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  • 101.
    Berlind, Torun
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad optik. Linköpings universitet, Tekniska högskolan.
    Hellgren, Niklas
    Frederick Seitz Materials Research Laboratory, University of Illinois, 104 South Goodwin Avenue, Urbana, IL 61801, USA.
    Johansson, Mats P.
    Thin Film Electronics AB, A°gatan 29, S-582 22 Link¨oping, Sweden.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Microstructure, mechanical properties, and wetting behaviorof Si-C-N thin films grown by reactive magnetron sputtering2001Ingår i: Surface and Coatings Technology, ISSN 0257-8972, Vol. 141, nr 2-3, s. 145-155Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Silicon–carbon–nitride (Si–C–N) thin films were deposited by reactive magnetron co-sputtering of C and Si targets in a mixed Ar/N2 discharge. Films were grown to a thickness of more than 0.5 μm on graphite and Si(001) substrates held at a negative floating potential of −35 V, and substrate temperature between 100 and 700°C. The total pressure was constant at 0.4 Pa (3 mtorr), and the nitrogen fraction in the gas mixture was varied between 0 and 100%. As-deposited films were analyzed with respect to composition, state of chemical bonding, microstructure, mechanical properties, and wetting behavior by Rutherford backscattering spectroscopy (RBS), energy dispersive spectroscopy (EDS), X-ray photoelectron spectrometry (XPS), transmission electron microscopy (TEM), scanning electron microscopy (SEM), nanoindentation and contact angle measurements, respectively. Depending on the deposition condition, ternary SixCyNz films within the composition range 1≤x≤34 at.%, 34≤y≤81 at.%, and 16.5≤z≤42 at.% were prepared with a textured, amorphous-to-graphite-like microstructure. For Si–C–N films with low Si content, C---C, C---N and Si---C bonds were present. At higher Si content, N preferentially bonds to Si, while less C---N bonds were observed. Films containing more than 12 at.% of Si contained widely dispersed crystallites, 2–20 nm in diameter. Incorporation of a few at.% Si resulted in a dramatic reduction of the film surface energy compared to pure CN films. The measured contact angles using distilled water and glycerol liquids were for some films comparable with those on a polytetrafluoroethylene (PTFE), Teflon® surface. The hardness of Si–C–N films could be varied over the range 9–28 GPa.

  • 102.
    Berlind, Torun
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad optik.
    Poksinski, Michal
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad optik.
    Hultman, Lars
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik.
    Tengvall, Pentti
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad Fysik.
    Arwin, Hans
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad optik.
    Adsorption of human serum albumin on carbon nitride films studied with in-situ ellipsometry2005Ingår i: American Vacuum Society 52 Int Symposium and Exhibition,2005, 2005Konferensbidrag (Övrigt vetenskapligt)
  • 103.
    Berlind, Torun
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad optik.
    Poksinski, Michal
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad optik.
    Hultman, Lars
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik.
    Tengvall, Pentti
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad Fysik.
    Arwin, Hans
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad optik.
    Bioadsorption studies on carbon nitride films using in-situ ellipsometry2005Ingår i: E-MRS spring meeting,2005, 2005Konferensbidrag (Övrigt vetenskapligt)
  • 104.
    Berlind, Torun
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad optik.
    Poksinski, Michal
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad optik.
    Hultman, Lars
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik.
    Tengvall, Pentti
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad Fysik.
    Arwin, Hans
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad optik.
    Protein Adsorption on Carbon Nitride Films Studied with in situ Ellipsometry2007Ingår i: 4th International Conference on Spectroscopic Ellipsometry,2007, Linköping: Linköpings universitet , 2007, s. 246-Konferensbidrag (Refereegranskat)
  • 105.
    Berlind, Torun
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad optik. Linköpings universitet, Tekniska högskolan.
    Tengvall, Pentti
    Department of Biomaterials, Institute of Surgical Sciences, The Sahlgrenska Academy, University of Gothenburg.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Arwin, Hans
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad optik. Linköpings universitet, Tekniska högskolan.
    Protein adsorption on thin films of carbon and carbon nitride monitored with in situ ellipsometry2011Ingår i: ACTA BIOMATERIALIA, ISSN 1742-7061, Vol. 7, nr 3, s. 1369-1378Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Amorphous carbon and amorphous, graphitic and fullerene-like carbon nitride thin filmswere deposited by reactive magnetron sputtering and optically characterized withspectroscopic ellipsometry. The films were exposed to human serum albumin and theadsorption was monitored in situ using dynamic ellipsometry. From the ellipsometric data theadsorbed amount of proteins was quantified in terms of surface mass density using de Feijter'smodel. The results indicated larger adsorption of proteins onto the amorphous films comparedto the films with a more ordered microstructure. Complementary studies with labeled HSAusing radioimmunoassay showed up to 6 times higher protein adsorption compared to theellipsometry measurement which partly might be explained by differences in surfaceroughness (from 0.3 to 13 nm) among the films. The elutability of adsorbed labeled HSAusing unlabeled HSA and sodium dodecyl sulphate was low compared to a silicon reference.In addition, the four types of films were incubated in blood plasma followed by antifibrinogen,anti-HMWK or anti-C3c revealing the materials response to complement andcontact activation. Three of the films indicated immunoactivity, whereas the amorphouscarbon showed less immunoactivity compared to a titanium reference. All films showedindications of a stronger ability to initiate the intrinsic pathway of coagulation, compared tothe reference. Finally, the surfaces bone bonding ability was investigated by examination oftheir ability to form calcium phosphate (CaP) crystals in a simulated body fluid, with a-CNxdepositing most CaP after 21 days of incubation.

  • 106.
    Bernard, M
    et al.
    CNRS, LEPES, F-38042 Grenoble 9, France Fac Sci & Tech St Jerome, MATOP, CNRS, F-13397 Marseille, France Linkoping Univ, Dept Phys, S-58183 Linkoping, Sweden.
    Deneuville, A
    CNRS, LEPES, F-38042 Grenoble 9, France Fac Sci & Tech St Jerome, MATOP, CNRS, F-13397 Marseille, France Linkoping Univ, Dept Phys, S-58183 Linkoping, Sweden.
    Thomas, O
    CNRS, LEPES, F-38042 Grenoble 9, France Fac Sci & Tech St Jerome, MATOP, CNRS, F-13397 Marseille, France Linkoping Univ, Dept Phys, S-58183 Linkoping, Sweden.
    Gergaud, P
    CNRS, LEPES, F-38042 Grenoble 9, France Fac Sci & Tech St Jerome, MATOP, CNRS, F-13397 Marseille, France Linkoping Univ, Dept Phys, S-58183 Linkoping, Sweden.
    Sandstrom, P
    Birch, Jens
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Raman spectra of TiN/AlN superlattices2000Ingår i: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 380, nr 1-2, s. 252-255Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    TiN (4.5 nm)/AIN (3, 6, 22 nm) superlattices deposited by DC magnetron sputtering on MgO(001) at a temperature of 850 degreesC exhibit Raman signals. They indicate N and Ti vacancies (as in thick TiN) in TiN1-x layers (x = 3 +/- 2%). x is higher for the sample with 3-nm thick AIN layers, which is ascribed to N diffusion from AIN (standing close to the TiN interfaces) to TiN. In comparison to Raman peaks of thick ALN, there are split signals of wurzite ALN phase, and a signal from another phase, which might be defective rocksalt AIN standing close to the TiN interfaces. The Raman signals clearly show interactions between ALN and TiN layers. (C) 2000 Elsevier Science B.V. All rights reserved.

  • 107.
    Beshkova, M.
    et al.
    Bulgarian Academic Science, Bulgaria.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Yakimova, Rositsa
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Device applications of epitaxial graphene on silicon carbide2016Ingår i: Vacuum, ISSN 0042-207X, E-ISSN 1879-2715, Vol. 128, s. 186-197Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    Graphene has become an extremely hot topic due to its intriguing material properties allowing for ground-breaking fundamental research and applications. It is one of the fastest developing materials during the last several years. This progress is also driven by the diversity of fabrication methods for graphene of different specific properties, size, quantity and cost. Graphene grown on SiC is of particular interest due to the possibility to avoid transferring of free standing graphene to a desired substrate while having a large area SiC (semi-insulating or conducting) substrate ready for device processing. Here, we present a review of the major current explorations of graphene on SiC in electronic devices, such as field effect transistors (FET), radio frequency (RF) transistors, integrated circuits (IC), and sensors. The successful role of graphene in the metrology sector is also addressed. Typical examples of graphene on SiC implementations are illustrated and the drawbacks and promises are critically analyzed. (C) 2016 Elsevier Ltd. All rights reserved.

