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  • 101.
    Mockuté, Aurelija
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Dahlqvist, Martin
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Emmerlich, Jens
    Rhein Westfal TH Aachen, Germany .
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Schneider, Jochen M
    Rhein Westfal TH Aachen, Germany .
    Persson, Per O A
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Rosén, Johanna
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Synthesis and ab initio calculations of nanolaminated (Cr,Mn)2AlC compounds2013In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 87, no 9Article in journal (Refereed)
    Abstract [en]

    We present an ab initio theoretical analysis of the temperature-dependent stability of inherently nanolaminated (Cr1−xMnx)2AlC. The results indicate energetic stability over the composition range x = 0.0 to 0.5 for temperatures ≥600 K. Corresponding thin film compounds were grown by magnetron sputtering from four elemental targets. X-ray diffraction in combination with analytical transmission electron microscopy, including electron energy-loss spectroscopy and energy dispersive x-ray spectroscopy analysis, revealed that the films were epitaxial (0001)-oriented single-crystals with x up to 0.16.

  • 102.
    Mockuté, Aurelija
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Dahlqvist, Martin
    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.
    O A Persson, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Rosén, Johanna
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Oxygen incorporation in Ti2AlC thin films studied by electron energy loss spectroscopy and ab initio calculations2013In: Journal of Materials Science, ISSN 0022-2461, E-ISSN 1573-4803, Vol. 48, no 10, p. 3686-3691Article in journal (Refereed)
    Abstract [en]

    Substitution of C with O in hexagonal inherently nanolaminated Ti2AlC has been studied experimentally and theoretically. Ti2Al(C1−x O x ) thin films with x ≤ 0.52 are synthesized by both cathodic arc deposition with the uptake of residual gas O, and solid-state reaction between understoichiometric TiC y and Al2O3(0001) substrates. The compositional analysis is made by analytical transmission electron microscopy, including electron energy loss spectroscopy. Furthermore, predictive ab initio calculations are performed to evaluate the influence of substitutional O on the shear stress at different strains for slip on the (0001) basal plane in the [−1010] and [1−210] directions.

  • 103.
    Mockuté, Aurelija
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Palisaitis, Justinas
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Alling, Björn
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering. Max Planck Institute Eisenforsch GmbH, Germany.
    Berastegui, P.
    Uppsala University, Sweden.
    Broitman, Esteban
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, Faculty of Science & Engineering.
    Näslund, Lars-Åke
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, Faculty of Science & Engineering.
    Nedfors, Nils
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Lu, Jun
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    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.
    Patscheider, J.
    EMPA, Switzerland.
    Jansson, U.
    Uppsala University, Sweden.
    Persson, Per O A
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Rosén, Johanna
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Age hardening in (Ti1-xAlx)B2+Delta thin films2017In: Scripta Materialia, ISSN 1359-6462, E-ISSN 1872-8456, Vol. 127, p. 122-126Article in journal (Refereed)
    Abstract [en]

    Thin films of (Ti0.71Al0.29)B2+1.08 have been deposited by magnetron sputtering. Post-deposition annealing at 1000 degrees C for 1 h results in increased hardness and elastic modulus, from 32 to 37 GPa and from 436 to 461 GPa, respectively. In both as-deposited and annealed states the films adhere well to the substrate, indicating no considerable internal stress. The initial high hardness is attributed to a columnar microstructure consisting of crystalline (Ti,Al)B-2 columns separated by an amorphous B matrix. The observed age hardening corresponds to phase separation within the (Ti,Al)B-2 columns including the formation of Ti-deficient crystallites within the grain interior upon annealing. (C) 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  • 104.
    Mockuté, Aurelija
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Palisaitis, Justinas
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Nedfors, Nils
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Berastegui, P.
    Uppsala Univ, Sweden.
    Broitman, Esteban
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, Faculty of Science & Engineering. SKF Res and Technol Dev Ctr, Netherlands.
    Alling, Björn
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering.
    Näslund, Lars-Åke
    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.
    Patscheider, J.
    Evatec AG, Switzerland.
    Jansson, U.
    Uppsala Univ, Sweden.
    Persson, Per O A
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Rosén, Johanna
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Synthesis and characterization of (Ti1-xAlx)B2+Delta thin films from combinatorial magnetron sputtering2019In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 669, p. 181-187Article in journal (Refereed)
    Abstract [en]

    (Ti1-xAlx)B2+Delta films with a lateral composition gradient of x = [0.30-0.66] and Delta = [0.07-1.22] were deposited on an Al2O3 wafer by dual magnetron sputtering at 400 degrees C from sintered TiB2 and AlB2 targets. Composition analysis indicates that higher Ti:Al ratios favor overstoichiometry in B and a reduced incorporation of O. Transmission electron microscopy reveals distinctly different microstructures of Ti- and Al-rich compositions, with formation of characteristic conical growth features for the latter along with a lower degree of crystallinity and significantly less tissue phase from B segregation at the grain boundaries. For Al-rich films, phase separation into Ti- and Al-rich diboride nanometer-size domains is observed and interpreted as surface-initiated spinodal decomposition. The hardness of the films ranges from 14 to 28 GPa, where the higher values were obtained for the Ti-rich regions of the metal boride.

    The full text will be freely available from 2020-10-26 15:00
  • 105.
    Mockuté, Aurelija
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Persson, Per O A
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Lu, Jun
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Arts and Sciences.
    Ingason, Arni Sigurdur
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Magnus, F.
    Uppsala University, Sweden .
    Olafsson, S.
    University of Iceland, Iceland .
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Rosén, Johanna
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Structural and magnetic properties of (Cr1-xMnx)(5)Al-8 solid solution and structural relation to hexagonal nanolaminates2014In: Journal of Materials Science, ISSN 0022-2461, E-ISSN 1573-4803, Vol. 49, no 20, p. 7099-7104Article in journal (Refereed)
    Abstract [en]

    Electron microscopy is used to reveal the competitive epitaxial growth of bcc structure (Cr1-x Mn (x) )(5)Al-8 and (Cr1-y Mn (y) )(2)AlC [M (n+1)AX (n) (MAX)] phase during both magnetron sputtering and arc deposition. X-ray diffraction theta-2 theta measurements display identical peak positions of (000n)-oriented MAX phase and (Cr1-x Mn (x) )(5)Al-8, due to the interplanar spacing of (Cr1-x Mn (x) )(5)Al-8 that matches exactly half a unit cell of (Cr1-y Mn (y) )(2)AlC. Vibrating sample magnetometry shows that a thin film exclusively consisting of (Cr1-x Mn (x) )(5)Al-8 exhibits a magnetic response, implying that the potential presence of this phase needs to be taken into consideration when evaluating the magnetic properties of (Cr, Mn)(2)AlC.

  • 106.
    Mockuté, Aurelija
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Persson, Per O A.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Magnus, F
    Department of Physics and Astronomy, Uppsala University, Uppsala, Sweden/University of Iceland, Iceland .
    Ingason, Arni Sigurdur
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Olafsson, S.
    University of Iceland, Iceland .
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Rosén, Johanna
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Synthesis and characterization of arc deposited magnetic (Cr,Mn)2AlC MAX phase films2014In: Physica Status Solidi. Rapid Research Letters, ISSN 1862-6254, E-ISSN 1862-6270, Vol. 8, no 5, p. 420-423Article in journal (Refereed)
    Abstract [en]

    (Cr1-xMnx)2AlC MAX phase thin films were synthesized by cathodic arc deposition. Scanning transmission electron microscopy including local energy dispersive X-ray spectroscopy analysis of the as-deposited films reveals a Mn incorporation of 10 at.% in the structure, corresponding to x = 0.2. Magnetic properties were characterized with vibrating sample magnetometry, revealing a magnetic response up to at least room temperature, thus verifying previous theoretical predictions of an antiferromagnetic or ferromagnetic ground state for Cr2AlC upon alloying with Mn.

