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  • 1.
    Bakoglidis, Konstantinos D.
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Broitman, Esteban
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Schmidt, Susann
    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.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Nanotribological properties of wear resistant a-CNx thin films deposited by mid-frequency magnetron sputteringManuscript (preprint) (Other academic)
    Abstract [en]

    The nanotribological properties of amorphous carbon nitride (a-CNx) thin films deposited with mid-frequency magnetron sputtering (MFMS) were investigated at the nanoscale using an in-situ technique in a Hysitron Triboindenter TI 950. The friction coefficient, wear rate, track roughness, and the track profiles were recorded as a function of the number of linear reciprocal cycles, revealing the manner that the nanotribological and surface properties change during the wear test. The surface composition of  the films was evaluated by x-ray photoelectron spectroscopy (XPS). The friction coefficient ranges between 0.05 – 0.07, while the wear coefficient ranges from 9.4 x 10-8 up to 1.5 x 10-4 mm3/Nm. Debris particles and surface modifications characterize the friction and lubrication behavior in the track. The friction and main lubrication mechanism on the modified surface changes after the removal of debris particles, while this change appears at different cycle for each CNx film depending on the substrate bias voltage. Films grown at higher bias are modified earlier than films grown at lower bias. The wear behavior can be divided into two, track roughnessdependent, regimes; (1) films with track roughness > 1 nm showed wear with obvious tracks and (2) the films with roughness < 1 nm showed negative wear at the nanometer scale with a volume of material projected in the area of the wear track. This material volume is believed to be result of a surface modification, where the molar volume of the modified surface is larger than the molar volume of the surface before the wear test.

  • 2.
    Bakoglidis, Konstantinos D.
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Schmidt, Susann
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Garbrecht, Magnus
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Ivanov, Ivan G.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. 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.
    Greczynski, Grzegorz
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Low-temperature growth of low friction wear-resistant amorphous carbon nitride thin films by mid-frequency, high power impulse, and direct current magnetron sputtering2015In: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films, ISSN 0734-2101, E-ISSN 1520-8559, Vol. 33, no 5, article id 05E112Article in journal (Refereed)
    Abstract [en]

    Amorphous carbon nitride (a-CNx) thin films were deposited on steel AISI52100 and Si(001) substrates using mid-frequency magnetron sputtering (MFMS) with an MF bias voltage, high power impulse magnetron sputtering (HiPIMS) with a synchronized HiPIMS bias voltage, and direct current magnetron sputtering (DCMS) with a DC bias voltage. The films were deposited at a low substrate temperature of 150 °C and a N2/Ar flow ratio of 0.16 at the total pressure of 400 mPa. The negative bias voltage (Vs) was varied from 20 V to 120 V in each of the three deposition modes. The microstructure of the films was characterized by high-resolution transmission electron microscopy (HRTEM) and selected area electron diffraction (SAED), while the film morphology was investigated by scanning electron microscopy (SEM). All films possessed amorphous microstructure with clearly developed columns extending throughout the entire film thickness. Layers grown with the lowest substrate bias of 20 V exhibited pronounced intercolumnar porosity, independent of the technique used. Voids closed and dense films formed at Vs ≥ 60 V, Vs ≥ 100 V and Vs = 120 V for MFMS, DCMS and HiPIMS, respectively. X-ray photoelectron spectroscopy (XPS) revealed that the nitrogen-to-carbon ratio, N/C, of the films ranged between 0.2 and 0.24. Elastic recoil detection analysis (ERDA) showed that Ar content varied between 0 and 0.8 at% and increases as a function of Vs for all deposition techniques. All films exhibited compressive residual stress, σ, which depends on the growth method; HiPIMS produces the least stressed films with stress between – 0.4 and – 1.2 GPa for all Vs values, while for CNx films deposited by MFMS σ = – 4.2 GPa. Nanoindentation showed a significant increase in film hardness and reduced elastic modulus with increasing Vs for all techniques. The harder films were produced by MFMS with hardness as high as 25 GPa. Low friction coefficients, between 0.05 and 0.06, were recorded for all films. Furthermore, CNx films produced by MFMS and DCMS at Vs = 100 V and 120 V presented a high wear resistance with wear coefficients of k ≤ 2.3 x 10-5 mm3/Nm.

  • 3.
    Bakoglidis, Konstantinos
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Nedelcu, Ileana
    SKF Engn and Research Centre, Netherlands.
    Schmidt, Susann
    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.
    Ehret, Pascal
    SKF Engn and Research Centre, Netherlands.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Rolling contact fatigue of bearing components coated with carbon nitride thin films2016In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 98, p. 100-107Article in journal (Refereed)
    Abstract [en]

    Bearing rollers were coated with CNx films using high power impulse magnetron sputtering deposition in order to reduce their rolling-contact fatigue as investigated using a Micro-Pitting Rig tribometer under poly-alpha-olefin lubricated conditions. Coated rollers with a similar to 15 nm thick W adhesion layer to the substrate, exhibit the best performance, presenting mild wear and no fatigue after 700 kcycles. The steady-state friction coefficient was similar to 0.05 for both uncoated and coated rollers. Uncoated rollers show run-in friction in the first 50 kcycles, because of steel-to-steel contact, which is absent for coated rollers. Analytical transmission electron microscopy and X-ray photoelectron spectroscopy show that the presence of a CNx coating prevents steel-to-steel contact of the counterparts, prior to the elastohydrodynamic lubrication, reducing their wear and increasing the lifetime expectancy. (C) 2016 Elsevier Ltd. All rights reserved.

  • 4.
    Goyenola, Cecilia
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Stafström, Sven
    Linköping University, Department of Physics, Chemistry and Biology, Computational Physics. Linköping University, The Institute of Technology.
    Schmidt, Susann
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Gueorguiev, Gueorgui Kostov
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Carbon Fluoride, CFx: Structural Diversity as Predicted by First Principles2014In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 118, no 12, p. 6514-6521Article in journal (Refereed)
    Abstract [en]

    Fluorinated carbon-based thin films offer a wide range of properties for many technological applications that depend on the microstructure of the films. To gain a better understanding of the role of fluorine in the structural formation of these films, CFx systems based on graphene-like fragments were studied by first-principles calculations. Generally, the F concentration determines the type of film that can be obtained. For low F concentrations (up to similar to 5 at. %), films with fullerene-like as well as graphite-like features are expected. Larger F concentrations (greater than= 10 at. %) give rise to increasingly amorphous carbon films. Further increasing the F concentration in the films leads to formation of a polymer-like microstructure. To aid the characterization of CFx systems generated by computational methods, a statistical approach is developed.

  • 5.
    Hänninen, Tuomas
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Schmidt, Susann
    IHI Ionbond AG, Industriestraße 211, Olten CH-4600, Switzerland.
    Ivanov, Ivan Gueorguiev
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. 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.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Högberg, Hans
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Silicon carbonitride thin films deposited by reactive high power impulse magnetron sputtering2018In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 335, p. 248-256Article in journal (Refereed)
    Abstract [en]

    Amorphous silicon carbonitride thin films for biomedical applications were deposited in an industrial coating unit from a silicon target in different argon/nitrogen/acetylene mixtures by reactive high power impulse magnetron sputtering (rHiPIMS). The effects of acetylene (C2H2) flow rate, substrate temperature, substrate bias voltage, and HiPIMS pulse frequency on the film properties were investigated. Low C2H2 flow rates (<10 sccm) resulted in silicon nitride-like film properties, seen from a dense morphology when viewed in cross-sectional scanning electron microscopy, a hardness up to ∼22 GPa as measured by nanoindentation, and Si-N bonds dominating over Si-C bonds in X-ray photoelectron spectroscopy core-level spectra. Higher C2H2 flows resulted in increasingly amorphous carbon-like film properties, with a granular appearance of the film morphology, mass densities below 2 g/cm3 as measured by X-ray reflectivity, and a hardness down to 4.5 GPa. Increasing substrate temperatures and bias voltages resulted in slightly higher film hardnesses and higher compressive residual stresses. The film H/E ratio showed a maximum at film carbon contents ranging between 15 and 30 at.% and at elevated substrate temperatures from 340 °C to 520 °C.

