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  • 1. Aijaz, Asim
    et al.
    Sarakinos, Kostas
    Lundin, Daniel
    Brenning, Nils
    KTH, School of Electrical Engineering (EES), Space and Plasma Physics.
    Helmersson, Ulf
    A strategy for increased carbon ionization in magnetron sputtering discharges2012In: Diamond and related materials, ISSN 0925-9635, E-ISSN 1879-0062, Vol. 23, p. 1-4Article in journal (Refereed)
    Abstract [en]

    A strategy that facilitates a substantial increase of carbon ionization in magnetron sputtering discharges is presented in this work. The strategy is based on increasing the electron temperature in a high power impulse magnetron sputtering discharge by using Ne as the sputtering gas. This allows for the generation of an energetic C+ ion population and a substantial increase in the C+ ion flux as compared to a conventional Ar-HiPIMS process. A direct consequence of the ionization enhancement is demonstrated by an increase in the mass density of the grown films up to 2.8 g/cm(3); the density values achieved are substantially higher than those obtained from conventional magnetron sputtering methods.

  • 2.
    Aijaz, Asim
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics. Linköping University, The Institute of Technology.
    Sarakinos, Kostas
    Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics. Linköping University, The Institute of Technology.
    Lundin, Daniel
    Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics. Linköping University, The Institute of Technology.
    Brenning, Nils
    Royal Institute of Technology.
    Helmersson, Ulf
    Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics. Linköping University, The Institute of Technology.
    A strategy for increased carbon ionization in magnetron sputtering discharges2012In: Diamond and related materials, ISSN 0925-9635, E-ISSN 1879-0062, Vol. 23, p. 1-4Article in journal (Refereed)
    Abstract [en]

    A strategy that facilitates a substantial increase of carbon ionization in magnetron sputtering discharges is presented in this work. The strategy is based on increasing the electron temperature in a high power impulse magnetron sputtering discharge by using Ne as the sputtering gas. This allows for the generation of an energetic C+ ion population and a substantial increase in the C+ ion flux as compared to a conventional Ar-HiPIMS process. A direct consequence of the ionization enhancement is demonstrated by an increase in the mass density of the grown films up to 2.8 g/cm3; the density values achieved are substantially higher than those obtained from conventional magnetron sputtering methods.

  • 3.
    Aijaz, Asim
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics. Linköping University, The Institute of Technology.
    Sarakinos, Kostas
    Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics. Linköping University, The Institute of Technology.
    Raza, Mohsin
    Chimie des Interactions Plasma-Surface (ChIPS), University of Mons, Belgium.
    Jensen, Jens
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Helmersson, Ulf
    Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics. Linköping University, The Institute of Technology.
    Principles for designing sputtering-based strategies for high-rate synthesis of dense and hard hydrogenated amorphous carbon thin films2014In: Diamond and related materials, ISSN 0925-9635, E-ISSN 1879-0062, Vol. 44, p. 117-122Article in journal (Refereed)
    Abstract [en]

    In the present study we contribute to the understanding that is required for designing sputtering-based routes for high rate synthesis of hard and dense amorphous carbon (a-C) films. We compile and implement a strategy for synthesis of a-C thin films that entails coupling a hydrocarbon gas (acetylene) with high density discharges generated by the superposition of high power impulse magnetron sputtering (HiPIMS) and direct current magnetron sputtering (DCMS). Appropriate control of discharge density (by tuning HiPIMS/DCMS power ratio), gas phase composition and energy of the ionized depositing species leads to a route capable of providing ten-fold increase in the deposition rate of a-C film growth compared to HiPIMS Ar discharge (Aijaz et al. Diamond and Related Materials 23 (2012) 1). This is achieved without significant incorporation of H (< 10 %) and with relatively high hardness (> 25 GPa) and mass density (~2.32 g/cm3). Using our experimental data together with Monte-Carlo computer simulations and data from the literature we suggest that: (i) dissociative reactions triggered by the interactions of energetic discharge electrons with hydrocarbon gas molecules is an important additional (to the sputtering cathode) source of film forming species and (ii) film microstructure and film hydrogen content are primarily controlled by interactions of energetic plasma species with surface and sub-surface layers of the growing film.

  • 4. Arvidsson, Igor
    Adsorption of H, NHx, BHx and BBrx on a (110) Surface of c-BN: A Quantum Mechanical DFT Study2007In: Diamond and related materials, ISSN 0925-9635, E-ISSN 1879-0062, Vol. 16, p. 131-Article in journal (Refereed)
  • 5.
    Arvidsson, Igor
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry.
    Larsson, Karin
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry.
    Adsorption of H, NHx, BHx and BBrx on a (110) surface of c-BN: A quantum-mechanical DFT study2007In: Diamond and related materials, ISSN 0925-9635, E-ISSN 1879-0062, Vol. 16, no 1, p. 131-137Article in journal (Refereed)
    Abstract [en]

    The adsorption of H, NHx, BHx and BBrx (x = 1, 2 and 3) on hydrogen-terminated (110) surfaces of c-BN has been investigated theoretically. Density Functional Theory (DFT) methods were used in order to study the adsorption processes of these different species on both nitrogen and boron sites at the surfaces. With one exception, all adsorption processes were found to be exothermic and in the order; BBr·  BH2· ≈H· > BH·  NH· ≈ BBr2· > NH2·  BH3· > NH3· > BBr3· for a nitrogen site, and NH2· > NH· > BBr· > H· > BH· > BH2· ≈ BBr2·  BBr3· ≈ NH3· ≈BH3· for a boron site. The exception was NH3 being bonded to a surface N site, for which the reaction was slightly endothermic. The various modeling parameters that were used in the calculations of these adsorption energies have been chosen by performing series of extensive test calculations, in which the effect of these parameters (e.g. template size, vacuum depth, atom constraints) on bond-strength have been carefully estimated. Moreover, a semi-empirical method has been evaluated with the purpose to study the usefulness of this type of method for the polar BN compound.