  • 107.
    Moubah, R.
    et al.
    Uppsala University. Sweden.
    Magnus, F.
    Uppsala University, Sweden.
    Warnatz, T.
    Uppsala University, Sweden.
    Palsson, G. K.
    Uppsala University, Sweden.
    Kapaklis, V.
    Uppsala University, Sweden.
    Devishvili, A.
    Uppsala University, Sweden.
    Palisaitis, Justinas
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Persson, Per O. A.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Hjörvarsson, B.
    Uppsala University, Sweden.
    Discrete Layer-by-Layer Magnetic Switching in Fe/MgO(001) Superlattices2016In: Physical Review Applied, ISSN 2331-7019, Vol. 5, no 044011Article in journal (Refereed)
    Abstract [en]

    We report on a discrete layer-by-layer magnetic switching in Fe=MgO superlattices driven by anantiferromagnetic interlayer exchange coupling. The strong interlayer coupling is mediated by tunnelingthrough MgO layers with thicknesses up to at least 1.8 nm, and the coupling strength varies with MgOthickness. Furthermore, the competition between the interlayer coupling and magnetocrystalline anisotropystabilizes both 90° and 180° periodic alignment of adjacent layers throughout the entire superlattice. Thetunable layer-by-layer switching, coupled with the giant tunneling magnetoresistance of Fe=MgO=Fejunctions, is an appealing combination for three-dimensional spintronic memories and logic devices.

  • 108.
    Muhammad, Junaid
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Chen, Yen-Ting
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. 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.
    Garbrecht, Magnus
    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, Thin Film Physics. 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.
    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.
    Liquid-target Reactive Magnetron Sputter Epitaxy of High Quality GaN(0001ɸ)ɸ Nanorods on Si(111)2015In: Materials Science in Semiconductor Processing, ISSN 1369-8001, E-ISSN 1873-4081, Vol. 39, p. 702-710Article in journal (Refereed)
    Abstract [en]

    Direct current magnetron sputter epitaxy with a liquid Ga sputtering target hasbeen used to grow single-crystal GaN(0001) nanorods directly on Si(111)substrates at different working pressures ranging from 5 to 20 mTorr of pure N2,.The as-grown GaN nanorods exhibit very good crystal quality from bottom to topwithout stacking faults, as determined by transmission electron microscopy. Thecrystal quality is found to increase with increasing working pressure. X-raydiffraction results show that all the rods are highly (0001)-oriented. Thenanorods exhibit an N-polarity, as determined by convergent beam electrondiffraction methods. Sharp and well-resolved 4 K photoluminescence peaks at ~3.474 eV with a FWHM ranging from 1.7 meV to 35 meV are attributed to theintrinsic GaN band edge emission and corroborate the superior structuralproperties of the material. Texture measurements reveal that the rods haverandom in-plane orientation when grown on Si(111) with native oxide, while theyhave an in-plane epitaxial relationship of GaN[110] // Si[110] when grown onsubstrates without surface oxide.

  • 109.
    Muhammad, Junaid
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Lundin, Daniel
    Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics. 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, Thin Film Physics. Linköping University, The Institute of Technology.
    Darakchieva, Vanya
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. 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.
    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, Thin Film Physics. Linköping University, The Institute of Technology.
    Lai, W-J
    National Taiwan University.
    Chen, L-C
    National Taiwan University.
    Chen, K-H
    National Taiwan University.
    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.
    Two-domain formation during the epitaxial growth of GaN (0001) on c-plane Al2O3 (0001) by high power impulse magnetron sputtering2011In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 110, no 12, p. 123519-Article in journal (Refereed)
    Abstract [en]

    We study the effect of high power pulses in reactive magnetron sputter epitaxy on the structural properties of GaN (0001) thin films grown directly on Al2O3 (0001) substrates. The epilayers are grown by sputtering from a liquid Ga target, using a high power impulse magnetron sputtering power supply in a mixed N2/Ar discharge. X-ray diffraction, micro-Raman, micro-photoluminescence, and transmission electron microscopy investigations show the formation of two distinct types of domains. One almost fully relaxed domain exhibits superior structural and optical properties as evidenced by rocking curves with a full width at half maximum of 885 arc sec and a low temperature band edge luminescence at 3.47 eV with the full width at half maximum of 10 meV. The other domain exhibits a 14 times higher isotropic strain component, which is due to the higher densities of the point and extended defects, resulting from the ion bombardment during growth. Voids form at the domain boundaries. Mechanisms for the formation of differently strained domains, along with voids during the epitaxial growth of GaN are discussed.

  • 110.
    Muhammad, Junaid
    et al.
    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, Thin Film Physics. 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.
    Darakchieva, Vanya
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Hsiao, Ching-Lien
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. 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.
    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.
    Stress Evolution during Growth of GaN (0001)/Al2O3 (0001) by Reactive DC Magnetron Sputter Epitaxy2014In: Journal of Physics D: Applied Physics, ISSN 0022-3727, E-ISSN 1361-6463, Vol. 47, no 14, p. 145301-Article in journal (Refereed)
    Abstract [en]

    We study the real time stress evolution, by in-situ curvature measurements, during magnetron sputter epitaxy of GaN (0001) epilayers at different growth temperatures, directly on Al2O3 (0001) substrates. The epilayers are grown by sputtering from a liquid Ga target in a mixed N2/Ar discharge. For 600 °C, a tensile biaxial stress evolution is observed, while for 700 °C and 800 °C, compressive stress evolutions are observed. Structural characterization by crosssectional transmission electron microscopy, and atomic force microscopy revealed that films grew at 700 °C and 800 °C in a layer-by-layer mode while a growth temperature of 600 °C led to an island growth mode. High resolution Xray diffraction data showed that edge and screw threading dislocation densities decreased with increasing growth temperature with a total density of 5.5×1010 cm-2. The observed stress evolution and growth modes are explained by a high adatom mobility during magnetron sputter epitaxy at 700 - 800 °C. Also other possible reasons for the different stress evolutions are discussed.

  • 111.
    Nedfors, Nils
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Mockuté, Aurelija
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Palisaitis, Justinas
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Persson, Per O A
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Näslund, Lars-Åke
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, Faculty of Science & Engineering.
    Rosén, Johanna
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Influence of pulse frequency and bias on microstructure and mechanical properties of TiB2 coatings deposited by high power impulse magnetron sputtering2016In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 304, p. 203-210Article in journal (Refereed)
    Abstract [en]

    The high plasma density and large fraction of ionized species created in a high power impulse magnetron sputtering (HiPIMS) discharge add new measures to control the sputtering process. We have studied the sputtering of TiB2 coatings by HiPIMS from a compound target in an industrial system. How the degree of ionized species effects coating microstructure and mechanical properties has been investigated by varying the pulse frequency between 200 Hz and 1000 Hz while keeping the average power constant at 2 kW. The coatings have a B/Ti atomic ratio amp;gt;= 2.5 and a microstructure exhibiting 001 textured nanocolumnar grains with an amorphous B tissue phase in grain boundaries. Lower frequencies provide higher degree of ionization, which does, however, increase the compressive residual stress in the coatings. This results in harder coatings and the highest hardness of 49 GPa is measured for the coating deposited at 200 Hz (-3.8 GPa residual stress). A change in texture from random orientation to 001 texture is achieved when going from regular dc sputtering to HiPIMS at a floating bias. Superhard (H = 43 GPa) TiB2 coatings with a relatively low compressive stress of about -1 GPa can be deposited by HiPIMS at 1000 Hz using floating bias. (C) 2016 Elsevier B.V. All rights reserved.

  • 112.
    Nedfors, Nils
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Mraz, Stanislav
    Rhein Westfal TH Aachen, Germany.
    Palisaitis, Justinas
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Persson, Per O A
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Lind, Hans
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Kolozsvari, Szilard
    Plansee Composite Mat GmbH, Germany.
    Schneider, Jochen M.
    Rhein Westfal TH Aachen, Germany.
    Rosén, Johanna
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Influence of the Al concentration in Ti-Al-B coatings on microstructure and mechanical properties using combinatorial sputtering from a segmented TiB2/AlB2 target2019In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 364, p. 89-98Article in journal (Refereed)
    Abstract [en]

    A series of (TixAl1-x)B2 +y coatings with compositions in the range of x = 0.01-0.94 and y = 1.70-2.92 has been synthesized using magnetron sputtering from a segmented TiB2/AlB2 target. The coatings are amorphous at x amp;lt;= 0.05 while a (TixAl1-x)B2+y solid solution forms for x amp;gt; 0.05. As a consequence of the sputtering process, the B/(Ti + Al) atomic ratio varied with the metal content resulting in the formation of under-stoichiometric coatings at x amp;lt; 0.35 and over-stoichiometric coatings at x amp;gt; 0.35. Surplus Al segregates to grain boundaries of the under-stoichiometric coatings whereas the over-stoichiometric coatings have a tissue phase containing mainly B and some Al. The B-rich tissue phase restrains grain growth in the in-plane direction while an increase in Ti content promotes the growth of columnar structured coatings with a pronounced (001) texture up to x = 0.84. The combination of such preferred orientation and tissue phase results in the highest hardness of 39 GPa for the (Ti0.79Al0.21)B-2.70 coating. The Youngs modulus, on the other hand, increases continuously from 262 GPa for the most Al-rich coating to 478 GPa for the most Ti-rich coating. Comparing to calculated values of Youngs modulus, good agreement is observed for the close to stoichiometric coatings (x = 0.40-0.50). For the off-stoichiometric coatings, the experimental values are lower due to the existence of the tissue phase.