  • 6.
    Hänninen, Tuomas
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Schmidt, Susann
    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.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Högberg, Hans
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Silicon oxynitride films deposited by reactive high power impulse magnetron sputtering using nitrous oxide as a single-source precursor2015In: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films, ISSN 0734-2101, E-ISSN 1520-8559, Vol. 33, no 5, p. 05E121-Article in journal (Refereed)
    Abstract [en]

    Silicon oxynitride thin films were synthesized by reactive high power impulse magnetron sputtering of silicon in argon/nitrous oxide plasmas. Nitrous oxide was employed as a single-source precursor supplying oxygen and nitrogen for the film growth. The films were characterized by elastic recoil detection analysis, x-ray photoelectron spectroscopy, x-ray diffraction, x-ray reflectivity, scanning electron microscopy, and spectroscopic ellipsometry. Results show that the films are silicon rich, amorphous, and exhibit a random chemical bonding structure. The optical properties with the refractive index and the extinction coefficient correlate with the film elemental composition, showing decreasing values with increasing film oxygen and nitrogen content. The total percentage of oxygen and nitrogen in the films is controlled by adjusting the gas flow ratio in the deposition processes. Furthermore, it is shown that the film oxygen-to-nitrogen ratio can be tailored by the high power impulse magnetron sputtering-specific parameters pulse frequency and energy per pulse. (C) 2015 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution 3.0 Unported License.

  • 7.
    Hänninen, Tuomas
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Schmidt, Susann
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Wissting, Jonas
    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.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Högberg, Hans
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Stoichiometric silicon oxynitride thin films reactively sputtered in Ar/N2O plasmas by HiPIMS2016In: Journal of Physics D: Applied Physics, ISSN 0022-3727, E-ISSN 1361-6463, Vol. 49, no 13, article id 135309Article in journal (Refereed)
    Abstract [en]

    Silicon oxynitride (SiOxNy, x = 0.2 − 1.3, y = 0.2 − 0.7) thin films were synthesized by reactive high power impulse magnetron sputtering from a pure silicon target in Ar/N2O atmospheres. It is found that the composition of the material can be controlled by the reactive gas flow and the average target power. X-ray photoelectron spectroscopy (XPS) shows that high average powers result in more silicon-rich films, while lower target powers yield silicon-oxide-like material due to more pronounced target poisoning. The amount of nitrogen in the films can be controlled by the percentage of nitrous oxide in the working gas. The nitrogen content remains at a constant level while the target is operated in the transition region between metallic and poisoned target surface conditions. The extent of target poisoning is gauged by the changes in peak target current under the different deposition conditions. XPS also shows that varying concentrations and ratios of oxygen and nitrogen in the films result in film chemical bonding structures ranging from silicon-rich to stoichiometric silicon oxynitrides having no observable Si−Si bond contributions. Spectroscopic ellipsometry shows that the film optical properties depend on the amount and ratio of oxygen and nitrogen in the compound, with film refractive indices measured at 633 nm ranging between those of SiO2 and Si3N4.

  • 8.
    Imam, Mewlude
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering. European Spallat Source ESS AB, Sweden.
    Höglund, Carina
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, Faculty of Science & Engineering. European Spallation Source ERIC, Lund, Sweden.
    Jensen, Jens
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Schmidt, Susann
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering. European Spallation Source ERIC, Lund, Sweden.
    Ivanov, Ivan Gueorguiev
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Hall-Wilton, Richard
    European Spallation Source ERIC, Lund, Sweden.
    Birch, Jens
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Pedersen, Henrik
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, Faculty of Science & Engineering.
    Trimethylboron as single-source precursor for boron-carbonthin film synthesis by plasma chemical vapor deposition2015Manuscript (preprint) (Other academic)
    Abstract [en]

    Boron-carbon (BxC) thin films are potential neutron converting layers for 10B-based neutron detectors. However, as common material choices for such detectors do not tolerate temperature above 500°C, a low temperature deposition route is required for this application. Here we study trimethylboron B(CH3)3 (TMB) as a single-source precursor for the deposition of BxC thin films by plasma CVD using Ar plasma. The effect of plasma power, TMB/Ar ratio and total pressure on the film composition, morphology and structure are investigated. The highest B/C ratio of 1.9 was achieved at high TMB flow in a low total pressure and high plasma power which rendered an approximate substrate temperature of ~ 300 °C. X-ray photoelectron spectroscopy shows that B-C bonds prevail in the films, although C-C and B-O bonds are also present. Raman spectroscopy confirms the presence of amorphous carbon phases in the films. The H content in the films is found to be 15±5 at. % by the time of flight elastic recoil detection analysis (Tof-ERDA). The film density as determined from X-ray reflectivity (XRR) measurements is 2. 16 ± 0.01  g/cm3 and the internal compressive stresses are measured to be less than 400 MPa.

  • 9.
    Kostov Gueorguiev, Gueorgui
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Goyenola, Cecilia
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Schmidt, Susann
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    CF(x): A first-principles study of structural patterns arising during synthetic growth2011In: Chemical Physics Letters, ISSN 0009-2614, E-ISSN 1873-4448, Vol. 516, no 1-3, p. 62-67Article in journal (Refereed)
    Abstract [en]

    Structural and bonding patterns arising from the incorporation of fluorine atoms in a graphene-like network relevant to the deposition of carbon fluoride (CF(x)) films were addressed by first-principles calculations. We find that large N-member (N = 8-12) rings, defects by sheet branching, and defects associated with bond rotation pertain to CF(x). The cohesive energy gains associated with these patterns are similar to 0.2-0.4 eV/at., which is similar to those for a wide range of defects in other C-based nanostructured solids. Fullerene-like CF(x) is predicted for F concentrations below similar to 10 at.%, while CF(x) compounds with higher F content are predominantly amorphous or polymeric.

  • 10.
    Muraro, A.
    et al.
    IFP CNR, Italy.
    Albani, G.
    University of Milano Bicocca, Italy.
    Perelli Cippo, E.
    IFP CNR, Italy.
    Croci, G.
    University of Milano Bicocca, Italy.
    Angella, G.
    IENI CNR, Italy.
    Birch, Jens
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Cazzaniga, C.
    STFC, England.
    Caniello, R.
    IFP CNR, Italy.
    DellEra, F.
    IFP CNR, Italy.
    Ghezzi, F.
    IFP CNR, Italy.
    Grosso, G.
    IFP CNR, Italy.
    Hall-Wilton, R.
    European Spallat Source ESS ERIC, Sweden.
    Höglund, Carina
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, Faculty of Science & Engineering.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Schmidt, Susann
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Robinson, Linda
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Rebai, M.
    University of Milano Bicocca, Italy.
    Salvato, G.
    IPCF CNR, Italy.
    Tresoldi, D.
    IPCF CNR, Italy.
    Vasi, C.
    IPCF CNR, Italy.
    Tardocchi, M.
    IFP CNR, Italy.
    Neutron radiography as a non-destructive method for diagnosing neutron converters for advanced thermal neutron detectors2016In: Journal of Instrumentation, ISSN 1748-0221, E-ISSN 1748-0221, Vol. 11, no C03033Article in journal (Refereed)
    Abstract [en]

    Due to the well-known problem of He-3 shortage, a series of different thermal neutron detectors alternative to helium tubes are being developed, with the goal to find valid candidates for detection systems for the future spallation neutron sources such as the European Spallation Source (ESS). A possible He-3-free detector candidate is a charged particle detector equipped with a three dimensional neutron converter cathode (3D-C). The 3D-C currently under development is composed by a series of alumina (Al2O3) lamellas coated by 1 mu m of B-10 enriched boron carbide (B4C). In order to obtain a good characterization in terms of detector efficiency and uniformity it is crucial to know the thickness, the uniformity and the atomic composition of the B4C neutron converter coating. In this work a non-destructive technique for the characterization of the lamellas that will compose the 3D-C was performed using neutron radiography. The results of these measurements show that the lamellas that will be used have coating uniformity suitable for detector applications. This technique (compared with SEM, EDX, ERDA, XPS) has the advantage of being global (i.e. non point-like) and non-destructive, thus it is suitable as a check method for mass production of the 3D-C elements.

