films exhibit an electrical resistivity of 150 m omega center dot cm, as measured by four-point-probe, and a Seebeck coefficient of -25 mu V/K. It is shown that high temperature (similar to 800 degrees C) annealing in a nitrogen atmosphere leads to the formation of a cubic LiTiO2-type superstructure as seen by high-resolution scanning transmission electron microscopy. The corresponding phase formation is possibly influenced by oxygen contamination present in the as-deposited films resulting in a cubic superstructure. Density functional theory calculations utilizing the generalized gradient approximation (GGA) functionals show that the LiTiO2-type TiMgN2 structure has a 0.07 eV direct bandgap.

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  • 26.
    Guo, Sisi
    et al.
    Shanghai Inst Technol, Peoples R China.
    Meng, Qiufeng
    Shanghai Inst Technol, Peoples R China.
    Qin, Jie
    Shanghai Inst Technol, Peoples R China.
    Du, Yong
    Shanghai Inst Technol, Peoples R China.
    Wang, Lei
    Shanghai Inst Technol, Peoples R China.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Le Febvrier, Arnaud
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Thermoelectric Characteristics of Self-Supporting WSe2-Nanosheet/PEDOT-Nanowire Composite Films2023In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 15, no 29, p. 35430-35438Article in journal (Refereed)
    Abstract [en]

    Conducting polymer poly(3,4-ethylenedioxythiophene) nanowires(PEDOTNWs) were synthesized by a modified self-assembled micellar soft-templatemethod, followed by fabrication by vacuum filtration of self-supportingexfoliated WSe2-nanosheet (NS)/PEDOT-NW composite films.The results showed that as the mass fractions of WSe2 NSsincreased from 0 to 20 wt % in the composite films, the electricalconductivity of the samples decreased from & SIM;1700 to & SIM;400S cm(-1), and the Seebeck coefficient increased from12.3 to 23.1 & mu;V K-1 at 300 K. A room-temperaturepower factor of 44.5 & mu;W m(-1) K-2 was achieved at 300 K for the sample containing 5 wt % WSe2 NSs, and a power factor of 67.3 & mu;W m(-1) K-2 was obtained at 380 K. The composite film containing5 wt % WSe2 NSs was mechanically flexible, as shown byits resistance change ratio of 7.1% after bending for 500 cycles ata bending radius of 4 mm. A flexible thermoelectric (TE) power generatorcontaining four TE legs could generate an output power of 52.1 nWat a temperature difference of 28.5 K, corresponding to a power densityof & SIM;0.33 W/m(2). This work demonstrates that the fabricationof inorganic nanosheet/organic nanowire TE composites is an approachto improve the TE properties of conducting polymers.

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  • 27.
    Hjort, Victor
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Singh, Niraj Kumar
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Medicine and Health Sciences.
    Chowdhury, Susmita
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Shu, Rui
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Le Febvrier, Arnaud
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Phase Composition and Thermoelectric Properties of Epitaxial CrMoVN Thin Films2023In: ADVANCED ENERGY AND SUSTAINABILITY RESEARCH, ISSN 2699-9412Article in journal (Refereed)
    Abstract [en]

    Thin films of CrMoVN are deposited on c-plane sapphire (Al2O3 (0001)) by direct current reactive magnetron sputtering, to investigate the effects of Mo and V addition to CrN-based films. All films grow epitaxially, but Mo incorporation affects the crystal structure and nitrogen content. All films in the CrMoVN series are understoichiometric in nitrogen, but largely retain the NaCl B1 structure of stoichiometric CrN films. Addition of vanadium increases the phase-stability range of the cubic phase, allowing for higher solubility of Mo than what has previously been reported for cubic CrN. The Seebeck coefficient and electrical resistivity are greatly affected by the alloying, showing a decrease of the Seebeck coefficient along with a decrease in resistivity. Cr0.83Mo0.11V0.06Nz shows a 70% increase in power factor (S2 sigma = 0.22 mW m-1 K-2) compared to the reference CrNz (S2 sigma = 0.13 mW m-1 K-2). Thermoelectric (TE) materials are in use in several applications, but often have too low efficiency. For more widespread use of these materials, fundamental research on TE material system is necessary. In this work, alloying in CrN, with the hope of pushing a material with great promise closer to applications, is investigated.image (c) 2023 WILEY-VCH GmbH

  • 28.
    Honnali, Sanath Kumar
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Poterie, Charlotte
    Univ Poitiers, France.
    Le Febvrier, Arnaud
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Lundin, Daniel
    Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics. Linköping University, Faculty of Science & Engineering.
    Greczynski, Grzegorz
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Effect of tilted closed-field magnetron design on the microstructure and mechanical properties of TiZrNbTaN coatings2023In: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films, ISSN 0734-2101, E-ISSN 1520-8559, Vol. 41, no 4, article id 043402Article in journal (Refereed)
    Abstract [en]

    A common design of sputtering systems is to integrate many magnetron sources in a tilted closed-field configuration, which can drastically affect the magnetic field in the chamber and thus plasma characteristics. To study this effect explicitly, multicomponent TiZrNbTaN coatings were deposited at room temperature using direct current magnetron sputtering (DCMS) and high-power impulse magnetron sputtering (HiPIMS) with different substrate biases. The coatings were characterized by x-ray diffraction, scanning electron microscopy, nano-indentation, and energy dispersive x-ray spectroscopy. Magnetic field simulations revealed ten times higher magnetic field strengths at the substrate in single-magnetron configuration when compared to the closed-field. As a result, the substrate ion current increased similar to 3 and 1.8 times for DCMS and HiPIMS, respectively. The film microstructure changed with the discharge type, in that DCMS coatings showed large sized columnar structures and HiPIMS coatings show globular nanosized structures with (111) orientation with a closed-field design. Coatings deposited from a single source showed dense columnar structures irrespective of the discharge type and developed (200) orientation only with HiPIMS. Coatings deposited with closed-field design by DCMS had low stress (0.8 to -1 GPa) and hardness in the range from 13 to 18 GPa. Use of HiPIMS resulted in higher stress (-3.6 to -4.3 GPa) and hardness (26-29 GPa). For coatings deposited with single source by DCMS, the stress (-0.15 to -3.7 GPa) and hardness were higher (18-26 GPa) than for coatings grown in the closed-field design. With HiPIMS and single source, the stress was in the range of -2.3 to -4.2 GPa with a similar to 6% drop in the hardness (24-27 GPa).