  • 113.
    Nedfors, Nils
    et al.
    Uppsala University, Sweden.
    Tengstrand, Olof
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Lu, Jun
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Persson, Per O A
    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.
    Jansson, Ulf
    Uppsala University, Sweden.
    Superhard NbB2 −x thin films deposited by dc magnetron sputtering2014In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 257, p. 295-300Article in journal (Refereed)
    Abstract [en]

    We have deposited weakly textured substoichiometric NbB2-x thin films by magnetron sputtering from an NbB2 target. The films exhibit superhardness (42 +/- 4 GPa), previously only observed in overstoichiometric TiB2 thin films, and explained by a self-organized nanostructuring, where thin TiB2 columnar grains hinder nucleation and slip of dislocations and a B-rich tissue phase between the grains prevent grain-boundary sliding. The wide homogeneity range for the NbB2 phase allows a similar ultra-thin B-rich tissue phase to form between thin (5-10 nm) columnar NbB2-x grains also for films with a B/Nb atomic ratio of 1.8, as revealed here by analytical aberration-corrected scanning transmission electron microscopy. Furthermore, a coefficient of friction of 0.16 is measured for an NbB2-x film sliding against stainless steel with a wear rate of 5 x 10(-7) mm(3)/Nm. X-ray photoelectron spectroscopy results suggest that the low friction is due to the formation of a lubricating boric acid film.

  • 114.
    Palisaitis, Justinas
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics.
    Bergman, Peder
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Persson, Per
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics.
    Two Dimensional X-ray Diffraction Mapping of Basal Plane Orientation on SiC Substrates2009In: ECSCRM2008,2009, Materials Science Forum Vols. 615-617: Trans Tech Publications , 2009, p. 275-278Conference paper (Refereed)
    Abstract [en]

    We have performed 2D X-ray diffraction mapping of the SiC lattice basal plane orientation over full 2” SiC substrates. Measurements of the omega angle were made in two perpendicular directions <11-20> and <1-100>, which gives the complete vectorized tilt of the basal planes. The Mapping revealed two characteristic bending behaviors on measured commercial wafers. The first is characterized by large variations in omega angle across the wafer in both crystallographic directions. The continuously changing omega angle in both directions gives the wafer an apparent rotationally symmetric bending which is concave towards the growth direction. The second characteristic behavior is seen in wafers with lower degree of omega angle variation. The variations in this type of wafers are not changing linearly, but are bending the basal planes with two-fold symmetry.

  • 115.
    Palisaitis, Justinas
    et al.
    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, 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.
    Birch, Jens
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. 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.
    Spinodal decomposition of Al0.3In0.7N(0001) layers following in-situ thermal annealing as investigated by STEM-VEELS2012Manuscript (preprint) (Other academic)
    Abstract [en]

    The thermal stability and spinodal decomposition of thin Al0.3In0.7N layers was studied in-situ by scanning transmission electron microscopy following annealing in a temperature range from 700 oC to 900 oC. The results show that for increasing layer thicknesses (from ~4 nm to ~22 nm) surface directed spinodal decomposition is initiated at Al0.3In0.7N/AlN interfaces and columnar boundaries in the Al0.3In0.7N layers. In the thin layers (~10 nm) annealing caused a single composition layer to split into doubly modulated layers with a compositional undulation perpendicular to the interfaces, while for the thicker layers (~22 nm) the spinodally decomposed structure is more random.

  • 116.
    Palisaitis, Justinas
    et al.
    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, 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.
    Birch, Jens
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. 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.
    Thermal stability of Al1−xInxN (0 0 0 1) throughout the compositional range as investigated during in situ thermal annealing in a scanning transmission electron microscope2013In: Acta Materialia, ISSN 1359-6454, E-ISSN 1873-2453, Vol. 61, no 12, p. 4683-4688Article in journal (Refereed)
    Abstract [en]

    The thermal stability of Al1−xInxN (0 ⩽ ⩽ 1) layers was investigated by scanning transmission electron microscopy (STEM) imaging, electron diffraction, and monochromated valence electron energy loss spectroscopy during in situ annealing from 750 to 950 °C. The results show two distinct decomposition paths for the layers richest in In (Al0.28In0.72N and Al0.41In0.59N) that independently lead to transformation of the layers into an In-deficient, nanocrystalline and a porous structure. The In-richest layer (Al0.28In0.72N) decomposes at 750 °C, where the decomposition process is initiated by In forming at grain boundaries and is characterized by an activation energy of 0.62 eV. The loss of In from the Al0.41In0.59N layer was initiated at 800 °C through continuous desorption. No In clusters were observed during this decomposition process, which is characterized by an activation energy of 1.95 eV. Finally, layers richest in Al (Al0.82In0.18N and Al0.71In0.29N) were found to resist thermal annealing, although the initial stages of decomposition were observed for the Al0.71In0.29N layer.

  • 117.
    Palisaitis, Justinas
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Hsiao, Ching-Lien
    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.
    Birch, Jens
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Persson, Per O A
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Core-shell formation in self-induced InAlN nanorods2017In: Nanotechnology, ISSN 0957-4484, E-ISSN 1361-6528, Vol. 28, no 11, article id 115602Article in journal (Refereed)
    Abstract [en]

    We have examined the early stages of self-induced InAlN core-shell nanorod (NR) formation processes on amorphous carbon substrates in plan-view geometry by means of transmission electron microscopy methods. The results show that the grown structure phase separates during the initial moments of deposition into a majority of Al-rich InAlN and a minority of In-enriched InAlN islands. The islands possess polygonal shapes and are mainly oriented along a crystallographic c-axis. The growth proceeds with densification and coalescence of the In-enriched islands, resulting in a base for the In-enriched NR cores with shape transformation to hexagonal. The Al-rich shell formation around such early cores is observed at this stage. The matured core-shell structure grows axially and radially, eventually reaching a steady growth state which is dominated by the axial NR growth. We discuss the NR formation mechanism by considering the adatom surface kinetics, island surface energy, phase separation of InAlN alloys, and incoming flux directions during dual magnetron sputter epitaxy.

  • 118.
    Palisaitis, Justinas
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Hsiao, Ching-Lien
    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.
    Birch, Jens
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Persson, Per O A
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Direct observation of spinodal decomposition phenomena in InAlN alloys during in-situ STEM heating2017In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 7, article id 44390Article in journal (Refereed)
    Abstract [en]

    The spinodal decomposition and thermal stability of thin In0.72Al0.28N layers and In0.72Al0.28N/AlN superlattices with AlN(0001) templates on Al2O3(0001) substrates was investigated by in-situ heating up to 900 degrees C. The thermally activated structural and chemical evolution was investigated in both plan-view and cross-sectional geometries by scanning transmission electron microscopy in combination with valence electron energy loss spectroscopy. The plan-view observations demonstrate evidence for spinodal decomposition of metastable In0.72Al0.28N after heating at 600 degrees C for 1 h. During heating compositional modulations in the range of 2-3 nm-size domains are formed, which coarsen with applied thermal budgets. Cross-sectional observations reveal that spinodal decomposition begin at interfaces and column boundaries, indicating that the spinodal decomposition has a surface-directed component.

  • 119.
    Palisaitis, Justinas
    et al.
    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.
    Junaid, Muhammad
    Linköping University, Department of Physics, Chemistry and Biology. 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.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Persson, Per O.Å.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Effect of strain on low-loss electron energy loss spectra of group III-nitrides2011In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 84, no 24, p. 245301-Article in journal (Refereed)
    Abstract [en]

    Low-loss EELS was used to acquire information about the strain state in group III-nitrides. Experimental and theoretical simulation results show that the bulk plasmon peak position varies near linearly with unit cell volume variations due to strain. A unit cell volume change of 1% results in a bulk plasmon peak shift of 0.159 eV, 0.168 eV, and 0.079 eV for AlN, GaN, and InN, respectively, according to simulations. The AlN peak shift was experimentally corroborated with a peak shift of 0.156 eV, where the applied strain caused a 1% volume change. It is also found that while the bulk plasmon energy can be used as a measure of the composition in a III-nitride alloy for relaxed structures, the presence of strain significantly affects such a measurement. The strain has a lower impact on the peak shift for Al(1-x)InxN (3% compositional error per 1 % volume change) and In(1-x)GaxN alloys compared to significant variations for Al(1-x)GaxN (16% compositional error for 1% volume change). Hence low-loss studies off III-nitrides, particularly for confined structures, must be undertaken with care and understanding.

