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  • 101.
    Helmersson, Ulf
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics .
    Ionized-PVD with HIPIMS - Industrial Potentials and Scientific Challenges2008In: 35th International Conference on Metallurgical Coatings and Thin Films,2008, 2008Conference paper (Other academic)
  • 102.
    Helmersson, Ulf
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics .
    Reactive HiPIMS Deposition of TiN and AI2O32008In: HIPIMS Days,2008, 2008Conference paper (Other academic)
  • 103.
    Helmersson, Ulf
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics .
    The use of high power impulse magnetron sputtering for improved thin film depositions2007In: International Colloquium on Plasma Processes,2007, 2007Conference paper (Other academic)
  • 104.
    Helmersson, Ulf
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics .
    The use of high power impulse magnetron sputtering for improved thin films and thin film processes2007In: International Workshop on Plasma-Based Ion Implantation Deposition,2007, 2007Conference paper (Other academic)
  • 105.
    Helmersson, Ulf
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics .
    Ahlberg, Martina
    IFM Linköping university.
    Lattemann, Martina
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics .
    The effect on film microstructure from the use of energetic deposition by HIPIMS2007In: SVC Annual Technical Conference,2007, 2007Conference paper (Other academic)
  • 106.
    Helmersson, Ulf
    et al.
    Linköping University, Department of Physics, Chemistry and Biology.
    Brenning, Nils
    Royal Institute of Technology, Stockholm .
    Söderström, Daniel
    Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics.
    Plasma sputtering process for producing particles2011Patent (Other (popular science, discussion, etc.))
  • 107.
    Helmersson, Ulf
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics .
    Lattemann, Martina
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics .
    Alami, Jones
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics .
    Böhlmark, Johan
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics .
    Ehiasarian, A.P.
    Sheffield Hallam University.
    Gudmundsson, J.T.
    University of Iceland.
    High Power Impulse Magnetron Sputtering Discharges and Thin Film Growth: A Brief Review2005In: 48th Annual Technical Conference of the Society of Vacuum Coaters,2005, 2005, p. 458-464Conference paper (Other academic)
  • 108.
    Helmersson, Ulf
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics .
    Lattemann, Martina
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics .
    Alami, Jones
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics .
    Böhlmark, Johan
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics .
    Ehiasarian, A.P.
    Sheffield Hallam University.
    Gudmundsson, J.T.
    University of Iceland.
    Highly Ionized Sputter Discharges for Thin Film Fabrication2006In: Bulletin of the Russian Academy of Sciences. Physics, ISSN 1062-8738, Vol. 70, no 8, p. 1421-1424Article in journal (Refereed)
  • 109.
    Helmersson, Ulf
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics. Linköping University, The Institute of Technology.
    Lattemann, Martina
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Böhlmark, Johan
    Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics. Linköping University, The Institute of Technology.
    Ehiasarian, Arutiun P.
    Materials and Engineering Research Institute, Sheffield Hallam University, Sheffield, UK.
    Gudmundsson, Jon Tomas
    Department of Electrical and Computer Engineering, University of Iceland, Reykjavik, Iceland and Science Institute, University of Iceland, Reykjavik, Iceland.
    Ionized physical vapor deposition (IPVD): A review of technology and applications2006In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 513, no 1-2, p. 1-24Article in journal (Refereed)
    Abstract [en]

    In plasma-based deposition processing, the importance of low-energy ion bombardment during thin film growth can hardly be exaggerated. Ion bombardment is an important physical tool available to materials scientists in the design of new materials and new structures. Glow discharges and in particular the magnetron sputtering discharge have the advantage that the ions of the discharge are abundantly available to the deposition process. However, the ion chemistry is usually dominated by the ions of the inert sputtering gas while ions of the sputtered material are rare. Over the past few years, various ionized sputtering techniques have appeared that can achieve a high degree of ionization of the sputtered atoms, often up to 50 % but in some cases as much as approximately 90%. This opens a complete new perspective in the engineering and design of new thin film materials. The development and application of magnetron sputtering systems for ionized physical vapor deposition (IPVD) is reviewed. The application of a secondary discharge, inductively coupled plasma magnetron sputtering (ICP-MS) and microwave amplified magnetron sputtering, is discussed as well as the high power impulse magnetron sputtering (HIPIMS), the self-sustained sputtering (SSS) magnetron, and the hollow cathode magnetron (HCM) sputtering discharges. Furthermore, filtered arc-deposition is discussed due to its importance as an IPVD technique. Examples of the importance of the IPVD-techniques for growth of thin films with improved adhesion, improved microstructures, improved coverage of complex shaped substrates, and increased reactivity with higher deposition rate in reactive processes are reviewed.

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  • 110.
    Helmersson, Ulf
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics. Linköping University, The Institute of Technology.
    Söderström, Daniel
    Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics. Linköping University, The Institute of Technology.
    Pilch, I.
    Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics. Linköping University, The Institute of Technology.
    Pillay, Sankara
    Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics. Linköping University, The Institute of Technology.
    Brenning, N.
    Royal Institute of Technology, School of Electrical Engineering, Division Space and Plasma Physics, Sweden.
    A novel pulsed high-density plasma process for nanoparticle synthesis2012In: Technical Proceedings of the 2012 NSTI Nanotechnology Conference and Expo, NSTI-Nanotech 2012:  , 2012, p. 368-370Conference paper (Refereed)
    Abstract [en]

    This work presents a new technique to produce nanoparticles in a controlled manor using highly ionized plasmas that will ionize the source material [1]. The advantage of ionizing the source material is that it will increase the trapping onto negatively charged nanoparticles (NPs) that should result in a significant increase in productivity. In this work we have performed both simulations and experiments. The experiments were performed using high power impulses to generate high plasma densities. The dense plasma yields a high degree of ionization of the sputtered metal species. Solid metal cylinders of Cu, Ag, Ti and Mo were used as hollow cathodes for the synthesis of NPs. By tuning the process parameters, pulsing energy, pulsing frequency, etc., the particle size can range from of 5 nm to 700 nm in diameter.

  • 111.
    Helmersson, Ulf
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics .
    Wallin, Erik
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics .
    Lattemann, Martina
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics .
    Hysteresis-free reactive deposi-tion of alpha-Al2O3 using high HIPIMS2007In: HIPIMS ABS-Days Conference,2007, 2007Conference paper (Other academic)
  • 112.
    Helmersson, Ulf
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics .
    Wallin, Erik
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics .
    Lattemann, Martina
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics .
    Reactive High Power Impulse Magnetron Sputter Deposition of Alumina2007In: AVS 54th International Symposium,2007, 2007Conference paper (Other academic)
  • 113.
    Horwat, David
    et al.
    University of Lorraine, France.
    Mickan, Martin
    Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics. Linköping University, Faculty of Science & Engineering. University of Lorraine, France.
    Chamorro, William
    University of Lorraine, France.
    New strategies for the synthesis of ZnO and Al-doped ZnO films by reactive magnetron sputtering at room temperature2016In: PHYSICA STATUS SOLIDI C: CURRENT TOPICS IN SOLID STATE PHYSICS, VOL 13 NO 10-12, WILEY-V C H VERLAG GMBH , 2016, Vol. 13, no 10-12, p. 951-957Conference paper (Refereed)
    Abstract [en]