  • 108.
    Beshkova, M.
    et al.
    Bulgarian Academy of Science, Sofia, Bulgaria.
    Zakhariev, Z.
    Bulgarian Academy of Science, Sofia, Bulgaria.
    Abrashev, M. V.
    University of Sofia, Bulgaria.
    Birch, Jens
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Postovit, A.
    Institute of Problem Microelectronics Technology and High Purity Materials, Moskow, Russia.
    Yakimova, Rositsa
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Properties of AlN epitaxial layers on 6H-SiC substrate grown by sublimation in argon, nitrogen, and their mixtures2006Ingår i: Materials Science & Engineering: B. Solid-state Materials for Advanced Technology, ISSN 0921-5107, E-ISSN 1873-4944, Vol. 129, nr 1-3, s. 228-231Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Epitaxial layers of aluminum nitride (AlN) have been grown at temperature 1900 °C on 10 mm × 10 mm 6H-SiC substrate via sublimation-recondensation in RF heated graphite furnace. The source material was polycrystalline sintered AlN. Growth of AlN layers in pure nitrogen, mixed nitrogen/argon and pure argon atmosphere of 50 mbar were compared. A maximum growth rate of about 30 µm/h was achieved in pure nitrogen atmosphere. The surface morphology reflects the hexagonal symmetry of the seed, which is characteristic of an epitaxial growth for samples grown in a pure nitrogen and mixed nitrogen/argon atmosphere. X-ray diffraction (XRD) measurements show very strong and well defined (0 0 0 2) reflection positioned at around 36° in symmetric ?-2? scans. Micro-Raman spectroscopy reveals that the films have a wurtzite structure. Secondary-ion mass spectroscopy (SIMS) results showed a low concentration of carbon incorporation in the AlN layers. This study demonstrates that nitrogen is necessary for the successful epitaxial growth of AlN on 6H-SiC by sublimation. © 2006 Elsevier B.V. All rights reserved.

  • 109.
    Beshkova, Milena
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Birch, Jens
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Syväjärvi, Mikael
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Yakimova, Rositsa
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Sublimation epitaxy of 3C-SiC grown at Si- and C-rich conditions2012Ingår i: Vacuum, ISSN 0042-207X, E-ISSN 1879-2715, Vol. 86, nr 10, s. 1595-1599Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    3C-SiC layers have been grown by using sublimation epitaxy at a source temperature of 2000 degrees C, under vacuum conditions (andlt;10(-5) mbar) on well oriented (on-axis) 6H-SiC (0001) substrates. Close space sublimation growth geometry has been used in a RF-heated furnace employing high-purity graphite crucible with a possibility to change the growth environment from Si vapor-rich to C vapor-rich. The optical microscopy in transmission mode reveals continuous 3C-domains for 3C-SiC with less than 0.4% 6H-inclusions for the layer grown at Si-rich conditions, and separate 3C-SiC domains for the layer grown at C-rich conditions. The type of 6H-inclusions for layers with continuous domain structure investigated by Atomic Force Microscopy (AFM) is discussed. 2Theta-omega scan shows 0006 and 111 peaks coming from the substrate and the layer, respectively with a higher intensity of the 111 peak for 3C-SiC grown at Si-rich conditions which is related with the continuous character of the 3C-SiC domains.

  • 110.
    Beshkova, Milena
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Lorenzzi, J.
    UMR-CNRS.
    Jegenyes, N.
    UMR-CNRS.
    Birch, Jens
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Syväjärvi, Mikael
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Ferro, G.
    UMR-CNRS.
    Yakimova, Rositsa
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Properties of 3C-SiC Grown by Sublimation Epitaxy on Different Type of Substrates2010Ingår i: Materials Science Forum, Vols. 645-648, Transtec Publications; 1999 , 2010, Vol. 645-648, s. 183-186Konferensbidrag (Refereegranskat)
    Abstract [en]

    3C-SiC layers have been grown by using sublimation epitaxy at a temperature of 2000 degrees C, on different types of on-axis 6H-SiC(0001) substrates. The influence of the type of substrate on the morphology of the layers investigated by Atomic Force Microscopy (AFM) is discussed. Stacking faults are studied by reciprocal space map (RSM) which shows that double positions domains exists.

  • 111.
    Beshkova, Milena
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Materiefysik.
    Syväjärvi, Mikael
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Materiefysik.
    Vasiliauskas, Remigijus
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Materiefysik.
    Birch, Jens
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik.
    Yakimova, Rositsa
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Materiefysik.
    Properties of 3C-SiC Grown by Sublimation Epitaxy2009Ingår i: ECSCRM2008,2008, 2009Konferensbidrag (Refereegranskat)
    Abstract [en]

      

  • 112.
    Beshkova, Milena
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial.
    Syväjärvi, Mikael
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial.
    Vasiliauskas, Remigijus
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial.
    Birch, Jens
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik.
    Yakimova, Rositsa
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial.
    Structural Properties of 3C-SiC Grown by Sublimation Epitaxy2009Ingår i: ECSCRM2009,2009, Materials Science Forum Vols. 615-617: Trans Tech Publications , 2009, s. 181-184Konferensbidrag (Refereegranskat)
    Abstract [en]

    The present paper deals with morphological and structural investigation of 3C-SiC layers grown by sublimation epitaxy on on axis 6H-SiC(0001) at source temperature 2000 °C, under vacuum conditions (<10-5 mbar) and different temperature gradients in the range of 5-8 °C/mm. The layer grown at a temperature gradient 6 °C/mm has the largest average domain size of 0.4 mm2 assessed by optical microscope in transmission mode. The rocking curve full width at half maximum (FWHM) of (111) reflection is 43 arcsec which suggests good crystalline quality. The AFM image of the same layer shows steps with height 0.25 nm and 0.75 nm which are characteristic of a stacking fault free 3C-SiC surface and c-axis repeat height, respectively.

  • 113.
    Beshkova, Milena
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial.
    Zakhariev, Z.
    Abrashev, M.V.
    Birch, Jens
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik.
    Kakanakova-Georgieva, Anelia
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial.
    Yakimova, Rositsa
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial.
    Low-pressure sublimation epitaxy of AlN films - growth and characterization2004Ingår i: Vacuum, ISSN 0042-207X, E-ISSN 1879-2715, Vol. 76, s. 143-146Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Epitaxial layers of aluminum nitride have been grown at temperatures 1900-2400degreesC on 10 x 10 mm(2) 4H-SiC substrate via sublimation recondensation in an RF heated graphite furnace. The source material was polycrystalline sintered AlN. A maximum growth rate of about 100 mum/h was achieved at 2400degreesC and seed to source distance of 1 mm. The surface morphology reflects the hexagonal symmetry of the seed suggesting an epitaxial growth. This was confirmed by X-ray diffraction (XRD). The spectra showed very strong and well-defined (0002) reflection position at around 36.04degrees in symmetric Theta-2Thetascans for all samples. Micro-Raman spectroscopy reveals that the films have a wurtzite structure. It is evidenced by the appearance of the A(1) (TO) (at 601 cm(-1)) and E-2((2)) (at 651 cm(-1)) lines in the spectra. Secondary-ion mass spectroscopy (SIMS) results showed a low concentration of carbon incorporation in the AlN films. A correlation between the growth conditions and properties of the AlN layers was established.

  • 114.
    Beshkova, Milena
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial.
    Zakhariev, Z
    Birch, Jens
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik.
    Kakanakova-Georgieva, Anelia
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial.
    Yakimova, Rositsa
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial.
    Properties of AlN layers grown by sublimation epitaxy2003Ingår i: Materials Science Forum, Vols. 433-436, 2003, Vol. 433-4, s. 995-998Konferensbidrag (Refereegranskat)
    Abstract [en]

    Epitaxial layers of aluminum nitride (AlN)less than or equal to 80 mum thick have been grown at the temperatures 1900 and 2100 degreesC on 10x10mm(2) 4H-SiC substrates via sublimation recondensation in a RF heated graphite furnace. The source material was polyerystalline sintered AlN. A maximum growth rate of 80 mum/h was achieved at 2100degreesC and seed to source separation of I mm. The surface morphology reflects the hexagonal symmetry of the seed that suggesting an epitaxial growth. All crystals show strong and well defined single crystalline XRD patterns. Only the (002) reflection positioned at around 36.04 was observed in symmetric Theta-2Theta scan. The rocking curves FWHM (full width half maximum) and peak positions arc reported.

  • 115.
    Beshkova, Milena
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial.
    Zakhariev, Z
    Birch, Jens
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik.
    Kakanakova-Georgieva, Anelia
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial.
    Yakimova, Rositsa
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial.
    Sublimation epitaxy of AIN layers on 4H-SiC depending on the type of crucible2003Ingår i: Journal of materials science. Materials in electronics, ISSN 0957-4522, E-ISSN 1573-482X, Vol. 14, nr 10-12, s. 767-768Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Epitaxial layers of aluminum nitride less than or equal to335 mum thick have been grown attemperatures of 1900 and 2100degreesC on 10 x 10 mm(2) (0001)-oriented alpha(4H) silicon carbide (SiC), with growth times of 1 and 4h, via sublimation-recondensation in a RF-heated graphite furnace. The source material was polycrystalline AIN. The sublimation process was performed in three types of graphite (C) crucible: C-1, C-2 with inner diameters of 35 and 51 mm, respectively, and C-3 with the same inner diameter as C-1, but coated with a layer of TaC. The surface morphology reflects the hexagonal symmetry of the substrate, suggesting an epitaxial growth for samples grown in C-1 and C-3 crucibles for all growth conditions. The same symmetry is observed for AIN layers grown in the C-2 crucible, but only at 2100degreesC. X-ray diffraction analyses confirm the epitaxial growth of AIN samples with the expected hexagonal symmetry. A high-resolution X-ray diffractometer was used to assess the quality of the single crystals. A full width at half maximum of 242 arcsec was achieved for an AIN layer grown in the crucible coated with TaC. (C) 2003 Kluwer Academic Publishers.