  • 120.
    Palisaitis, Justinas
    et al.
    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, Thin Film Physics. Linköping University, The Institute of Technology.
    Junaid, Muhammad
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Xie, Mengyao
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Darakchieva, Vanya
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Carlin, Jean-Francois
    Ecole Polytechnique Fédérale de Lausanne.
    Grandjean, Nicolas
    Ecole Polytechnique Fédérale de Lausanne.
    Birch, 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.
    Persson, Per O.Å.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Standard-free composition measurements of Alx In1–xN by low-loss electron energy loss spectroscopy2011In: physica status solidi (RRL) – Rapid Research Letters, ISSN 1862-6270, Vol. 5, no 2, p. 50-52Article in journal (Refereed)
    Abstract [en]

    We demonstrate a standard-free method to retrieve compositional information in Alx In1–xN thin films by measuring the bulk plasmon energy (Ep), employing electron energy loss spectroscopy (EELS) in a scanning transmission electron microscope (STEM). Two series of samples were grown by magnetron sputter epitaxy (MSE) and metal organic vapor phase epitaxy (MOVPE), which together cover the full com- positional range 0 ≤ x ≤ 1. Complementary compositional measurements were obtained using Rutherford backscattering spectroscopy (RBS) and the lattice parameters were obtained by X-ray diffraction (XRD). It is shown that Ep follows a linear relation with respect to composition and lattice parameter between the alloying elements from AlN to InN allowing for straightforward compositional analysis.

  • 121.
    Palisaitis, Justinas
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Lundskog, Anders
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Forsberg, Urban
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Janzén, Erik
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. 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.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. 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.
    Characterization of InGaN/GaN quantum well growth using monochromated valence electron energy loss spectroscopy2014In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 115, no 3, p. 034302-Article in journal (Refereed)
    Abstract [en]

    The early stages of InGaN/GaN quantum wells growth for In reduced conditions have been investigated for varying thickness and composition of the wells. The structures were studied by monochromated STEM–VEELS spectrum imaging at high spatial resolution. It is found that beyond a critical well thickness and composition, quantum dots (>20 nm) are formed inside the well. These are buried by compositionally graded InGaN, which is formed as GaN is grown while residual In is incorporated into the growing structure. It is proposed that these dots may act as carrier localization centers inside the quantum wells.

  • 122.
    Palisaitis, Justinas
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Persson, Ingemar
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Halim, Joseph
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Rosén, Johanna
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Persson, Per O. Å.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    On the Structural Stability of MXene and the Role of Transition Metal Adatoms2018In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 10, no 23, p. 10850-10855Article in journal (Refereed)
    Abstract [en]

    In the present communication, the atomic structure and coordination of surface adsorbed species on Nb2C MXene is investigated over time. In particular, the influence of the Nb adatoms on the structural stability and oxidation behavior of the MXene is addressed. This investigation is based on plan-view geometry observations of single Nb2C MXene sheets by a combination of atomic-resolution scanning transmission electron microscopy (STEM), electron energy loss spectroscopy (EELS) and STEM image simulations.

  • 123.
    Palmquist, Jens-Petter
    et al.
    Uppsala University, Department of Materials Chemistry, The Ångström Laboratory, Uppsala, Sweden.
    Li, Sa
    Uppsala University, Department of Physics, The Ångström Laboratory, Uppsala, Sweden.
    Persson, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Emmerlich, Jens
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Wilhelmsson, Ola
    Uppsala University, Department of Materials Chemistry, The Ångström Laboratory, Uppsala, Sweden.
    Högberg, Hans
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Katsnelson, M. I.
    Uppsala University, Department of Physics, The Ångström Laboratory, Uppsala, Sweden.
    Johansson, Börje
    Uppsala University, Department of Physics, The Ångström Laboratory, Uppsala, Sweden.
    Ahuja, Rajeev
    Uppsala University, Department of Physics, The Ångström Laboratory, Uppsala, Sweden.
    Eriksson, Olle
    Uppsala University, Department of Physics, The Ångström Laboratory, Uppsala, Sweden.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Jansson, Ulf
    Uppsala University, Department of Materials Chemistry, The Ångström Laboratory, Uppsala, Sweden.
    Mn+1AXn phases in the Ti-Si-C system studied by thin-film synthesis and ab initio calculations2004In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 70, no 16, p. 165401-Article in journal (Refereed)
    Abstract [en]

    Thin films of Mn+1AXn layered compounds in the Ti-Si-C system were deposited on MgO(111) and Al2O3(0001) substrates held at 900°C using dc magnetron sputtering from elemental targets of Ti, Si, and C. We report on single-crystal and epitaxial deposition of Ti3SiC2 (the previously reported MAX phase in the Ti-Si-C system), a previously unknown MAX phase Ti4SiC3 and another type of structure having the stoichiometry of Ti5Si2C3 and Ti7Si2C5. The latter two structures can be viewed as an intergrowth of 2 and 3 or 3 and 4 M layers between each A layer. In addition, epitaxial films of Ti5Si3Cx were deposited and Ti5Si4 is also observed. First-principles calculations, based on density functional theory (DFT) of Tin+1SiCn for n=1,2,3,4 and the observed intergrown Ti5Si2C3 and Ti7Si2C5 structures show that the calculated difference in cohesive energy between the MAX phases reported here and competing phases (TiC, Ti3SiC2, TiSi2, and Ti5Si3) are very small. This suggests that the observed Ti5Si2C3 and Ti7Si2C5 structures at least should be considered as metastable phases. The calculations show that the energy required for insertion of a Si layer in the TiC matrix is independent of how close the Si layers are stacked. Hardness and electrical properties can be related to the number of Si layers per Ti layer. This opens up for designed thin film structures the possibility to tune properties.

  • 124.
    Palmquist, J.-P.
    et al.
    Uppsala University, Department of Materials Chemistry, Ångström Laboratory, P.O. Box 538, SE-751 21 Uppsala, Sweden.
    Jansson, U.
    Uppsala University, Department of Materials Chemistry, Ångström Laboratory, P.O. Box 538, SE-751 21 Uppsala, Sweden.
    Seppänen, Timo
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics.
    Persson, Per
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics.
    Birch, Jens
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics.
    Hultman, Lars
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics.
    Isberg, P.
    ABB Group Services Center AB, Corporate Research, SE-721 78 Västerås, Sweden.
    Magnetron sputtered epitaxial single-phase Ti3SiC2 thin films2002In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 81, no 5, p. 835-Article in journal (Refereed)
    Abstract [en]

    [No abstract available]

  • 125.
    Paskova, Tanja
    et al.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Darakchieva, Vanya
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Paskov, Plamen
    Linköping University, Department of Physics, Chemistry and Biology. 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.
    Valcheva, E.
    Persson, Per
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics.
    Arnaudov, B.
    Tungasmita, S.
    Monemar, Bo
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Nonpolar a-plane HVPE GaN: growth and in-plane anisotropic properties2005In: Physica Status Solidi. C, Current topics in solid state physics, ISSN 1610-1634, E-ISSN 1610-1642, Vol. 2, p. 2027-2031Article in journal (Refereed)
  • 126.
    Paskova, Tanja
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Darakchieva, Vanya
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Paskov, Plamen
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Birch, Jens
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics.
    Valcheva, E
    Persson, Per
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics.
    Arnaudov, B
    Tungasmitta, S
    Monemar, Bo
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Properties of nonpolar a-plane GaN films grown by HVPE with AlN buffers2005In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 281, no 1, p. 55-61Article in journal (Refereed)
    Abstract [en]

    The influence of high temperature AlN buffer layers on the morphology, structural and optical characteristics of a-plane GaN grown by hydride vapour phase epitaxy on r-plane sapphire was investigated. While the morphology of the a-GaN was found to be significantly improved by using a-plane AlN buffer layer similarly to the effect observed in c-plane hydride vapour phase epitaxy GaN growth, the microstructure ensemble was revealed to be more complicated in comparison to that of the c-plane GaN. Higher dislocation density and prismatic stacking faults were observed. Moreover, in-plane anisotropic structural characteristics were revealed by high resolution X-ray diffraction employing azimuthal dependent and edge X-ray measurement symmetric geometry. In addition, the near band edge photo luminescence peaks, red-shifted with respect to that in c-plane GaN were observed. The latter were explained by the influence of the higher defect density and more complex strain distribution. (c) 2005 Elsevier B.V. All rights reserved.