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  • 29.
    Le Febvrier, Arnaud
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering. University of Rennes 1, France.
    Deputier, S.
    University of Rennes 1, France.
    Demange, V.
    University of Rennes 1, France.
    Bouquet, V.
    University of Rennes 1, France.
    Galca, A. C.
    National Institute Mat Phys, Romania.
    Iuga, A.
    National Institute Mat Phys, Romania.
    Pintilie, L.
    National Institute Mat Phys, Romania.
    Guilloux-Viry, M.
    University of Rennes 1, France.
    Effect of in-plane ordering on dielectric properties of highly {111}-oriented bismuth-zinc-niobate thin films2017In: Journal of Materials Science, ISSN 0022-2461, E-ISSN 1573-4803, Vol. 52, no 19, p. 11306-11313Article in journal (Refereed)
    Abstract [en]

    Bi1.5-xZn0.92-yNb1.5O6.92-delta (BZN) thin films were grown by pulsed laser deposition on two different Pt-covered substrates, namely textured {111} Pt/TiO2/SiO2/(100) Si substrate (Pt/Si) and epitaxial {111} Pt/R-plane sapphire substrate (Pt/sapphire). In both cases, the BZN films present {111} and {100} out-of-plane orientations, in relative ratios of 65: 35 on Pt/Si and 80: 20 on Pt/sapphire, respectively. The film grown on Pt/Si is textured, while the film deposited on Pt/sapphire presents epitaxial-like relationships with the substrate, for both out-of-plane orientations. Dielectric measurements were taken on both types of thin films, using Pt/BZN/Pt planar capacitor structures. The BZN/Pt/sapphire film presents higher dielectric constant (245 at 100 kHz) and higher tunability (12% at 600 kV/cm) than the BZN/Pt/Si film (200; 6%), while the dielectric losses values are nearly same (similar to 0.05).

  • 30.
    Le Febvrier, Arnaud
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Gambino, Davide
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering.
    Giovannelli, Fabien
    Univ Tours, France.
    Bakhit, Babak
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Hurand, Simon
    Univ Poitiers, France.
    Abadias, Gregory
    Univ Poitiers, France.
    Alling, Björn
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    p-type behavior of CrN thin films via control of point defects2022In: Physical Review B, ISSN 2469-9950, E-ISSN 2469-9969, Vol. 105, no 10, article id 104108Article in journal (Refereed)
    Abstract [en]

    We report the results of a combined experimental and theoretical study on nonstoichiometric CrN1+δ thinfilms grown by reactive magnetron sputtering on c-plane sapphire and MgO (100) substrates in an Ar/N2 gasmixture using different percentages of N2. There is a transition from n-type to p-type behavior in the layersas a function of nitrogen concentration varying from 48 to 52 at. % in CrN films. The compositional changefollows a similar trend for all substrates, with a N/Cr ratio increasing from approximately 0.7 to 1.06–1.11 byincreasing the percentage of N2 in the gas flow ratio. As a result of the change in stoichiometry, the latticeparameter and the Seebeck coefficient increase together with the increase of N in CrN1+δ ; in particular, theSeebeck value coefficient transitions from –50 μV K–1 for CrN0.97 to +75μV K–1 for CrN1.1. Density functionaltheory calculations show that Cr vacancies can account for the change in the Seebeck coefficient, since they pushthe Fermi level down in the valence band, whereas N interstitial defects in the form of N2 dumbbells are neededto explain the increasing lattice parameter. Calculations including both types of defects, which have a strongtendency to bind together, reveal a slight increase in the lattice parameter and a simultaneous formation of holesin the valence band. To explain the experimental trends, we argue that both Cr vacancies and N2 dumbbells,possibly in combined configurations, are present in the films. We demonstrate the possibility of controlling thesemiconducting behavior of CrN with intrinsic defects from n to p type, opening possibilities to integrate thiscompound in energy-harvesting thermoelectric devices.

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  • 31.
    Le Febvrier, Arnaud
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Jensen, Jens
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Wet-cleaning of MgO(001): Modification of surface chemistry and effects on thin film growth investigated by x-ray photoelectron spectroscopy and time-of-flight secondary ion mass spectroscopy2017In: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films, ISSN 0734-2101, E-ISSN 1520-8559, Vol. 35, no 2, article id 021407Article in journal (Refereed)
    Abstract [en]

    The effect of the wet-cleaning process using solvents and detergent on the surface chemistry of MgO(001) substrate for film deposition was investigated. Six different wet-cleaning processes using solvent and detergent were compared. The effect on film growth was studied by the example system ScN. The surface chemistry of the cleaned surface was studied by x-ray photoelectron spectroscopy and the film/substrate interface after film growth was investigated by time-of-flight secondary ion mass spectroscopy. The surface composition is dependent on the wet-cleaning process. Sonication in a detergent before the solvents yield a pure oxide surface compared to hydroxide/carbonate contaminated surface for all the other processes. An annealing step is efficient for the removal of carbon contamination as well as most of the hydroxide or carbonates. The study of the film/substrate interface revealed that the wet-cleaning process significantly affects the final interface and film quality. The substrate cleaned with detergent followed by solvent cleaning exhibited the cleanest surface of the substrate before annealing, after annealing, in addition to the sharpest film/substrate interface. (C) 2017 American Vacuum Society.