    We review our recent findings that reactive magnetron sputtering can be operated without thermal assistance to produce epitaxial ZnO films and highly conductive and transparent aluminum-doped ZnO (AZO) films on large surface area. The growth of epitaxial films requires working in direct current (DC) mode at large oxygen partial pressure but high power impulse magnetron sputtering (HiPIMS) is preferred to optimize the electrical and optical properties of AZO films on large surface areas. The results are interpreted by the ability of DC sputtering to easily oxidize the target surface and the HiPIMS mode cleans and returns it to metallic during pulses. Fast oxygen atoms (ions) may be emitted in large amount using DC and bring fuel to the growing ZnO film to induce epitaxy onto sapphire. The signature of oxygen interstitials is found in DC with increasing magnitude as the oxygen content is increased in the gas phase. In contrast, the discharge voltage plays a significant role in HiPIMS to adjust the sputtering rate and clean the target surface for deposition of slightly sub-stoichiometric AZO films over the entire range of lateral positions. Thereby, transparent yet highly conductive films with resistivity in the range 4-15x10(-4) Omega m can be produced. (C) 2016 WILEY-VCH Verlag GmbH amp; Co. KGaA, Weinheim

  • 114. Hugosson, HW
    et al.
    Grechnev, GE
    Ahuja, R
    Helmersson, Ulf
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics .
    Sa, L
    Eriksson, Olivia
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Stabilization of potential superhard RuO2 phases: A theoretical study2002In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 66, no 17Article in journal (Refereed)
    Abstract [en]

    First-principles full-potential linear muffin-tin orbital calculations have been used to study RuO2 in the fluorite (CaF2) and rutile structures. An investigation of the effects of metal and nonmetal alloying, oxygen vacancies, and lattice strain on the phase stabilities and electronic structure has been made. From these theoretical results suggestions on how the cubic phase may be stabilized are made. The pressure induced phase transitions between the rutile, CaCl2, Pa3 and fluorite phases and the bulk moduli of several 4d and 5d transition metal dioxides have also been studied.

  • 115.
    Huo, Chunqing
    et al.
    KTH Royal Institute Technology, Sweden; Hainan University, Peoples R China.
    Lundin, D.
    University of Paris Saclay, France.
    Gudmundsson, J. T.
    KTH Royal Institute Technology, Sweden; University of Paris Saclay, France; University of Iceland, Iceland.
    Raadu, M. A.
    KTH Royal Institute Technology, Sweden.
    Bradley, J. W.
    University of Liverpool, England.
    Brenning, Nils
    Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics. Linköping University, Faculty of Science & Engineering. KTH Royal Institute Technology, Sweden.
    Particle-balance models for pulsed sputtering magnetrons2017In: Journal of Physics D: Applied Physics, ISSN 0022-3727, E-ISSN 1361-6463, Vol. 50, no 35, article id 354003Article in journal (Refereed)
    Abstract [en]

    The time-dependent plasma discharge ionization region model (IRM) has been under continuous development during the past decade and used in several studies of the ionization region of high-power impulse magnetron sputtering (HiPIMS) discharges. In the present work, a complete description of the most recent version of the IRM is given, which includes improvements, such as allowing for returning of the working gas atoms from the target, a separate treatment of hot secondary electrons, addition of doubly charged metal ions, etc. To show the general applicability of the IRM, two different HiPIMS discharges are investigated. The first set concerns 400 mu s long discharge pulses applied to an Al target in an Ar atmosphere at 1.8 Pa. The second set focuses on 100 mu s long discharge pulses applied to a Ti target in an Ar atmosphere at 0.54 Pa, and explores the effects of varying the magnetic field strength. The model results show that Al2+-ions contribute negligibly to the production of secondary electrons, while Ti2+-ions effectively contribute to the production of secondary electrons. Similarly, the model results show that for an argon discharge with Al target the contribution of Al+-ions to the discharge current at the target surface is over 90% at 800 V. However, at 400 V the Al+-ions and Ar+-ions contribute roughly equally to the discharge current in the initial peak, while in the plateau region Ar+-ions contribute to roughly 2/3 of the current. For high currents the discharge with Al target develops almost pure self-sputter recycling, while the discharge with Ti target exhibits close to a 50/50 combination of self-sputter recycling and working gas-recycling. For a Ti target, a self-sputter yield significantly below unity makes working gas-recycling necessary at high currents. For the discharge with Ti target, a decrease in the B-field strength, resulted in a corresponding stepwise increase in the discharge resistivity.

  • 116.
    Huo, Chunqing
    et al.
    Royal Institute Technology, Sweden .
    Raadu, Michael A
    Royal Institute Technology, Sweden .
    Lundin, Daniel
    Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics. Linköping University, The Institute of Technology.
    Gudmundsson, Jon Tomas
    Shanghai Jiao Tong University, Peoples R China University of Iceland, Iceland .
    Anders, Andre
    University of Calif Berkeley, CA 94720 USA .
    Brenning, Nils
    Royal Institute Technology, Sweden .
    Gas rarefaction and the time evolution of long high-power impulse magnetron sputtering pulses2012In: Plasma sources science & technology (Print), ISSN 0963-0252, E-ISSN 1361-6595, Vol. 21, no 4, p. 045004-Article in journal (Refereed)
    Abstract [en]

    Model studies of 400 mu s long discharge pulses in high-power impulse magnetron sputtering have been made to study the gas dynamics and plasma chemistry in this type of pulsed processing plasma. Data are taken from an experiment using square voltage pulses applied to an Al target in an Ar atmosphere at 1.8 Pa. The study is limited to low power densities, andlt; 0.5 kW cm(-2), in which the discharge is far away from the runaway self-sputtering mode. The model used is the ionization region model, a time-dependent plasma chemistry discharge model developed for the ionization region in magnetron sputtering discharges. It gives a close fit to the discharge current during the whole pulse, both an initial high-current transient and a later plateau value of constant lower current. The discharge current peak is found to precede a maximum in gas rarefaction of the order of Delta n(Ar)/n(Ar),(0) approximate to 50%. The time durations of the high-current transient, and of the rarefaction maximum, are determined by the time it takes to establish a steady-state diffusional refill of process gas from the surrounding volume. The dominating mechanism for gas rarefaction is ionization losses, with only about 30% due to the sputter wind kick-out process. During the high-current transient, the degree of sputtered metal ionization reaches 65-75%, and then drops to 30-35% in the plateau phase. The degree of self-sputtering (defined here as the metal ion fraction of the total ion current to the target) also varies during the pulse. It grows from zero at pulse start to a maximum of 65-70% coinciding in time with the maximum gas rarefaction, and then stabilizes in the range 40-45% during the plateau phase. The loss in deposition rate that can be attributed to the back-attraction of the ionized sputtered species is also estimated from the model. It is low during the initial 10-20 mu s, peaks around 60% during the high-current transient, and finally stabilizes around 30% during the plateau phase.