  • 127.
    Paskova, Tanja
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Tungasmita, Sukkaneste
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Valcheva, E
    Linkoping Univ, IFM, S-58183 Linkoping, Sweden Univ Sofia, Fac Phys, Sofia 1164, Bulgaria Aixtron AG, D-52072 Aachen, Germany.
    Svedberg, EB
    Arnaudov, B
    Linkoping Univ, IFM, S-58183 Linkoping, Sweden Univ Sofia, Fac Phys, Sofia 1164, Bulgaria Aixtron AG, D-52072 Aachen, Germany.
    Evtimova, S
    Linkoping Univ, IFM, S-58183 Linkoping, Sweden Univ Sofia, Fac Phys, Sofia 1164, Bulgaria Aixtron AG, D-52072 Aachen, Germany.
    Persson, Per
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics.
    Henry, Anne
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Beccard, R
    Linkoping Univ, IFM, S-58183 Linkoping, Sweden Univ Sofia, Fac Phys, Sofia 1164, Bulgaria Aixtron AG, D-52072 Aachen, Germany.
    Heuken, M
    Linkoping Univ, IFM, S-58183 Linkoping, Sweden Univ Sofia, Fac Phys, Sofia 1164, Bulgaria Aixtron AG, D-52072 Aachen, Germany.
    Monemar, Bo
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Hydride vapour phase homoepitaxial growth of GaN on MOCVD-grown 'templates'2000Conference paper (Refereed)
    Abstract [en]

    We report on an improved quality of thick HVPE-GaN grown on MOCVD-GaN 'template' layers compared to the material grown directly on sapphire. The film-substrate interface revealed by cathodoluminescence measurements shows an absence of highly doped columnar structures which are typically present in thick HVPE-GaN films grown directly on sapphire. This improved structure results in a reduction of two orders of magnitude of the free carrier concentration from Hall measurements. It was found that the structure, morphology, electrical and optical properties of homoepitaxial thick GaN layers grown by HVPE were strongly influenced by the properties of the MOCVD-GaN 'template'. Additionally the effect of Si doping of the GaN buffer layers on the HVPE-GaN properties was analysed.

  • 128.
    Paskova, Tanja
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Valcheva, E
    Linkoping Univ, Dept Phys & Measurement Technol, S-58183 Linkoping, Sweden Aixtron AG, D-52072 Aachen, Germany.
    Birch, Jens
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics.
    Tungasmita, Sukkaneste
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Persson, Per
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics.
    Beccard, R
    Linkoping Univ, Dept Phys & Measurement Technol, S-58183 Linkoping, Sweden Aixtron AG, D-52072 Aachen, Germany.
    Heuken, M
    Linkoping Univ, Dept Phys & Measurement Technol, S-58183 Linkoping, Sweden Aixtron AG, D-52072 Aachen, Germany.
    Monemar, Bo
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Effect of Si doping of metalorganic chemical vapor deposition-GaN templates on the defect arrangement in hydride vapor phase epitaxy-GaN overgrown layers2000In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 88, no 10, p. 5729-5732Article in journal (Refereed)
    Abstract [en]

    Two different types of dislocation arrangements have been observed in hydride vapor-phase epitaxial GaN films grown on sapphire substrates using both undoped and Si-doped GaN templates grown by metalorganic chemical vapor deposition: (i) predominantly straight threading dislocations parallel to the [0001] direction in the layer grown on an undoped template, and (ii) a network of interacting dislocations of edge, screw, and mixed character in the layer grown on a Si-doped template. The two types of defect distribution result in essentially different surface morphologies, respectively: (i) low-angle grain boundaries formed by pure edge dislocations around spiral grown hillocks, and (ii) smooth surface intersected by randomly distributed dislocations. The Si doping of the GaN templates was found to enhance defect interaction in the templates and to enable a reduction of the dislocation density in the overgrown thick GaN films, although it does not lead to an improvement of the overall structural properties of the material. (C) 2000 American Institute of Physics. [S0021-8979(00)08422-X].

  • 129.
    Paskova, Tanja
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Valcheva, E.
    Birch, Jens
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics.
    Tungasmita, Sukkaneste
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Persson, Per
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics.
    Paskov, Plamen
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Evtimova, S.
    Faculty of Physics, Sofia University, 5, J. Bourchier blvd., 1164 Sofia, Bulgaria.
    Abrashev, M.
    Faculty of Physics, Sofia University, 5, J. Bourchier blvd., 1164 Sofia, Bulgaria.
    Monemar, Bo
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Defect and stress relaxation in HVPE-GaN films using high temperature reactively sputtered AlN buffer2001In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 230, no 3-4, p. 381-386Article in journal (Refereed)
    Abstract [en]

    The influence of high temperature buffer layers on the structural characteristics of GaN grown by hydride vapour phase epitaxy on sapphire was investigated. Strain relaxation as well as mismatch-induced defect reduction in thick GaN layers grown on AlN buffer was microscopically identified using cathodoluminescence and micro-Raman spectroscopy in cross-section of the films. The results were correlated with photoluminescence and Hall-effect data of layers with different thicknesses. These relaxation processes were suggested to account for the specific defect distribution in the buffers revealed by high-resolution X-ray diffraction and transmission electron microscopy. © 2001 Elsevier Science B.V. All rights reserved.

  • 130.
    Persson, Ingemar
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    El Ghazaly, Ahmed
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Tao, Quanzheng
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Halim, Joseph
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Kota, Sankalp
    Drexel Univ, PA 19104 USA.
    Darakchieva, Vanya
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Palisaitis, Justinas
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Barsoum, Michel W.
    Drexel Univ, PA 19104 USA.
    Rosén, Johanna
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Persson, Per O A
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Tailoring Structure, Composition, and Energy Storage Properties of MXenes from Selective Etching of In-Plane, Chemically Ordered MAX Phases2018In: Small, ISSN 1613-6810, E-ISSN 1613-6829, Vol. 14, no 17, article id 1703676Article in journal (Refereed)
    Abstract [en]

    The exploration of 2D solids is one of our times generators of materials discoveries. A recent addition to the 2D world is MXenes that possses a rich chemistry due to the large parent family of MAX phases. Recently, a new type of atomic laminated phases (coined i-MAX) is reported, in which two different transition metal atoms are ordered in the basal planes. Herein, these i-MAX phases are used in a new route for tailoriong the MXene structure and composition. By employing different etching protocols to the parent i-MAX phase (Mo2/3Y1/3)(2)AlC, the resulting MXene can be either: i) (Mo2/3Y1/3)(2)C with in-plane elemental order through selective removal of Al atoms or ii) Mo1.33C with ordered vacancies through selective removal of both Al and Y atoms. When (Mo2/3Y1/3)(2)C (ideal stoichiometry) is used as an electrode in a supercapacitor-with KOH electrolytea volumetric capacitance exceeding 1500 F cm(-3) is obtained, which is 40% higher than that of its Mo1.33C counterpart. With H2SO4, the trend is reversed, with the latter exhibiting the higher capacitance (approximate to 1200 F cm(-3)). This additional ability for structural tailoring will indubitably prove to be a powerful tool in property-tailoring of 2D materials, as exemplified here for supercapacitors.

  • 131.
    Persson, Ingemar
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Halim, Joseph
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Lind, Hans
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Hansen, Thomas W.
    Tech Univ Denmark DTU, Denmark.
    Wagner, Jakob B.
    Tech Univ Denmark DTU, Denmark.
    Näslund, Lars-Åke
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Darakchieva, Vanya
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Palisaitis, Justinas
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Rosén, Johanna
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Persson, Per O A
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    2D Transition Metal Carbides (MXenes) for Carbon Capture2019In: Advanced Materials, ISSN 0935-9648, E-ISSN 1521-4095, Vol. 31, no 2, article id 1805472Article in journal (Refereed)
    Abstract [en]

    Global warming caused by burning of fossil fuels is indisputably one of mankinds greatest challenges in the 21st century. To reduce the ever-increasing CO2 emissions released into the atmosphere, dry solid adsorbents with large surface-to-volume ratio such as carbonaceous materials, zeolites, and metal-organic frameworks have emerged as promising material candidates for capturing CO2. However, challenges remain because of limited CO2/N-2 selectivity and long-term stability. The effective adsorption of CO2 gas (approximate to 12 mol kg(-1)) on individual sheets of 2D transition metal carbides (referred to as MXenes) is reported here. It is shown that exposure to N-2 gas results in no adsorption, consistent with first-principles calculations. The adsorption efficiency combined with the CO2/N-2 selectivity, together with a chemical and thermal stability, identifies the archetype Ti3C2 MXene as a new material for carbon capture (CC) applications.