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  • 32.
    Le Febvrier, Arnaud
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Landälv, Ludvig
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering. Sandvik Coromant AB, Sweden.
    Liersch, Thomas
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Sandmark, David
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering. Saab AB Aeronaut, Broderna Ugglas Gata, S-58254 Linkoping, Sweden.
    Sandström, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    An upgraded ultra-high vacuum magnetron-sputtering system for high-versatility and software-controlled deposition2021In: Vacuum, ISSN 0042-207X, E-ISSN 1879-2715, Vol. 187, article id 110137Article in journal (Refereed)
    Abstract [en]

    Magnetron sputtering is a widely used physical vapor deposition technique. Reactive sputtering is used for the deposition of, e.g, oxides, nitrides and carbides. In fundamental research, versatility is essential when designing or upgrading a deposition chamber. Furthermore, automated deposition systems are the norm in industrial production, but relatively uncommon in laboratory-scale systems used primarily for fundamental research. Combining automatization and computerized control with the required versatility for fundamental research constitutes a challenge in designing, developing, and upgrading laboratory deposition systems. The present article provides a detailed description of the design of a lab-scale deposition chamber for magnetron sputtering used for the deposition of metallic, oxide, nitride and oxynitride films with automated controls, dc or pulsed bias, and combined with a coil to enhance the plasma density near the substrate. LabVIEW software (provided as Supplementary Information) has been developed for a high degree of computerized or automated control of hardware and processes control and logging of process details.

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  • 33.
    Le Febvrier, Arnaud
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Tureson, Nina
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Stilkerich, Nina
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Greczynski, Grzegorz
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Effect of impurities on morphology, growth mode, and thermoelectric properties of (111) and (001) epitaxial-like ScN films2019In: Journal of Physics D: Applied Physics, ISSN 0022-3727, E-ISSN 1361-6463, Vol. 52, no 3, article id 035302Article in journal (Refereed)
    Abstract [en]

    ScN is an emerging semiconductor with an indirect bandgap. It has attracted attention for its thermoelectric properties, use as seed layers, and for alloys for piezoelectric application. ScN and other transition metal nitride semiconductors used for their interesting electrical properties are sensitive to contaminants, such as oxygen or fluorine. In this present article, the influence of depositions conditions on the amount of oxygen contaminants incorporated in ScN films were investigated and their effects on the electrical properties (electrical resistivity and Seebeck coefficient) were studied. Epitaxial-like films of thickness 125 +/- 5 nm to 155 +/- 5 nm were deposited by DC-magnetron sputtering on c-plane Al-2, O-3(111) and r-plane Al2O3 at substrate temperatures ranging from 700 degrees C to 950 degrees C. The amount of oxygen contaminants in the film, dissolved into ScN or as an oxide, was related to the adatom mobility during growth, which is affected by the deposition temperature and the presence of twin domain growth. The lowest values of electrical resistivity of 50 mu Omega cm were obtained on ScN(1 1 1)/ MgO(111) and on ScN(001)/r-plane Al2O3 grown at 950 degrees C with no twin domains and the lowest amount of oxygen contaminant. At the best, the films exhibited an electrical resistivity of 50 mu Omega cm with Seebeck coefficient values maintained at -40 mu V K-1, thus a power factor estimated at 3.2 x 10(-3) W m(-1) K-2 (at room temperature).

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  • 34.
    Le Febvrier, Arnaud
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Van Nong, Ngo
    Tech Univ Denmark, Denmark.
    Abadias, Gregory
    Univ Poitiers, France.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    P-type Al-doped Cr-deficient CrN thin films for thermoelectrics2018In: APPLIED PHYSICS EXPRESS, ISSN 1882-0778, Vol. 11, no 5, article id 051003Article in journal (Refereed)
    Abstract [en]

    Thermoelectric properties of chromium nitride (CrN)-based films grown on c-plane sapphire by dc reactive magnetron sputtering were investigated. In this work, aluminum doping was introduced in CrN (degenerate n-type semiconductor) by co-deposition. Under the present deposition conditions, over-stoichiometry in nitrogen (CrN1+delta) rock-salt structure is obtained. A p-type conduction is observed with nitrogen-rich CrN combined with aluminum doping. The Cr0.96Al0.04N1.17 film exhibited a high Seebeck coefficient and a sufficient power factor at 300 degrees C. These results are a starting point for designing p-type/n-type thermoelectric materials based on chromium nitride films, which are cheap and routinely grown on the industrial scale. (C) 2018 The Japan Society of Applied Physics

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  • 35.
    Linder, Clara
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, Faculty of Science & Engineering. RISE, Sweden.
    Gangaprasad Rao, Smita
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Boyd, Robert
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, Faculty of Science & Engineering. Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics.
    Le Febvrier, Arnaud
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Munktell, Sara
    Swerim AB, Sweden.
    Björk, Emma
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, Faculty of Science & Engineering.
    Corrosion Resistance and Catalytic Activity toward the Oxygen Reduction Reaction of CoCrFexNi (0 < x < 0.7) Thin Films2022In: ACS Applied Energy Materials, E-ISSN 2574-0962, Vol. 5, no 9, p. 10838-10848Article in journal (Refereed)
    Abstract [en]

    Corrosion resistance and catalytic activity toward the oxygen reduction reaction (ORR) in an alkaline environment are two key properties for water recombination applications. In this work, CoCrFexNi (0 &lt;= x &lt;= 0.7) thin films were deposited by magnetron sputtering on polished steel substrates. The native passive layer was 2-4 nm thick and coherent to the columnar grains determined by transmission electron microscopy. The effect of Fe on the corrosion properties in 0.1 M NaCl and 1 M KOH and the catalytic activity of the films toward ORR were investigated. Electrochemical impedance spectroscopy and potentiodynamic polarization measurements indicate that CoCrFe0.7Ni and CoCrFe0.3Ni have the highest corrosion resistance of the studied films in NaCl and KOH, respectively. The high corrosion resistance of the CoCrFe0.7Ni film in NaCl was attributed to the smaller overall grain size, which leads to a more homogeneous film with a stronger passive layer. For CoCrFe0.3Ni in KOH, it was attributed to a lower Fe dissolution into the electrolyte and the build-up of a thick and protective hydroxide layer. Scanning Kelvin probe force microscopy showed no potential differences globally in any of the films, but locally, a potential gradient between the top of the columns and grain boundaries was observed. Corrosion of the films was likely initiated at the top of the columns where the potential was lowest. It was concluded that Fe is essential for the electrochemical activation of the surfaces and the catalytic activity toward ORR in an alkaline medium. The highest catalytic activity was recorded for high Fe-content films (x &gt;= 0.5) and was attributed to the formation of platelet-like oxide particles on the film surface upon anodization. The study showed that the combination of corrosion resistance and catalytic activity toward ORR is possible for CoCrFexNi, making this material system a suitable candidate for water recombination in an alkaline environment.