  • 6.
    Askari, SJ
    et al.
    Institute of Manufacturing Engineering, PNEC, National University of Sciences and Technology (NUST), Karachi.
    Chen, GC
    Department of High Tech Thin Films, School of Materials Science and Engineering, University of Science and Technology Beijing.
    Akhtar, Farid
    Department of High Tech Thin Films, School of Materials Science and Engineering, University of Science and Technology Beijing.
    Lu, FX
    Department of High Tech Thin Films, School of Materials Science and Engineering, University of Science and Technology Beijing.
    Adherent and low friction nano-crystalline diamond film grown on titanium using microwave CVD plasma2008In: Diamond and related materials, ISSN 0925-9635, E-ISSN 1879-0062, Vol. 17, no 3, p. 294-299Article in journal (Refereed)
    Abstract [en]

    The use of titanium alloys for aerospace and biomedical applications could increase if their tribological behavior was improved. The deposition of an adherent diamond coating can resolve this issue. However, due to the different thermal expansion coefficients of the two materials, it is difficult to grow adherent thin diamond layers on Ti and its metallic alloys. In the present work microwave plasma chemical vapor deposition (MWPCVD) was used to deposit smooth nano-crystalline diamond (NCD) film on pure titanium substrate using Ar, CH4 and H2 gases at moderate deposition temperatures. Of particular interest in this study was the exceptional adhesion of approximately 2 μm-thick diamond film to the metal substrate as observed by indentation testing up to 150 kg load. The friction coefficient, which was measured with a cemented carbide ball of 10 mm diameter with 20 N load, was estimated to be around 0.04 in dry air. Morphology, surface roughness, diamond crystal orientation and quality were obtained by characterizing the sample with field emission electron microscopy (FE-SEM), atomic force microscopy (AFM), X-ray diffraction (XRD) and Raman spectroscopy, respectively.

  • 7. Barankova, Hana
    et al.
    Bardos, L
    Berg, Sören
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Studies of the optical emission from a hydrogen-hydrocarbon rf plasma jet stream during diamond film deposition1993In: Diamond and related materials, ISSN 0925-9635, E-ISSN 1879-0062, Vol. 2, p. 347-352Article in journal (Refereed)
  • 8. Bardos, L
    et al.
    Berg, Sören
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Barankova, Hana
    An r.f. plasma jet applied to diamond, glassy carbon and silicon carbide film synthesis1993In: Diamond and related materials, ISSN 0925-9635, E-ISSN 1879-0062, Vol. 2, p. 517-522Article in journal (Refereed)
  • 9. Bardos, L
    et al.
    Nyberg, T
    Berg, Sören
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Barankova, Hana
    Effect of the space charge sheath on properties of carbon and diamond films grown in the radio frequency plasma jet1994In: Diamond and related materials, ISSN 0925-9635, E-ISSN 1879-0062, Vol. 3, no 4-6, p. 528-530Article in journal (Refereed)
  • 10. Bardos, L
    et al.
    Nyberg, T
    Berg, Sören
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Barankova, Hana
    Effect of the space charge sheath on properties of carbon and diamond films grown in the radio sheath on properties of carbon and diamond films grown in the radio frequency plasma jet1994In: Diamond and related materials, ISSN 0925-9635, E-ISSN 1879-0062, Vol. 3, no 4-6, p. 528-530Article in journal (Refereed)
  • 11. Bertilsson, K.
    et al.
    Dubaric, E.
    Nilsson, H. E.
    Hjelm, M.
    Petersson, C. Sture
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Monte Carlo simulation of vertical MESFETs in 2H, 4H and 6H-SiC2001In: Diamond and related materials, ISSN 0925-9635, E-ISSN 1879-0062, Vol. 10, no 3-7, p. 1283-1286Article in journal (Refereed)
    Abstract [en]

    The 4H-SiC static induction transistor (SIT) is a very competitive device for high frequency and high power applications (3-6 GHz range). The large breakdown voltage and the high thermal conductivity of 4H-SiC allow transistors with extremely high current density at high voltages. The SIT transistor shows better output power capabilities but the unity current-gain frequency is lower compared to a MESFET device. In this work we show, using a very accurate numerical model, that a compromise between the features given by the SIT structure and the ordinary MESFET structure can be obtained using the vertical MESFET structure. The device dimension has been selected very aggressively to demonstrate the performance of an optimized technology. We also present results from drift-diffusion simulations of devices, using transport parameters obtained from the Monte Carlo simulation. The simulations indicate that 2H-SiC is superior to both 4H and 6H-SiC for vertical devices. For lateral devices, 2H-SiC is slightly faster compared to an identical 4H-SiC device.

  • 12.
    Bertilsson, Kent
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Dubaric, Ervin
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Nilsson, Hans-Erik
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Hjelm, Mats
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Petersson, Sture
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Monte Carlo simulation of vertical MESFETs in 2H, 4H and 6H-SiC2001In: Diamond and related materials, ISSN 0925-9635, E-ISSN 1879-0062, Vol. 10, no 3-7, p. 1283-1286Article in journal (Refereed)
    Abstract [en]

    The 4H-SiC static induction transistor (SIT) is a very competitive device for high frequency and high power applications (3-6 GHz range). The large breakdown voltage and the high thermal conductivity of 4H-SiC allow transistors with extremely high current density at high voltages. The SIT transistor shows better output power capabilities but the unity current-gain frequency is lower compared to a MESFET device. In this work we show, using a very accurate numerical model, that a compromise between the features given by the SIT structure and the ordinary MESFET structure can be obtained using the vertical MESFET structure. The device dimension has been selected very aggressively to demonstrate the performance of an optimized technology. We also present results from drift-diffusion simulations of devices, using transport parameters obtained from the Monte Carlo simulation. The simulations indicate that 2H-SiC is superior to both 4H and 6H-SiC for vertical devices. For lateral devices, 2H-SiC is slightly faster compared to an identical 4H-SiC device

  • 13.
    Bertilsson, Kent
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Nilsson, Hans-Erik
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Optimization of 2H, 4H and 6H-SiC high-speed vertical MESFETs2002In: Diamond and related materials, ISSN 0925-9635, E-ISSN 1879-0062, Vol. 11, no 3-6, p. 1254-1257Article in journal (Refereed)
    Abstract [en]

    Silicon carbide vertical MESFET devices are well suited for high speed and high power electronic devices. In this work we have optimized the geometry of vertical MESFETs for microwave applications, using iterative two-dimensional simulations. Relevant parasitics are included in the simulations to investigate the performance of realistic devices. The state of the art device has f(T)=7 GHz and we show that vertical MESFETs fabricated with traditional technology are totally limited by parasitics. Two different approaches to reduce the parasitics in the vertical MESFET are proposed where f(T) increases significantly.

  • 14. 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
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics.
    Carbon nitride films on orthopedic substrates2000In: Diamond and related materials, ISSN 0925-9635, E-ISSN 1879-0062, Vol. 9, no 12, p. 1984-1991Article in journal (Refereed)
    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.