  • 11.
    Pettersson, M
    et al.
    Uppsala University, Sweden.
    Tkachenko, S
    Uppsala University, Sweden.
    Schmidt, Susann
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Berlind, Torun
    Linköping University, Department of Physics, Chemistry and Biology, Applied Optics . Linköping University, The Institute of Technology.
    Jacobson, S
    Uppsala University, Sweden.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Engqvist, H
    Uppsala University, Sweden.
    Persson, C
    Uppsala University, Sweden.
    Mechanical and tribological behavior of silicon nitride and silicon carbon nitride coatings for total joint replacements2013In: Journal of The Mechanical Behavior of Biomedical Materials, ISSN 1751-6161, E-ISSN 1878-0180, Vol. 25, p. 41-47Article in journal (Refereed)
    Abstract [en]

    Total joint replacements currently have relatively high success rates at 10–15 years; however, increasing ageing and an active population places higher demands on the longevity of the implants. A wear resistant configuration with wear particles that resorb in vivo can potentially increase the lifetime of an implant. In this study, silicon nitride (SixNy) and silicon carbon nitride (SixCyNz) coatings were produced for this purpose using reactive high power impulse magnetron sputtering (HiPIMS). The coatings are intended for hard bearing surfaces on implants. Hardness and elastic modulus of the coatings were evaluated by nanoindentation, cohesive, and adhesive properties were assessed by micro-scratching and the tribological performance was investigated in a ball-on-disc setup run in a serum solution. The majority of the SixNy coatings showed a hardness close to that of sintered silicon nitride (∼18 GPa), and an elastic modulus close to that of cobalt chromium (∼200 GPa). Furthermore, all except one of the SixNy coatings offered a wear resistance similar to that of bulk silicon nitride and significantly higher than that of cobalt chromium. In contrast, the SixCyNz coatings did not show as high level of wear resistance.

  • 12.
    Pettersson, Maria
    et al.
    Uppsala University, Sweden.
    Berlind, Torun
    Linköping University, Department of Physics, Chemistry and Biology, Applied Optics . Linköping University, The Institute of Technology.
    Schmidt, Susann
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Jacobsson, Staffan
    Uppsala University, Sweden.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Persson, Cecilia
    Uppsala University, Sweden.
    Engqvist, Håkan
    Uppsala University, Sweden.
    Structure and composition of silicon nitride and silicon carbon nitride coatings for joint replacements2013In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 235, no 25, p. 827-834Article in journal (Refereed)
    Abstract [en]

    SiNx and SiCxNy coatings were fabricated with high power impulse magnetron sputtering (HiPIMS). The coatings microstructure, growth pattern, surface morphology, composition, and bonding structure were investigated by AFM, SEM, GIXRD, TEM, EDS as well as XPS, and related to the deposition parameters target powers and substrate temperature. Cross-sections of SiCxNy coatings showed either dense and laminar, or columnar structures. These coatings varied in roughness (Ra between 0.2 and 3.8 nm) and contained up to 35 at.% C. All coatings were substoichiometric (with an N/Si ratio from 0.27 to 0.65) and contained incorporated particles (so called droplets). The SiNx coatings, in particular those deposited at the lower power on the silicon target, demonstrated a dense microstructure and low surface roughness (Ra between 0.2 and 0.3 nm). They were dominated by an (X-ray) amorphous structure and consisted mainly of Si–N bonds. The usefulness of these coatings is discussed for bearing surfaces for hip joint arthroplasty in order to prolong their life-time. The long-term aim is to obtain a coating that reduces wear and metal ion release, that is biocompatible, and with wear debris that can dissolve in vivo.

  • 13.
    Pettersson, Maria
    et al.
    Uppsala University, Sweden.
    Bryant, Michael
    University of Leeds, England.
    Schmidt, Susann
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Engqvist, Hakan
    Uppsala University, Sweden.
    Hall, Richard M.
    University of Leeds, England.
    Neville, Anne
    University of Leeds, England.
    Persson, Cecilia
    Uppsala University, Sweden.
    Dissolution behaviour of silicon nitride coatings for joint replacements2016In: Materials science & engineering. C, biomimetic materials, sensors and systems, ISSN 0928-4931, E-ISSN 1873-0191, Vol. 62, p. 497-505Article in journal (Refereed)
    Abstract [en]

    In this study, the dissolution rate of SiNx coatings was investigated as a function of coating composition, in comparison to a cobalt chromium molybdenum alloy (CoCrMo) reference. SiNx coatings with N/Si ratios of 03, 0.8 and 1.1 were investigated. Electrochemical measurements were complemented with solution (inductively coupled plasma techniques) and surface analysis (vertical scanning interferometry and x-ray photoelectron spectroscopy). The dissolution rate of the SiNx coatings was evaluated to 0.2-1.4 nm/day, with a trend of lower dissolution rate with higher N/Si atomic ratio in the coating. The dissolution rates of the coatings were similar to or lower than that of CoCrMo (0.7-1.2 nm/day). The highest nitrogen containing coating showed mainly Si-N bonds in the bulk as well as at the surface and in the dissolution area. The lower nitrogen containing coatings showed Si-N and/or Si-Si bonds in the bulk and an increased formation of Si-O bonds at the surface as well as in the dissolution area. The SiNx coatings reduced the metal ion release from the substrate. The possibility to tune the dissolution rate and the ability to prevent release of metal ions encourage further studies on SiNx coatings for joint replacements.

  • 14.
    Pfeiffer, D.
    et al.
    European Spallat Source ESS AB, Sweden; CERN, Switzerland.
    Resnati, F.
    European Spallat Source ESS AB, Sweden; CERN, Switzerland.
    Birch, Jens
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Etxegarai, M.
    European Spallat Source ESS AB, Sweden.
    Hall-Wilton, R.
    European Spallat Source ESS AB, Sweden; Mid Sweden University, Sweden.
    Höglund, Carina
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, Faculty of Science & Engineering. European Spallat Source ESS AB, Sweden.
    Hultman, L.
    Mid Sweden University, Sweden.
    Llamas-Jansa, I.
    European Spallat Source ESS AB, Sweden; Institute Energy Technology IFE, Norway.
    Oliveri, E.
    CERN, Switzerland.
    Oksanen, E.
    European Spallat Source ESS AB, Sweden.
    Robinson, L.
    European Spallat Source ESS AB, Sweden.
    Ropelewski, L.
    CERN, Switzerland.
    Schmidt, Susann
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering. European Spallat Source ESS AB, Sweden.
    Streli, C.
    Vienna University of Technology, Austria.
    Thuiner, P.
    CERN, Switzerland; Vienna University of Technology, Austria.
    First measurements with new high-resolution gadolinium-GEM neutron detectors2016In: Journal of Instrumentation, ISSN 1748-0221, E-ISSN 1748-0221, Vol. 11, no P05011Article in journal (Refereed)
    Abstract [en]

    European Spallation Source instruments like the macromolecular diffractometer (NMX) require an excellent neutron detection efficiency, high-rate capabilities, time resolution, and an unprecedented spatial resolution in the order of a few hundred micrometers over a wide angular range of the incoming neutrons. For these instruments solid converters in combination with Micro Pattern Gaseous Detectors (MPGDs) are a promising option. A GEM detector with gadolinium converter was tested on a cold neutron beam at the IFE research reactor in Norway. The mu TPC analysis, proven to improve the spatial resolution in the case of B-10 converters, is extended to gadolinium based detectors. For the first time, a Gd-GEM was successfully operated to detect neutrons with a measured efficiency of 11.8% at a wavelength of 2 angstrom and a position resolution better than 250 mu m.