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  • 36.
    Linder, Clara
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, Faculty of Science & Engineering. RISE, Sweden.
    Gangaprasad Rao, Smita
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Le Febvrier, Arnaud
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Greczynski, Grzegorz
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Sjovall, Rune
    SAFT AB, Sweden.
    Munktell, Sara
    Swer AB, Sweden.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Björk, Emma
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, Faculty of Science & Engineering.
    Cobalt thin films as water-recombination electrocatalysts2020In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 404, article id 126643Article in journal (Refereed)
    Abstract [en]

    Catalysts and electmcatalysts are crucial for energy production and storage. To develop cost-efficient systems taking advantage of functionalized surfaces, the catalysts can be synthesized as nanomaterials or thin films. In this work, cobalt thin films were deposited on low-alloyed steel using magnetron sputtering. The films are uniform with a smooth surface and a thickness of similar to 400 nm. The films were electrochemically oxidized via anodization to a mix of cobalt oxides, one of them being Co3O4, at room temperature in an alkaline solution. The electrocatalytic performances of the anodized films were evaluated in 1 M KOH electrolyte saturated with oxygen. Cathodic currents in -0.5 mA/cm(2) range, corresponding to oxygen reduction reaction (ORR) activity, were measured with cyclic voltammetry. The catalytic activity of the films was evaluated as a function of time. The anodized Co coating exhibited three times higher activity than the steel substrate. The kinetics for the ORR were evaluated through Tafel plots and a slope of 226 mV/decade was found. Post-ORR characterization of the films revealed hexagonal plate-like oxide particles on the surface. After 50 cyclic voltammograms, the film was further oxidized, indicating that the ORR activity also affects the overall surface state of the film. This study demonstrates that thin films, after electrochemical modification, can be electrocatalysts for the oxygen reduction reaction and potentially used for applications in energy production and storage.

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  • 37.
    Ma, Hairui
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering. Nanjing Univ Aeronaut & Astronaut, Peoples R China.
    Miao, Qiang
    Nanjing Univ Aeronaut & Astronaut, Peoples R China; Nanjing Univ Aeronaut & Astronaut, Peoples R China.
    Liang, Wenping
    Nanjing Univ Aeronaut & Astronaut, Peoples R China.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Le Febvrier, Arnaud
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Synthesis and characterization of c-TiAlN/h-Cr2N multilayer films deposited by magnetron sputtering on Si (100) substrates2024In: Journal of Alloys and Compounds, ISSN 0925-8388, E-ISSN 1873-4669, Vol. 976, article id 173273Article in journal (Refereed)
    Abstract [en]

    A series of c-TiAlN/ h-Cr2N multilayer films with modulation periods Lambda of 10, 20 and 30 nm and thickness ratios (Cr2N thickness /Lambda) of 25%, 50% and 75% were prepared by dc magnetron sputtering on the Si substrate. The microstructures were characterized by scanning electron microscopy, x-ray diffraction, and the mechanical properties were measured by curvature measurement method and nanoindentation. With the Cr2N ratio increasing from 25% to 75%, the orientation of Cr2N layers changed from a randomly orientation to a 0001 preferential orientation, while inversely, the c-TiAlN layer changed from a 001 preferential orientation to a 111 preferential orientation or a randomly orientation. In the meantime, and regardless of the modulation period, the lattice parameter of c-TiAlN decreased from 4.16 angstrom to 4.12 angstrom and was explained by an increase of tensile stress between + 0.2 and + 1.3 GPa when the increase of Cr2N% in the modulation. With the increase of Cr2N ratio, the morphology of the film changed and led to surface with apparent porosity and large grain sizes of 100 x 300 nm. The film with 25% Cr2N ratio and modulation period of 20 nm exhibited the highest hardness reaching 22 +/- 1.3 GPa and reduced Young's modulus of 253 +/- 6 GPa.

  • 38.
    Ma, Hairui
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Medicine and Health Sciences. Nanjing Univ Aeronaut & Astronaut, Peoples R China.
    Miao, Qiang
    Nanjing Univ Aeronaut & Astronaut, Peoples R China.
    Liang, Wenping
    Nanjing Univ Aeronaut & Astronaut, Peoples R China.
    Persson, Per O A
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Palisaitis, Justinas
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Gao, Xiguang
    Nanjing Univ Aeronaut & Astronaut, Peoples R China.
    Song, Yindong
    Nanjing Univ Aeronaut & Astronaut, Peoples R China.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Le Febvrier, Arnaud
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Effect of modulation period and thickness ratio on the growth and mechanical properties of heteroepitaxial c-Ti0.4Al0.6N/h-Cr2N multilayer films2023In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 472, article id 129921Article in journal (Refereed)
    Abstract [en]

    c-TiAlN/h-Cr2N multilayer thin films, with modulation period lambda of 10 nm, 20 nm, and 30 nm and different Cr2N/lambda thickness ratios (25 %, 50 % and 75 %), were deposited on c-plane sapphire using reactive DC magnetron sputtering. All multilayers exhibited preferred orientation [Cr2N(0001)/ TiAlN(111)](x), regardless of the modulation period and thickness ratios. X-ray diffraction f-scans revealed an influence of the Cr2N layer thickness on the overall orientation quality of the multilayer, where the thicker the Cr2N layer the higher orientation quality. Atomically resolved high-angle annular dark-field scanning transmission electron microscopy revealed well defined and homogeneous atom stacking in the Cr2N layers. In contrast, the cubic TiAlN layer was found to be composed of coherent cubic AlN-rich and TiN-rich regions. Additionally, the TiAlN layers were found with a higher density of grain boundaries compared to the Cr2N layers. Mechanical properties evaluation revealed that the film with a 20 nm period and 75 % Cr2N thickness ratio exhibited the highest hardness of 27.11 +/- 0.72 GPa and an reduced elastic modulus of 349.1 +/- 6.84 GPa. The hardness increased as the thickness of Cr2N increased, until reaching 10 nm, after which it remained at a high level (similar to 25 GPa).