  • 15.
    De Feudis, M.
    et al.
    University of Salento, Italy; INFN National Institute Nucl Phys, Italy.
    Caricato, A. P.
    University of Salento, Italy; INFN National Institute Nucl Phys, Italy.
    Taurino, A.
    CNR IMM Institute Microelect and Microsyst, Italy.
    Ossi, P. M.
    Politecn Milan, Italy.
    Castiglioni, C.
    Politecn Milan, Italy.
    Brambilla, L.
    Politecn Milan, Italy.
    Maruccio, G.
    NNL CNR Nanotec, Italy.
    Monteduro, A. G.
    NNL CNR Nanotec, Italy.
    Broitman, Esteban
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, Faculty of Science & Engineering.
    Chiodini, G.
    INFN National Institute Nucl Phys, Italy.
    Martino, M.
    University of Salento, Italy; INFN National Institute Nucl Phys, Italy.
    Diamond graphitization by laser-writing for all-carbon detector applications2017In: Diamond and related materials, ISSN 0925-9635, E-ISSN 1879-0062, Vol. 75, p. 25-33Article in journal (Refereed)
    Abstract [en]

    The surface of a detector grade CVD polycrystalline diamond sample (5 x 5 x 0.05 mm(3)) was irradiated by an ArF excimer laser (lambda = 193 nm, T = 20 ns) to produce graphitic conductive layers. In particular, two sets of four parallel graphitic strip-like contacts, with 1 mm pitch, were created along the whole sample on the top and on the rear surfaces of the sample respectively. The two series of stripes lie normally to each other. Such a grid allows to obtain a segmented all-carbon device capable of giving bi-dimensional information on particle detection processes in nuclear applications. Afterwards, an extensive characterization of the samples was performed: SEM and micro-Raman investigations to study the morphological and structural evolution of the irradiated areas, EDS measurements to individuate any absorption phenomena from environment associated to laser treatment, and nanoindentation mapping to understand how the hard-soft transformation occurred depending on the locally transferred energy. Finally, current-voltage analyses were carried out checking the ohmic behavior of the diamond-graphite contact. By comparing the results of the different characterization analyses, a strong periodidty of the modified surface properties was found, confirming the reliability and reproducibility of the laser-induced graphitization process. The results demonstrate that the laser-writing technique is a good and fast solution to produce graphitic contacts on diamond surface and therefore represents a promising way to fabricate segmented all-carbon devices. (C) 2016 Elsevier B.V. All rights reserved.

  • 16. Doyle, J P
    et al.
    Aboelfotoh, M O
    Svensson, B G
    Schoner, A
    Nordell, N
    Characterization of electrically active deep level defects in 4H and 6H SiC1997In: Diamond and related materials, ISSN 0925-9635, E-ISSN 1879-0062, Vol. 6, no 10, p. 1388-1391Article in journal (Refereed)
  • 17.
    Dzwilewski, Andrzej
    et al.
    Umeå University, Faculty of Science and Technology, Physics. Umeå University, Faculty of Science and Technology, Physics.
    Talyzin, Alexandr
    Umeå University, Faculty of Science and Technology, Physics. Umeå University, Faculty of Science and Technology, Physics. Experimental Physics.
    Bromiley, G.
    Dub, S.
    Dubrovinsky, Leonid
    Characterization of phases synthesized close to the boundary of C60 collapse at high temperature high pressure conditions2007In: Diamond and related materials, ISSN 0925-9635, E-ISSN 1879-0062, Vol. 16, no 8, p. 1550-1556Article in journal (Other (popular science, discussion, etc.))
    Abstract [en]

    Two sets of samples were synthesized at high pressure high temperature conditions in the P-T region where C-60 molecules collapse into a nearly amorphous graphite-like hard carbon phase. For the first set, heating temperature was varied at fixed pressure and preparation time. For the second set, synthesis time was varied at fixed pressure and fixed temperature. Detailed structural characterization of samples was performed using Raman spectroscopy and powder XRD. Mechanical properties of the samples have been studied by nanoindentation method. It has been found that duration of heat treatment under high pressure is an important parameter which influences the temperature of fullerene cage collapse. Both tetragonal and rhombohedral polymeric phases transform into hard carbon phase over a rather narrow temperature interval, but the tetragonal phase shows somewhat increased stability against C-60 collapse. Viscoelastic mechanical behavior during nanoindentation was observed for fullerene polymers but not for graphite-like hard carbon phase. Possible mechanism for nucleation of the hard carbon phase in polymeric C-60 networks is discussed.

  • 18.
    Fanchini, G.
    et al.
    Dipartimento di Fisica Sperimentale, Università di Torino.
    Mandracci, P.
    Dipartimento di Fisica Sperimentale, Università di Torino.
    Tagliaferro, A.
    Dipartimento di Fisica Sperimentale, Università di Torino.
    Rodil, S. E.
    Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones.
    Vomiero, Alberto
    Laboratori Nazionali di Legnaro.
    Mea, G. Della
    Laboratori Nazionali di Legnaro.
    Growth and characterisation of polymeric amorphous carbon and carbon nitride films from propane2005In: Diamond and related materials, ISSN 0925-9635, E-ISSN 1879-0062, Vol. 14, no 3-7, p. 928-933Article in journal (Refereed)
    Abstract [en]

    In this work, we report about the deposition of a-C(N):H films by electron-cyclotron-resonance using propane as a carbon precursor. The films generally present high H contents (up to 61 at.%) and large optical gaps. The maximum N content we obtained is 13 at.%. In nitrogenated films, we observed a strong decrease of the stretching intensity of the infrared spectra of the hydrocarbon (CHn) vibrations, even at very low nitrogen content, the H content being still comparable to that of pure a-C:H. The various phenomena that can lead to such an effect are discussed: (i) different type of hydrogen bonding (CHn and NHn) in presence and in absence of nitrogenation; (ii) weakening of the cross-section of the CHn groups in presence of nitrogen; (iii) large presence of non-bonded hydrogen meaning, with this, either the presence of molecular H2 or unbounded hydrogen. In addition, the residual amount of IR absorption due to C-H vibrations shows that, in a-CN:H, C-H bonded and non-bonded hydrogen does coexist. © 2005 Elsevier B.V. All rights reserved.