  • 116.
    Bi, Shubo
    et al.
    Shanghai Univ, Peoples R China; Sci and Technol Near Surface Detect Lab, Peoples R China.
    Wang, Chi
    Shanghai Univ, Peoples R China; Sci and Technol Near Surface Detect Lab, Peoples R China.
    Zhu, Jun
    Sci and Technol Near Surface Detect Lab, Peoples R China.
    Yuan, Zhiwen
    Sci and Technol Near Surface Detect Lab, Peoples R China.
    Yu, Yingjie
    Shanghai Univ, Peoples R China.
    Valyukh, Sergiy
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Asundi, Anand
    Nanyang Technol Univ, Singapore.
    Influence of no-core fiber on the focusing performance of an ultra-small gradient-index fiber probe2018Ingår i: Optics and lasers in engineering, ISSN 0143-8166, E-ISSN 1873-0302, Vol. 107, s. 46-53Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The light-beam expansion effect of a no-core fiber on the focusing performance of an ultra-small gradient-index fiber probe is investigated with a view to optimizing the optical performance of such probes. By taking the variable relationship between the focusing performance (including the working distance and the focusing spot size) of the probe and the length of the no-core fiber as the criterion, the effective beam expansion length of the no-core fiber in the ultra-small gradient-index fiber probe is calculated based on the basic properties of the Gaussian beam. Verification and analysis are done by numerical calculations and experimental measurements, respectively. The obtained results show that the working distance of an ultra-small gradient-index fiber probe can be increased effectively by adding a no-core fiber; however, this will lead to increasing the focusing spot size. For the parameters of the fiber probe studied here, the effective beam expansion length of the no-core fiber spacer is less than 0.357 mm. (C) 2018 Elsevier Ltd. All rights reserved.

  • 117.
    Bigault, Thierry
    et al.
    Institut Laue Langevin, Grenoble, Cedex 9, France.
    Birch, Jens
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Buffet, J. C.
    Institut Laue Langevin, Grenoble, Cedex 9, France.
    Correa, Jonathan
    Institut Laue Langevin, Grenoble, Cedex 9, France.
    Hall-Wilton, Richard
    European Spallation Source ESS AB, Lund, Sweden.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Höglund, Carina
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Guérard, Bruno
    Institut Laue Langevin, Grenoble, Cedex 9, France.
    Khaplanov, Anton
    Institut Laue Langevin, Grenoble, Cedex 9, France.
    Piscitelli, Fransesco
    Institut Laue Langevin, Grenoble, Cedex 9, France.
    van Esch, P.
    Institut Laue Langevin, Grenoble, Cedex 9, France.
    10B multi-grid proportional gas counters for large area thermal neutron detectors2012Ingår i: Neutron News, ISSN 1044-8632, E-ISSN 1931-7352, Vol. 23, nr 4, s. 20-24Artikel i tidskrift (Refereegranskat)
  • 118.
    Birch, Jens
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Single-crystal Mo/V superlattices: growth, structure, and hydrogen uptake1994Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Fundamental studies concerning the growth, structural characterization and hydrogen uptake of single-crystal (00 l )-oriented Mo/V superlattices have been performed. The superlattices were grown by dual-target magnetron sputtering in pure Ar-atmosphere < 6·10-3 Torr on (001)-oriented MgO substrates. X-ray diffraction (XRD), X-ray and neutron reflectivity, high resolution (HR) as well as ordinary crosssectional transmission electron microscopy (XTEM) and selected area electron diffraction (SAED) were used for the structural characterization. Hydrogen depth-profiling was performed by the 15N method.

    For growth of periodic Mo/V superlattices, it is shown that substrate temperatures in the range of 600-700 °C is feasible for epitaxy. At higher growth temperatures substantial interdiffusion occurred. Furthermore, simulations of XRDpatterns gave the width of the interfaces to be ±1 monolayer (±0,154 nm) which was confirmed by XRD and HRXTEM analyses of a superlattice grown with layer thicknesses DMo=Dv=0,31 nm (2 monolayers). A transition from smooth to wavy V-layers was found to occur at a critical V-layer thickness Dc. In superlattices where the relative amount of V is large, De is large and vice versa for superlattices containing thin V-layers. In superlattices with equally thick Mo- and V-layers Dc was found to be ~2,5 nm. Mo was found to grow with a uniform thickness following the surface of the V-layers. The layer thickness fluctuations are non-accumulative and disappear if the periodicity of a growing Mo/V superlattice is changed so that Dv becomes smaller than Dc. The origin of the 3D evolution is explained in terms of surface strain and the roughening transition. The interfaces of Mo/V superlattices grown under the influence of energetic ion bombardment ranging from about 15 eV to 250 eV was studied by HRXTEM and XRD. Both techniques indicated a continous deterioration of the interface quality and an increasing amount of defects with increasing ion energy.

    The diffraction peaks from a clas of quasi-periodic superlattices which can be generated by the inflation rules A→AmB, B→A (m = positive integer) was analytically, experimentally and numerically found to be located at the wavevectors q = 2πɅ-1rγ(m)k where r and k are integers and A is an average superlattice period. The ratios, γ(m), between the thicknesses of the two superlattice building blocks, A and B, must be chosen such that γ(m) = (m + (m2 + 4) 1/2 )/2.

    The uptake of hydrogen in the superlattices is found to decrease with decreasing A and for 5,5 nm the transition between α-VHx and β-VHx is not observed. A model is proposed which explains the A-dependent behaviour of the hydrogen uptake by a transfer of interstitial electrons from Mo to V, creating a 0,49 nm wide H-free interface layer. The existence of this layer is shown both by the 15N method performed on samples containing several A:s and by combining simulations of X-ray and neutron reflectivities with measurements on superlattices loaded with either hydrogen or deuterium. The structural change of Mo/V(OOl) superlattices upon H-loading was measured by a method derived in this work which utilises a combination of X-ray reflectivity and reciprocal space mapping by XRD. The lattice parameters in the layers are measured in the growth direction as well a in the plane of the sample. It is found that the V lattice expands in the growth direction and that the hydrogenation process is associated with relaxation of coherency strain.

  • 119.
    Birch, Jens
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Buffet, J. -C.
    Institute Laue Langevin, France.
    Clergeau, J. -F.
    Institute Laue Langevin, France.
    van Esch, P.
    Institute Laue Langevin, France.
    Ferraton, M.
    Institute Laue Langevin, France.
    Guerard, B.
    Institute Laue Langevin, France.
    Hall-Wilton, R.
    European Spallat Source, Sweden; Mid Sweden University, Sweden.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Höglund, Carina
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten. European Spallat Source, Sweden.
    Jensen, Jens
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Khaplanov, A.
    Institute Laue Langevin, France; European Spallat Source, Sweden.
    Piscitelli, F.
    Institute Laue Langevin, France; European Spallat Source, Sweden.
    Investigation of background in large-area neutron detectors due to alpha emission from impurities in aluminium2015Ingår i: Journal of Instrumentation, ISSN 1748-0221, E-ISSN 1748-0221, Vol. 10, s. 1-14Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Thermal neutron detector based on films of (B4C)-B-10 have been developed as an alternative to He-3 detectors. In particular, The Multi-Grid detector concept is considered for future large area detectors for ESS and ILL instruments. An excellent signal-to-background ratio is essential to attain expected scientific results. Aluminium is the most natural material for the mechanical structure of of the Multi-Grid detector and other similar concepts due to its mechanical and neutronic properties. Due to natural concentration of alpha emitters, however, the background from alpha particles misidentified as neutrons can be unacceptably high. We present our experience operating a detector prototype affected by this issue. Monte Carlo simulations have been used to confirm the background as alpha particles. The issues have been addressed in the more recent implementations of the Multi-Grid detector by the use of purified aluminium as well as Ni-plating of standard aluminium. The result is the reduction in background by two orders of magnitude. A new large-area prototype has been built incorporating these modifications.

  • 120.
    Birch, Jens
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Buffet, J. C.
    Institut Laue Langevin, Grenoble, Cedex 9, France.
    Correa, Jonathan
    Institut Laue Langevin, Grenoble, Cedex 9, France.
    van Esch, P.
    Institut Laue Langevin, Grenoble, Cedex 9, France.
    Guerard, Bruno
    Institut Laue Langevin, Grenoble, Cedex 9, France.
    Hall-Wilton, Richard
    European Spallation Source ESS AB, Lund, Sweden.
    Höglund, Carina
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Khaplanov, Anton
    Institut Laue Langevin, Grenoble, Cedex 9, France.
    Piscitelli, Fransesco
    Institut Laue Langevin, Grenoble, Cedex 9, France.
    (B4C)-B-10 Multi-Grid as an Alternative to He-3 for Large Area Neutron Detectors2013Ingår i: IEEE Transactions on Nuclear Science, ISSN 0018-9499, E-ISSN 1558-1578, Vol. 60, nr 2, s. 871-878Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Despite its present shortage, 3He continues to be the most common neutron converter for detectors in neutron scattering science. However, it is obvious that the development of large area neutron detectors based on alternative neutron converters is rapidly becoming a matter of urgency. In the technique presented here, grids each comprising 28 10B4C layers (each 1 μm thick) are used to convert neutrons into ionizing particles which are subsequently detected in proportional gas counters. The total active area of the prototype is 8 cm × 200 cm. To instrument this detector 4.6 m2 of 10B-enriched boron carbide were coated onto aluminium blades using a DC magnetron sputtering machine.