  • 39.
    Naumovska, Elena
    et al.
    Chalmers University of Technology, Sweden.
    Nzulu, Gabriel Kofi
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Mazzei, Laura
    Chalmers University of Technology, Sweden.
    Le Febvrier, Arnaud
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Komander, Kristina
    Uppsala University, Sweden.
    Magnuson, Martin
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Wolff, Max
    Uppsala University, Sweden.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Karlsson, Maths
    Chalmers University, Sweden.
    Local structure of hydrated nanocrystalline films of the proton conductor BaZr1-Sc O3-/2 studied by infrared spectroscopy2024In: Vibrational Spectroscopy, ISSN 0924-2031, E-ISSN 1873-3697, Vol. 130, article id 103622Article in journal (Refereed)
    Abstract [en]

    We report results from a study of the local structure of hydrated nanocrystalline 2 �m films of the well known proton conductor BaZr1-xScxO3-x/2 with x = 0.45, 0.54 and 0.64, using infrared (IR) spectroscopy. The films were prepared by magnetron sputtering. Analysis of the IR spectra focused on the O–H stretching region (2000—3700 cm-1), which reveals the presence of several distinct O–H stretching bands for which the intensity and frequency of each band vary in an unsystematic manner with Sc concentration. The spectra for the two higher Sc concentrations, x = 0.54 and 0.64, exhibit a distinct, highly intense O–H stretching band centered at around 3400–3500 cm-1, which is assigned to relatively symmetric, weakly hydrogen-bonding, proton configurations. The spectrum for the lower Sc concentration, x = 0.45, does not feature such a band but a broader, weaker, O–H stretching band between approximately 2500 and 3700 cm-1, suggesting that the protons are more homogeneously distributed over a range of different local proton coordinations in this relatively weakly doped material. A comparison to the IR spectra of powder samples of similar compositions suggests that for x = 0.45, the spectra and proton coordination of films and powder samples are similar, whereas for x = 0.54 and 0.64, a larger fraction of protons seems to be located in weakly hydrogen-bonding proton configurations in the films compared to the respective powder samples.

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  • 40.
    Nayak, Sanjay Kumar
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Shanmugham, Sathish Kumar
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Petrov, Ivan
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering. Univ Illinois, IL 61801 USA.
    Rosén, Johanna
    Linköping University, Department of Physics, Chemistry and Biology, Materials design. Linköping University, Faculty of Science & Engineering.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Birch, Jens
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Le Febvrier, Arnaud
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Growth and stability of epitaxial zirconium diboride thin films on silicon (111) substrate2023In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 134, no 13, article id 135303Article in journal (Refereed)
    Abstract [en]

    The epitaxial growth of boron rich hexagonal zirconium diborides (h-ZrB2+delta) thin films on Si(111) substrates using the magnetron co-sputtering technique with elemental zirconium and boron is reported. The effect of process temperature (700-900 degrees C) on the compositions and epitaxy quality was investigated. The chemical composition of the films was found to have a higher boron to zirconium ratio than the ideal stoichiometric AlB2-type ZrB2 and was observed to be sensitive to process temperature. Films deposited at 700 degrees C exhibited intense diffraction peaks along the growth direction corresponding to (000l) of h-ZrB2 using both lab and synchrotron-based x-ray diffractograms. The thermal and compositional stability of the epitaxial h-ZrB2+delta film was further evaluated under a nitrogen-rich environment through isothermal annealing which showed a reduction in in-plane misorientation during thermal annealing. The relative stability of deviating compositions and the energetics of impurity incorporations were analyzed using density functional theory simulations, and the formation of native point defects or impurity incorporation in h-ZrB2 was found to be endothermic processes. Our experimental results showed that an epitaxial thin film of h-ZrB2+delta can be grown on Si(111) substrate using a magnetron co-sputtering technique at a relatively low processing temperature (700 degrees C) and has the potential to be used as a template for III-nitride growth on Si substrates.

  • 41.
    Nzulu, Gabriel Kofi
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Naumovska, Elena
    Department of Chemistry and Chemical Engineering, Chalmers University of Technology, Sweden.
    Karlsson, Maths
    Department of Chemistry and Chemical Engineering, Chalmers University of Technology, Sweden.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Magnuson, Martin
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    le Febvrier, Arnaud
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Growth and thermal stability of Sc-doped BaZrO3 thin films deposited on single crystal substrates2023In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 772, article id 139803Article in journal (Refereed)
    Abstract [en]

    Thin films of BaZr1-xScxO3-x/2, (0 ≤ x ≤ 0.64), well known as proton conducting solid electrolytes for intermediatetemperature solid oxide fuel cell, were deposited by magnetron sputtering. X-ray diffraction analysis of theas deposited films reveals the presence of single-phase perovskite structure. The films were deposited on fourdifferent substrates (c-Al2O3, LaAlO3〈100〉, LaAlO3〈110〉, LaAlO3〈111〉) yielding random, (110)- or (100)-orientedfilms. The stability of the as-deposited films was assessed by annealing in air at 600 ◦C for 2 h. Theannealing treatment revealed instabilities of the perovskite structure for the (110) and randomly oriented films,but not for (100) oriented film. The instability of the coating under heat treatment was attributed to the lowoxygen content in the film (understoichiometry) prior annealing combined with the surface energy and atomiclayers stacking along the growth direction. An understoichiometric (100) oriented perovskite films showedhigher stability of the structure under an annealing in air at 600 ◦C.

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  • 42.
    Pallier, Camille
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Djemia, Philippe
    Univ Sorbonne Paris Nord, France.
    Fournier, Daniele
    Sorbonne Univ, France.
    Belliard, Laurent
    Sorbonne Univ, France.
    Lu, Jun
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Eriksson, Fredrik
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Greczynski, Grzegorz
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Le Febvrier, Arnaud
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Thermal, electrical, and mechanical properties of hard nitrogen-alloyed Cr thin films deposited by magnetron sputtering2022In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 441, article id 128575Article in journal (Refereed)
    Abstract [en]

    Cr-N based materials, including stoichiometric CrN and Cr:N with a wide range of nitrogen contents, are commonly used as hard and corrosion-resistant coatings. Cr-rich films in this materials system can retain the bcc structure of metallic Cr with few percent of dissolved nitrogen, which can be used for tailoring the mechanical, thermal, and electrical properties. Here, we investigated low nitrogen containing Cr thin films deposited by high ion assisted magnetron sputtering with a substrate temperature of 200 degrees C. With the gas flow ratio maintained at f(N2/Ar) = 0.02, the substrate bias and the target power allows for control of the film composition (0.03 &lt; N/Cr &lt; 0.34). The films comprise a mixture of bcc-Cr and hexagonal Cr2N1-delta phases. The mechanical properties studied by nanoindentation and Brillouin inelastic light scattering revealed a hardening effect due to the multiphase nanostructure. The mechanical properties of the Cr:N films depend on the residual stress, on the amount of h-Cr2N1-delta phase and on the nanostructuring nature of the coatings. A maximum hardness of 37 GPa was achieved for a dense film with a Youngs modulus of 340 GPa, a shear modulus of 118 GPa, and a relatively low thermal conductivity of 7 W/mK.