  • 19.
    Forsberg, Pontus
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Jorge, Eleonora de Oliveira
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry, Inorganic Chemistry.
    Nyholm, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry, Inorganic Chemistry.
    Nikolajeff, Fredrik
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Karlsson, Mikael
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Fabrication of boron doped diamond microband electrodes for electrochemical detection in a microfluidic channel2011In: Diamond and related materials, ISSN 0925-9635, E-ISSN 1879-0062, Vol. 20, no 8, p. 1121-1124Article in journal (Refereed)
    Abstract [en]

    The manufacturing and electrochemical characterisation of an array of 20 boron doped nanocrystalline diamond (BNCD) microband electrodes for use in a poly(dimethylsiloxane) (PDMS) based microfluidic system are described. The electrodes were fabricated by plasma etching of a silicon oxide- and BNCD thin film coated silicon wafer and the resulting surface structured silicon wafer was subsequently bonded to the PDMS so that the BNCD microband electrodes were located within the PDMS microchannel. The electrochemical performance of the BNCD electrodes was studied and the electrodes were found to exhibit significantly better stability than previously employed gold microband arrays.

  • 20.
    Forsberg, Pontus
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Karlsson, Mikael
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    High aspect ratio optical gratings in diamond2013In: Diamond and related materials, ISSN 0925-9635, E-ISSN 1879-0062, Vol. 34, p. 19-24Article in journal (Refereed)
    Abstract [en]

    In this paper we describe a process for fabricating high aspect ratio gratings in single- or polycrystalline diamond with the high precision required by micro-optics. Nanoimprint lithography with a soft stamp and several layers of hard masks allowed for rapid and accurate replication of patterns written by e-beam or laser into thick Al masks on diamond substrates as large as 2 cm in diameter. Vertical sidewalls in the mask were crucial for avoiding microvilli formation during diamond plasma etching and were achieved by etching and oxidizing the Al mask in cycles. Circularly symmetric half-wave plates for wavelength bands around 4 and 11 mu m were fabricated with deep circular gratings on one side and antireflective gratings on the other.

  • 21.
    Fujita, N.
    et al.
    University of Exeter.
    Jones, R.
    University of Exeter.
    Öberg, Sven
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mathematical Science.
    Briddon, P.R.
    University of Newcastle Upon Tyne.
    Large spherical vacancy clusters in diamond: origin of the brown colouration?2009In: Diamond and related materials, ISSN 0925-9635, E-ISSN 1879-0062, Vol. 18, no 5-8, p. 843-845Article in journal (Refereed)
    Abstract [en]

    The origin of the brown colouration of diamond is still under discussion. Recent experiments indicate that the brown colour is caused by vacancy-type extended defects, however the shape and size of these defects remains unknown. In this work, we investigate the structural, electrical and optical properties of a large spherical vacancy clusters consisting of 71 vacancies by means of density functional theory. A comparison of our calculations with recent experimental measurements on brown natural diamond shows striking similarities and hence we suggest the brown colouration originates from large spherical vacancy clusters.

  • 22.
    Fujita, N.
    et al.
    University of Exeter.
    Jones, R.
    University of Exeter.
    Öberg, Sven
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mathematical Science.
    Briddon, P.R.
    School of Natural Science, University of Newcastle upon Tyne.
    Theoretical investigation on the interaction of nitrogen with dislocations in single crystal CVD diamond2008In: Diamond and related materials, ISSN 0925-9635, E-ISSN 1879-0062, Vol. 17, no 2, p. 123-126Article in journal (Refereed)
    Abstract [en]

    In recent experimental studies, evidence for an atmosphere of nitrogen around the cores of dislocations was found in irradiated single crystal CVD diamond. In this paper, we present a first-principles study on the interaction of nitrogen with dislocations in single crystal CVD diamond, where dislocations are observed as mixed-type 45° and 90° edge-type dislocations lying along <100>. We find a strong binding of nitrogen to the dislocation core for both types of dislocations and show that our results are in consistency with the experiment.

  • 23.
    Goss, J.P.
    et al.
    School of Physics, University of Exeter.
    Coomer, B.J.
    School of Physics, University of Exeter.
    Jones, R.
    School of Physics, University of Exeter.
    Shaw, T.D.
    Department of Physics, University of Newcastle.
    Briddon, P.R.
    Department of Physics, University of Newcastle.
    Öberg, Sven
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mathematical Science.
    Interstitial aggregates in diamond2001In: Diamond and related materials, ISSN 0925-9635, E-ISSN 1879-0062, Vol. 10, no 3, p. 434-438Article in journal (Refereed)
    Abstract [en]

    Theoretical modelling of magnetic resonance signals lead to convincing models for the first three self-interstitial aggregates in diamond. These in turn suggest the manner in which larger more stable aggregates including the platelet, observed in annealed type I diamonds, are formed.

  • 24.
    Hammersberg, Johan
    et al.
    ABB Corporate Research, Department of Materials and Chemical Engineering, 721 78 Vasteras, Sweden.
    Isberg, Jan
    ABB Corporate Research, Department of Materials and Chemical Engineering, 721 78 Vasteras, Sweden.
    Johansson, E.
    ABB Corporate Research, Department of Materials and Chemical Engineering, 721 78 Vasteras, Sweden.
    Lundström, T.
    ABB Corporate Research, Department of Materials and Chemical Engineering, 721 78 Vasteras, Sweden.
    Hjortstam, O.
    ABB Corporate Research, Department of Materials and Chemical Engineering, 721 78 Vasteras, Sweden.
    Bernhoff, Hans
    ABB Corporate Research, Department of Materials and Chemical Engineering, 721 78 Vasteras, Sweden.
    Injection dependent long carrier lifetimes in high quality CVD diamond2001In: Diamond and related materials, ISSN 0925-9635, E-ISSN 1879-0062, Vol. 10, no 3-7, p. 574-579Article in journal (Refereed)
    Abstract [en]

    In this paper we report an experimental study of photocurrent mobility x lifetime products and free carrier lifetimes in CVD grown polycrystalline diamond of various qualities. The investigated samples are low impurity samples, nitrogen content similar to 10(15) cm(-3), with an average grain size ranging from 25 mum up to 110 mum. This large difference in average grain size makes it possible to distinguish effects due to Lifetime limiting trapping and recombination defect centers inside the grains from effects caused by defect centers at grain boundaries. At low carrier densities, < 10(13) cm(-3) the effective free carrier lifetime is in the sub-nanosecond to nanosecond range in all samples due to intra-grain trapping and recombination centers. At high carrier densities, > 10(13) cm(-3), the intra-grain centers becomes saturated and the effective lifetime becomes predominately given by carrier diffusion to and recombination at the defects related to the grain boundaries. Hence, the effective lifetime at high carrier densities is strongly related to the average grain size and increases up to several tens of nanoseconds, in samples with a large average grain size, whereas it remains in the nanosecond range for samples with small average grain size. In addition, we observe a lower mobility x lifetime product and decay constant with increasing nitrogen content, clearly showing the negative influence of nitrogen and nitrogen-related defects on these important material parameters.