  • 121.
    Birch, Jens
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Buffet, J.-C.
    Institute Laue Langevin, Rue Jules Horowitz, FR-38000 Grenoble, France.
    Clergeau, J.-F.
    Institute Laue Langevin, Rue Jules Horowitz, FR-38000 Grenoble, France.
    Correa, J.
    Institute Laue Langevin, Rue Jules Horowitz, FR-38000 Grenoble, France.
    van Esch, P.
    Institute Laue Langevin, Rue Jules Horowitz, FR-38000 Grenoble, France.
    Ferraton, M.
    Institute Laue Langevin, Rue Jules Horowitz, FR-38000 Grenoble, France.
    Guerard, B.
    Institute Laue Langevin, Rue Jules Horowitz, FR-38000 Grenoble, France.
    Halbwachs, J.
    Institute Laue Langevin, Rue Jules Horowitz, FR-38000 Grenoble, France.
    Hall-Wilton, R.
    European Spallation Source ESS AB, P.O Box 176, SE-221 00 Lund, Sweden.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Höglund, Carina
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan. European Spallation Source ESS AB, P.O Box 176, SE-221 00 Lund, Sweden.
    Khaplanov, A.
    Institute Laue Langevin, Rue Jules Horowitz, FR-38000 Grenoble, France; European Spallation Source ESS AB, P.O Box 176, SE-221 00 Lund, Sweden.
    Koza, M.
    Institute Laue Langevin, Rue Jules Horowitz, FR-38000 Grenoble, France.
    Piscitelli, F.
    Institute Laue Langevin, Rue Jules Horowitz, FR-38000 Grenoble, France.
    Zbiri, M.
    Institute Laue Langevin, Rue Jules Horowitz, FR-38000 Grenoble, France.
    In-beam test of the Boron-10 Multi-Grid neutron detector at the IN6 time-of-flight spectrometer at the ILL2014Ingår i: INTERNATIONAL WORKSHOP ON NEUTRON OPTICS AND DETECTORS (NOPandD 2013), IOP Publishing: Conference Series / Institute of Physics (IoP) , 2014, Vol. 528, nr 012040Konferensbidrag (Refereegranskat)
    Abstract [en]

    A neutron detector concept based on solid layers of boron carbide enriched in 1 B has been in development for the last few years as an alternative for He-3 by collaboration between the ILL, ESS and Linkoping University. This Multi-Grid detector uses layers of aluminum substrates coated with (B4C)-B-10 on both sides that are traversed by the incoming neutrons. Detection is achieved using a gas counter readout principle. By segmenting the substrate and using multiple anode wires, the detector is made inherently position sensitive. This development is aimed primarily at neutron scattering instruments with large detector areas, such as time-of-flight chopper spectrometers. The most recent prototype has been built to be interchangeable with the He-3 detectors of IN6 at ILL. The 1 B detector has an active area of 32 x 48 cm(2). It was installed at the IN6 instrument and operated for several weeks, collecting data in parallel with the regularly scheduled experiments, thus providing the first side-by-side comparison with the conventional He-3 detectors. Results include an efficiency comparison, assessment of the in-detector scattering contribution, sensitivity to gamma-rays and the signal-to-noise ratio in time-of-flight spectra. The good expected performance has been confirmed with the exception of an unexpected background count rate. This has been identified as natural alpha activity in aluminum. New convertor substrates are under study to eliminate this source of background.

  • 122.
    Birch, Jens
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik.
    Eriksson, Fredrik
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik.
    Johansson, G.A.
    Biomedical and X-ray Physics, Royal Institute of Technology, SCFAB, SE-106 91 Stockholm, Sweden.
    Hertz, H.M.
    Biomedical and X-ray Physics, Royal Institute of Technology, SCFAB, SE-106 91 Stockholm, Sweden.
    Recent advances in ion-assisted growth of Cr/Sc multilayer X-ray mirrors for the water window2002Konferensbidrag (Refereegranskat)
    Abstract [en]

    Cr/Sc multilayer X-ray mirrors intended for normal incidence reflection in the water window wavelength range, ?=[2.4-4.4nm], have been grown by ion-assisted sputter deposition and characterized using soft and hard X-ray reflectivity. By extracting low-energy ions, with energies, Eion, ranging from 9 to 113eV and with ion-to-metal flux ratios, F, between 0.76 and 23.1, from the sputtering plasma to the growing film, the nano-structure of the multilayer interfaces could be modified. A significantly increased soft X-ray reflectivity, using ?=3.374nm, for Cr/Sc multilayers with layer thicknesses in the range 0.4-2.8nm, was obtained when high ion-to-metal flux ratios, FCr=7.1 and FSc=23.1, and low energy ions, Eion=9eV, were used. An experimental reflectivity of 5.5% was obtained at 76° for a multilayer with 400 bi-layers. Simulations of the reflectivity data showed that the interface widths are <0.425nm. It could be concluded that roughness of low spatial frequency is reduced at lower ion energies than the high spatial frequency which was eliminated at the expense of intermixing at the interfaces at higher ion energies. The predicted performance of normal incidence multilayer mirrors grown at optimum conditions and designed for ?=3.374 and 3.115nm indicates possible reflectivities of 6.5% and 14%, respectively. © 2002 Elsevier Science Ltd. All rights reserved.

  • 123.
    Birch, Jens
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Joelsson, Torbjörn
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Eriksson, Fredrik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Ghafoor, Naureen
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Single crystal CrN/ScN superlattice soft X-ray mirrors: epitaxial growth, structure, and properties2006Ingår i: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 514, nr 1-2, s. 10-19Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Single crystal CrN/ScN superlattice films with modulation periods of 1.64 nm were grown on MgO(001) substrates. By utilizing a magnetically enhanced plasma in the vicinity of the substrate and a negative substrate bias, ion/metal nitride flux ratios of 45 and 144 were achieved during deposition of CrN and ScN, respectively. The effects of ion energies in the range [16–58 eV] and substrate temperatures in the range [535–853 °C] on the composition, interface width, crystal quality, and microstructure evolution were investigated using elastic recoil detection analysis, hard X-ray reflectivity, X-ray diffraction, and transmission electron microscopy (TEM). Minimal interface widths of 0.2 nm = 1/2 nitride unit cell were achieved at a growth temperature of 735 °C and ion energies of 24 and 28 eV for CrN and ScN, respectively. Under these conditions, also an optimum in the crystal quality was observed for near stoichiometric composition of CrN and ScN. TEM confirmed a cube-on-cube epitaxial relationship for the system with CrN(001)ScN(001)MgO(001) and CrN[100]ScN[100]MgO[100]. Also, the layers were coherently strained to each other with no misfit dislocations, threading dislocations, surface cusps, voids or gas bubbles present. Higher ion energies or lower deposition temperatures gave over-stoichiometric films with poor superlattice modulation while higher growth temperatures yielded a decreased crystal quality, due to loss of N. As-deposited superlattices with only 61 periods exhibited an absolute soft X-ray reflectance of 6.95% at an energy of 398.8 eV (Sc 2p-absorption edge) which is comparable to the performance of Cr/Sc. The compositional modulation and phase structure was stable during extended annealing at 850 °C, which is the highest thermal stability for an X-ray multilayer mirror. It is concluded that the ScN layers serve as effective diffusion barriers to hinder decomposition of the CrN layers and stabilize the pseudomorphic superlattice structure. Nanoindentation experiments showed that the hardness of the CrN/ScN superlattice films was 19 GPa.

  • 124.
    Bofelli, Daniel
    et al.
    University of Buenos Aires, Argentina.
    Broitman, Esteban
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan. University of Buenos Aires, Argentina.
    Zimmerman, Rosa
    University of Buenos Aires, Argentina.
    Electrical and Piezoresistive Properties of Thick Film Resistors (Propiedades Eléctricas y Piezorresistivas de Resistores de Película Gruesa)1997Ingår i: Anales AFA, ISSN 1850-1158, Vol. 8, nr 1, s. 198-200Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Thick film cermet resistors, adjusted by conventional trimming methods, undergo irreversible changes in successive deformation cycles. In this work the stability of resistors adjusted by laser irradiation is evaluated. Resistance, thermal coefficient of resistance, and strain gauge factor in resistors with and without surface treatment are studied. The irradiated surface was characterized by Auger spectroscopy.