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  • 43.
    Pankratova, Daria
    et al.
    Lulea Univ Technol, Sweden.
    Yusupov, Khabib
    Linköping University, Department of Physics, Chemistry and Biology, Materials design. Linköping University, Faculty of Science & Engineering.
    Vomiero, Alberto
    Lulea Univ Technol, Sweden; Ca Foscari Univ Venice, Italy.
    Honnali, Sanath Kumar
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Boyd, Robert
    Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics. Linköping University, Faculty of Science & Engineering.
    Fournier, Daniele
    Sorbonne Univ, France.
    Ekeroth, Sebastian
    Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics. Linköping University, Faculty of Science & Engineering.
    Helmersson, Ulf
    Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics. Linköping University, Faculty of Science & Engineering.
    Azina, Clio
    9165 RWTH Aachen Univ, Germany.
    Le Febvrier, Arnaud
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Enhanced Thermoelectric Properties by Embedding Fe Nanoparticles into CrN Films for Energy Harvesting Applications2024In: ACS Applied Nano Materials, E-ISSN 2574-0970, Vol. 7, no 3, p. 3428-3435Article in journal (Refereed)
    Abstract [en]

    Nanostructured materials and nanocomposites have shown great promise for improving the efficiency of thermoelectric materials. Herein, Fe nanoparticles were imbedded into a CrN matrix by combining two physical vapor deposition approaches, namely, high-power impulse magnetron sputtering and a nanoparticle gun. The combination of these techniques allowed the formation of nanocomposites in which the Fe nanoparticles remained intact without intermixing with the matrix. The electrical and thermal transport properties of the nanocomposites were investigated and compared to those of a monolithic CrN film. The measured thermoelectric properties revealed an increase in the Seebeck coefficient, with a decrease of hall carrier concentration and an increase of the electron mobility, which could be explained by energy filtering by internal phases created at the NP/matrix interface. The thermal conductivity of the final nanocomposite was reduced from 4.8 W m(-1) K-1 to a minimum of 3.0 W m(-1) K-1. This study shows prospects for the nanocomposite synthesis process using nanoparticles and its use in improving the thermoelectric properties of coatings.

  • 44.
    Paschalidou, Eirini-Maria
    et al.
    Uppsala Univ, Sweden.
    Shu, Rui
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Boyd, Robert
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Papaderakis, Athanasios A.
    Univ Manchester, England; Univ Manchester, England.
    Bakhit, Babak
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Le Febvrier, Arnaud
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Greczynski, Grzegorz
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Nyholm, Leif
    Uppsala Univ, Sweden.
    The effect of the Nb concentration on the corrosion resistance of nitrogen-containing multicomponent TiZrTaNb-based films in acidic environments2022In: Journal of Alloys and Compounds, ISSN 0925-8388, E-ISSN 1873-4669, Vol. 927, article id 167005Article in journal (Refereed)
    Abstract [en]

    Multicomponent as well as high-entropy-based nitrides have received increasing interest in the field of materials science and engineering. The structural characteristics of these compounds result in a mix of covalent, metallic, and ionic bonds that give rise to a number of attractive properties including high hardness, electrical and thermal conductivities as well as chemical stability. These properties render these materials promising candidates for various industrial applications involving harsh operating conditions. Herein, the corrosion resistances of dc magnetron sputtered nitrogen-containing TiZrTaNby thin films with Nb content ranging from 8.0 to 24.5 at% have been investigated to provide insights regarding the corrosion resistances of multicomponent systems containing more than one passive element. The corrosion resistances and anodic behavior of the films were examined by electrochemical means in 0.1 M H2SO4 and 0.1 M HCl solutions. The results demonstrate that despite the significant differences in the concentration of one of the two main passive elements in the films i.e., Nb, the corrosion resistance did not differ significantly between the films. To provide insights into this phenomenon, the surface chemical state and composition of the prepared films were probed using X-ray photoelectron spectroscopy. It was shown that all samples exhibited Ta-rich surfaces after positive polarization up to 3.0 V vs. Ag/AgCl (3 M NaCl) as a result of the anodic dissolution of Zr and Ti. The thickness of the oxide layer formed upon different anodic polarization was studied using transmission electron microscopy, while complementary electrochemical impedance studies were performed. The extent of Nb dissolution from the surface of the films was, on the other hand, found to be small. These findings highlight the dominant role of Ta in the passivation of the films and demonstrate the minor effect of Nb concentration on the corrosion resistances of the films. However, it was demonstrated that the presence of Nb was still important for the corrosion resistance of the films above 1.4 V vs. Ag/AgCl (3 M NaCl), when replacing Nb with Cr, due to transpassive dissolution of Cr. These results facilitate the design of highly corrosion resistant multicomponent nitrides containing more than one passive element.(c) 2022 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

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  • 45.
    Sadowski, Grzegorz
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering. Malmo Univ, Sweden.
    Shu, Rui
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Le Febvrier, Arnaud
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Han, Zhijia
    Southern Univ Sci & Technol, Peoples R China.
    Music, Denis
    Malmo Univ, Sweden; Malmo Univ, Sweden.
    Liu, Weishu
    Southern Univ Sci & Technol, Peoples R China; Southern Univ Sci & Technol, Peoples R China.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Structural evolution and thermoelectric properties of Mg3SbxBi2-x thin films deposited by magnetron sputtering2023In: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films, ISSN 0734-2101, E-ISSN 1520-8559, Vol. 41, no 4, article id 043409Article in journal (Refereed)
    Abstract [en]