  • 117.
    Jian, Jingxin
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Shi, Yuchen
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Ekeroth, Sebastian
    Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics. Linköping University, Faculty of Science & Engineering.
    Keraudy, Julien
    Oerlikon Balzers, Liechtenstein.
    Syväjärvi, Mikael
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Yakimova, Rositsa
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. 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.
    Sun, Jianwu
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    A nanostructured NiO/cubic SiC p-n heterojunction photoanode for enhanced solar water splitting2019In: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 7, no 9, p. 4721-4728Article in journal (Refereed)
    Abstract [en]

    Photoelectrochemical (PEC) water-splitting offers a promising method to convert the intermittent solar energy into renewable and storable chemical energy. However, the most studied semiconductors generally exhibit a poor PEC performance including low photocurrent, small photovoltage, and/or large onset potential. In this work, we demonstrate a significant enhancement of photovoltage and photocurrent together with a substantial decrease of onset potential by introducing electrocatalytic and p-type NiO nanoclusters on an n-type cubic silicon carbide (3C-SiC) photoanode. Under AM1.5G 100 mW cm(-2) illumination, the NiO-coated 3C-SiC photoanode exhibits a photocurrent density of 1.01 mA cm(-2) at 0.55 V versus reversible hydrogen electrode (V-RHE), a very low onset potential of 0.20 V-RHE and a high fill factor of 57% for PEC water splitting. Moreover, the 3C-SiC/NiO photoanode shows a high photovoltage of 1.0 V, which is the highest value among reported photovoltages. The faradaic efficiency measurements demonstrate that NiO also protects the 3C-SiC surface against photo-corrosion. The impedance measurements evidence that the 3C-SiC/NiO photoanode facilitates the charge transfer for water oxidation. The valence-band position measurements confirm the formation of the 3C-SiC/NiO p-n heterojunction, which promotes the separation of the photogenerated carriers and reduces carrier recombination, thus resulting in enhanced solar water-splitting.

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  • 118.
    Jin, P.
    et al.
    Natl. Indust. Res. Inst. of Nagoya, Kita-ku, 462-8510, Nagoya, Japan.
    Tazawa, M.
    Natl. Indust. Res. Inst. of Nagoya, Kita-ku, 462-8510, Nagoya, Japan.
    Yoshimura, K.
    Natl. Indust. Res. Inst. of Nagoya, Kita-ku, 462-8510, Nagoya, Japan.
    Igarashi, K.
    Natl. Indust. Res. Inst. of Nagoya, Kita-ku, 462-8510, Nagoya, Japan.
    Tanemura, S.
    Natl. Indust. Res. Inst. of Nagoya, Kita-ku, 462-8510, Nagoya, Japan.
    MacAk, K.
    Helmersson, Ulf
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics .
    Epitaxial growth of W-doped VO2/V2O3 multilayer on a-Al2O3(110) by reactive magnetron sputtering2000In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 375, no 1-2, p. 128-131Article in journal (Refereed)
    Abstract [en]

    Multilayer epitaxy with a W-VO2 top layer over a bottom layer of which the crystal phase depends on the starting oxygen flow, was done on a-Al2O3(110) by reactively sputtering a V-W (1.6 at.% wt.) alloy target at linearly increasing oxygen flow without interrupting film growth. For the film deposited in the oxygen flow from 10 to 26 sccm, a W-VO2/W-V2O3 multilayer was formed on a-Al2O3(110) with the epitaxial relationship being (001)f?(110)s, (110)f?(001)s for W-V2O3, and (010)f?(110)s, (100)f?(001)s for W-VO2 where f and s denote the film and substrate, respectively. The formation of a triple domain structure was confirmed in the W-VO2 top layer due to the strong influence from the symmetry of the substrate. The multilayer shows phase transition behavior differing from the single layer film, which was presumably due to the effects of W-doping, compositional gradient, and strain.

  • 119.
    Jin, P.
    et al.
    National Institute of AIST, 2266-98 Anagahora, Shimoshidami, Nagoya, 463-8560, Japan.
    Xu, G.
    National Institute of AIST, 2266-98 Anagahora, Shimoshidami, Nagoya, 463-8560, Japan.
    Tazawa, M.
    National Institute of AIST, 2266-98 Anagahora, Shimoshidami, Nagoya, 463-8560, Japan.
    Yoshimura, K.
    National Institute of AIST, 2266-98 Anagahora, Shimoshidami, Nagoya, 463-8560, Japan.
    Music, Denis
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics.
    Alami, Jones
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics .
    Helmersson, Ulf
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics .
    Low temperature deposition of a-Al2O3 thin films by sputtering using a Cr2O3 template2002In: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films, ISSN 0734-2101, E-ISSN 1520-8559, Vol. 20, no 6, p. 2134-2136Article in journal (Refereed)
    Abstract [en]

    A description about low temperature deposition of a-Al2O3 thin films by sputtering was presented. Cr2O3 thin layer was used as a template. Nanoindentation was used to study the mechanical properties of the deposited films. Calculations were made to obtain the hardness and Young's modulus of the films.

  • 120.
    Johansson, Viktor
    Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics.
    Off-normal Film Growth by High Power Impulse Magnetron Sputtering2011Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In this study we contribute towards establishing the process-microstructure relationships in thin films grown off-normally by ionized physical vapor deposition. High power impulse magnetron sputtering (HiPIMS) is used at various peak target powers and deposition rates to grow copper (Cu) and chromium (Cr) films from a cathode placed at an angle 90 degrees with respect to the substrate normal. Films are also deposited by direct current magnetron sputtering (DCMS), for reference. Scanning electron microscopy is employed to investigate column tilting and deposition rate while X-ray diffraction techniques are utilized to study crystal structure and grain tilting.

    It is demonstrated that the columnar structure of Cu tilts less with respect to the substrate normal as the peak target power increases, which has been shown to correspond to a higher ionization degree of the sputtered material [1]. One explanation for this is that the trajectories of the ions are deflected towards the substrate and therefore deposited closer to the normal, as has been suggested in the literature (see e.g. [2]). Energetic bombardment by ions might also increase surface mobility, which further raises the columns. It is also concluded that the change in tilting is not caused by a lower deposition rate obtained when employing HiPIMS. The same is not seen for Cr, where all deposited films exhibit the same tilting angle. When the column tilting of Cu and Cr is compared a large difference is observed, where the columns of Cr are closer to the substrate normal. The reasons for this difference are discussed in light of nucleation and growth characteristics in the two materials.

    X-ray diffraction analysis reveals that Cu films exhibit an (111) fiber texture. Comparison of films grown by DCMS and HiPIMS shows that in the HiPIMS cases the grains are closer to the surface normal and better oriented with each other. In the case of Cr both DCMS and HiPIMS grown films are (110) biaxially aligned. 