  • 125.
    Bouhafs, Chamseddine
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Darakchieva, Vanya
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Persson, Ingemar
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Tiberj, A.
    University of Montpellier 2, France.
    Persson, Per O A
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Paillet, M.
    University of Montpellier 2, France.
    Zahab, A. -A.
    University of Montpellier 2, France.
    Landois, P.
    University of Montpellier 2, France.
    Juillaguet, S.
    University of Montpellier 2, France.
    Schoeche, S.
    University of Nebraska, NE 68588 USA; University of Nebraska, NE 68588 USA.
    Schubert, M.
    University of Nebraska, NE 68588 USA; University of Nebraska, NE 68588 USA.
    Yakimova, Rositsa
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Structural properties and dielectric function of graphene grown by high-temperature sublimation on 4H-SiC(000-1)2015Ingår i: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 117, nr 8, s. 085701-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Understanding and controlling growth of graphene on the carbon face (C-face) of SiC presents a significant challenge. In this work, we study the structural, vibrational, and dielectric function properties of graphene grown on the C-face of 4H-SiC by high-temperature sublimation in an argon atmosphere. The effect of growth temperature on the graphene number of layers and crystallite size is investigated and discussed in relation to graphene coverage and thickness homogeneity. An amorphous carbon layer at the interface between SiC and the graphene is identified, and its evolution with growth temperature is established. Atomic force microscopy, micro-Raman scattering spectroscopy, spectroscopic ellipsometry, and high-resolution cross-sectional transmission electron microscopy are combined to determine and correlate thickness, stacking order, dielectric function, and interface properties of graphene. The role of surface defects and growth temperature on the graphene growth mechanism and stacking is discussed, and a conclusion about the critical factors to achieve decoupled graphene layers is drawn. (C) 2015 AIP Publishing LLC.

  • 126.
    Boyd, Robert
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Plasma och beläggningsfysik. Linköpings universitet, Tekniska fakulteten.
    Pilch, Iris
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Plasma och beläggningsfysik. Linköpings universitet, Tekniska fakulteten.
    Garbrecht, Magnus
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Halvarsson, M
    Department of Applied Physics, Chalmers University of Technology, Göteborg, Sweden.
    Helmersson, Ulf
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Plasma och beläggningsfysik. Linköpings universitet, Tekniska fakulteten.
    Double oxide shell layer formed on a metal nanoparticle as revealed by aberration corrected (scanning) transmission electron microscopy2014Ingår i: Materials Research Express, E-ISSN 2053-1591, Vol. 1, nr 2, artikel-id 025016Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Determining the extent of oxidation in batches of metal nanoparticles is essential to predict the behaviour of the material. Using aberration corrected transmission electron microscopy (TEM) it was possible to detect the formation of an oxide shell, of thickness 3 nm, on the surface of copper nanoparticles. Further analysis showed that this shell actually consists of two layers, both of which were polycrystalline in nature with domains in the size range of 1-2 nm, and having a thickness of 1.5 nm each. Energy dispersive x-ray spectroscopy confirms that the layers arise due to the formation of oxides, but it was not possible to determine their exact nature. Analysis of the intensity variation within images obtained via probe corrected scanning TEM combined with a high angle annular dark field detector indicates that the shell consists of an inner layer of cuprous oxide (Cu2O) and an outer layer of cupric oxide (CuO). This work was complemented by conventional TEM which provided size distribution and revealed that the majority of particles have a core consisting of a single crystal of copper. This demonstrates the ability of TEM to help to determine the oxidation state of nanoparticles and its potential to be applied to a wide range of homogenous and heterogeneous nanoparticles.

  • 127.
    Boyd, Robert
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Plasma och beläggningsfysik. Linköpings universitet, Tekniska fakulteten.
    Söderlind, Fredrik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Kemi. Linköpings universitet, Tekniska fakulteten.
    Helmersson, Ulf
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Plasma och beläggningsfysik. Linköpings universitet, Tekniska fakulteten.
    Odén, Magnus
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska fakulteten.
    Pilch, Iris
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Complex 3D nanocoral like structures formed by copper nanoparticle aggregation on nanostructured zinc oxide rods2016Ingår i: Materials letters (General ed.), ISSN 0167-577X, E-ISSN 1873-4979, Vol. 184, s. 127-130Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper reports a new strategy for nanoparticle surface assembly so that they form anisotropic fibril like features, consisting of particles directly attached to each other, which can extend 500 nm from the surface. The particles are both formed and deposited in a single step process enabled via the use of a pulsed plasma based technique. Using this approach, we have successfully modified zinc oxide rods, up to several hundred nanometers in diameter, with 25 nm diameter copper nanoparticles for catalytic applications. The resulting structure could be modelled using a diffusion limited aggregation based approach. This gives the material the appearance of marine coral, hence the term nanocoral. (C) 2016 Elsevier B.V. All rights reserved.

  • 128.
    Broitman, E.
    et al.
    Carnegie Mellon Univ, Dept Chem Engn, Pittsburgh, PA 15213 USA.
    Furlan, Andrej
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Kostov Gueorguiev, Gueorgui
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Czigany, Zs.
    Res Inst Tech Phys and Mat Sci, H-1525 Budapest, Hungary.
    Tarditi, A M
    Univ Nacl Litoral, RA-3000 Santa Fe, Argentina.
    Gellman, A J
    Carnegie Mellon Univ, Dept Chem Engn, Pittsburgh, PA 15213 USA.
    Stafström, Sven
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Beräkningsfysik. Linköpings universitet, Tekniska högskolan.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Water adsorption on phosphorous-carbide thin films2009Ingår i: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 204, nr 6-7, s. 1035-1039Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Amorphous phosphorous-carbide films have been considered as a new tribological coating material with unique electrical properties. However, such CPx films have not found practical use until now because they tend to oxidize/hydrolyze rapidly when in contact with air. Recently, we demonstrated that CPx thin films with a fullerene-like structure can be deposited by magnetron sputtering, whereby the structural incorporation of P atoms induces the formation of strongly bent and inter-linked graphene planes. Here, we compare the uptake of water in fullerene-like phosphorous-carbide (FL-CPx) thin films with that in amorphous phosphorous-carbide (a-CPx), and amorphous carbon (a-C) thin films. Films of each material were deposited on quartz crystal substrates by reactive DC magnetron sputtering to a thickness in the range 100-300 nm. The film microstructure was characterized by X-ray photoelectron spectroscopy, and high resolution transmission electron microscopy. A quartz crystal microbalance placed in a vacuum chamber was used to measure their water adsorption. Measurements indicate that FL-CPx films adsorbed less water than the a-CPx and a-C ones. To provide additional insight into the atomic structure of defects in the FL-CPx and a-CPx compounds, we performed first-principles calculations within the framework of density functional theory. Cohesive energy comparison reveals that the energy cost formation for dangling bonds in different configurations is considerably higher in FL-CPx than for the amorphous films. Thus, the modeling confirms the experimental results that dangling bonds are less likely in FL-CPx than in a-CPx and a-C films.

  • 129.
    Broitman, E.
    et al.
    Department of Applied Science, College of William and Mary, Williamsburg, VA 23187-8795, United States.
    Hellgren, N.
    Frederick Seitz Materials Res. Lab., University of Illinois, Urbana, IL 61801, United States.
    Czigany, Zs.
    Twesten, R.D.
    Frederick Seitz Materials Res. Lab., University of Illinois, Urbana, IL 61801, United States.
    Luning, J.
    Stanford Synchrotron Radiation Lab., Stanford, CA 94309, United States.
    Petrov, I.
    Frederick Seitz Materials Res. Lab., University of Illinois, Urbana, IL 61801, United States.
    Hultman, Lars
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik.
    Holloway, B.C.
    Department of Applied Science, College of William and Mary, Williamsburg, VA 23187-8795, United States.
    Structural and mechanical properties of diamond-like carbon films deposited by direct current magnetron sputtering2003Ingår i: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films, ISSN 0734-2101, E-ISSN 1520-8559, Vol. 21, nr 4, s. 851-859Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A systematic study of physical properties of sputter-deposited DLC films was performed as a function of flux ratio and ion energy. The energy and flux ions and neutral atoms impinging on the surface of the growing films were deduced from Langmuir probe measurements and theoretical calculations. The bombardment of growing films by the energetic particles led to changes in microstructure and mechanical properties. Results suggest that the presence of defective graphite formed by subplanted C and Ar atoms is the dominant influence on the mechanical properties of the DLC films.