    Mg3Bi2-based compounds are of great interest for thermoelectric applications near room temperature. Here, undoped p-type Mg3SbxBi2-x thin films were synthesized using magnetron sputtering (three elemental targets in Ar atmosphere) with a growth temperature of 200 ? on three different substrates, namely, Si as well as c- and r-sapphire. The elemental composition was measured with energy-dispersive x-ray spectroscopy and the structure by x-ray diffraction. The electrical resistivity and the Seebeck coefficient were determined under He atmosphere from room temperature to the growth temperature. All samples are crystalline exhibiting the La2O3-type crystal structure (space group P-3m1). The observed thermoelectric response is consistent with a semiconductive behavior. With increasing x, the samples become more electrically resistive due to the increasing bandgap. High Bi content (x &lt; 1) is thus beneficial due to lower resistivity and a higher power factor near room temperature. Thermoelectric thin films synthesized at low temperatures may provide novel pathways to enable flexible devices on polymeric and other heat-sensitive substrates.

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  • 46.
    Sadowski, Grzegorz
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Zhu, Yongbin
    Southern Univ Sci & Technol, Peoples R China.
    Shu, Rui
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Feng, Tao
    Southern Univ Sci & Technol, Peoples R China.
    Le Febvrier, Arnaud
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Music, Denis
    Malmo Univ, Sweden.
    Liu, Weishu
    Southern Univ Sci & Technol, Peoples R China; Southern Univ Sci & Technol, Peoples R China.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Epitaxial growth and thermoelectric properties of Mg3Bi2 thin films deposited by magnetron sputtering2022In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 120, no 5, article id 051901Article in journal (Refereed)
    Abstract [en]

    Mg3Sb2-based thermoelectric materials attract attention for applications near room temperature. Here, Mg-Bi films were synthesized using magnetron sputtering at deposition temperatures from room temperature to 400 & DEG;C. Single-phase Mg3Bi2 thin films were grown on c-plane-oriented sapphire and Si(100) substrates at a low deposition temperature of 200 & DEG;C. The Mg3Bi2 films grew epitaxially on c-sapphire and fiber-textured on Si(100). The orientation relationships for the Mg3Bi2 film with respect to the c-sapphire substrate are (0001) Mg3Bi2||(0001) Al2O3 and [11 2 over bar 0] Mg3Bi2||[11 2 over bar 0] Al2O3. The observed epitaxy is consistent with the relatively high work of separation, calculated by the density functional theory, of 6.92 J m(-2) for the Mg3Bi2 (0001)/Al2O3 (0001) interface. Mg3Bi2 films exhibited an in-plane electrical resistivity of 34 mu omega m and a Seebeck coefficient of +82.5 mu V K-1, yielding a thermoelectric power factor of 200 mu W m(-1) K-2 near room temperature.

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  • 47.
    Shu, Rui
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Du, Hao
    Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics. Linköping University, Faculty of Science & Engineering. Guizhou Univ, Peoples R China.
    Sadowski, Grzegorz
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Dorri, Megan
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Rosén, Johanna
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Sortica, Mauricio A.
    Uppsala Univ, Sweden.
    Primetzhofer, Daniel
    Uppsala Univ, Sweden; Uppsala Univ, Sweden.
    Lundin, Daniel
    Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics. Linköping University, Faculty of Science & Engineering. Univ Paris Saclay, France.
    Le Febvrier, Arnaud
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Multicomponent TixNbCrAl nitride films deposited by dc and high-power impulse magnetron sputtering2021In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 426, article id 127743Article in journal (Refereed)
    Abstract [en]

    Multicomponent TixNbCrAl nitride films were deposited on Si(100) substrates by reactive direct current magnetron sputtering (dcMS) and high power impulse magnetron sputtering (HiPIMS) in the absence of substrate heating and bias. Three single Ti, Nb, and Cr50Al50 targets were either driven by three de or three HiPIMS power supplies. The Ti content in the films was varied by tuning the power applied to the Ti target. The composition was determined by ion beam analysis. The nitrogen content is nearly stoichiometric (48-50 at.%) in the HiPIMS series, while the dcMS are understoichiometric (39-45 at.%). The crystal structure, stress and density of the studied film were investigated by X-ray techniques and the microstructure was examined by scanning electron microscopy. All the Ti-containing films for both series exhibit an fcc NaCl-type phase structure. In particular, the dcMS series shows a (111) preferred orientation, resulting in a faceted surface morphology compared to a dense and smooth microstructure of the HiPIMS films. The compressive stress of the HiPIMS series (&gt; 2.0 GPa) is significantly larger than the values of the dcMS series (&lt;0.5 GPa). Nanoindentation measurements show a maximum hardness of 29.9 GPa and Youngs modulus of 304 GPa were obtained in the HiPIMS series. The results may promote HiPIMS techniques for the synthesis of complex multicomponent films for the application aspect to protective and hard coatings.

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  • 48.
    Shu, Rui
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering. Southern Univ Sci & Technol, Peoples R China.
    Han, Zhijia
    Southern Univ Sci & Technol, Peoples R China.
    Elsukova, Anna
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Zhu, Yongbin
    Southern Univ Sci & Technol, Peoples R China.
    Qin, Peng
    Southern Univ Sci & Technol, Peoples R China.
    Jiang, Feng
    Southern Univ Sci & Technol, Peoples R China.
    Lu, Jun
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Persson, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Palisaitis, Justinas
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Le Febvrier, Arnaud
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Zhang, Wenqing
    Southern Univ Sci & Technol, Peoples R China.
    Cojocaru-Miredin, Oana
    Rhein Westfal TH Aachen, Germany.
    Yu, Yuan
    Rhein Westfal TH Aachen, Germany.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Liu, Weishu
    Southern Univ Sci & Technol, Peoples R China; Southern Univ Sci & Technol, Peoples R China.
    Solid-State Janus Nanoprecipitation Enables Amorphous-Like Heat Conduction in Crystalline Mg3Sb2-Based Thermoelectric Materials2022In: Advanced Science, E-ISSN 2198-3844, Vol. 9, no 25, article id 2202594Article in journal (Refereed)
    Abstract [en]

    Solid-state precipitation can be used to tailor material properties, ranging from ferromagnets and catalysts to mechanical strengthening and energy storage. Thermoelectric properties can be modified by precipitation to enhance phonon scattering while retaining charge-carrier transmission. Here, unconventional Janus-type nanoprecipitates are uncovered in Mg3Sb1.5Bi0.5 formed by side-by-side Bi- and Ge-rich appendages, in contrast to separate nanoprecipitate formation. These Janus nanoprecipitates result from local comelting of Bi and Ge during sintering, enabling an amorphous-like lattice thermal conductivity. A precipitate size effect on phonon scattering is observed due to the balance between alloy-disorder and nanoprecipitate scattering. The thermoelectric figure-of-merit ZT reaches 0.6 near room temperature and 1.6 at 773 K. The Janus nanoprecipitation can be introduced into other materials and may act as a general property-tailoring mechanism.