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    Johansson - Off-normal Film Growth by High Power Impulse Magnetron Sputtering
  • 121.
    Junaid, Muhammad
    et al.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Lundin, Daniel
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Palisaitis, Justinas
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Hsiao, Ching-Lien
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Jensen, Jens
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Persson, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Sandström, Per
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Lai, W.-J.
    Center for Condensed Matter Sciences, National Taiwan University, Taipei 106, Taiwan.
    Chen, L.-C.
    Center for Condensed Matter Sciences, National Taiwan University, Taipei 106, Taiwan.
    Chen, K.-H.
    Center for Condensed Matter Sciences, National Taiwan University, Taipei 106, Taiwan/Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei, Taiwan.
    Helmersson, Ulf
    Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating 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.
    Birch, Jens
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Epitaxial Growth of GaN (0001)/Al2O3 (0001) by Reactive High Power Impulse Magnetron Sputter DepositionManuscript (preprint) (Other academic)
    Abstract [en]

    Epitaxial GaN (0001) thin films were grown on Al2O3 (0001) substrates by reactive high power impulse magnetron sputtering of liquid Ga targets in a mixed N2/Ar discharge. A combination of x-ray diffraction, electron microscopy, atomic force microscopy, μ-Raman mapping and spectroscopy, μ-photoluminescence, time of flight elastic recoil detection, and cathodoluminescence showed the formation of relaxed and strained domains in the same films. While the strained domains form due to ion bombardment during growth, the relaxed domains exhibit

  • 122.
    Jädernäs, Daniel
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics .
    Lattemann, Martina
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics .
    Helmersson, Ulf
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics .
    Interface engineering and surface pretreatment utilizing ionized PVD2007In: International Vacuum Congress,2007, 2007Conference paper (Other academic)
    Abstract [en]

      

  • 123.
    Jädernäs, Daniel
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics .
    Lattemann, Martina
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics .
    Helmersson, Ulf
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics .
    Interface engineering and surface pretreatment utilizing ionized PVD2007In: Symposium on Ionized Physical Vapor Deposition,2007, 2007Conference paper (Other academic)
  • 124.
    Jädernäs, Daniel
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics .
    Lattemann, Martina
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics .
    Helmersson, Ulf
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics .
    Interface investigation of steel substrates pretreated by high power impulse magnetron sputtering2007In: AVS 54th International Symposium,2007, 2007Conference paper (Other academic)
  • 125.
    Keraudy, Julien
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics. Linköping University, Faculty of Science & Engineering. IRT Jules Verne, France; IMN Jean Rouxel, France.
    Athouel, L.
    IMN Jean Rouxel, France.
    Hamon, J.
    IMN Jean Rouxel, France.
    Girault, B.
    Univ Nantes, France.
    Gloaguen, D.
    Univ Nantes, France.
    Richard-Plouet, M.
    IMN Jean Rouxel, France.
    Jouan, P. -Y.
    IMN Jean Rouxel, France.
    Electrochemical characteristics of NixN thin films deposited by DC and HiPIMS reactive magnetron sputtering2019In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 669, p. 659-664Article in journal (Refereed)
    Abstract [en]

    This study deals with the DC and HiPIMS reactive magnetron deposition process using a pure nickel target (99.995%) in an Ar-N-2 gas mixture with varied nitrogen gas flow and bias voltage (floating or -100 V). The characterization of the NiN films has been carried out by X-ray diffraction (XRD), X-ray photoelectrons spectroscopy (XPS) and Energy dispersive X-ray Spectroscopy (EDXS). XRD measurements have highlighted the deformation of the Ni cubic cell as a function of nitrogen content, and a mixture of nitrided phases (Ni4N, Ni3N and Ni2N) appears for 20% N-2 in the discharge. XPS and EDX are well correlated and permit us to determine three zones: metallic between 0 and 20% N-2, Ni4N between 20% and 42% N-2 and finally Ni3N for N-2 above 50%. These three zones are in good agreement with deposition rates and optical emission spectroscopy measurements. Cyclic voltammetry has been performed in a conventional three-electrode cell using neutral, alkaline and acidic aqueous electrolytes. The NixN electrochemical behavior shows a pseudocapacitive charge storage mechanism in LiNO3 and KOH electrolytes using an appropriate voltage window, suitable for supercapacitors, whereas NixN exhibits reversible faradaic redox peaks beyond one potential in KOH, depicting NixN film as a battery-type electrode.

  • 126.
    Keraudy, Julien
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating 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.
    Shimizu, Tetsuhide
    Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics. Linköping University, Faculty of Science & Engineering. Tokyo Metropolitan Univ, Japan.
    Helmersson, Ulf
    Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics. Linköping University, Faculty of Science & Engineering.
    Jouan, P-Y
    Univ Nantes, France.
    Phase separation within NiSiN coatings during reactive HiPIMS discharges: A new pathway to grow NixSi nanocrystals composites at low temperature2018In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 454, p. 148-156Article in journal (Refereed)
    Abstract [en]

    The precise control of the growth nanostructured thin films at low temperature is critical for the continued development of microelectronic enabled devices. In this study, nanocomposite Ni-Si-N thin films were deposited at low temperature by reactive high-power impulse magnetron sputtering. A composite Ni-Si target (15 at.% Si) in combination with a Ar/N-2 plasma were used to deposit films onto Si(0 01) substrates, without any additional substrate heating or any post-annealing. The films microstructure changes from a polycrystalline to nanocomposite structure when the nitrogen content exceeds 16 at.%. X-ray diffraction and (scanning) transmission electron microscopy analyses reveal that the microstructure consists of nanocrystals, NixSi (x amp;gt; 1) 7-8 nm in size, embedded in an amorphous SiN x matrix. It is proposed that this nanostructure is formed at low temperatures due to the repeated-nucleation of NixSi nanocrystals, the growth of which is restricted by the formation of the SiNx phase. X-ray photoelectron spectroscopy revealed the trace presence of a ternary solid solution mainly induced by the diffusion of Ni into the SiNx matrix. Four-probe electrical measurements reveal all the deposited films are electrically conducing.

  • 127.
    Keraudy, Julien
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics. Linköping University, Faculty of Science & Engineering. IRT, France; University of Nantes, France.
    Delfour-Peyrethon, Brice
    University of Nantes, France.
    Ferrec, Axel
    University of Nantes, France.
    Garcia Molleja, Javier
    University of Nantes, France; Yachay Tech, Ecuador.
    Richard-Plouet, Mireille
    University of Nantes, France.
    Payen, Christophe
    University of Nantes, France.
    Hamon, Jonathan
    University of Nantes, France.
    Corraze, Benoit
    University of Nantes, France.
    Goullet, Antoine
    University of Nantes, France.
    Jouan, Pierre-Yves
    University of Nantes, France.
    Process- and optoelectronic-control of NiOx thin films deposited by reactive high power impulse magnetron sputtering2017In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 121, no 17, article id 171916Article in journal (Refereed)
    Abstract [en]

    In this contribution, based on the analyses of the discharge behavior as well as final properties of the deposited Ni-O films during reactive high power impulse magnetron sputtering discharge, we have demonstrated that monitoring the oxygen flow rate leads to 4 different regimes of discharge. Tuning the oxygen partial pressure allows deposition of a large range of chemical compositions from pure nickel to nickel-deficient NiOx (xamp;gt; 1) in the poisoned mode. Investigation of the plasma dynamics by time-resolved optical emission spectroscopy suggests that the discharge behavior in the poisoned mode principally comes from the higher contribution of both oxygen and argon ions in the total ionic current, leading to a change in the ion induced secondary electron emission coefficient. Additionally, material characterizations have revealed that optoelectronic properties of NiOx films can be easily tuned by adjusting the O/Ni ratio, which is influenced by the change of the oxygen flow rate. Stoichiometric NiO films (O/Ni ratio similar to 1) are transparent in the visible range with a transmittance similar to 80% and insulating as expected with an electrical resistivity similar to 10 6 Omega cm. On the other hand, increasing the O/Niamp;gt; 1 leads to the deposition of more conductive coating (p similar to 10 Omega cm) films with a lower transmittance similar to 50%. These optoelectronic evolutions are accompanied by a band-gap narrowing 3.65 to 3.37 eV originating from the introduction of acceptor states between the Fermi level and the valence band maximum. In addition, our analysis has demonstrated that nickel vacancies are homogeneously distributed over the film thickness, explaining the p-type of the films. Published by AIP Publishing.