  • 15.
    Piscitelli, F.
    et al.
    European Spallat Source ERIC, Sweden; ILL Grenoble, France; University of Perugia, Italy.
    Khaplanov, A.
    European Spallat Source ERIC, Sweden; ILL Grenoble, France.
    Devishvili, A.
    Ruhr University of Bochum, Germany.
    Schmidt, Susann
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering. European Spallat Source ERIC, Sweden.
    Höglund, Carina
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, Faculty of Science & Engineering. European Spallat Source ERIC, Sweden.
    Birch, Jens
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Dennison, A. J. C.
    ILL Grenoble, France; Uppsala University, Sweden.
    Gutfreund, P.
    ILL Grenoble, France.
    Hall-Wilton, R.
    European Spallat Source ERIC, Sweden; Mid Sweden University, Sweden.
    Van Esch, P.
    ILL Grenoble, France.
    Neutron reflectometry on highly absorbing films and its application to (B4C)-B-10-based neutron detectors2016In: Proceedings of the Royal Society. Mathematical, Physical and Engineering Sciences, ISSN 1364-5021, E-ISSN 1471-2946, Vol. 472, no 2185, p. 20150711-Article in journal (Refereed)
    Abstract [en]

    Neutron reflectometry is a powerful tool used for studies of surfaces and interfaces. The absorption in the typical studied materials is neglected and this technique is limited only to the reflectivity measurement. For strongly absorbing nuclei, the absorption can be directly measured by using the neutron-induced fluorescence technique which exploits the prompt particle emission of absorbing isotopes. This technique is emerging from soft matter and biology where highly absorbing nuclei, in very small quantities, are used as a label for buried layers. Nowadays, the importance of absorbing layers is rapidly increasing, partially because of their application in neutron detection; a field that has become more active also due to the He-3-shortage. We extend the neutron-induced fluorescence technique to the study of layers of highly absorbing materials, in particular (B4C)-B-10. The theory of neutron reflectometry is a commonly studied topic; however, when a strong absorption is present the subtle relationship between the reflection and the absorption of neutrons is not widely known. The theory for a general stack of absorbing layers has been developed and compared to measurements. We also report on the requirements that a (B4C)-B-10 layer must fulfil in order to be employed as a converter in neutron detection.

  • 16.
    Schmidt, Susann
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Carbon based Thin Films Prepared by HiPIMS and DCMS2012Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    The present thesis focuses on carbon based thin films prepared by high power impulse magnetron sputtering (HiPIMS) and direct current magnetron sputtering (DCMS). The properties of such thin films can be tailored to an extensive variety; the film microstructure, for example, ranges in the presented work from fully amorphous, graphitic films to fullerene like (FL). Consequently, the applications of these films migh be as wide spread as their properties.

    Carbon nitride (CNx, 0 < x < 0.20) as well as carbon fluoride (CFx 0.16 < x < 0.35)thin films were synthesized in an industrial deposition chamber by reactive sputtering  ofgraphite in an Ar/N2 and Ar/CF4 ambient. In order to gain a better understanding of thegrowth processes the C/Ar/N2 and the C/Ar/CF4 plasma was investigated by ion massspectroscopy at room temperature. Further understanding in this context gave thedetailed evaluation of target current and target voltage waveforms, acquired whengraphite was sputtered in HiPIMS mode. First principle calculations were carried out forthe growth of CFx and gave additional grasp about the most probable plasma precursorsas well as structure defining defects. Data gained from these characterisations of thedeposition processes were successfully related to the film properties. In order to linkdifferent process parameters to film properties, the synthesized films werecharacterized with regards to their thickness and deposition rate (secondary electronmicroscopy, SEM), chemical composition (elastic recoil detection analysis, ERDA and xrayphotoelectron spectroscopy, XPS), the chemical bonding (XPS), microstructure (transmission electron spectroscopy, TEM and selected area electron diffraction, SAED).Another part on thin film characterization comprised measurements for possibleapplications. For this, mainly nanoindentation and surface energy measurements wereperformed.

    Application-related measurements revealed a hardness of up to 23 GPa at high elastic recoveries of ~ 90 % for CNx (x = 0.1) films that exhibited a weakly pronounced fullerene like structure. The hardness correlated with the microstructure and N incorporation rate of the thin film. Evidence by TEM for an increased amount of N intercalations in CNx HiPIMS thin films is supported by ion mass spectroscopic measurements. As expected, higher ion particle energies as well as amounts particularly for C+ and N+ were measured in the reactive HiPIMS plasma.

    CFx thin films were found to show surface energies equivalent to superhydrophobic material for x > 0.26 while such films were polymeric in nature accounting for hardnesses below 1 GPa. Whereas, an amorphous structure for carbon-based films with fluorine contents ranging between 16 % and 23 % was observed. For such films, the hardness increased with decreasing fluorine content and ranged between 16 GPa and 4 GPa.

    List of papers
    1. CF(x) thin solid films deposited by high power impulse magnetron sputtering: Synthesis and characterization
    Open this publication in new window or tab >>CF(x) thin solid films deposited by high power impulse magnetron sputtering: Synthesis and characterization
    Show others...
    2011 (English)In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 206, no 4, p. 646-653Article in journal (Refereed) Published
    Abstract [en]

    Fluorine containing amorphous carbon films (CF(x), 0.16 andlt;= x andlt;= 0.35) have been synthesized by reactive high power impulse magnetron sputtering (HiPIMS) in an Ar/CF(4) atmosphere. The fluorine content of the films was controlled by varying the CF(4) partial pressure from 0 mPa to 110 mPa at a constant deposition pressure of 400 mPa and a substrate temperature of 110 degrees C. The films were characterized regarding their composition, chemical bonding and microstructure as well as mechanical properties by applying elastic recoil detection analysis, X-ray photoelectron spectroscopy, Raman spectroscopy, transmission electron microscopy, and nanoindentation. First-principles calculations were carried out to predict and explain F-containing carbon thin film synthesis and properties. By geometry optimizations and cohesive energy calculations the relative stability of precursor species including C(2), F(2) and radicals, resulting from dissociation of CF4, were established. Furthermore, structural defects, arising from the incorporation of F atoms in a graphene-like network, were evaluated. All as-deposited CF(x) films are amorphous. Results from X-ray photoelectron spectroscopy and Raman spectroscopy indicate a graphitic nature of CF(x) films with x andlt;= 0.23 and a polymeric structure for films with x andgt;= 0.26. Nanoindentation reveals hardnesses between similar to 1 GPa and similar to 16 GPa and an elastic recovery of up to 98%.

    Place, publisher, year, edition, pages
    Elsevier, 2011
    Keywords
    Fluorine containing carbon thin films, HiPIMS, CF(x), First principle calculations, XPS, TEM
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-72809 (URN)10.1016/j.surfcoat.2011.06.055 (DOI)000297086700011 ()
    Note

    Funding Agencies|Hungarian Academy of Sciences||

    Available from: 2011-12-09 Created: 2011-12-08 Last updated: 2017-12-08
    2. CF(x): A first-principles study of structural patterns arising during synthetic growth
    Open this publication in new window or tab >>CF(x): A first-principles study of structural patterns arising during synthetic growth
    2011 (English)In: Chemical Physics Letters, ISSN 0009-2614, E-ISSN 1873-4448, Vol. 516, no 1-3, p. 62-67Article in journal (Refereed) Published
    Abstract [en]

    Structural and bonding patterns arising from the incorporation of fluorine atoms in a graphene-like network relevant to the deposition of carbon fluoride (CF(x)) films were addressed by first-principles calculations. We find that large N-member (N = 8-12) rings, defects by sheet branching, and defects associated with bond rotation pertain to CF(x). The cohesive energy gains associated with these patterns are similar to 0.2-0.4 eV/at., which is similar to those for a wide range of defects in other C-based nanostructured solids. Fullerene-like CF(x) is predicted for F concentrations below similar to 10 at.%, while CF(x) compounds with higher F content are predominantly amorphous or polymeric.