  • 130. Broitman, E.
    et al.
    Hellgren, N.
    Järrendahl, Kenneth
    Linköpings universitet, Tekniska högskolan.
    Johansson, M.P.
    Olafsson, S.
    Radnoczi, G.
    Radnóczi, G., Res. Inst. Tech. Phys. and Mat. Sci., P.O. Box 49, H-1525 Budapest, Hungary.
    Sundgren, J.-E.
    Hultman, Lars
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik.
    Electrical and optical properties of CNx(0=x=0.25) films deposited by reactive magnetron sputtering2001Ingår i: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 89, nr 2, s. 1184-1190Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The electrical and optical properties of carbon-nitride CNx films (O=x=0.25) deposited by unbalanced reactive magnetron sputtering from a graphite target in mixed Ar/N2 discharges at a substrate temperature of 350°C have been investigated. Pure C films exhibit a dark conductivity at room temperature of 250 O-1 cm-1, which grows up to 250 O-1 cm-1 for CNx films with N content of 20%. For CNx films, temperature-dependent conductivity measurements suggest that two electron conduction processes exist in the investigated temperature range 130

  • 131.
    Broitman, E
    et al.
    Coll William & Mary, Dept Appl Sci, Williamsburg, VA 23187 USA Univ Illinois, Frederick Seitz Mat Res Lab, Urbana, IL 61801 USA Linkoping Univ, Dept Phys & Measurement Technol, SE-58183 Linkoping, Sweden Carnegie Mellon Univ, Dept Chem Engn, Pittsburgh, PA 15213 USA.
    Hellgren, N
    Coll William & Mary, Dept Appl Sci, Williamsburg, VA 23187 USA Univ Illinois, Frederick Seitz Mat Res Lab, Urbana, IL 61801 USA Linkoping Univ, Dept Phys & Measurement Technol, SE-58183 Linkoping, Sweden Carnegie Mellon Univ, Dept Chem Engn, Pittsburgh, PA 15213 USA.
    Neidhardt, Jörg
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik.
    Brunell, I
    Coll William & Mary, Dept Appl Sci, Williamsburg, VA 23187 USA Univ Illinois, Frederick Seitz Mat Res Lab, Urbana, IL 61801 USA Linkoping Univ, Dept Phys & Measurement Technol, SE-58183 Linkoping, Sweden Carnegie Mellon Univ, Dept Chem Engn, Pittsburgh, PA 15213 USA.
    Hultman, Lars
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik.
    Letter: Electrical properties of carbon nitride thin films: Role of morphology and hydrogen content2002Ingår i: Journal of Electronic Materials, ISSN 0361-5235, E-ISSN 1543-186X, Vol. 31, nr 9, s. L11-L15s. 957-961Artikel i tidskrift (Övrigt vetenskapligt)
    Abstract [en]

    The influence of hydrogen content and ambient humidity on the electrical properties of carbon nitride (CNX) films deposited by reactive magnetron sputtering from a graphite target in Ar discharges mixed with N-2 and H-2 at a substrate temperature of 350degreesC have been investigated. Carbon films deposited in pure Ar exhibit a dark resistivity at room temperature of similar to4 X 10(-2) Omegacm, while the resistivity is one order of magnitude lower for CN0.25 films deposited in pure N-2, due to their denser morphology. The increasing H-2 fraction in the discharge gas leads to an increased resistivity for all gas mixtures. This is most pronounced for the nitrogen-free films deposited in an Ar/H-2 mixture, where the resistivity increases by over four orders of magnitude. This can be related to a decreased electron mobility as H inhibits the formation of double bonds. After exposure to air, the resistivity increases with time through two different diffusion regimes. The measured electrical properties of the films are related to the apparent film microstructure, bonding nature, and ambient humidity.

  • 132. Broitman, E.
    et al.
    Hellgren, N.
    Wanstrand, O.
    Wänstrand, O., Department of Materials Science, Ångström Laboratory, Uppsala University, SE-751 21 Uppsala, Sweden.
    Johansson, M.P.
    Berlind, Torun
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad optik.
    Sjostrom, H.
    Sjöström, H., Sjöstrom Coating Consulting, KarlGustavsgatan 21A, SE-411 20 Göteborg, Sweden.
    Sundgren, J.-E.
    Office of the President, Chalmers University of Technology, SE-412 96 Göteborg, Sweden.
    Larsson, M.
    Department of Materials Science, Ångström Laboratory, Uppsala University, SE-751 21 Uppsala, Sweden.
    Hultman, Lars
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik.
    Mechanical and tribological properties of CNx films deposited by reactive magnetron sputtering2001Ingår i: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 248, nr 1-2, s. 55-64Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The hardness, elasticity, wear rate and friction coefficient of carbon nitride (CNx) films of defined microstructure and composition are presented. CNx films were deposited by dc reactive magnetron sputtering from a C target in N2/Ar plasma. Films were grown on Si (001), Ni, and HSS substrates to thickness of ~0.5 µm at a total pressure of 3 mTorr with the N2 fraction varied from 0 to 1, and the substrate temperature Ts, varied from ambient to 350°C. The mechanical and tribological properties of the coatings were evaluated by nanoindentation and dry ball-on-disk test. For CNx (0 = x = 0.35) films deposited below 200°C (amorphous structure), the elastic recovery and hardness do not change significantly with increasing N concentration, however, the friction coefficient increases from 0.19 to 0.45, while the coating wear rate is low. For CNx (0 = x = 0.15) films grown at Ts = 350°C, where a transition from a graphite-like to a "fullerene-like" phase occurs, a dramatic increase in hardness and elasticity is observed. Furthermore, the rms surface roughness decreases from 15.0 to 0.4 nm. For 0.15 = x = 0.20, CNx films deposited at Ts = 350°C (fullerene-like phase) exhibit a smooth surface, high hardness and elasticity (~90% recovery), and a coefficient of friction against hard steel of ~0.25. For all substrates, film friction coefficient tends to increase as the nitrogen content in the film is increased. Results also indicate the formation of a transfer layer which improves the tribological properties of the films. © 2001 Elsevier Science B.V. All rights reserved.

  • 133.
    Broitman, E
    et al.
    Carnegie Mellon University.
    Kostov Gueorguiev, Gueorgui
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Furlan, Andrej
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Son, Tien Nguyen
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Gellman, A J
    Carnegie Mellon University.
    Stafström, Sven
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Beräkningsfysik. Linköpings universitet, Tekniska högskolan.
    Hultman , Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Water adsorption on fullerene-like carbon nitride overcoats2008Ingår i: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 517, nr 3, s. 1106-1110Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Humidity influences the tribological performance of the head-disk interface in magnetic data storage devices. In this work we compare the uptake of water of amorphous carbon nitride (a-CNx) films, widely used as protective overcoats in computer disk drive systems, with fullerene-like carbon nitride (FL-CNx) and amorphous carbon (a-C) films. Films with thickness in the range 10-300 run were deposited on quartz crystal substrates by reactive DC magnetron sputtering. A quartz crystal microbalance placed in a vacuum chamber was used to measure the water adsorption. Electron paramagnetic resonance (EPR) has been used to correlate water adsorption with film microstructure and surface defects (dangling bonds). Measurements indicate that the amount of adsorbed water is highest for the pure a-C films and that the FL-CNx films adsorbed less than a-CNx. EPR data correlate the lower water adsorption on FL-CNx films with a possible lack of dangling bonds on the film surface. To provide additional insight into the atomic structure of defects in the FL-CNx, a-CNx and a-C compounds, we performed first-principles calculations within the framework of Density Functional Theory. Emphasis was put on the energy cost for formation of vacancy defects and dangling bonds in relaxed systems. Cohesive energy comparison reveals that the energy cost formation for dangling bonds in different configurations is considerably higher in FL-CNx than for the amorphous films. These simulations thus confirm the experimental results showing that dangling bonds are much less likely in FL-CNx than in a-CNx and a-C films.

  • 134.
    Broitman, E.
    et al.
    College of William and Mary, Williamsburg, Virginia .
    Lindquist, O.P.A.
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska högskolan.
    Hellgren, N.
    University of Illinois, Urbana.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Holloway, B.C.
    College of William and Mary, Williamsburg, Virginia .
    Structural, electrical, and optical properties of diamondlike carbon films deposited by dc magnetron sputtering2003Övrigt (Övrigt vetenskapligt)
    Abstract [en]

    The electrical and optical properties of diamondlike carbon films deposited by direct current magnetron sputtering on Si substrates at room temperature have been measured as a function of the ion energy (Eion) and ion-to-carbon flux (Jion/JC). The results show that, in the ranges of 5 eV⩽Eion⩽85 eV and 1.1⩽Jion/JC⩽6.8, the presence of defective graphite formed by subplanted C and Ar atoms, voids, and the surface roughness, are the dominant influences on the resistivity and optical absorption