  • 128.
    Keraudy, Julien
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics. Linköping University, Faculty of Science & Engineering. IRT, France; University of Nantes, France.
    Ferrec, Axel
    University of Nantes, France.
    Richard-Plouet, Mireille
    University of Nantes, France.
    Hamon, Jonathan
    University of Nantes, France.
    Goullet, Antoine
    University of Nantes, France.
    Jouan, Pierre-Yves
    University of Nantes, France.
    Nitrogen doping on NiO by reactive magnetron sputtering: A new pathway to dynamically tune the optical and electrical properties2017In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 409, p. 77-84Article in journal (Refereed)
    Abstract [en]

    N-doped nickel oxide (NiO:N) thin films were deposited on glass and silicon substrates by reactive DC magnetron sputtering in Ar/O-2/N-2 gas atmosphere with a series of N-2/O-2 gas ratio ranging from 0 to 80%. X-ray diffraction measurements have revealed that the films are constituted of Ni1_xO grains and showed enhanced polycrystalline features with increasing N-doping concentration. For the first time, we report here that N-doping in the Ni-deficient NiO (Ni1-xO) film leads to a band-gap narrowing from 3.6 to 2.3 eV. X-ray photoelectron spectroscopy (XPS) measurements proved that up to 4 atomic percent (at.%) nitrogen can be incorporated at least at the surface of the NiO:N samples. In addition, XPS valence band spectra and UV-vis transmission measurements have demonstrated that the band-gap narrowing may originates from the contribution of an intermediate band (IB) similar to 2.4 eV just above the valence band maximum and the up-shifting of the valence band edge (similar to 0.3 eV) due to the introduction of occupied N 2p states. Local I-V measurements, carried out by conductive AFM (C-AFM), have revealed that the extrinsic doping of N atoms within the oxide can be a good way to precisely control the electrical conductivity of such p-type materials. (C) 2017 Elsevier B.V. All rights reserved.

  • 129.
    Keraudy, Julien
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics. Linköping University, Faculty of Science & Engineering. Oerlikon Surface Solut AG, Liechtenstein.
    Viloan, Rommel Paulo
    Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics. Linköping University, Faculty of Science & Engineering.
    Raadu, Michael A.
    KTH Royal Inst Technol, Sweden.
    Brenning, Nils
    Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics. Linköping University, Faculty of Science & Engineering. KTH Royal Inst Technol, Sweden; Univ Paris Saclay, France.
    Lundin, Daniel
    Univ Paris Saclay, France.
    Helmersson, Ulf
    Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics. Linköping University, Faculty of Science & Engineering.
    Bipolar HiPIMS for tailoring ion energies in thin film deposition2019In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 359, p. 433-437Article in journal (Refereed)
    Abstract [en]

    The effects of a positive pulse following a high-power impulse magnetron sputtering (HiPIMS) pulse are studied using energy-resolved mass spectrometry. This includes exploring the influence of a 200 mu s long positive voltage pulse (U-rev = 10-150 V) following a typical HiPIMS pulse on the ion-energy distribution function (IEDF) of the various ions. We find that a portion of the Ti+ flux is affected and gains an energy which corresponds to the acceleration over the full potential U-rev. The Ar+ IEDF on the other hand illustrates that a large fraction of the accelerated Ar+, gain energies corresponding to only a portion of U-rev. The Ti+ IEDFs are consistent with the assumption that practically all the TO-, that are accelerated during the reverse pulse, originates from a region adjacent to the target, in which the potential is uniformly increased with the applied potential U-rev while much of the Ar+ originates from a region further away from the target over which the potential drops from U-rev to a lower potential consistent with the plasma potential achieved without the application of U-rev. The deposition rate is only slightly affected and decreases with U-rev, reaching 90% at U-rev = 150 V. Both the Ti IEDF and the small deposition rate change indicate that the potential increase in the region close to the target is uniform and essentially free of electric fields, with the consequence that the motion of ions inside the region is not much influenced by the application of U-rev. In this situation, Ti will flow towards the outer boundary of the target adjacent region, with the momentum gained during the HiPIMS discharge pulse, independently of whether the positive pulse is applied or not. The metal ions that cross the boundary in the direction towards the substrate, and do this during the positive pulse, all gain an energy corresponding to the full positive applied potential U-rev.

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  • 130.
    Konofaos, N.
    et al.
    Comp. Engineering/Informatics Dept., University of Patras, Patras 26500, Greece.
    Evangelou, E.K.
    Laboratorio MDM-INFM, Agrate Briana 20041, Italy.
    Wang, Z.
    Helmersson, Ulf
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics .
    Properties of Al-SrTiO3-ITO capacitors for microelectronic device applications2004In: IEEE Transactions on Electron Devices, ISSN 0018-9383, E-ISSN 1557-9646, Vol. 51, no 7, p. 1202-1205Article in journal (Refereed)
    Abstract [en]

    Growth of SrTiO3 (STO) thin films on indium tin oxide (ITO) substrates took place by RF magnetron sputtering under various deposition conditions. Subsequent AI metallization created metal-insulator-metal (MIM) capacitors. The properties of such capacitors were investigated by means of structural and electrical measurements, revealing the films transparency, the dielectric constant, the switching time characteristics, and the trapped charges density. Dielectric constant values as high as 120 were obtained for low frequencies of around 2 kHz, the switching time was found to be 3.2 µs and the trapped charges were found equal to 2.9 nCcm-2. The results showed that the films were suitable for use in electronic devices where high capacitance is required and for potential applications in optical devices. © 2004 IEEE.

  • 131.
    Konofaos, N.
    et al.
    Department of Physics, University of Ioannina, P.O. Box 1186, 451 10 Ioannina, Greece.
    Evangelou, E.K.
    Department of Physics, University of Ioannina, P.O. Box 1186, 451 10 Ioannina, Greece.
    Wang, Z.
    Kugler, Veronika Mozhdeh
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Helmersson, Ulf
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics .
    Electrical characterisation of SrTiO3/Si interfaces2002In: Journal of Non-Crystalline Solids, ISSN 0022-3093, E-ISSN 1873-4812, Vol. 303, no 1, p. 185-189Article in journal (Refereed)
    Abstract [en]

    Deposition of SrTiO3 (STO) thin films by ultra-high vacuum rf magnetron sputtering was performed in order to produce high-quality STO/p-Si (1 0 0) interfaces and STO insulator layers with high dielectric constants. The deposition temperatures were in the range from room temperature to 550 °C. Capacitance-voltage (C-V) and conductance-frequency measurements showed that the dielectric constant of the films ranges from 55 to 120. C-V measurements on Al/STO/p-Si structures clearly revealed the creation of metal-insulator-semiconductor diodes. The interface state densities (Dit) at the STO/p-Si interfaces were obtained from admittance spectroscopy measurements. The samples deposited at lower temperatures revealed values of Dit between 2 × 1011 and 3.5 × 1012 eV-1 cm-2 while the higher temperature deposited samples had a higher Dit ranging between 1 × 1011 and 1 × 1013 eV-1 cm-2. The above results were also well correlated to X-ray diffraction measurements, Rutherford backscattering spectroscopy, and spectroscopic ellipsometry. © 2002 Elsevier Science Ltd. All rights reserved.