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  • 49.
    Shu, Rui
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Lundin, Daniel
    Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics. Linköping University, Faculty of Science & Engineering. Univ Paris Saclay, France.
    Xin, Binbin
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Sortica, Mauricio A.
    Uppsala Univ, Sweden.
    Primetzhofer, Daniel
    Uppsala Univ, Sweden; Uppsala Univ, Sweden.
    Magnuson, Martin
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Le Febvrier, Arnaud
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Influence of Metal Substitution and Ion Energy on Microstructure Evolution of High-Entropy Nitride (TiZrTaMe)N1-x (Me = Hf, Nb, Mo, or Cr) Films2021In: ACS APPLIED ELECTRONIC MATERIALS, ISSN 2637-6113, Vol. 3, no 6, p. 2748-2756Article in journal (Refereed)
    Abstract [en]

    Multicomponent or high-entropy ceramics show unique combinations of mechanical, electrical, and chemical properties of importance in coating applications. However, generalizing controllable thin-film processes for these complex materials remains a challenge. Here, understoichiometric (TiZrTaMe)N1–x (Me = Hf, Nb, Mo, or Cr, 0.12 ≤ x ≤ 0.30) films were deposited on Si(100) substrates at 400 °C by reactive magnetron sputtering using single elemental targets. The influence of ion energy during film growth was investigated by varying the negative substrate bias voltage from ∼10 V (floating potential) to 130 V. The nitrogen content for the samples determined by elastic recoil detection analysis varied from 34.9 to 43.8 at. % (0.12 ≤ x ≤ 0.30), and the metal components were near-equimolar and not affected by the bias voltage. On increasing the substrate bias, the phase structures of (TiZrTaMe)N1–x (Me = Hf, Nb, or Mo) films evolved from a polycrystalline fcc phase to a (002) preferred orientation along with a change in surface morphology from faceted triangular features to a dense and smooth structure with nodular mounds. All the four series of (TiZrTaMe)N1–x (Me = Hf, Nb, Mo, or Cr) films exhibited increasing intrinsic stress with increasing negative bias. The maximum compressive stress reached ∼3.1 GPa in Hf- and Cr-containing films deposited at −130 V. The hardness reached a maximum value of 28.0 ± 1.0 GPa at a negative bias ≥100 V for all the four series of films. The effect of bias on the mechanical properties of (TiNbZrMe)N1–x films can thus guide the design of protective high-entropy nitride films.

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  • 50.
    Shu, Rui
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Paschalidou, Eirini-Maria
    Department of Chemistry-Ångström, Uppsala University.
    Gangaprasad Rao, Smita
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Bakhit, Babak
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Boyd, Robert
    Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics. Linköping University, Faculty of Science & Engineering.
    Moro, Marcos Vinicius
    Department of Physics and Astronomy, Uppsala University.
    Primetzhofer, Daniel
    Department of Physics and Astronomy, Uppsala University.
    Greczynski, Grzegorz
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Nyholm, Leif
    Department of Chemistry-Ångström, Uppsala University.
    Le Febvrier, Arnaud
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Effect of nitrogen content on microstructure and corrosion resistance of sputter-deposited multicomponent (TiNbZrTa)Nx films2020In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 404, article id 126485Article in journal (Refereed)
    Abstract [en]

    Multicomponent (TiNbZrTa)Nx films were deposited on Si(100) substrates at room temperature using magnetron sputtering with a nitrogen flow ratio fN [fN = N2/(Ar + N2)], which was varied from 0 to 30.8%. The nitrogen content in the films varied between 0 and 45.2 at.%, i.e., x = 0 to 0.83. The microstructure was characterized by X-ray diffraction and electron microscopy. The metallic TiNbZrTa film comprised a dominant bcc solid-solution phase, whereas a single NaCl-type face-centred cubic structure was observed in all nitrogen-containing films (TiNbZrTa)Nx. The mechanical, electrical, and electrochemical properties of these films varied with nitrogen content. The maximum hardness was achieved at 22.1 ± 0.3 GPa when N = 43.0 at.%. The resistivities increased from 95 to 424 μΩcm with increasing nitrogen content. A detailed study of the variation of morphology and chemical bonding with nitrogen content was performed and the corrosion resistance of the TiNbZrTa nitride films was explored in 0.1 M H2SO4. While all the films had excellent corrosion resistances at potentials up to 2.0 V vs. Ag/AgCl, the metallic film and the films with low nitrogen contents (x < 0.60) exhibited an almost stable current plateau up to 4.0 V vs. Ag/AgCl. For the films with higher nitrogen contents (x ≥ 0.68), the current plateau was retained up to 2.0 V vs. Ag/AgCl, above which a higher nitrogen content resulted in a higher current. The decrease in the corrosion resistance at these high potentials indicate the presence of a potential-dependent activation effect resulting in an increased oxidation rate of the nitrides (present under the passive oxide film) yielding a release of nitrogen from the films. TEM results indicate that the oxide layer formed after this corrosion measurement was thick and porous for the film with x = 0.76, in very good agreement with the increased corrosion rate for this film. The results demonstrate that an increased nitrogen content in (TiNbZrTa)Nx system improves their mechanical properties with retained high corrosion resistance at potentials up to 2.0 V vs. Ag/AgCl in 0.1 M H2SO4. At even higher potentials, however, the corrosion resistance decreases with increasing nitrogen concentration for films with sufficiently high nitrogen contents (i.e. x ≥ 0.68).

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