  • 135. Broitman, E.
    et al.
    Macdonald, W.
    Department of Biomaterials, Göteborg University, SE-413 90 Goteborg, Sweden.
    Hellgren, N.
    Radnoczi, G.
    Radnóczi, G., Research Institute for Technical Physics and Material Sciences, P.O. Box 49, H-1525 Budapest, Hungary.
    Czigany, Z.
    Wennerberg, A.
    Department of Biomaterials, Göteborg University, SE-413 90 Goteborg, Sweden.
    Jacobsson, M.
    Department of Biomaterials, Göteborg University, SE-413 90 Goteborg, Sweden.
    Hultman, Lars
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik.
    Carbon nitride films on orthopedic substrates2000Ingår i: Diamond and related materials, ISSN 0925-9635, E-ISSN 1879-0062, Vol. 9, nr 12, s. 1984-1991Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The mechanical and tribological properties of carbon nitride (CN(X)) films deposited on orthopedic substrates are presented. CN(X) films were prepared by d.c. reactive magnetron sputtering from a graphite target in N2/Ar plasma. Films were grown on Ni and ZrO2 substrates to a thickness of ~1 µm at a total pressure of 3 mtorr and a substrate temperature of 250°C. High-resolution transmission electron microscopy (HRTEM) shows dense and homogeneous films, with 'fullerene-like' micro-structures consisting of curved, frequently intersecting, and highly in-plane oriented basal lattice planes. Nanoindentation measurements revealed a change in the mechanical properties of films treated with three different biological solutions. Spectroscopic analysis confirmed a change in the chemical structure of the treated films. The friction coefficients of CN(X) films against high speed steel (HSS), ZrO2 and Ultra-High Molecular Weight Polyethylene (UHMWPE) balls were evaluated by ball-on-disk tests in dry and lubricated conditions. In the case of dry sliding against a HSS ball, the steady state friction coefficient values are 0.22 for the film on the Ti substrate and 0.26 for the film on the ZrO2 substrate. The friction coefficients under human serum lubrication conditions were below 0.18 for the ZrO2 and UHMWPE balls. An increase in wettability of human plasma on CN(X) films was observed compared to the orthopedic surfaces, which could enhance the retention of synovial fluid on those surfaces, improving the lubrication of the bearings of total joint arthroplasty components during function. (C) 2000 Elsevier Science B.V. All rights reserved.The mechanical and tribological properties of carbon nitride (CNX) films deposited on orthopedic substrates are presented. CNX films were prepared by d.c. reactive magnetron sputtering from a graphite target in N2/Ar plasma. Films were grown on Ni and ZrO2 substrates to a thickness of approximately 1 µm at a total pressure of 3 mtorr and a substrate temperature of 250 °C. High-resolution transmission electron microscopy (HRTEM) shows dense and homogeneous films, with `fullerene-like' microstructures consisting of curved, frequently intersecting, and highly in-plane oriented basal lattice planes. Nanoindentation measurements revealed a change in the mechanical properties of films treated with three different biological solutions. Spectroscopic analysis confirmed a change in the chemical structure of the treated films. The friction coefficients of CNX films against high speed steel (HSS), ZrO2 and Ultra-High Molecular Weight Polyethylene (UHMWPE) balls were evaluated by ball-on-disk tests in dry and lubricated conditions. In the case of dry sliding against a HSS ball, the steady state friction coefficient values are 0.22 for the film on the Ti substrate and 0.26 for the film on the ZrO2 substrate. The friction coefficients under human serum lubrication conditions were below 0.18 for the ZrO2 and UHMWPE balls. An increase in wettability of human plasma on CNX films was observed compared to the orthopedic surfaces, which could enhance the retention of synovial fluid on those surfaces, improving the lubrication of the bearings of total joint arthroplasty components during function.

  • 136.
    Broitman, E.
    et al.
    Department of Chemical Engineering, Carnegie Mellon University, Pittsburgh, PA 15213, USA.
    Pushkarev, V. V.
    Department of Chemical Engineering, Carnegie Mellon University, Pittsburgh, PA 15213, USA.
    Gellman, A. J.
    Department of Chemical Engineering, Carnegie Mellon University, Pittsburgh, PA 15213, USA.
    Neidhardt, Jörg
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Furlan, Andrej
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Water adsorption on lubricated fullerene-like CNx films2006Ingår i: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 515, nr 3, s. 979-983Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Humidity influences the tribological performance of the head–disk interface in magnetic data storage devices. In this work we compare the uptake of water of amorphous hydrogenated carbon (a-CHy) and carbon nitride (a-CNx) films, widely used as protective overcoats in computer disk drive systems, with two types of amorphous non-hydrogenated carbon (a-C and a-Csp2) films, and fullerene-like carbon nitride (FL-CNx) films. Carbon films were deposited on quartz crystal substrates by reactive dc magnetron sputtering in Ar/N2 discharges. After deposition, some of the films were coated with a 2-nm-thick layer of Z-tetraol, a lubricant used in hard disk devices. A quartz crystal microbalance placed in a vacuum chamber was used to measure the adsorption of water at room temperature and at pressures of water corresponding to relative humidities in the range RH = 0 to 90%. Water adsorption and desorption is fast, indicating that equilibrium with ambient humidity is reached on time scales of minutes, much faster than the time scales for fluctuations in ambient humidity. The amount of water adsorbed on the non-lubricated amorphous carbon films is significantly higher than that on the fullerene-like films. The presence of the lubricant influences water adsorption but its impact differs on different carbon films.

  • 137.
    Broitman, Esteban
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    A new method for in-situ measurement of nano-friction and nano-wear of thin films by using the Triboindenter TI-9502014Ingår i: Nanobrucken 2014, Saarbrucken, Germany: INM - Leibniz Institute for New Materials , 2014, s. 24-Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    The Triboindenter present many advantages for the measurement of friction and wear at the nanoscale. A reciprocating multi-cycle linear test can be programmed, from where it is possible to obtain simultaneously the friction force and wear rate from the lateral force and vertical displacement sensors, respectively. The friction values have high precision but the wear data is usually wrong in long duration tests because the drift rate is only measured just before the test start. Alternatively, one can program the SPM scanning mode of the instrument with a high load in order to produce the wear of the surface. At the end of the experiment, a squared hole is produced which can be measured using the SPM facility of the system. However, this wear experiment does not allow the simultaneous measurement of the friction coefficient.In this talk I will present a new methodology to measure in-situ the friction and wear of thin films using a Triboindenter TI-950 from Hysitron. I will show how the possible changes of drift rate during long-time tests can be overcome, obtaining simultaneous precise values of friction and wear rate as a function of time. I will discuss how the Triboimage® software can be adapted to this methodology in order to get realistic values of friction and wear. Finally I will show some results for soft (H < 1GPa) Pb films and very hard (H ~ 35 GPa) nitride coatings

  • 138.
    Broitman, Esteban
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Editorial Material: INTRODUCTION in POLYMERS and POLYMER COMPOSITES, vol 22, issue 8, pp2014Ingår i: Polymers & polymer composites, ISSN 0967-3911, E-ISSN 1478-2391, Vol. 22, nr 8Artikel i tidskrift (Övrigt vetenskapligt)
    Abstract [en]

    n/a

  • 139.
    Broitman, Esteban
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Editorial Material: Novel insights in polymer and composite materials in E-POLYMERS, vol 15, issue 5, pp 285-2862015Ingår i: E-Polymers, ISSN 1618-7229, E-ISSN 1618-7229, Vol. 15, nr 5, s. 285-286Artikel i tidskrift (Övrigt vetenskapligt)
    Abstract [en]

    n/a

  • 140.
    Broitman, Esteban
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    The nature of the frictional force at the macro-, micro-, and nano-scales2014Ingår i: Friction, E-ISSN 2223-7690, Vol. 2, nr 1, s. 40-46Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Nowadays it is accepted that the friction force is a combined effect arising from various phenomena: adhesive forces, capillary forces, contact elasticity, topography, surface chemistry, and generation of a third body, etc. Any of them can dominate depending on the experimental force and length scales of the study. Typical forces in macro-tribology are in the Newtons, while are reduced to milli-/micro-Newtons, and nano-Newtons in micro- and nano-tribology, respectively. In this paper, experimental friction results from fullerene like CN x films and single-crystal Si at the three scales will be discussed. The complex and broad variety of processes and phenomena connected with the dry friction coefficient at the macro-, micro-, and nano-scale point of view will be highlighted.

  • 141.
    Broitman, Esteban
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Becker, Richard
    Studsvik Nuclear AB.
    Dozaki, Koji
    The Japan Atomic Power Company.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    A Novel Oxide Characterization Method of Nickel Base Alloy 600 Used in Nuclear Plant Reactors2013Ingår i: / [ed] F. Marquis, Hoboken, NJ, USA: John Wiley & Sons, 2013, s. 415-Konferensbidrag (Refereegranskat)
    Abstract [en]

    The Alloy 600 is a polycrystalline nickel base alloy used in pressurized water reactors (PWR) of nuclear power plants. Long term exposure of the alloy to primary water of PWR generates an oxide film that strongly influences the stress corrosion cracking behavior of the alloy. Recently, it has been shown that the oxide film structure, composition and thickness depend on the dissolved hydrogen content in the primary water. In this work we have explored a novel approach which enables a high spatial resolution oxide thickness measurement by nanomechanical testing. Oxide films have been grown on Alloy 600 specimens exposed between 5000 and 35000 hours at 320-330°C with hydrogen levels in the range 5 to 25 mL H2/kg H2O. A Triboindenter TI-950 from Hysitron was used to measure the change of nanomechanical properties in polished cross-sections. The increase of hardness has been correlated to the presence of oxides.

  • 142.
    Broitman, Esteban
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Bojorge, C
    CINSO, Argentina.
    Elhordoy, F
    Instituto de Física & CINQUIFIMA, Uruguay.
    Kent, V.
    Instituto de Física & CINQUIFIMA, Uruguay.
    Zanini Gadioli, G
    Instituto de Física Gleb Wataghin, Brazil.
    Marotti, R.
    Instituto de Física & CINQUIFIMA, Uruguay.
    Canepa, H
    CINSO, Argentina.
    Dalchiele, E. A.
    Instituto de Física & CINQUIFIMA, Uruguay.
    Comparative study on the properties of ZnO nanowires and nanocrystalline thin films2012Ingår i: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 213, s. 59-64Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The microstructural, morphological, optical and water-adsorption properties of nanocrystalline ZnO thin films and ZnO nanowires were studied and compared. The ZnO thin films were obtained by a sol–gel process, while the ZnO nanowires were electrochemically grown onto a ZnO sol–gel spin-coated seed layer. Thin films and nanowire samples were deposited onto crystalline quartz substrates covered by an Au electrode, able to be used in a quartz crystal microbalance. X-ray diffraction measurements reveal in both cases a typical diffraction pattern of ZnO wurtzite structure. Scanning electron microscopic images of nanowire samples show the presence of nanowires with hexagonal sections, with diameters ranging from 30 to 90 nm. Optical characterization reveals a bandgap energy of 3.29 eV for the nanowires and 3.35 eV for the thin films. A quartz crystal microbalance placed in a vacuum chamber was used to quantify the amount and kinetics of water adsorption onto the samples. Nanowire samples, which have higher surface areas than the thin films, adsorb significantly more water.