  • 132.
    Kubart, T
    et al.
    Uppsala University.
    Aiempanakit, Montri
    Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics. Linköping University, The Institute of Technology.
    Andersson, J
    Uppsala University.
    Nyberg, T
    Uppsala University.
    Berg, S
    Uppsala University.
    Helmersson, Ulf
    Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics. Linköping University, The Institute of Technology.
    Studies of hysteresis effect in reactive HiPIMS deposition of oxides2011In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 205, p. S303-S306Article in journal (Refereed)
    Abstract [en]

    igh power impulse magnetron sputtering (HiPIMS) has proven to be capable of substantial improvement of the quality of deposited coatings. Lately, there have been a number of reports indicating that the hysteresis effect may be reduced in HiPIMS mode resulting in an increase of the deposition rate of stoichiometric compound as compared to a direct current magnetron sputtering process in oxide mode. In this contribution, we have studied the hysteresis behaviour of Ti metal targets sputtered in Ar + O(2) mixtures. For fixed pulse on time and a constant average power, there is an optimum frequency minimizing the hysteresis. The effect of gas dynamics was analyzed by measurements of the gas refill time and rarefaction. Results indicate that the gas rarefaction may be responsible for the observed hysteresis behaviour. The results are in agreement with a previous study of Al oxide reactive process.

  • 133.
    Kugler, Veronika Mozhdeh
    et al.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Söderlind, Fredrik
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Music, Denis
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Helmersson, Ulf
    Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics. Linköping University, The Institute of Technology.
    Andreasson, J.
    Department of Materials Engineering, Luleå University of Technology, Luleå, Sweden.
    Lindback, T.
    Department of Materials Engineering, Luleå University of Technology, Luleå, Sweden.
    Low temperature growth and characterization of (Na,K)NbOx thin films2003In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 254, no 3-4, p. 400-404Article in journal (Refereed)
    Abstract [en]

    Thin (Na,K)NbOx perovskite films (NKN) have been deposited on SiO2/Si(0 0 1) substrates at low temperatures, from 350°C to 550°C, by RF magnetron sputtering. The effects of substrate temperature on microstructure, electrical-, and mechanical properties of the NKN films have been studied. X-ray diffraction analysis revealed that films deposited at temperatures in the range of 450–550°C were crystalline, growing as a single phase, with a preferred orientation of (0 0 1). Films deposited at 350°C, were shown to be amorphous. The growth temperature had a strong influence on the electrical properties of the NKN films and the relative dielectric constants of the obtained films were in between 38 and 78. Variations of the mechanical properties of the NKN films were observed for different substrate temperatures: The elastic moduli and the hardness values ranged from 205±26 to 93±29 GPa, and from 12±2 to around 2 GPa, for films deposited at 550°C and 450°C, respectively.

  • 134.
    Kugler, Veronika Mozhdeh
    et al.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Söderlind, Fredrik
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Music, Denis
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics.
    Helmersson, Ulf
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics.
    Andreasson, J.
    Department of Materials Engineering, Luleå University of Technology, Luleå, Sweden.
    Lindback, T.
    Department of Materials Engineering, Luleå University of Technology, Luleå, Sweden.
    Microstructure/dielectric property relationship of low temperature synthesised (Na,K)NbOx thin films2004In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 262, no 1-4, p. 322-326Article in journal (Refereed)
    Abstract [en]

    Thin films of (Na,K)NbOx (NKN) were grown by reactive RF magnetron sputtering on polycrystalline Pt80Ir20 substrates, at relatively low growth temperatures between 300°C and 450°C. The results show that the electrical performance and the microstructure of the films are a strong function of the substrate temperature. X-ray diffraction of films grown up to 400°C revealed the formation of only one crystalline NKN-phase with a preferred (0 0 2)-orientation. However, a mixed orientation together with a secondary, paraelectric potassium niobate phase, were observed for NKN films deposited at 450°C. The differences in the microstructure explains the variations in the dielectric constants and losses: The single phase NKN films displayed a dielectric constant and a dielectric loss of 506 and 0.011, respectively, while the films with mixed phases exhibited values of 475 and 0.022, respectively. The possibility of fabricating NKN films with relatively high dielectric properties at low growth temperatures, as demonstrated here, is of high technological importance.

  • 135.
    Lai, Chung-Chuan
    Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics .
    Growth and Phase Stability of Titanium Aluminum Nitride Deposited by High Power Impulse Magnetron Sputtering2011Independent thesis Advanced level (degree of Master (Two Years)), 30 credits / 45 HE creditsStudent thesis
    Abstract [en]

    In this work, we investigate the relation between the diffusion behavior of Ti1-xAlxN at elevated temperatures and the microstructure. Thinfilm samples are synthesized by reactive co-sputtering with two cathodes. One cathode equipped with Ti target is connected to a highpower impulse magnetron sputtering (HiPIMS) power supply, and the other cathode equipped with Al target is operated with a directcurrent power source. The spinodal decomposition of cubic metastable Ti1-xAlxN controlled by thermally activated diffusion is observe fordiffusion behavior. Various HiPIMS pulsing frequencies are used to achieve different microstructure, while altered power applied to Altarget is used to change the Al content in films. In the phase composition analysis achieved by GI-XRD, the right-shift of (111) film peakalong with increasing Al-power is observed. A saturation of the right-shift and h-AlN peaks are also observed at certain Al-power. Thechemical composition determined by ERDA shows trends of reducing Al solubility limit in metastable phase and O contamination upondecreasing the pulsing frequency. More N deficiency is found in samples deposited with higher frequency. In the 500 Hz and 250 Hzsamples deposited into similar composition and thickness, no apparent difference of the microstructure is observed from the SEM crosssectionalimages. From HT-XRD, we observe higher intensity of TiO2 and h-AlN peaks in 500 Hz sample at elevated temperature ascompared with 250 Hz one. From the reduction of O contamination, denser Ti1-xAlxN films are able to be deposited with lower HiPIMSpulsing frequency. In addition, the higher intensity observed in HT-XRD patterns indicates that the 500 Hz sample is more open todiffusion and therefore allows the new formed phases to grow in larger grains.