    The full text will be freely available from 2019-11-04 08:00
  • 132.
    Persson, Ingemar
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Näslund, Lars-Åke
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Halim, Joseph
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering. Drexel University, PA 19104 USA.
    Barsoum, Michel
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering. Drexel University, PA 19104 USA.
    Darakchieva, Vanya
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Palisaitis, Justinas
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Rosén, Johanna
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Persson, Per O A
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    On the organization and thermal behavior of functional groups on Ti3C2 MXene surfaces in vacuum2018In: 2D MATERIALS, ISSN 2053-1583, Vol. 5, no 1, article id 015002Article in journal (Refereed)
    Abstract [en]

    The two-dimensional (2D) MXene Ti(3)C(2)Tx is functionalized by surface groups (T-x) that determine its surface properties for, e.g. electrochemical applications. The coordination and thermal properties of these surface groups has, to date, not been investigated at the atomic level, despite strong variations in the MXene properties that are predicted from different coordinations and from the identity of the functional groups. To alleviate this deficiency, and to characterize the functionalized surfaces of single MXene sheets, the present investigation combines atomically resolved in situ heating in a scanning transmission electron microscope (STEM) and STEM simulations with temperature-programmed x-ray photoelectron spectroscopy (TP-XPS) in the room temperature to 750 degrees C range. Using these techniques, we follow the surface group coordination at the atomic level. It is concluded that the F and O atoms compete for the DFT-predicted thermodynamically preferred site and that at room temperature that site is mostly occupied by F. At higher temperatures, F desorbs and is replaced by O. Depending on the O/F ratio, the surface bare MXene is exposed as F desorbs, which enables a route for tailored surface functionalization.

  • 133.
    Persson, P. O. Å.
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Höglund, Carina
    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.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Ti2Al(O,N) formation by solid state reaction between substoichiometric TiN thin films and Al2O3(0001) substrates2011In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 519, no 8, p. 2421-2425Article in journal (Refereed)
    Abstract [en]

    Titanium nitride TiNx (0.1 ≤ x ≤ 1) thin films were deposited onto Al2O3(0001) substrates using reactive magnetron sputtering at substrate temperatures (Ts) ranging from 800 ºC to 1000 ºC and N2 partial pressures (pN2) between 0.1 and 1.0 mTorr. It is found that Al and O from the substrates diffuse into the substoichiometric TiNx films during deposition. Solid state reactions between the film and substrate result in the formation of Ti2O and Ti3Al domains at low N2 partial pressures, while for increasing pN2, the Ti2AlN MAX phase nucleates and grows together with TiNx. Depositions at increasingly stoichiometric conditions result in a decreasing incorporation of the substrate species into the growing film. Eventually, a stoichiometric deposition gives a stable TiN(111) || Al2O3(0001) structure without the incorporation of substrate species. Growth at Ts 1000 ºC yields Ti2AlN(0001), leading to a reduced incorporation of substrate species compared to films grown at 900 ºC, but contains also Ti2AlN(101ɸ3) grains. Finally, the Ti2AlN domains incorporate O, likely on the N site, such that a MAX phase oxynitride Ti2Al(O,N) is formed. The results were obtained by a combination of structural methods, including X-ray diffraction (XRD) and (scanning) transmission electron microscopy ((S)TEM), together with spectroscopy methods, which comprise elastic recoil detection analysis (ERDA), energy dispersive X-ray spectroscopy (EDX), and electron energy loss spectroscopy (EELS).

  • 134.
    Persson, Per
    Linköping University, Department of Physics, Measurement Technology, Biology and Chemistry. Linköping University, The Institute of Technology.
    Electron microscopy of ion implanted silicon carbide2000Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis investigates structural defects into Silicon Carbide (SiC) in processed Al and B ion implantated samples. Ion implantation is currently the preferred way to introduce impurity atoms into the SiC crystal lattice. The structural defects found was concluded to be extrinsic dislocation loops composed of excess Si interstitials. A model for these loops was developed and the mechanisms for loop evolution during processing were identified. The results of this thesis contributes to an improved processing technology of SiC as a semiconducting material, which will be used in electrical components for high power, high temperature and high frequency applications.

  • 135.
    Persson, Per
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics.
    Hultman, Lars
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics.
    Growth evolution of dislocation loops in ion implanted 4H-SiC2000In: Materials Science Forum, ISSN 0255-5476, E-ISSN 1662-9752, Vol. 353-3, p. 315-318Article in journal (Refereed)
    Abstract [en]

    Transmission electron microscopy (TEM) was used to investigate Al ion-implanted 4H-SiC epilayers. A set of annealing experiments were performed to study the evolution of dislocation loops in the implanted region. It was concluded that the dislocation loops evolve according to the extended Ostwald ripening model for small planar precipitates. The activation energy for loop growth was determined to be 2.8 eV.

  • 136.
    Persson, Per
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics.
    Hultman, Lars
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics.
    Jacobson, H.
    Bergman, Peder
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Janzén, Erik
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Molina-Aldareguia, J.M.
    Department of Materials Science and Metallurgy, University of Cambridge, Pembroke Street, Cambridge, CB2 3QZ, United Kingdom.
    Clegg, W.J.
    Department of Materials Science and Metallurgy, University of Cambridge, Pembroke Street, Cambridge, CB2 3QZ, United Kingdom.
    Tuomi, T.
    Optoelectronics Laboratory, Helsinki University of Technology, P.O. Box 3000, 02015 TKK, Finland.
    Structural defects in electrically degraded 4H-SiC p+/n-/n+ diodes2002In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 80, no 25, p. 4852-Article in journal (Refereed)
    Abstract [en]

    [No abstract available]

  • 137.
    Persson, Per
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics.
    Hultman, Lars
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics.
    Janson, M.S.
    Royal Institute of Technology, Solid State Electronics, P.O. Box E229, S-164 40 Kista-Stockholm, Sweden.
    Hallen, A.
    Hallén, A., Royal Institute of Technology, Solid State Electronics, P.O. Box E229, S-164 40 Kista-Stockholm, Sweden.
    Ostwald ripening of interstitial-type dislocation loops in 4H-silicon carbide2006In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 100, no 5Article in journal (Refereed)
    Abstract [en]

    The annealing behavior of interstitial-type basal plane dislocation loops in Al ion implanted 4H-SiC is investigated. It is shown that the loops undergo a dynamical ripening process. For annealing below 1700°C the total area of dislocation loops increases, indicating that point defects are still available for accumulation, but for annealing times longer than 100 min at this temperature the value of the total loop area saturates. For longer annealing times, or higher temperatures, the dislocation loops are subjected to a conservative coarsening process, also known as Ostwald ripening. In this process the mean loop radius increases with increasing annealing time and temperature while the number of loops decreases. Meanwhile the summarized area of the loops stays constant. The observed ripening is suggested to occur by a mechanism, which involves coarsening by direct loop coalescence. Through this mechanism, loops on the same basal plane move towards each other until they coalesce into one, but loops on neighboring basal planes can only move until their loop edges meet (in a basal plane projection) where they remain. Climb along the c axis is not favorable as shown by experimental results and is suggested to be caused by the atomic configuration of the loop. Upon continuous annealing, this results in a situation where the loops are confined in clusters. © 2006 American Institute of Physics.

  • 138.
    Persson, Per
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics.
    Hultman, Lars
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics.
    Janson, M.S.
    Royal Institute of Technology, Solid State Electronics, P.O. Box E229, S-164 40 Kista-Stockholm, Sweden.
    Hallen, A.
    Hallén, A., Royal Institute of Technology, Solid State Electronics, P.O. Box E229, S-164 40 Kista-Stockholm, Sweden.
    Yakimova, Rositsa
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Dislocation loop evolution in ion implanted 4H-SiC2003In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 93, no 11, p. 9395-9397Article in journal (Refereed)
    Abstract [en]

    The evolution of dislocation loop in the ion implanted 4H-SiC epilayers was investigated. The formation of dislocation loop after high temperature annealing was studied using transmission electron microscopy (TEM). The variation in the loop area with increase in implanted dose was found to be linear. For both, prolonged annealing and increasing temperature, the amount of interstitials bound to loops remained constant.