  • 25. Howell, D.
    et al.
    Piazolo, Sandra
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Dobson, D. P.
    Wood, I. G.
    Jones, A. P.
    Walte, N.
    Frost, D. J.
    Fisher, D.
    Griffin, W. L.
    Quantitative characterization of plastic deformation of single diamond crystals: A high pressure high temperature (HPHT) experimental deformation study combined with electron backscatter diffraction (EBSD)2012In: Diamond and related materials, ISSN 0925-9635, E-ISSN 1879-0062, Vol. 30, p. 20-30Article in journal (Refereed)
    Abstract [en]

    We report the results of a high-pressure high-temperature (HPHT) experimental investigation into the deformation of diamonds using the D-DIA apparatus. Electron backscatter diffraction (EBSD) data confirm that well-defined 300-700 nm wide {111} slip lamellae are in fact deformation micro-twins with a 60 degrees rotation around a < 111 > axis. Such twins formed at high confining pressures even without any apparatus-induced differential stress; mechanical anisotropy within the cell assembly was sufficient for their formation with very little subsequent lattice bending (<1 degrees per 100 mu m). When apparatus-induced differential stresses were applied to diamonds under HPHT conditions, deformation twin lamellae were generated, and continuous and discontinuous crystal lattice bending occurred (4-18 degrees per 100 mu m), including bending of the {111} twin lamellae. The (111) < 011 > slip system dominates as expected for the face-centred cubic (FCC) structure of diamond. Slip occurs on multiple {111} planes resulting in rotation around < 112 > axes. Deformation microstructure characteristics depend on the orientation of the principal stress axes and finite strain but are independent of confining pressure and nitrogen content. All of the uniaxially deformed samples took on a brown colour, irrespective of their initial nitrogen characteristics. This is in contrast to the two quasi-hydrostatic experiments, which retained their original colour (colourless for nitrogen free diamond, yellow for single substitutional nitrogen, Type lb diamond) despite the formation of (111) twin lamellae. Comparison of our experimental data with those from two natural brown diamonds from Finsch mine (South Africa) shows the same activation of the dominant slip system. However, no deformation twin lamellae are present in the natural samples. This difference may be due to the lower strain rates experienced by the natural samples investigated. Our study shows the applicability and potential of this type of analysis to the investigation of plastic deformation of diamonds under mantle conditions.

  • 26.
    Isberg, Jan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Majdi, Saman
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Gabrysch, Markus
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Friel, I.
    Balmer, R. S.
    A lateral time-of-flight system for charge transport studies2009In: Diamond and related materials, ISSN 0925-9635, E-ISSN 1879-0062, Vol. 18, no 9, p. 1163-1166Article in journal (Refereed)
    Abstract [en]

    A measurement system for lateral ToF charge carrier transport studies in intrinsic diamond is described. In the lateral ToF geometry, carriers travel close to the sample surface and the system is therefore particularly suited for studies of thin layers as well as the influence of different surface conditions on transport dynamics. A 213nm pulsed UV laser is used to create electron-hole pairs along a line focus between two parallel metal electrodes on one surface. The use of reflective UV-optics with short focal length allows for a narrow focal line and also for imaging the sample in UV or visible light without any dispersion. A clear hole transit was observed in one homoepitaxial single crystalline diamond film for which the substrate was treated by a Ar/Cl plasma etch prior to deposition. The hole transit signal was sufficiently clear to measure the near-surface hole drift mobility of about 860cm2/Vs across a contact spacing of 0.3mm.

  • 27.
    Jacobsohn, L. G.
    et al.
    Materials Science and Technology Division, Los Alamos National Laboratory.
    Nastasi, M.
    Materials Science and Technology Division, Los Alamos National Laboratory.
    Daemen, L. L.
    Manuel Lujan Jr. Neutron Scattering Center, Los Alamos National Laboratory.
    Jenei, Zsolt
    Stockholm University, Faculty of Science, Department of Physics.
    Asoka-Kumar, P.
    Lawrence Livermore National Laboratory.
    Positron annihilation spectroscopy of sputtered boron carbide films2005In: Diamond and related materials, ISSN 0925-9635, E-ISSN 1879-0062, Vol. 14, no 2, p. 201-205Article in journal (Refereed)
    Abstract [en]

    Positron annihilation spectroscopy (PAS) was carried out on boron carbide films deposited by sputtering and the results correlated to the bombardment conditions during film growth. Films were deposited with substrate bias voltages in the range of 0 to −200 V with a working pressure of 5 mTorr of Ar. Films deposited with bias voltages from −100 to −200 V present the same type of defect and the defect concentration increased linearly with the bias voltage. This defect was ascribed to vacancies in agreement with Monte Carlo simulations of Ar+ bombardment of boron carbide. On the other hand, films deposited with 0 V bias presented a higher S parameter values, whose origin was tentatively attributed to a relatively more open nanosized columnar structure, as suggested by the structure zone model. Annealing up to 800 °C for 30 min did not change the defect content.

  • 28.
    Khatibi, Zahra
    et al.
    Iran Univ Sci & Technol, Dept Phys, Tehran 1684613114, Iran.
    Namiranian, Afshin
    Iran Univ Sci & Technol, Dept Phys, Tehran 1684613114, Iran.
    Parhizgar, Fariborz
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Inst Res Fundamental Sci IPM, Sch Phys, Tehran 193955531, Iran.
    Strain impacts on commensurate bilayer graphene superlattices: Distorted trigonal warping, emergence of bandgap and direct-indirect bandgap transition2019In: Diamond and related materials, ISSN 0925-9635, E-ISSN 1879-0062, Vol. 92, p. 228-234Article in journal (Refereed)
    Abstract [en]

    Due to low dimensionality, the controlled stacking of graphene films and their electronic properties are susceptible to environmental changes including strain. The strain-induced modification of the electronic properties such as the emergence and modulation of bandgaps crucially depends on the stacking of the graphene films, However, to date, only the impact of strain on electronic properties of Bernal and AA-stacked bilayer graphene has been extensively investigated in theoretical studies. Exploiting density functional theory and tight-binding calculation, we investigate the impacts of in-plane strain on two different classes of commensurate twisted bilayer graphene (TBG) which are even/odd under sublattice exchange (SE) parity. We find that the SE odd TBG remains gapless whereas the bandgap increases for the SE even TBG when applying equibiaxial tensile strain. Moreover, we observe that for extremely large mixed strains both investigated TBG superstructures demonstrate direct-indirect bandgap transition.