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  • 136.
    Lattemann, Martina
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics .
    Effect of adspecies flux on texture and structure evolution in TiN thin films deposited by pulsed i-PVD2007In: Symposium on Ionized Physical Vapor Deposition,2007, 2007Conference paper (Other academic)
  • 137.
    Lattemann, Martina
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics .
    High power impulse magnetron sputtering (HIPIMS)2007In: International Symposium on Reactive Sputter Deposition,2007, 2007Conference paper (Other academic)
    Abstract [en]

     High power impulse magnetron sputtering is an area presently under active and rapid development. Pulsing the power at low duty cycles allows for instantaneous high power levels to be used, causing the plasma to enter a new operating regime. Thus a plasma with a high plasma density is achieved increasing the ionization level of the sputtered material. This opens for several improvements in the deposition process in terms of the particle transport and alignment of the deposition flux as well as in the nucleation and growth of the film. The talk will highlight important aspects of process understanding and opportunities for improved process control and film growth. Examples from technologically relevant applications will be discussed. E.g., for low temperature growth of TiN it was shown that the intrinsic energy of the depositing species with energies exceeding values of 20~eV is sufficient for improved film quality. Moreover, biasing of the substrate during film deposition in pulsed mode provides an effective tool allowing growth under controlled ion impact conditions not normally available in a sputtering plasma and previously only available in cathodic arc plasmas. Ion impacts can be utilized - besides for controlling the film morphology and intrinsic stresses - for substrate cleaning and surface modification by ion implantation promoting epitaxial growth and good adhesion. In addition, results demonstrating an improvement in the stability of reactive sputtering processes by HIPIMS will be presented.

  • 138.
    Lattemann, Martina
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics .
    Physics of High Power Impulse Magnetron Sputtering2008In: 15th Gaseous Electronics Meeting,2008, 2008Conference paper (Other academic)
    Abstract [en]

      

  • 139.
    Lattemann, Martina
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Ehiasarian, A.P.
    Materials Research Institute, Sheffield Hallam University, United Kingdom.
    Böhlmark, Johan
    Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics . Linköping University, The Institute of Technology.
    Persson, Per .Å.O.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Helmersson, Ulf
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Investigation of high power impulse magnetron sputtering pretreated interfaces for adhesion enhancement of hard coatings on steel2006In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 200, no 22-23, p. 6495-6499Article in journal (Refereed)
    Abstract [en]

    In order to improve the adhesion of hard coatings such as CrN, a surface pretreatment by the novel high power impulse magnetron sputtering (HIPIMS) technique followed by reactive unbalanced d.c. magnetron sputtering deposition was performed using a Cr target. The HIPIMS plasma comprising a high metal ion-to-neutral ratio consisting of single- and double-charged metal species identified by mass spectrometry increased the metal ion flux to the substrate. When applying a negative substrate bias Ub the adhesion was enhanced due to sputter cleaning of the surface and metal ion intermixing in the interface region. This intermixing, resulting in a gradual change of the composition, is considered to enhance the adhesion of the hard coatings on steel substrates. The pretreatment was carried out in an inert gas atmosphere at a pressure of pAr = 1 mTorr, the duration was varied between 25 and 75 min, whereas the negative substrate bias was varied between 400 V and 1200 V. The adhesion was found to depend on the substrate bias as well as on the target power and, for low substrate bias, on the duration of the pretreatment. For CrN the critical load of failure determined by scratch test could be increased in comparison to the values reported for specimens pretreated by conventional Ar etching. The influence of the target peak voltage, the substrate bias as well as pretreatment time on the constitution and morphology of the interface after the pretreatment is discussed applying analytical transmission electron microscopy.

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  • 140.
    Lattemann, Martina
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics .
    Helmersson, Ulf
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics .
    Effect of adspecies flux on texture and structure evolution in TiN thin films deposited by pulsed i-PVD2007In: International Vacuum Congress,2007, 2007Conference paper (Other academic)
  • 141.
    Lattemann, Martina
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics .
    Helmersson, Ulf
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics .
    HIPIMS I-PVD the easy way?2007In: Symposium on Vacuum Based Science and Technology,2007, 2007Conference paper (Other academic)
  • 142.
    Lattemann, Martina
    et al.
    Technical University Darmstadt & Karlsruhe Institute of Technology.
    Helmersson, Ulf
    Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics. Linköping University, The Institute of Technology.
    Greene, J.E.
    Department of Materials Science, University of Illinois, Urbana, Illinois, USA.
    Fully dense, non-faceted 111-textured high power impulse magnetron sputtering TiN films grown in the absence of substrate heating and bias2010In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 518, no 21, p. 5978-5980Article in journal (Refereed)
    Abstract [en]

    We demonstrate the deposition of fully dense, stoichiometric TiN films on amorphous SiO2 by reactive high power impulse magnetron sputtering (HiPIMS) in the absence of both substrate heating and applied bias. Contrary to the highly underdense layers obtained by reactive dc magnetron sputtering (dcMS) under similar conditions, the film nanostructure exhibits neither intra- nor intergrain porosity, exhibiting a strong 111 preferred orientation with flat surfaces. Competitive grain growth occurs only during the early stages of deposition 100 nm). The strong differences in the kinetically-limited nanostructural evolution for HiPIMS vs. dcMS are explained by high real-time deposition rates with long relaxation times, high ionization probabilities for Ti, and broad ion energy distributions.

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  • 143.
    Lattemann, Martina
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics .
    Sell, K.
    Forschungszentrum Karlsruhe.
    Ye, J.
    Forschungszentrum Karlsruhe.
    Persson, Per
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics.
    Ulrich, S.
    Forschungszentrum Karlsruhe.
    Stress reduction in nanocomposite coatings consisting of hexagonal and cubic boron nitride2006In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 200, no 22-23 SPEC. ISS., p. 6459-6464Article in journal (Refereed)
    Abstract [en]

    Cubic boron nitride (c-BN) can be produced by PVD and CVD techniques by intensive ion bombardment leading to highly stressed films. To overcome the problem of highly stressed films, nanocomposite coatings consisting of hexagonal and cubic boron nitride (h-/c-BN) phases have been successfully deposited by reactive rf magnetron sputtering from an h-BN target at a substrate temperature of 350 °C and a dc substrate bias of - 700 V close to the resputtering limit. The morphology of the films was characterized using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction/reflectivity (XRD/XRR) and high-resolution transmission electron microscopy (HRTEM). At low ion energy levels corresponding to low substrate bias values of up to ≈ 200 V pure h-BN was deposited. Higher ion energies led to a strong increase of the c-BN content as well as the residual stress in the films reaching their maximum at ≈ - 300 V substrate bias before decreasing again. Both the c-BN content and the residual stress showed qualitatively the same behaviour with a steeper drop of the residual stress between the maximum and the resputter limit. HRTEM investigation of the films with the maximum densification deposited at a substrate bias of ≈ - 300 V showed an h-BN interlayer growing on the Si substrate with the basal planes perpendicular to the substrate surface on which then almost pure c-BN was identified. The density of these coatings was 3.5 g/cm3 and the residual stress was determined to ≈ - 29 GPa. Depositing boron nitride at a substrate bias of - 700 V, these films comprised a hexagonal interlayer and c-BN in an h-BN matrix on top showing a lower density of 3.2 g/cm3 and a significantly reduced residual stress of - 9 GPa. A further reduction of the residual stress can be achieved by a following heat treatment at 900 °C for 2 h resulting in a value of ≈ - 3 GPa. © 2005 Elsevier B.V. All rights reserved.