    Place, publisher, year, edition, pages
    Elsevier, 2011
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-72251 (URN)10.1016/j.cplett.2011.09.045 (DOI)000296582400011 ()
    Note

    Funding Agencies|Swedish Governmental Agency for Innovation Systems (VINNOVA)||European Research Council (ERC)||

    Available from: 2011-11-24 Created: 2011-11-24 Last updated: 2017-12-08
    3. Ion mass spectroscopy investigations during high power pulsed 1 magnetron sputtering and DCMS of Carbon in an Ar and Ar/N2 discharge
    Open this publication in new window or tab >>Ion mass spectroscopy investigations during high power pulsed 1 magnetron sputtering and DCMS of Carbon in an Ar and Ar/N2 discharge
    (English)Manuscript (preprint) (Other academic)
    Abstract [en]

    The composition of carbon discharges were investigated during reactive high power impulse magnetron sputtering (HiPIMS) and direct current magnetron sputtering (DCMS) using mass spectroscopy measurements in an industrial deposition system. During the sputter process 16 the ion flux was analyzed with regards to composition and energy. The ion energy distribution was measured in time-averaged and time-resolved mode for Ar+, C+, N2+, N+, and CxNy+ ions. While the N2-to-Ar flow ratio (ƒN2 / Ar) was varied, a constant deposition pressure and comparable energy per pulses were kept.

    The results show that an increase of the N2-to-Ar flow ratio (keeping the pulse width, pulse frequency and pulse energies constant) an significant increase in C+, N+- and CN+-energy, while other ion flux energies did not considerably vary with the changes in working gas chemistry. A comparison with DCMS measurements showed the expected increase in ion energies as well as a significant increase of C+ ions in the HiPIMS plasma. The time evolution of the plasma species was analyzed in detail and showed the sequential arrival of working gas ions, ions ejected from the target and later during the pulse on time molecular ions such as CN+ as well as C2N+. Mass spectroscopic results in combination with the evaluation 1 of target current and target voltage waveforms as well as TEM (transmission electron microscopy) images and SAED (selected area electron diffraction patterns) for films deposited in DCMS and HiPIMS mode help to explain the formation of fullerene-like structured CNx thin films.

    Keywords
    HiPIMS, CNx, mass spectroscopy, carbon, sputtering, high power impulse magnetron 8 sputtering, HPPMS, high power pulse magnetron sputtering
    National Category
    Natural Sciences
    Identifiers
    urn:nbn:se:liu:diva-74746 (URN)
    Available from: 2012-02-07 Created: 2012-02-07 Last updated: 2016-08-31Bibliographically approved
  • 17.
    Schmidt, Susann
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Carbon Nitride and Carbon Fluoride Thin Films Prepared by HiPIMS2013Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The present thesis focuses on carbon based thin films prepared by high power impulse magnetron sputtering (HiPIMS) and direct current magnetron sputtering (DCMS). Carbon nitride (CNx: 0 < x < 0.20) as well as carbon fluoride (CFx: 0.16 < x < 0.35) thin films were synthesized in an industrial deposition chamber by reactive magnetron sputtering of graphite in Ne/N2, Ar/N2, Kr/N2, Ar/CF4, and Ar/C4F8 ambients. In order to increase the understanding of the deposition processes of C in the corresponding reactive gas mixture plasmas, ion mass spectroscopy was carried out. A detailed evaluation of target current and target voltage waveforms was performed when graphite was sputtered in HiPIMS mode. First principle calculations targeting the growth of CFx thin films revealed most probable film forming species as well as CFx film structure defining defects. In order to set different process parameters into relation with thin film properties, the synthesized carbon based thin films were characterized with regards to their chemical composition, chemical bonding, and microstructure. A further aspect was the thin film characterization for possible applications. For this, mainly nanoindentation and contact angle measurements were performed. Theoretical calculations and the results from the characterization of the deposition processes were successfully related to the thin film properties.

    The reactive graphite/N2/inert gas HiPIMS discharge yielded high ion energies as well as elevated C+ and N+ abundances. Under such conditions, amorphous CNx thin films with hardnesses of up to 40 GPa were deposited. Elastic, fullerene like CNx thin films, on the other hand, were deposited at increased substrate temperatures in HiPIMS discharges exhibiting moderate ion energies. Here, a pulse assisted chemical sputtering at the target and the substrate was found to support the formation of a fullerene-like microstructure.

    CFx thin films were found to have surface energies equivalent to super-hydrophobic materials for x > 0.26 while such films were polymeric in nature accounting for hardnesses below 1 GPa. Whereas, an amorphous structure for carbon-based films with fluorine contents ranging between 16 % and 23 % was observed. For those films, the hardness increased with decreasing fluorine content and ranged between 16 GPa and 4 GPa. The HiPIMS process in fluorinecontaining atmosphere was found to be a powerful tool in order to change the surface properties of carbon based thin films.

    List of papers
    1. CF(x) thin solid films deposited by high power impulse magnetron sputtering: Synthesis and characterization
    Open this publication in new window or tab >>CF(x) thin solid films deposited by high power impulse magnetron sputtering: Synthesis and characterization
    Show others...
    2011 (English)In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 206, no 4, p. 646-653Article in journal (Refereed) Published
    Abstract [en]

    Fluorine containing amorphous carbon films (CF(x), 0.16 andlt;= x andlt;= 0.35) have been synthesized by reactive high power impulse magnetron sputtering (HiPIMS) in an Ar/CF(4) atmosphere. The fluorine content of the films was controlled by varying the CF(4) partial pressure from 0 mPa to 110 mPa at a constant deposition pressure of 400 mPa and a substrate temperature of 110 degrees C. The films were characterized regarding their composition, chemical bonding and microstructure as well as mechanical properties by applying elastic recoil detection analysis, X-ray photoelectron spectroscopy, Raman spectroscopy, transmission electron microscopy, and nanoindentation. First-principles calculations were carried out to predict and explain F-containing carbon thin film synthesis and properties. By geometry optimizations and cohesive energy calculations the relative stability of precursor species including C(2), F(2) and radicals, resulting from dissociation of CF4, were established. Furthermore, structural defects, arising from the incorporation of F atoms in a graphene-like network, were evaluated. All as-deposited CF(x) films are amorphous. Results from X-ray photoelectron spectroscopy and Raman spectroscopy indicate a graphitic nature of CF(x) films with x andlt;= 0.23 and a polymeric structure for films with x andgt;= 0.26. Nanoindentation reveals hardnesses between similar to 1 GPa and similar to 16 GPa and an elastic recovery of up to 98%.

    Place, publisher, year, edition, pages
    Elsevier, 2011
    Keywords
    Fluorine containing carbon thin films, HiPIMS, CF(x), First principle calculations, XPS, TEM
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-72809 (URN)10.1016/j.surfcoat.2011.06.055 (DOI)000297086700011 ()
    Note

    Funding Agencies|Hungarian Academy of Sciences||

    Available from: 2011-12-09 Created: 2011-12-08 Last updated: 2017-12-08
    2. CF(x): A first-principles study of structural patterns arising during synthetic growth
    Open this publication in new window or tab >>CF(x): A first-principles study of structural patterns arising during synthetic growth
    2011 (English)In: Chemical Physics Letters, ISSN 0009-2614, E-ISSN 1873-4448, Vol. 516, no 1-3, p. 62-67Article in journal (Refereed) Published
    Abstract [en]

    Structural and bonding patterns arising from the incorporation of fluorine atoms in a graphene-like network relevant to the deposition of carbon fluoride (CF(x)) films were addressed by first-principles calculations. We find that large N-member (N = 8-12) rings, defects by sheet branching, and defects associated with bond rotation pertain to CF(x). The cohesive energy gains associated with these patterns are similar to 0.2-0.4 eV/at., which is similar to those for a wide range of defects in other C-based nanostructured solids. Fullerene-like CF(x) is predicted for F concentrations below similar to 10 at.%, while CF(x) compounds with higher F content are predominantly amorphous or polymeric.