  • 29.
    Kovi, Kiran Kumar
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Balmer, Richard S.
    Global Innovat Ctr, Element Six Ltd, Didcot OX11 0QR, Oxon, England.
    Isberg, Jan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Semi-isotropic surface etching of diamond using a Faraday cage2015In: Diamond and related materials, ISSN 0925-9635, E-ISSN 1879-0062, Vol. 58, p. 185-189Article in journal (Refereed)
    Abstract [en]

    Etching of diamond is one of the most important process steps to realize diamond based devices. Isotropic etching in diamond yielding a high etch rate is challenging owing to its material properties. In the current study, single-crystalline diamond is etched using a Faraday cage that acts as the mask to attain semi-isotropic etching. An oxygen/chlorine plasma discharge with a pressure of 10 mTorr is used. The etching process is optimized by varying the applied plasma power, and the substrate bias together with varying parameters such as the thickness of the mask, the mask-to-diamond surface distance and the diameter of the holes in the mask. After optimization, semi-isotropic etched surface profiles up to a depth of 5 μm with an etch rate of 80 nm/min and surface roughness close to that of the unetched surface are achieved.

  • 30.
    Larsson, Karin
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Lunell, Sten
    Adsorption of Halogen-Containing Methane on Diamond1998In: Diamond and related materials, ISSN 0925-9635, E-ISSN 1879-0062, p. 1138-Article in journal (Refereed)
  • 31.
    Larsson, Karin
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Lunell, Sten
    Carlsson, Jan-Otto
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Ab Initio Study of Hydrocarbons on Diamond (111)1993In: Diamond and related materials, ISSN 0925-9635, E-ISSN 1879-0062, Vol. 2, p. 949-Article in journal (Refereed)
  • 32. Majidi, Roya
    et al.
    Odelius, Michael
    Stockholm University, Faculty of Science, Department of Physics.
    AlTaha, Shafigheh
    Stockholm University, Faculty of Science, Department of Physics. Shahid Rajaee Teacher Training University, Iran.
    Structural and electronic properties of nitrogenated holey nanotubes: A density functional theory study2018In: Diamond and related materials, ISSN 0925-9635, E-ISSN 1879-0062, Vol. 82, p. 96-101Article in journal (Refereed)
    Abstract [en]

    The structural and electronic properties of nanotubes based on C2N sheet known as nitrogenated holey graphene are investigated using density functional theory. The cohesive and strain energies, electronic band structures, total and partial density of states of the armchair and zigzag nanotubes constructed by rolling up nitrogenated holey graphene are calculated. The calculated cohesive energies indicate that the zigzag nitrogenated holey nanotubes are more stable than the armchair ones. The energetic stability of the considered nanotubes increases with increasing tube diameter. It is found that both armchair and zigzag nitrogenated holey nanotubes show semiconducting properties similar to nitrogenated holey graphene sheet. The semiconducting properties of nitrogenated holey nanotubes are dependent on the tube size and chirality. The results provide new insight into nanomaterials for use in emerging nanoelectronic devices.

  • 33.
    Makarova, T. L.
    Umeå University.
    Magnetic properties of nanocarbon2007In: Diamond and related materials, ISSN 0925-9635, E-ISSN 1879-0062, Vol. 16, no 10, p. 1841-1846Article in journal (Refereed)
  • 34.
    Mukherjee, Debarati
    et al.
    Inst Telecomunicacoes, Campus Univ Santiago, P-3810193 Aveiro, Portugal.;Univ Aveiro, Dept Elect Telecommun & Informat, P-3810193 Aveiro, Portugal..
    Oliveira, Filipe
    Univ Aveiro, Dept Mat & Ceram Engn, CICECO, P-3810193 Aveiro, Portugal..
    Trippe, Simone Camargo
    Ctr Univ FEI, Phys Dept, Sao Bernardo Do Campo, SP, Brazil..
    Rotter, Shlomo
    Smart Diamond Technol Lda, Aveiro, Portugal..
    Neto, Miguel
    Univ Aveiro, Dept Mat & Ceram Engn, CICECO, P-3810193 Aveiro, Portugal..
    Silva, Rui
    Univ Aveiro, Dept Mat & Ceram Engn, CICECO, P-3810193 Aveiro, Portugal..
    Mallik, Awadesh Kumar
    Hasselt Univ, Inst Mat Res IMO, Wetenschapspk 1, B-3590 Diepenbeek, Belgium.;IMEC VZW, IMOMEC, Wetenschapspk 1, B-3590 Diepenbeek, Belgium..
    Haenen, Ken
    Hasselt Univ, Inst Mat Res IMO, Wetenschapspk 1, B-3590 Diepenbeek, Belgium.;IMEC VZW, IMOMEC, Wetenschapspk 1, B-3590 Diepenbeek, Belgium..
    Zetterling, Carl-Mikael
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electronics and Embedded systems.
    Mendes, Joana Catarina
    Inst Telecomunicacoes, Campus Univ Santiago, P-3810193 Aveiro, Portugal.;Univ Aveiro, Ctr Mech Technol & Automat, P-3810193 Aveiro, Portugal..
    Deposition of diamond films on single crystalline silicon carbide substrates2020In: Diamond and related materials, ISSN 0925-9635, E-ISSN 1879-0062, Vol. 101, article id 107625Article in journal (Refereed)
    Abstract [en]

    Silicon carbide (SiC) is a wide band gap material that is slowly but steadily asserting itself as a reliable alternative to silicon (Si) for high temperature electronics applications, in particular for the electrical vehicles industry. The passivation of SiC devices with diamond films is expected to decrease leakage currents and avoid premature breakdown of the devices, leading to more efficient devices. However, for an efficient passivation the interface between both materials needs to be virtually void free and high quality diamond films are required from the first stages of growth. In order to evaluate the impact of the deposition and seeding parameters in the properties of the deposits, diamond films were deposited on SiC substrates by hot filament chemical vapor deposition (HFCVD). Before the seeding step the substrates were exposed to diamond growth conditions (pretreatment PT) and seeding was performed with a solution of detonation nanodiamond (DND) particles and with 6-12 and 40-60 mu m grit. Diamond films were then grown at different temperatures and with different methane concentrations and the deposits were observed in a scanning electron microscope (SEM); their quality was assessed with Raman spectroscopy.