  • 139.
    Persson, Per
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics.
    Hultman, Lars
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics.
    Janson, M.S.
    Royal Institute of Technology, Solid State Electronics, P.O. Box E229, S-164 40 Kista-Stockholm, Sweden.
    Hallen, A.
    Hallén, A., Royal Institute of Technology, Solid State Electronics, P.O. Box E229, S-164 40 Kista-Stockholm, Sweden.
    Yakimova, Rositsa
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Panknin, D.
    FWIM Forschungszentrum Rossendorf, D-01474 Schoenfeld-Weissig, Germany.
    Skorupa, W.
    FWIM Forschungszentrum Rossendorf, D-01474 Schoenfeld-Weissig, Germany.
    On the nature of ion implantation induced dislocation loops in 4H-silicon carbide2002In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 92, no 5, p. 2501-Article in journal (Refereed)
    Abstract [en]

    [No abstract available]

  • 140.
    Persson, Per
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics.
    Jacobson, H
    Molina-Aldareguia, JM
    Linkoping Univ, Dept Phys, SE-58183 Linkoping, Sweden Univ Cambridge, Dept Mat Sci & Met, Cambridge CB2 3QZ, England ABB Corp Res, SE-72178 Vasteras, Sweden Univ Helsinki, Optoelect Lab, FI-02015 Helsinki, Finland.
    Bergman, Peder
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Tuomi, T
    Linkoping Univ, Dept Phys, SE-58183 Linkoping, Sweden Univ Cambridge, Dept Mat Sci & Met, Cambridge CB2 3QZ, England ABB Corp Res, SE-72178 Vasteras, Sweden Univ Helsinki, Optoelect Lab, FI-02015 Helsinki, Finland.
    Clegg, WJ
    Linkoping Univ, Dept Phys, SE-58183 Linkoping, Sweden Univ Cambridge, Dept Mat Sci & Met, Cambridge CB2 3QZ, England ABB Corp Res, SE-72178 Vasteras, Sweden Univ Helsinki, Optoelect Lab, FI-02015 Helsinki, Finland.
    Janzén, Erik
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Hultman, Lars
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics.
    Structural defects in electrically degraded 4H-SiC PiN diodes2002In: Materials Science Forum, Vols. 389-393, 2002, Vol. 389-3, p. 423-426Conference paper (Refereed)
    Abstract [en]

    Triangular structural defects, occasionally generated during long term operation of 4H-SiC pin diodes, are known to negatively affect the forward characteristics of the diode. We have used synchrotron white beam X-ray topography, scanning electron microscopy, in situ cathodo luminescence and transmission electron microscopy for characterizing the structure and formation mechanisms of such defects. It is shown from high-resolution images that the defect results from glide slip on the (0001) basal plane. The defect consists of a stacking fault bound by two partial dislocations with Burgers vectors 1/3<11 (1) over bar0> and 1/3<01 (1) over bar0>. The fault is a means for stress relaxation in the epilayer, near the contact layer using an existing dislocation as a nucleation source.

  • 141.
    Persson, Per
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics.
    Kodambaka, S.
    Department of Materials Science, the Frederick Seitz Materials Research Laboratory, University of Illinois, 104 South Goodwin Avenue, Urbana, IL 61801, United States.
    Petrov, I.
    Department of Materials Science, the Frederick Seitz Materials Research Laboratory, University of Illinois, 104 South Goodwin Avenue, Urbana, IL 61801, United States.
    Hultman, Lars
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics.
    Epitaxial Ti2AlN(0 0 0 1) thin film deposition by dual-target reactive magnetron sputtering2007In: Acta Materialia, ISSN 1359-6454, E-ISSN 1873-2453, Vol. 55, no 13, p. 4401-4407Article in journal (Refereed)
    Abstract [en]

    Ultrahigh-vacuum dual-target reactive magnetron sputtering, in a mixed Ar/N2 discharge was used to deposit epitaxial single-crystal MAX phase Ti2AlN(0 0 0 1) thin films, without seed layers, onto Al2O3(0 0 0 1) substrates kept at 1050 °C. By varying the N2 partial pressure a narrow process window was identified for the growth of single-crystal Ti2AlN. The film microstructure was characterized by a combination of X-ray diffraction, spherical aberration (Cs) corrected transmission electron microscopy (TEM), high-resolution image simulation and high-resolution scanning TEM. Nitrogen-depleted deposition conditions resulted in the concurrent formation of N-free Ti-Al intermetallics at the film/substrate interface and a steady-state growth of Ti2AlN together with N-free intermetallic phases. At higher N2 partial pressures the growth assumes a columnar epitaxial nature. 1 Å resolution of the lattice enabling location of all elements in the Ti2AlN unit cell is demonstrated. © 2007 Acta Materialia Inc.

  • 142.
    Persson, Per
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics.
    Olsson, E
    Hultman, Lars
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics.
    HREM investigation of structural defects in Al- and B- implanted 4H and 6H SiC1999In: Institute of Physics Conference Series, ISSN 0951-3248, E-ISSN 2154-6630, no 164, p. 525-528Article in journal (Refereed)
    Abstract [en]

    Ion implantation is currently the tool for selective area doping of SiC. However, ion implantation results in crystal damage. High-temperature implantation and annealing (greater than or equal to 1600 degreesC) are used to restore the crystal order. High resolution electron microscopy and electron-energy loss elemental mapping were used to study the nature of defects found in both Al and B implanted SiC. Microscopy revealed small loops on the basal (0001) planes when the dopant concentration is higher than 10(17) cm(-3). Defect size increases with annealing temperature and time. Elemental mapping revealed an elevated level of dopants in the regions of the defects.

  • 143.
    Persson, Per
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Rosén, Johanna
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    McKenzie, D R
    University of Sydney.
    Bilek, M M M
    University of Sydney.
    Formation of the MAX-phase oxycarbide Ti2AlC1-xOx studied via electron energy-loss spectroscopy and first-principles calculations2009In: PHYSICAL REVIEW B, ISSN 1098-0121, Vol. 80, no 9, p. 092102-Article in journal (Refereed)
    Abstract [en]

    Oxygen incorporation in the Ti2AlC MAX phase and TiC was investigated in the electron microscope using spatially resolved fine-structure electron energy-loss spectroscopy analysis. Corresponding fine structures were calculated within the full-potential-linearized augmented plane-wave framework. In the calculations, oxygen was substituted for aluminum and carbon in Ti2AlC as well as for carbon in TiC, in concentrations of 3.1, 6.2, and 12.5 at %. Comparison of calculated and measured spectra shows that oxygen is incorporated on the carbon site in both TiC and Ti2AlC. These findings reveal the existence of MAX phase oxycarbide MA(O,C) alloys and O as a third X element in addition to C and N.

  • 144.
    Petruhins, Andrejs
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Ingason, Arni Sigurdur
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Dahlqvist, Martin
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Mockuté, Aurelija
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Junaid, Muhammad
    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.
    Lu, Jun
    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.
    Persson, Per O A
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Rosén, Johanna
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Phase stability of Crn+1GaCn MAX phases from first principles and Cr2GaC thin-film synthesis using magnetron sputtering from elemental targets2013In: Physica Status Solidi. Rapid Research Letters, ISSN 1862-6254, E-ISSN 1862-6270, Vol. 7, no 11, p. 971-974Article in journal (Refereed)
    Abstract [en]

    Ab-initio calculations have been used to investigate the phase stability and magnetic state of Crn+ 1GaCn MAX phase. Cr2GaC (n = 1) was predicted to be stable, with a ground state corresponding to an antiferromagnetic spin configuration. Thin-film synthesis by magnetron sputtering from elemental targets, including liquid Ga, shows the formation of Cr2GaC, previously only attained from bulk synthesis methods. The films were deposited at 650 degrees C on MgO(111) substrates. X-ray diffraction and high-resolution transmission electron microscopy show epitaxial growth of (000) MAX phase.