    Place, publisher, year, edition, pages
    Elsevier, 2011
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-72251 (URN)10.1016/j.cplett.2011.09.045 (DOI)000296582400011 ()
    Note

    Funding Agencies|Swedish Governmental Agency for Innovation Systems (VINNOVA)||European Research Council (ERC)||

    Available from: 2011-11-24 Created: 2011-11-24 Last updated: 2017-12-08
    3. Reactive High Power Impulse Magnetron Sputtering of CFx Thin Films in Mixed Ar/CF4 and Ar/C4F8 Discharges
    Open this publication in new window or tab >>Reactive High Power Impulse Magnetron Sputtering of CFx Thin Films in Mixed Ar/CF4 and Ar/C4F8 Discharges
    Show others...
    (English)Manuscript (preprint) (Other academic)
    Abstract [en]

    The reactive high power impulse magnetron sputtering (HiPIMS) processes of C in Ar/tetrafluoromethane CF4 and Ar/octafluorocyclobutane (c-C4F8) have been characterized. Amorphous carbon fluoride (CFx) films were synthesized at deposition pressure and substrate temperature of 400 mPa and 110 oC, respectively. The CFx film composition was controlled in the range of 0.15 < x < 0.35 by varying the partial pressure of the F-containing gases from 0 mPa to 110 mPa. The reactive plasma was studied employing time averaged positive ion mass spectrometry and the resulting thin films were characterized regarding their composition, chemical bonding and microstructure as well as mechanical properties by elastic recoil detection analysis, X-ray photoelectron spectroscopy, transmission electron microscopy, nanoindentation, and water droplet contact angle measurements, respectively. The experimental results were compared to results obtained by first-principles calculations based on density functional theory.

    The modeling of the most abundant precursor fragment from the dissociation of CF4 and C4F8 provided their relative stability, abundance, and reactivity, thus permitting to evaluate the role of each precursor during film growth. Positive ion mass spectrometry of both F plasmas show an abundance of CF+, C+, CF⁺₂, and CF⁺₃ (in this order) as corroborated by first-principles calculations. Only CF⁺₃ exceeded the Ar+ signal in a CF4 plasma. Two deposition regimes are found depending on the partial pressure of the F-containing reactive gas, where films with fluorine contents below 24 at% exhibit a graphitic nature, whereas a polymeric structure applies to films with fluorine contents exceeding 27 at%. Moreover, abundant precursors in the plasma are correlated to the mechanical response of the different CFx thin films. The decreasing hardness with increasing F content can be attributed to the abundance of CF⁺₃ precursor species, weakening the C matrix.

    Keywords
    c-C4F8, CF4, fluorine containing carbon thin films, HiPIMS, CFx, first principle calculations, XPS, TEM, positive ion mass spectrometry
    National Category
    Natural Sciences
    Identifiers
    urn:nbn:se:liu:diva-90908 (URN)
    Available from: 2013-04-08 Created: 2013-04-08 Last updated: 2017-05-05Bibliographically approved
    4. Ion mass spectrometry investigations of the discharge during reactive high power pulsed and direct current magnetron sputtering of carbon in Ar and Ar/N-2
    Open this publication in new window or tab >>Ion mass spectrometry investigations of the discharge during reactive high power pulsed and direct current magnetron sputtering of carbon in Ar and Ar/N-2
    Show others...
    2012 (English)In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 112, no 1, p. 013305-Article in journal (Refereed) Published
    Abstract [en]

    Ion mass spectrometry was used to investigate discharges formed during high power impulse magnetron sputtering (HiPIMS) and direct current magnetron sputtering (DCMS) of a graphite target in Ar and Ar/N-2 ambient. Ion energy distribution functions (IEDFs) were recorded in time-averaged and time-resolved mode for Ar+, C+, N-2(+), N+, and CxNy+ ions. An increase of N-2 in the sputter gas (keeping the deposition pressure, pulse width, pulse frequency, and pulse energy constant) results for the HiPIMS discharge in a significant increase in C+, N+, and CN+ ion energies. Ar+, N-2(+), and C2N+ ion energies, in turn, did not considerably vary with the changes in working gas composition. The HiPIMS process showed higher ion energies and fluxes, particularly for C+ ions, compared to DCMS. The time evolution of the plasma species was analyzed for HiPIMS and revealed the sequential arrival of working gas ions, ions ejected from the target, and later during the pulse-on time molecular ions, in particular CN+ and C2N+. The formation of fullerene-like structured CNx thin films for both modes of magnetron sputtering is explained by ion mass-spectrometry results and demonstrated by transmission electron microscopy as well as diffraction.

    Place, publisher, year, edition, pages
    American Institute of Physics (AIP), 2012
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-80790 (URN)10.1063/1.4733692 (DOI)000306513400018 ()
    Note

    Funding Agencies|Hungarian Academy of Sciences||

    Available from: 2012-08-30 Created: 2012-08-30 Last updated: 2017-12-07
    5. Influence of inert gases on the reactive high power pulsed magnetron sputtering process of carbon-nitride thin films
    Open this publication in new window or tab >>Influence of inert gases on the reactive high power pulsed magnetron sputtering process of carbon-nitride thin films
    Show others...
    2013 (English)In: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films, ISSN 0734-2101, E-ISSN 1520-8559, Vol. 31, no 1, p. 011503-Article in journal (Refereed) Published
    Abstract [en]

    The influence of inert gases (Ne, Ar, Kr) on the sputter process of carbon and carbon-nitride (CNx) thin films was studied using reactive high power pulsed magnetron sputtering (HiPIMS). Thin solid films were synthesized in an industrial deposition chamber from a graphite target. The peak target current during HiPIMS processing was found to decrease with increasing inert gas mass. Time averaged and time resolved ion mass spectroscopy showed that the addition of nitrogen, as reactive gas, resulted in less energetic ion species for processes employing Ne, whereas the opposite was noticed when Ar or Kr were employed as inert gas. Processes in nonreactive ambient showed generally lower total ion fluxes for the three different inert gases. As soon as N-2 was introduced into the process, the deposition rates for Ne and Ar-containing processes increased significantly. The reactive Kr-process, in contrast, showed slightly lower deposition rates than the nonreactive. The resulting thin films were characterized regarding their bonding and microstructure by x-ray photoelectron spectroscopy and transmission electron microscopy. Reactively deposited CNx thin films in Ar and Kr ambient exhibited an ordering toward a fullerene-like structure, whereas carbon and CNx films deposited in Ne atmosphere were found to be amorphous. This is attributed to an elevated amount of highly energetic particles observed during ion mass spectrometry and indicated by high peak target currents in Ne-containing processes. These results are discussed with respect to the current understanding of the structural evolution of a-C and CNx thin films.

    Place, publisher, year, edition, pages
    American Vacuum Society, 2013
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-89755 (URN)10.1116/1.4769725 (DOI)000313931300007 ()
    Note

    Funding Agencies|ERC||Hungarian Academy of Sciences||

    Available from: 2013-03-05 Created: 2013-03-05 Last updated: 2017-12-06
    6. The Influence of Inert Gases on the a-C and CNx Thin Film Deposition: A Comparison between DCMS and HiPIMS Processes
    Open this publication in new window or tab >>The Influence of Inert Gases on the a-C and CNx Thin Film Deposition: A Comparison between DCMS and HiPIMS Processes
    Show others...
    (English)Manuscript (preprint) (Other academic)
    Abstract [en]

    DCMS and HiPIMS discharges of C in Ne, Ar, and Kr as well as their reactive counterparts (N2/Ne, N2/Ar, and N2/Kr) were investigated for the growth of carbon and carbon-nitride (CNx) thin films. The thin films were synthesized in an industrial deposition chamber from a pure graphite target. Time averaged plasma mass spectroscopy showed that the energies of the most abundant plasma cations depend on the inert gas and the amount of N2 in the sputter gas rather than the sputter modes. The ion species population in the plasma, on the other hand, was found to depend heavily on the sputter mode; HiPIMS processes yield approximately ten times higher flux ratios of ions originating from the target to ions originating from the process gas. Exceptional cases are the discharges in Ne or N2/Ne mixtures containing up to 20% N2. Here, no influence of the sputter mode on cation energies and population was found. CNx and a-C thin films deposited in 14% N2/inert gas mixture and pure inert gas, respectively, were characterized regarding the chemical composition, chemical bonding and microstructure as well as their mechanical properties using elastic recoil detection analysis, X-ray photoelectron spectroscopy, transmission electron microscopy in combination with selected area electron diffraction, and nanoindentation, respectively. The thin film characteristics showed strong correlations to the energies of abundant plasma cations (namely C+, Ar+, Ar++, Ne+,22Ne+, Ne++, 82Kr+, 84Kr+, 86Kr+, Kr++, N+, N2+, CN+ as well as C2N2+)and cation population of the corresponding deposition process. High amounts of C bond in sp3 hybridization state were found for thin films sputtered in Ne, accounting for their elevated hardness and amorphous microstructure. With increasing inert gas atomic number the a-C and CNx thin films show an increasingly distinct near range ordered microstructural evolution. This effect is more pronounced for HiPIMS processes and accompanied by a lowered hardness, but elevated elastic properties.