  • 35.
    Neidhardt, Jörg
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics.
    Hultman, Lars
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics.
    Broitman, Esteban
    Scharf, T. W.
    Singer, Irwin L.
    Structural, mechanical and tribological behavior of fullerene-like and amorphous carbon nitride coatings2004In: Diamond and related materials, ISSN 0925-9635, E-ISSN 1879-0062, Vol. 13, no 10, p. 1882-1888Article in journal (Refereed)
    Abstract [en]

    The mechanical and tribological properties of fullerene-like (FL) and amorphous carbon nitride (CNX) coatings synthesized by reactive unbalanced magnetron sputtering were analyzed and compared to carbon coatings deposited without N2. Elastic recoil detection analysis (ERDA) was used to determine the amount of incorporated nitrogen while X-ray photoelectron spectroscopy (XPS) was used to study the local bonding environment. Nano-indentation revealed a large spread in hardness, elastic modulus and elastic recovery. The tribological performance of the coatings was tested with a reciprocating sliding tribometer that allowed in situ visualization of the sliding contact. Tests were performed with a sapphire hemisphere sliding at 4 mm/s in dry and ambient humidity air. Friction coefficients of the FL-CN X coatings in both humidities were slightly higher than those of diamond-like carbon coatings (DLC), the values were between 0.1 and 0.25, dropping as the bias voltage increased. FL-CNX coatings had higher wear resistance than amorphous CNX, DLC and graphite coatings in sliding contact although the hardnesses of the coatings were comparable. Wear rates of the FL-CNX coatings in ambient air were lower than in dry air and orders of magnitude lower than the other carbon coatings. Furthermore, the most wear-resistant high-temperature FL-CNX coating had the highest hardness, but the shortest wear life of the three high-temperature FL-CN X coatings. In situ visualization indicated films transferred from the coating to the sapphire hemisphere, the transfer film isolated the hemisphere from the coating, thereby controlling both the friction coefficient and the wear behavior. Effects of deposition conditions, structure and hardness on wear and friction behavior are discussed. © 2004 Elsevier B.V. All rights reserved.

  • 36. Osipov, V. Yu.
    et al.
    Baranov, A. V.
    Ermakov, V. A.
    Makarova, Tatiana
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Chungong, L. F.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Shames, A. I.
    Takai, K.
    Enoki, T
    Kaburagi, Y
    Endo, M
    Vul', A. Ya.
    Raman characterization and UV optical absorption studies of surface plasmonresonance in multishell nanographite2011In: Diamond and related materials, ISSN 0925-9635, E-ISSN 1879-0062, Vol. 20, no 2, p. 205-209Article in journal (Refereed)
    Abstract [en]

    Nanographite (NG) particles were produced by annealing of superpurified detonation nanodiamonds (grain size ~ 5 nm) at 1600 °C. The aim of this research was to provide Raman characterization of nanographites obtained and to investigate characteristic features of UV optical absorption in NG suspensions caused by the excitation of surface plasmon resonance (SPR) and its dependence on disorder and defectiveness of graphene shells during their transformation. The 1-st and 2-nd order Raman spectra of the NG samples excited at 514 nm were analyzed. Two different approaches applied for evaluation of the in-plane NG crystallite sizes by using the D- and G-band intensities ratio gave quite different results (~ 3.5 nm and ~ 5.5 nm) reflecting, most likely, a complicated NG structure. The changes in both intensity and position of SPR absorption peak for water suspension of NG particles may originate in structural imperfections and/or changes in aggregation of NG particles.

  • 37.
    Paskova, Tanja
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Valcheva, E.
    Paskov, Plamen
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Monemar, Bo
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Roskowski, A.M.
    Dept of Mat Science and Engineering, North Carolina State University, Raleigh, NC 27695-7919, United States.
    Davis, R.F.
    Dept of Mat Science and Engineering, North Carolina State University, Raleigh, NC 27695-7919, United States.
    Beaumont, B.
    2720 Clemin Saint Bernard, Vallauris F-06220, France.
    Gibart, P.
    2720 Clemin Saint Bernard, Vallauris F-06220, France.
    HVPE-GaN: Comparison of emission properties and microstructure of films grown on different laterally overgrown templates2004In: Diamond and related materials, ISSN 0925-9635, E-ISSN 1879-0062, Vol. 13, no 4-8, p. 1125-1129Article in journal (Refereed)
    Abstract [en]

    We report on a comparative study of defect and emission distributions in thick hydride vapor phase epitaxial (HVPE) GaN films grown on two different patterned template structures separately produced by multi-step procedures using metalorganic vapor phase epitaxy (MOVPE). The observed differences in the microstructures and emission distributions at the early stages of the growth in both cases were related to the change of the dominating growth mode sequence and point defects incorporation. Both template structures were found to favor formation of voids in the coalescence regions, which leads to a partial strain relaxation and allows overgrowth of thicker films without cracks. © 2003 Elsevier B.V. All rights reserved.

  • 38.
    Rashid, S. J.
    et al.
    Department of Engineering, University of Cambridge, Trumpington Street, Cambridge CB2 1PZ, UK.
    Tajani, A.
    Element Six Ltd., King's Ride Park, Ascot, Berkshire SL5 8BP, UK.
    Coulbeck, L.
    Dynex Semiconductors Ltd., Doddington Road, Lincoln LN6 3LF, UK.
    Brezeanu, M.
    Department of Engineering, University of Cambridge, Trumpington Street, Cambridge CB2 1PZ, UK.
    Garraway, A.
    Dynex Semiconductors Ltd., Doddington Road, Lincoln LN6 3LF, UK.
    Butler, T.
    Department of Engineering, University of Cambridge, Trumpington Street, Cambridge CB2 1PZ, UK.
    Rupesinghe, N. L.
    Department of Engineering, University of Cambridge, Trumpington Street, Cambridge CB2 1PZ, UK.
    Twitchen, D. J.
    Element Six Ltd., King's Ride Park, Ascot, Berkshire SL5 8BP, UK.
    Amaratunga, G. A. J.
    Department of Engineering, University of Cambridge, Trumpington Street, Cambridge CB2 1PZ, UK.
    Udrea, F.
    Department of Engineering, University of Cambridge, Trumpington Street, Cambridge CB2 1PZ, UK.
    Taylor, P.
    Dynex Semiconductors Ltd., Doddington Road, Lincoln LN6 3LF, UK.
    Dixon, M.
    Element Six Ltd., King's Ride Park, Ascot, Berkshire SL5 8BP, UK.
    Isberg, Jan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity. Avdelningen för elektricitetslära och åskforskning.
    Modelling of single-crystal diamond Schottky diodes for high-voltage applications2006In: Diamond and related materials, ISSN 0925-9635, E-ISSN 1879-0062, Vol. 15, p. 317-323Article in journal (Refereed)
    Abstract [en]