  • 144.
    Lattemann, Martina
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics .
    Ulrich, S.
    Forschungszentrum Karlsruhe.
    Investigation of structure and mechanical properties of magnetron sputtered monolayer and multilayer coatings in the ternary system Si-B-C2007In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 201, no 9-11 SPEC. ISS., p. 5564-5569Article in journal (Refereed)
    Abstract [en]

    In the present work SiC and B4C monolayers as well as SiC/B4C multilayer coatings have been investigated with respect to their composition and mechanical properties. The coatings have been deposited on silicon substrates and polished cemented carbide inserts by non-reactive dual radio frequency (r.f.) magnetron sputtering from stoichiometric, high-purity silicon carbide (99.5%) and boron carbide (99.9%) targets. Amorphous stoichiometric SiC and B4C have been achieved with high hardness of 2950 HV0.01 and 4160 HV0.01 with a residual stress of - 3.4 GPa and - 2.9 GPa, respectively. The number of monolayers in the multilayer system with a constant total layer thickness has been varied in order to investigate the influence of the number of interfaces on film composition and properties. Additionally, the monolayer thickness ratio for a constant modulation period (double layer thickness) was varied. In this multilayer system no notable hardness enhancement could be observed. Despite the absence of the hardness enhancement, the toughness is expected to be enhanced due to stress relaxation and a reduction of crack propagation by crack dissipation along the interfaces. An abrupt interface is considered to be an indispensable requirement. However, the strain fields and the difference of the mechanical properties in the interfacial region are also of importance. © 2006 Elsevier B.V. All rights reserved.

  • 145.
    Lattemann, Martina
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics.
    Ulrich, S.
    Forschungszentrum Karlsruhe.
    Ye, J.
    Forschungszentrum Karlsruhe.
    New approach in depositing thick, layered cubic boron nitride coatings by oxygen addition-structural and compositional analysis2006In: Thin solid films : an international journal on the science and technology of thin and thick films, ISSN 0040-6090, Vol. 515, no 3, p. 1058-1062Article in journal (Refereed)
    Abstract [en]

    Cubic boron nitride (c-BN) can be produced by PVD and PA-CVD techniques by intensive ion bombardment leading to highly stressed films limiting its use in industrial applications. Various attempts have been undertaken to reduce the compressive stress of c-BN thin films. A significant reduction in compressive stress and a substantially improved adhesion was achieved by a new coating concept consisting of a two-step adhesion-promoting base layer, a compositional-graded nucleation layer obtained by a stepwise decrease of the oxygen content in the Ar/N2/O2 atmosphere and a low-stressed c-BN:O top layer with controlled oxygen addition. The four-layer c-BN:O film with a thickness of 3 ìm was deposited by unbalanced radio frequency magnetron sputtering of a hot-pressed hexagonal boron nitride target on silicon substrates. The adhesion layer was deposited in a mixed Ar/O2 atmosphere of 0.26 Pa with a stepwise increased nitrogen gas flow and a subsequent increase of the ion energy by increasing the substrate bias from 0 to − 250 V. The c-BN nucleation was gradually initiated by decreasing the O2 gas flow. The present study was focused on the investigation of the morphology, the microstructure on the nanoscale, and the bonding structure using scanning electron microscopy (SEM), Fourier-Transmission infra-red spectroscopy (FTIR), high-resolution transmission electron microscopy (HRTEM) and electron energy loss spectroscopy (EELS) employing analytical scanning transmission electron microscopy (ASTEM). The HRTEM images revealed a four-layer coating consisting of a gradual nucleation of t-BN, on which a gradual nucleation of c-BN was achieved by decreasing the oxygen gas flow.

  • 146.
    Lattemann, Martina
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics .
    Wallin, Erik
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics .
    Helmersson, Ulf
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics .
    Microstructure evolution in high power impulse magnetron sputtering deposited titanium nitride2007In: AVS 54th International Symposium,2007, 2007Conference paper (Other academic)
  • 147. Lewin, E.
    et al.
    Persson, Per
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics.
    Lattemann, Martina
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics .
    Stüber, M.
    Gorgoi, M.
    Sandell, A.
    Ziebert, C.
    Schäfers, F.
    Braun, W.
    Halbritter, J.
    Ulrich, S.
    Eberhardt, W.
    Hultman, Lars
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics.
    Siegbahn, H.
    Svensson, S.
    Jansson, U.
    On the origin of a third spectral component of C1s XPS-spectra for nc-TiC/a-C nanocomposite thin films2008In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 202, no 15, p. 3563-3570Article in journal (Refereed)
    Abstract [en]

    X-ray photoelectron spectroscopy (XPS) spectra of sputter-etched nc-TiC/a-C nanocomposite thin films published in literature show an extra feature of unknown origin in the C1s region. This feature is situated between the contributions of carbide and the carbon matrix. We have used high kinetic energy XPS (HIKE-XPS) on magnetron-sputtered nc-TiC/a-C thin films to show that this feature represents a third chemical environment in the nanocomposites, besides the carbide and the amorphous carbon. Our results show that component is present in as-deposited samples, and that the intensity is strongly enhanced by Ar+-ion etching. This third chemical environment may be due to interface or disorder effects. The implications of these observations on the XPS analysis of nanocomposites are discussed in the light of overlap problems for ternary carbon based systems. © 2008 Elsevier B.V. All rights reserved.

  • 148.
    Lundin, D.
    et al.
    University of Paris Saclay, France.
    Gudmundsson, J. T.
    University of Paris Saclay, France; KTH Royal Institute Technology, Sweden; University of Iceland, Iceland.
    Brenning, Nils
    Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics. Linköping University, Faculty of Science & Engineering. University of Paris Saclay, France; KTH Royal Institute Technology, Sweden.
    Raadu, M. A.
    KTH Royal Institute Technology, Sweden.
    Minea, T. M.
    University of Paris Saclay, France.
    study of the oxygen dynamics in a reactive Ar/O-2 high power impulse magnetron sputtering discharge using an ionization region model2017In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 121, no 17, article id 171917Article in journal (Refereed)
    Abstract [en]

    The oxygen dynamics in a reactive Ar/O-2 high power impulse magnetron sputtering discharge has been studied using a new reactive ionization region model. The aim has been to identify the dominating physical and chemical reactions in the plasma and on the surfaces of the reactor affecting the oxygen plasma chemistry. We explore the temporal evolution of the density of the ground state oxygen molecule O-2(X-1 Sigma(-)(g)), the singlet metastable oxygen molecules O-2(a(1)Delta(g)) and O-2(b(1) Sigma(g)), the oxygen atom in the ground state O(P-3), the metastable oxygen atom O(D-1), the positive ions O-2(+) and O+, and the negative ion O-. We furthermore investigate the reaction rates for the gain and loss of these species. The density of atomic oxygen increases significantly as we move from the metal mode to the transition mode, and finally into the compound (poisoned) mode. The main gain rate responsible for the increase is sputtering of atomic oxygen from the oxidized target. Both in the poisoned mode and in the transition mode, sputtering makes up more than 80% of the total gain rate for atomic oxygen. We also investigate the possibility of depositing stoichiometric TiO2 in the transition mode. Published by AIP Publishing.

  • 149.
    Lundin, Daniel
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics .
    Cross-field Ion Transport in High Power Impulse Magnetron Sputtering and it's Effect on Deposition Rates2008In: HIPIMS Days,2008, 2008Conference paper (Other academic)
  • 150.
    Lundin, Daniel
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics .
    Effect on Thin Film Growth due to Anomalous Transport in High Power Impulse Magnetron Sputtering2008In: AVS 55:th International Symposium,2008, 2008Conference paper (Other academic)
    Abstract [en]

      

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