    National Category
    Natural Sciences
    Identifiers
    urn:nbn:se:liu:diva-90910 (URN)
    Available from: 2013-04-08 Created: 2013-04-08 Last updated: 2016-08-31Bibliographically approved
  • 18.
    Schmidt, Susann
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Czigany, Zs
    Hungarian Academic Science, Hungary .
    Greczynski, Grzegorz
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Jensen, Jens
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Ion mass spectrometry investigations of the discharge during reactive high power pulsed and direct current magnetron sputtering of carbon in Ar and Ar/N-22012In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 112, no 1, p. 013305-Article in journal (Refereed)
    Abstract [en]

    Ion mass spectrometry was used to investigate discharges formed during high power impulse magnetron sputtering (HiPIMS) and direct current magnetron sputtering (DCMS) of a graphite target in Ar and Ar/N-2 ambient. Ion energy distribution functions (IEDFs) were recorded in time-averaged and time-resolved mode for Ar+, C+, N-2(+), N+, and CxNy+ ions. An increase of N-2 in the sputter gas (keeping the deposition pressure, pulse width, pulse frequency, and pulse energy constant) results for the HiPIMS discharge in a significant increase in C+, N+, and CN+ ion energies. Ar+, N-2(+), and C2N+ ion energies, in turn, did not considerably vary with the changes in working gas composition. The HiPIMS process showed higher ion energies and fluxes, particularly for C+ ions, compared to DCMS. The time evolution of the plasma species was analyzed for HiPIMS and revealed the sequential arrival of working gas ions, ions ejected from the target, and later during the pulse-on time molecular ions, in particular CN+ and C2N+. The formation of fullerene-like structured CNx thin films for both modes of magnetron sputtering is explained by ion mass-spectrometry results and demonstrated by transmission electron microscopy as well as diffraction.

  • 19.
    Schmidt, Susann
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Czigany, Zsolt
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Greczynski, Grzegorz
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Jensen, Jens
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Influence of inert gases on the reactive high power pulsed magnetron sputtering process of carbon-nitride thin films2013In: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films, ISSN 0734-2101, E-ISSN 1520-8559, Vol. 31, no 1, p. 011503-Article in journal (Refereed)
    Abstract [en]

    The influence of inert gases (Ne, Ar, Kr) on the sputter process of carbon and carbon-nitride (CNx) thin films was studied using reactive high power pulsed magnetron sputtering (HiPIMS). Thin solid films were synthesized in an industrial deposition chamber from a graphite target. The peak target current during HiPIMS processing was found to decrease with increasing inert gas mass. Time averaged and time resolved ion mass spectroscopy showed that the addition of nitrogen, as reactive gas, resulted in less energetic ion species for processes employing Ne, whereas the opposite was noticed when Ar or Kr were employed as inert gas. Processes in nonreactive ambient showed generally lower total ion fluxes for the three different inert gases. As soon as N-2 was introduced into the process, the deposition rates for Ne and Ar-containing processes increased significantly. The reactive Kr-process, in contrast, showed slightly lower deposition rates than the nonreactive. The resulting thin films were characterized regarding their bonding and microstructure by x-ray photoelectron spectroscopy and transmission electron microscopy. Reactively deposited CNx thin films in Ar and Kr ambient exhibited an ordering toward a fullerene-like structure, whereas carbon and CNx films deposited in Ne atmosphere were found to be amorphous. This is attributed to an elevated amount of highly energetic particles observed during ion mass spectrometry and indicated by high peak target currents in Ne-containing processes. These results are discussed with respect to the current understanding of the structural evolution of a-C and CNx thin films.

  • 20.
    Schmidt, Susann
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Czigany, Zsolt
    Hungarian Academic Science, Hungary.
    Wissting, Jonas
    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.
    Janzén, Erik
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. 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.
    Ivanov, Ivan Gueorguiev
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    A comparative study of direct current magnetron sputtering and high power impulse magnetron sputtering processes for CNX thin film growth with different inert gases2016In: Diamond and related materials, ISSN 0925-9635, E-ISSN 1879-0062, Vol. 64, p. 13-26Article in journal (Refereed)
    Abstract [en]

    Reactive direct current magnetron sputtering (DCMS) and high power impulse magnetron sputtering (HiPIMS) discharges of carbon in different inert gas mixtures (N-2/Ne, N-2/Ar, and N-2/Kr) were investigated for the growth of carbon-nitride (CNX) thin films. Ion mass spectrometry showed that energies of abundant plasma cations are governed by the inert gas and the N-2-to-inert gas flow ratios. The population of ion species depends on the sputter mode; HiPIMS yields approximately ten times higher flux ratios of ions originating from the target to process gas ions than DCMS. Exceptional are discharges in Ne with N-2-to-Ne flow ratios &lt;20%. Here, cation energies and the amount of target ions are highest without influence on the sputter mode. CNX thin films were deposited in 14% N-2/inert gas mixtures at substrate temperatures of 110 degrees C and 430 degrees C. The film properties show a correlation to the substrate temperature, the applied inert gas and sputter mode. The mechanical performance of the films is mainly governed by their morphology and composition, but not by their microstructure. Amorphous and fullerene-like CN0.14 films exhibiting a hardness of similar to 15 GPa and an elastic recovery of similar to 90% were deposited at 110 degrees C in reactive Kr atmosphere by DCMS and HiPIMS.

  • 21.
    Schmidt, Susann
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Czigány, Zs.
    Research Institute for Technical Physics and Materials Science, Hungarian Academy of 8 Sciences, P.O. Box 49, H-1525 Budapest, Hungary.
    Greczynski, G.
    Research Institute for Technical Physics and Materials Science, Hungarian Academy of 8 Sciences, P.O. Box 49, H-1525 Budapest, Hungary.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Ion mass spectroscopy investigations during high power pulsed 1 magnetron sputtering and DCMS of Carbon in an Ar and Ar/N2 dischargeManuscript (preprint) (Other academic)
    Abstract [en]

    The composition of carbon discharges were investigated during reactive high power impulse magnetron sputtering (HiPIMS) and direct current magnetron sputtering (DCMS) using mass spectroscopy measurements in an industrial deposition system. During the sputter process 16 the ion flux was analyzed with regards to composition and energy. The ion energy distribution was measured in time-averaged and time-resolved mode for Ar+, C+, N2+, N+, and CxNy+ ions. While the N2-to-Ar flow ratio (ƒN2 / Ar) was varied, a constant deposition pressure and comparable energy per pulses were kept.

    The results show that an increase of the N2-to-Ar flow ratio (keeping the pulse width, pulse frequency and pulse energies constant) an significant increase in C+, N+- and CN+-energy, while other ion flux energies did not considerably vary with the changes in working gas chemistry. A comparison with DCMS measurements showed the expected increase in ion energies as well as a significant increase of C+ ions in the HiPIMS plasma. The time evolution of the plasma species was analyzed in detail and showed the sequential arrival of working gas ions, ions ejected from the target and later during the pulse on time molecular ions such as CN+ as well as C2N+. Mass spectroscopic results in combination with the evaluation 1 of target current and target voltage waveforms as well as TEM (transmission electron microscopy) images and SAED (selected area electron diffraction patterns) for films deposited in DCMS and HiPIMS mode help to explain the formation of fullerene-like structured CNx thin films.