  • 145.
    Prasalovich, S.
    et al.
    Department of Physics, Göteborg University, 41296 Göteborg, Sweden.
    Popok, V.
    Department of Physics, Göteborg University, 41296 Göteborg, Sweden.
    Persson, Per
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics.
    Campbell, E.E.B.
    Department of Physics, Göteborg University, 41296 Göteborg, Sweden.
    Experimental studies of complex crater formation under cluster implantation of solids2005In: European Physical Journal D: Atomic, Molecular and Optical Physics, ISSN 1434-6060, E-ISSN 1434-6079, Vol. 36, no 1, p. 79-88Article in journal (Refereed)
    Abstract [en]

    The results of a systematic study of surface defect formation after energetic Arn+ (n = 12, 22, 32, 54) and Xen+ (n = 4, 16) cluster ion implantation into silicon and sapphire are presented. Implantation energies vary from 3 to 18 keV/ion. Two cases of comparative studies are carried out: the same cluster species are implanted into two different substrates, i.e. Arn+ cluster ions into silicon and sapphire and two different cluster species Arn+ and Xen+ are implanted into the same kind of substrate (silicon). Atomic force, scanning electron and transmission electron microscopies (AFM, SEM and TEM) are used to study the implanted samples. The analysis reveals the formation of two types of surface erosion defects: simple and complex (with centrally positioned hillock) craters. It is found that the ratio of simple to complex crater formation as well as the hillock dimensions depend strongly on the cluster species, size and impact energy as well as on the type of substrate material. Qualitative models describing the two comparative cases of cluster implantation, the case of different cluster species and the case of different substrate materials, are proposed. © EDP Sciences, Società Italiana di Fisica, Springer-Verlag 2005.

  • 146.
    Qin, Leiqian
    et al.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, Faculty of Science & Engineering.
    Tao, Quanzheng
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Liu, Xianjie
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Fahlman, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Halim, Joseph
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Persson, Per O A
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Rosén, Johanna
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Zhang, Fengling
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering. Jinan Univ, Peoples R China.
    Polymer-MXene composite films formed by MXene-facilitated electrochemical polymerization for flexible solid-state microsupercapacitors2019In: Nano Energy, ISSN 2211-2855, E-ISSN 2211-3282, Vol. 60, p. 734-742Article in journal (Refereed)
    Abstract [en]

    Materials with tailored properties are crucial for high performance electronics applications. Hybrid materials composed of inorganic and organic components can possess unique merits for broad application by synergy between the advantages the respective material type offers. Here we demonstrate a novel electrochemical polymerization (EP) enabled by a 2D transition metal carbide MXene for obtaining conjugated polymer-MXene composite films deposited on conducting substrates without using traditional electrolytes, indispensable compounds for commonly electrochemical polymerization. The universality of the process provides a novel approach for EP allowing fast facile process for obtaining different new polymer/MXene composites with controlled thickness and micro-pattern. Furthermore, high performance microsupercapacitors and asymmetric microsupercapacitors are realized based on the excellent composites benefiting from higher areal capacitance, better rate capabilities and lower contact resistance than conventional electropolymerized polymers. The AMSCs exhibit a maximum areal capacitance of 69.5 mF cm(-2), an ultrahigh volumetric energy density (250.1 mWh cm(-3)) at 1.6 V, and excellent cycling stability up to 10000 cycles. The excellent electrochemical properties of the composite polymerized with MXene suggest a great potential of the method for various energy storage applications.

  • 147.
    Rakpongsiri, Pornchai
    et al.
    Chulalongkorn Univ, Thailand; Western Digital Corp, Thailand.
    Pintasiri, Suphakit
    Western Digital Corp, Thailand.
    Ruthe, Kurt
    Western Digital Corp, Thailand.
    Persson, Per O A
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Tungasmita, Sukkaneste
    Chulalongkorn Univ, Thailand.
    Thermal Stress Evaluation of Tunneling Magnetoresistive Structures in Data Storage Devices2018In: IEEE Magnetics Letters, ISSN 1949-307X, E-ISSN 1949-3088, Vol. 9, article id 2506104Article in journal (Refereed)
    Abstract [en]

    The conventional read sensor technology used in hard disk drives is the tunneling magnetoresistive (TMR) device. The technology evolution of the TMR device toward higher signal-to-noise performance has been achieved through aggressive scaling of the thin film layered structures in the device to the point that thermal stability and thermally induced degradation have come to limit reliability. In this study, a thermal stress has been applied to TMR devices between 150-250 degrees C, and the resistance, amplitude, and asymmetry parameters, both before and after the thermal stress, were measured using a quasi-static test (QST). The results reveal a temperature dependence of the TMR device performance. The microstructure of the annealed devices was further studied using transmission electron microscopy and energy dispersive X-ray analysis, revealing structural defects that are related to the QST parametric changes. Both atomic misalignment of the MgO layer and Ir depletion are proposed as origins for the instability of the magnetic response in the device after thermal stress.

  • 148.
    Rantzer, Annika
    et al.
    Linköping University, Department of Electrical Engineering. Linköping University, The Institute of Technology.
    Hjörvarsson, B.
    Department of Physics, Uppsala University, Uppsala, Sweden.
    Persson, Per O. A.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Kim, H.
    IBM TJ Watson Research Center, Yorktown Heights, NY, USA.
    Greene, J. E.
    Department of Materials Science and Frederick Seitz Materials Research Laboratory, University of Illinois, USA.
    Järrendahl, Kenneth
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Arwin, Hans
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Birch, Jens
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Sputter-deposited a-Si:H for p-i-n photodiodesManuscript (preprint) (Other academic)
    Abstract [en]

    DC magnetron sputter deposition is explored as an alternative for fabricating vertically integrated sensor systems in the form of p-i-n diodes of hydrogenated amorphous silican deposited on CMOS integrated circuit substrates in a post-processing step. We focus here on dopant oncorporation and surface morphological evolution during synthesis of the p-i-n diode sensor structures. The Doping was accomplished using doped targets in a mixed H2/Ar environment. Incorporated P concetrations range from 2.62 to 4.8 x 1019 cm-3 with corresponding conductivities, σ, up to 1.4 x10-5 ohm-1cm-1. B contentrations are between 2.79 and 6.7 X 1020 cm-3 with σ = 4 x 10-5 to 4 x 10-2 ohm-1cm-1. The results of the dopant incorporation are in agreement with reported molecular dynamics simulations. The best intrinsic films have a light to dark conductivity ratio of 102 for white light at an intensity of 10 W/m2. The dark conductivity is a 8 x 10-9 ohm-1cm-1. We conclude that dc magnetron sputter deposition is a good candidate for future device fabrication.

  • 149.
    Selegård, Linnéa
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Molecular Surface Physics and Nano Science. Linköping University, Faculty of Science & Engineering.
    Ahrén, Maria
    Linköping University, Department of Physics, Chemistry and Biology, Molecular Surface Physics and Nano Science. Linköping University, Faculty of Science & Engineering.
    Brommesson, Caroline
    Linköping University, Department of Physics, Chemistry and Biology, Molecular Surface Physics and Nano Science. Linköping University, The Institute of Technology.
    Söderlind, Fredrik
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, The Institute of Technology.
    Persson, Per. O. Å
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Uvdal, Kajsa
    Linköping University, Department of Physics, Chemistry and Biology, Molecular Surface Physics and Nano Science. Linköping University, Faculty of Science & Engineering.
    Bifunctional gadolinium decorated ZnO nanocrystals integrating both enhanced MR signal and bright fluorescence2013Manuscript (preprint) (Other academic)
    Abstract [en]

    Gadolinium decorated ZnO nanoparticles simultaneously possess both fluorescent and MR enhancement properties. These ZnO nanoparticles are crystalline and shielded by an amorphous gadolinium acetate matrix. Interestingly, the Gd-acetate decoration enhances the fluorescence emission of the ZnO nanoparticles. The quantum yield does increase for samples with high Gd/Zn relative ratios and these samples do also show a higher colloidal stability.

    In addition, these nanoparticles show an enhanced relaxivity value per Gd atom (r119.9mM1s-1) compared to results earlier reported both on Gd alloyed ZnO nanoparticles and pure Gd2O3 nanoparticles. This improvement is considered to be due to the close proximity of Gd atoms and surrounding water molecules. A comprehensive study of the quantum yield and the relaxivity, as a function of composition, enable us to identify the ultimate design/composition of gadolinium decorated ZnO nanoparticles for optimum fluorescence and MR enhancement properties.

  • 150.
    Seppänen, Timo
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. 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.
    Hultman, Lars
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics.
    Birch, Jens
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Radnoczi, G. Z.
    Magnetron sputter epitaxy of wurtzite Al1-xInxN (0.1 x 0.9) by Dual Reactive DC Magnetron Sputter Deposition2005In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 97, p. 83503-1-83503-9Article in journal (Refereed)
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