  • 143.
    Broitman, Esteban
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska högskolan.
    Czigany, Zs.
    Res Inst Tech Phys and Mat Sci,Budapest.
    Greczynski, Grzegorz
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska högskolan.
    Bohlmark, J.
    Sandvik Tooling RandD.
    Cremer, R.
    CemeCon AG.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Industrial-scale deposition of highly adherent CNx films on steel substrates2010Ingår i: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 204, nr 21-22, s. 3349-3357Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Highly adherent carbon nitride (CNx) films were deposited using a novel pretreatment with two high power impulse magnetron sputtering (HIPIMS) power supplies in a master-slave configuration: one to establish the discharge and one to produce a pulsed substrate bias. During the pretreatment, SKF3 (AISI 52100) steel substrates were pulse-biased in the environment of a HIPIMS Cr plasma in order to sputter clean the surface and to implant Cr metal ions. Subsequently. CNx films were prepared at room temperature by DC unbalanced magnetron sputtering from a high purity graphite target in a N-2/Ar discharge at 3 mTorr. All processing was done in an industrial CemeCon CC800 system. A series of depositions were obtained with samples at different bias voltages (DC and pulsed) in the range of 0-800 V. Scanning transmission microscopy (STEM) and high resolution transmission electron microscopy (HRTEM) show the formation of an interface comprising a polycrystalline Cr layer of 100 nm and an amorphous transition layer of 5 nm. The adhesion of CNx films evaluated by the Daimler-Benz Rockwell-C reach strength quality HF1, and the scratch tests gives critical loads of 84 N. Adhesion results are correlated to the formation of an optimal interfacial mixing layer of Cr and steel.

  • 144.
    Broitman, Esteban
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Flores-Ruiz, Francisco
    Centro de Investigacion y de Estudios Avanzados del I.P.N., Unidad Queretaro.
    Novel method for in-situ and simultaneous nanofriction and nanowear characterization of materials2015Ingår i: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films, ISSN 0734-2101, E-ISSN 1520-8559, Vol. 34, artikel-id 043201Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Nowadays, there is an increased need to know the nanotribological properties of protectivecoatings used in part devices operating under nano- and microcontact situations, e.g., hard diskdrives, magnetic heads, microelectromechanical systems and microsensors, etc. Therefore, there isa demand for instruments and methods testing friction and wear at the nano- and microscales. Inthis work, the authors present a new methodology to measure simultaneously the friction, and wearof a surface. The authors have designed an experiment, where a probe is permanently scanning a10 lm track in a reciprocal movement. Different loads are applied in order to obtain thetopographic information which is used to calculate the wear rate and roughness evolution. Forcelateral sensors register simultaneously the friction force variations. The experimental input data areinformation vectors that contain: load (lN), friction force (lN), vertical Z displacement (nm),lateral X displacement (nm), and time (s). The data are processed using a simple program runningin MathLabVR which eliminates the thermal drift. The software output gives the resulting frictioncoefficient, track roughness, and wear rate as a function of the running cycles of the probe. Thenew method builds a novel bridge to relate tribological mechanisms at different scales

  • 145.
    Broitman, Esteban
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Flores-Ruiz, Francisco J.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten. IPN, Mexico.
    Di Giulio, Massimo
    University of Salento, Italy.
    Gontad, Francisco
    University of Salento, Italy; Ist Nazl Fis Nucl, Italy.
    Lorusso, Antonella
    University of Salento, Italy; Ist Nazl Fis Nucl, Italy.
    Perrone, Alessio
    University of Salento, Italy; Ist Nazl Fis Nucl, Italy.
    Microstructural, nanomechanical, and microtribological properties of Pb thin films prepared by pulsed laser deposition and thermal evaporation techniques2016Ingår i: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films, ISSN 0734-2101, E-ISSN 1520-8559, Vol. 34, nr 2, s. 021505-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this work, the authors compare the morphological, structural, nanomechanical, and microtribological properties of Pb films deposited by thermal evaporation (TE) and pulsed laser deposition (PLD) techniques onto Si (111) substrates. Films were investigated by scanning electron microscopy, surface probe microscopy, and x-ray diffraction in theta-2 theta geometry to determine their morphology, root-mean-square (RMS) roughness, and microstructure, respectively. TE films showed a percolated morphology with densely packed fibrous grains while PLD films had a granular morphology with a columnar and tightly packed structure in accordance with the zone growth model of Thornton. Moreover, PLD films presented a more polycrystalline structure with respect to TE films, with RMS roughness of 14 and 10 nm, respectively. Hardness and elastic modulus vary from 2.1 to 0.8 GPa and from 14 to 10 GPa for PLD and TE films, respectively. A reciprocal friction test has shown that PLD films have lower friction coefficient and wear rate than TE films. Our study has demonstrated for first time that, at the microscale, Pb films do not show the same simple lubricious properties measured at the macroscale. (C) 2015 American Vacuum Society.

  • 146.
    Broitman, Esteban
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Furlan, Andrej
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Geuorguiev, G. K.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Czigany, Zsolt
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska högskolan.
    Högberg, Hans
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Structural and Mechanical Properties of CNx and CPx Thin Solid Films2012Ingår i: Key Engineering Materials, ISSN 1013-9826, E-ISSN 1662-9795, Vol. 488-489, s. 581-584Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The inherent resiliency, hardness and relatively low friction coefficient of the fullerene-like (FL) allotrope of carbon nitride (CNx) thin solid films give them potential in numerous tribological applications. In this work, we study the substitution of N with P to grow FL-CPx to achieve better cross- and inter-linking of the graphene planes, improving thus the materials mechanical and tribological properties. The CNx and CPx films have been synthesized by DC magnetron sputtering. HRTEM have shown the CPx films exhibit a short range ordered structure with FL characteristics for substrate temperature of 300 degrees C and for a phosphorus content of 10-15 at.%. These films show better mechanical properties in terms of hardness and resiliency compared to those of the FL-CNx films. The low water adsorption of the films is correlated to the theoretical prediction for low density of dangling bonds in both, CNx and CPx. First-principles calculations based on Density Functional Theory (DFT) were performed to provide additional insight on the structure and bonding in CNx, CPx and a-C compounds.

  • 147.
    Broitman, Esteban
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Adhesion improvement of carbon-based coatings through a high ionization deposition technique2012Ingår i: Journal of Physics, Conference Series, ISSN 1742-6588, E-ISSN 1742-6596, Vol. 370, nr 012009Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The deposition of highly adherent carbon nitride (CNx) films using a pretreatment with two high power impulse magnetron sputtering (HIPIMS) power supplies in a master-slave configuration is reviewed. SKF3 (AISI 52100) steel substrates were pretreated in the environment of a high ionized Cr+Ar plasma in order to sputter clean the surface and implant Cr metal ions. CNx films were subsequently deposited at room temperature by DC magnetron sputtering from a high purity C target in a N-2/Ar plasma discharge. All processing was done in an industrial-scale CemeCon CC800 coating system. A series of depositions were obtained with samples pretreated at different bias voltages (DC and pulsed). The adhesion of CNx films, evaluated by the Daimler-Benz Rockwell-C test, reaches strength quality HF1. Adhesion results are correlated to high resolution transmission electron microscopy observations confirming the formation of an optimal interfacial mixing layer of Cr and steel. The throwing power increase for HIPIMS coatings is associated to the higher ionization in the plasma discharge.

  • 148.
    Broitman, Esteban
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Advanced Carbon-Based Coatings2014Ingår i: Comprehensive Materials Processing, Elsevier, 2014, 4, s. 389-412Kapitel i bok, del av antologi (Refereegranskat)
    Abstract [en]

    This chapter focuses on the development of alloyed diamondlike coatings, in particular a new class of fullerene-like (FL) materials. We describe unique resilient FL compounds by self-organization of nano-curved sp2-hybridized carbon features, with tuned mechanical and surface energy properties. These unique resilient materials consist of bent and intersecting hexagonal basal planes, fabricated by the incorporation of odd-member rings. Cross-linking enables the material to extend the strength of the covalently 2D hexagonal graphene network into 3D. The microstructural properties of three types of coatings, which have the possibility to be applied on a large scale, are described: carbon nitride, phosphorous carbide, and carbon fluoride.

  • 149.
    Broitman, Esteban
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Beschichtungsverfahren und Vorrichtung zum Beschichten2009Patent (Övrig (populärvetenskap, debatt, mm))
  • 150.
    Broitman, Esteban
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Tribology of Carbon-Based Coatings: Past, Present, and Future2013Ingår i: Proceeding of the 2nd International Workshop of Tribology Tribaries 2013, 2013, s. 7-10Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    In this talk, the development of carbon-based coatings will be reviewed. The most recent findings in the synthesis, characterization and application of carbon-based coatings will be highlighted. Future perspectives of new fullerene-like carbon-based tribological coatings will be discussed. Novel applications of fullerene-like CNx, CPx, and CFx will be envisioned.

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