  • 22.
    Schmidt, Susann
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Czigány, Zs
    Research Institute for Technical Physics and Materials Science, Hungarian Academy of Sciences, Budapest, Hungary.
    Greczynski, Grzegorz
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics.
    Jensen, Jens
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    The Influence of Inert Gases on the a-C and CNx Thin Film Deposition: A Comparison between DCMS and HiPIMS ProcessesManuscript (preprint) (Other academic)
    Abstract [en]

    DCMS and HiPIMS discharges of C in Ne, Ar, and Kr as well as their reactive counterparts (N2/Ne, N2/Ar, and N2/Kr) were investigated for the growth of carbon and carbon-nitride (CNx) thin films. The thin films were synthesized in an industrial deposition chamber from a pure graphite target. Time averaged plasma mass spectroscopy showed that the energies of the most abundant plasma cations depend on the inert gas and the amount of N2 in the sputter gas rather than the sputter modes. The ion species population in the plasma, on the other hand, was found to depend heavily on the sputter mode; HiPIMS processes yield approximately ten times higher flux ratios of ions originating from the target to ions originating from the process gas. Exceptional cases are the discharges in Ne or N2/Ne mixtures containing up to 20% N2. Here, no influence of the sputter mode on cation energies and population was found. CNx and a-C thin films deposited in 14% N2/inert gas mixture and pure inert gas, respectively, were characterized regarding the chemical composition, chemical bonding and microstructure as well as their mechanical properties using elastic recoil detection analysis, X-ray photoelectron spectroscopy, transmission electron microscopy in combination with selected area electron diffraction, and nanoindentation, respectively. The thin film characteristics showed strong correlations to the energies of abundant plasma cations (namely C+, Ar+, Ar++, Ne+,22Ne+, Ne++, 82Kr+, 84Kr+, 86Kr+, Kr++, N+, N2+, CN+ as well as C2N2+)and cation population of the corresponding deposition process. High amounts of C bond in sp3 hybridization state were found for thin films sputtered in Ne, accounting for their elevated hardness and amorphous microstructure. With increasing inert gas atomic number the a-C and CNx thin films show an increasingly distinct near range ordered microstructural evolution. This effect is more pronounced for HiPIMS processes and accompanied by a lowered hardness, but elevated elastic properties.

  • 23.
    Schmidt, Susann
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Goyenola, Cecilia
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Gueorguiev, Gueorgui Kostov
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Jensen, Jens
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Greczynski, Grzegorz
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Gueorguiev Ivanov, Ivan
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Czigany, Zs
    Hungarian Academic Science, Hungary .
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Reactive high power impulse magnetron sputtering of CFx thin films in mixed Ar/C4F4 and Ar/C4F8 discharges2013In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 542, p. 21-30Article in journal (Refereed)
    Abstract [en]

    The reactive high power impulse magnetron sputtering processes of carbon in argon/tetrafluoromethane (CF4) and argon/octafluorocyclobutane (c-C4F8) have been characterized. Amorphous carbon fluoride (CFx) films were synthesized at deposition pressure and substrate temperature of 400 mPa and 110 degrees C, respectively. The CFx film composition was controlled in the range of 0.15 andlt; x andlt; 0.35 by varying the partial pressure of the F-containing gases from 0 mPa to 110 mPa. The reactive plasma was studied employing time averaged positive ion mass spectrometry and the resulting thin films were characterized regarding their composition, chemical bonding and microstructure as well as mechanical properties by elastic recoil detection analysis, X-ray photoelectron spectroscopy, transmission electron microscopy, nanoindentation, and water droplet contact angle measurements, respectively. The experimental results were compared to results obtained by first-principles calculations based on density functional theory. The modeling of the most abundant precursor fragment from the dissociation of CF4 and C4F8 provided their relative stability, abundance, and reactivity, thus permitting to evaluate the role of each precursor during film growth. Positive ion mass spectrometry of both fluorine plasmas shows an abundance of CF+, C+, CF2+, and CF3+ (in this order) as corroborated by first-principles calculations. Only CF3+ exceeded the Ar+ signal in a CF4 plasma. Two deposition regimes are found depending on the partial pressure of the fluorine-containing reactive gas, where films with fluorine contents below 24 at.% exhibit a graphitic nature, whereas a polymeric structure applies to films with fluorine contents exceeding 27 at.%. Moreover, abundant precursors in the plasma are correlated to the mechanical response of the different CFx thin films. The decreasing hardness with increasing fluorine content can be attributed to the abundance of CF3+ precursor species, weakening the carbon matrix.

  • 24.
    Schmidt, Susann
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Goyenola, Cecilia
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Gueorguiev, Gueorgui Kostov
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Jensen, Jens
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Greczynski, Grzegorz
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics.
    Ivanov, Ivan Gueorguiev
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Czigány, Zs
    Research Institute for Technical Physics and Materials Science, Hungarian Academy of Sciences, Budapest, Hungary.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Reactive High Power Impulse Magnetron Sputtering of CFx Thin Films in Mixed Ar/CF4 and Ar/C4F8 DischargesManuscript (preprint) (Other academic)
    Abstract [en]

    The reactive high power impulse magnetron sputtering (HiPIMS) processes of C in Ar/tetrafluoromethane CF4 and Ar/octafluorocyclobutane (c-C4F8) have been characterized. Amorphous carbon fluoride (CFx) films were synthesized at deposition pressure and substrate temperature of 400 mPa and 110 oC, respectively. The CFx film composition was controlled in the range of 0.15 < x < 0.35 by varying the partial pressure of the F-containing gases from 0 mPa to 110 mPa. The reactive plasma was studied employing time averaged positive ion mass spectrometry and the resulting thin films were characterized regarding their composition, chemical bonding and microstructure as well as mechanical properties by elastic recoil detection analysis, X-ray photoelectron spectroscopy, transmission electron microscopy, nanoindentation, and water droplet contact angle measurements, respectively. The experimental results were compared to results obtained by first-principles calculations based on density functional theory.

    The modeling of the most abundant precursor fragment from the dissociation of CF4 and C4F8 provided their relative stability, abundance, and reactivity, thus permitting to evaluate the role of each precursor during film growth. Positive ion mass spectrometry of both F plasmas show an abundance of CF+, C+, CF⁺₂, and CF⁺₃ (in this order) as corroborated by first-principles calculations. Only CF⁺₃ exceeded the Ar+ signal in a CF4 plasma. Two deposition regimes are found depending on the partial pressure of the F-containing reactive gas, where films with fluorine contents below 24 at% exhibit a graphitic nature, whereas a polymeric structure applies to films with fluorine contents exceeding 27 at%. Moreover, abundant precursors in the plasma are correlated to the mechanical response of the different CFx thin films. The decreasing hardness with increasing F content can be attributed to the abundance of CF⁺₃ precursor species, weakening the C matrix.

  • 25.
    Schmidt, Susann
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Greczynski, Grzegorz
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Goyenola, Cecilia
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Kostov Gueorguiev, Gueorgui
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Czigany, Zs
    Hungarian Academic Science.
    Jensen, Jens
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Gueorguiev Ivanov, Ivan
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    CF(x) thin solid films deposited by high power impulse magnetron sputtering: Synthesis and characterization2011In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 206, no 4, p. 646-653Article in journal (Refereed)
    Abstract [en]

    Fluorine containing amorphous carbon films (CF(x), 0.16 andlt;= x andlt;= 0.35) have been synthesized by reactive high power impulse magnetron sputtering (HiPIMS) in an Ar/CF(4) atmosphere. The fluorine content of the films was controlled by varying the CF(4) partial pressure from 0 mPa to 110 mPa at a constant deposition pressure of 400 mPa and a substrate temperature of 110 degrees C. The films were characterized regarding their composition, chemical bonding and microstructure as well as mechanical properties by applying elastic recoil detection analysis, X-ray photoelectron spectroscopy, Raman spectroscopy, transmission electron microscopy, and nanoindentation. First-principles calculations were carried out to predict and explain F-containing carbon thin film synthesis and properties. By geometry optimizations and cohesive energy calculations the relative stability of precursor species including C(2), F(2) and radicals, resulting from dissociation of CF4, were established. Furthermore, structural defects, arising from the incorporation of F atoms in a graphene-like network, were evaluated. All as-deposited CF(x) films are amorphous. Results from X-ray photoelectron spectroscopy and Raman spectroscopy indicate a graphitic nature of CF(x) films with x andlt;= 0.23 and a polymeric structure for films with x andgt;= 0.26. Nanoindentation reveals hardnesses between similar to 1 GPa and similar to 16 GPa and an elastic recovery of up to 98%.

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