    The modelling of Schottky m-i-p(+) (SMIP) diodes fabricated on chemical vapour deposited (CVD) single crystal (SC) diamond intrinsic layers grown on highly boron doped CVD diamond Substrates is reported. Variations in intrinsic layer thickness, Schottky metal type and operating temperature have been included in the analysis. Numerical models that take into account the activation of dopants, concentration and temperature dependant mobility and avalanche coefficients have been derived to successfully simulate experimental diamond devices.

  • 39. Ribbing, C.
    et al.
    Cederström, Björn
    KTH, Superseded Departments, Physics.
    Lundqvist, M.
    Microstructured diamond X-ray source and refractive lens2003In: Diamond and related materials, ISSN 0925-9635, E-ISSN 1879-0062, Vol. 12, no 11-okt, p. 1793-1799Article in journal (Refereed)
    Abstract [en]

    This paper treats microstructured CVD diamond in two X-ray applications, a miniature X-ray source and a refractive X-ray lens. The X-ray source consists of boron doped diamond membrane electrodes and an intermediate insulator. The cathode has a pyramidal shape, which is field-emitting and the anode is a metal film on a diamond membrane. Anode radiation emerges through both membrane electrodes. The source has not been vacuum sealed, therefore, all measurements so far have been made in a vacuum chamber. The refractive X-ray lens has saw-tooth geometry and a tunable focal length. It was made by microwave plasma assisted CVD of diamond onto anisotropically etched silicon masters. The lens has been used for one-dimensional focusing of a synchrotron beam to 1.9 mum line width.

  • 40.
    Ruuska, Henna
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry, Inorganic Chemistry.
    Larsson, Karin
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry, Inorganic Chemistry.
    Surface reactivities of (111), (100), and (110) planes of c-BN: A quantum mechanical approach2007In: Diamond and related materials, ISSN 0925-9635, E-ISSN 1879-0062, Vol. 16, no 1, p. 118-123Article in journal (Refereed)
    Abstract [en]

    Surface reactivities of the three low-index planes (111), (100), and (110) of cubic boron nitride were theoretically investigated using density functional theory under periodic boundary conditions. Surface energies for non-terminated (bulk vs. optimized structure) and H-terminated (optimized structure) surfaces were calculated. The optimized structure is identical to the local low-energy structure closest to the initial bulk geometry. The adsorption process of hydrogen atoms on the various surface planes was also examined. On the basis of these calculations, the orders of reactivities for the cubic BN planes are (110) > (100) > (111) (bulk) and (100) > (110) > (111) (optimized) for non-terminated surfaces. The most reactive form of the (110) surface (i.e. bulk structure) became the most stable one when the surface was completely terminated with H species.

  • 41.
    Schmidt, Susann
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Czigany, Zsolt
    Hungarian Academic Science, Hungary.
    Wissting, Jonas
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Greczynski, Grzegorz
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Janzén, Erik
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Jensen, Jens
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Ivanov, Ivan Gueorguiev
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    A comparative study of direct current magnetron sputtering and high power impulse magnetron sputtering processes for CNX thin film growth with different inert gases2016In: Diamond and related materials, ISSN 0925-9635, E-ISSN 1879-0062, Vol. 64, p. 13-26Article in journal (Refereed)
    Abstract [en]

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

  • 42. Schoner, A
    et al.
    Rottner, K
    Nordell, N
    Linnarsson, Margareta
    Peppermuller, C
    Helbig, R
    Hydrogen incorporation in epitaxial layers of 4H- and 6H-silicon carbide grown by vapor-phase epitaxy1997In: Diamond and related materials, ISSN 0925-9635, E-ISSN 1879-0062, Vol. 6, p. 1293-1296Article in journal (Refereed)
    Abstract [en]

    The incorporation of hydrogen during vapor phase epitaxy was investigated using secondary ion mass spectroscopy, low temperature photoluminescence, and capacitance-voltage measurements. It was found that hydrogen incorporation is strongly dependent on the concentration of the acceptor dopants aluminum and boron, regardless of changes in the doping concentration caused by varying the concentration ratio between carbon and silicon or the dopant precursor flow. An electrical passivation of the acceptor dopants was found and could be reduced by annealing at temperatures above 1000 degrees C. At the same anneal temperature hydrogen-related photoluminescence was considerably reduced and the diffusion of hydrogen was detected. (C) 1997 Elsevier Science S.A.

  • 43.
    Shuainan, Zhao
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Karin, Larsson
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    First principle study of the attachment of graphene onto non-doped and doped diamond (111)2016In: Diamond and related materials, ISSN 0925-9635, E-ISSN 1879-0062, Vol. 66, p. 52-60Article in journal (Refereed)
    Abstract [en]

    Density function theory (DFT) calculations have in the present study been used to study the adhesion of a graphene monolayer onto a non-, B-, or N-doped diamond (111) surface. Semiempirical dispersion corrections were used to take the Van-der-Waals corrections into consideration. In case of non-doped diamond as a substrate, DFT calculations (based on the local density approximation (LDA)) have shown a strong binding between graphene and the diamond (111) surface at a shorter distance (2.47 Å). The binding energy was − 14.5 kJ/mol per Cgraphene atom. In comparison, the generalized gradient spin density approximation (GG(S)A) was found to predict a weaker (− 9.6 kJ/mol) interfacial bond at a distance of 3.10 Å. For the situation with B-, or N-, doped diamond, the optimized shorter diamond-graphene distance was found to be 3.01 and 3.24 Å, respectively. The corresponding adhesion energies per Cgraphene atom was − 9.9 kJ/mol (B-doping) and − 9.6 kJ/mol (N-doping), which are quite similar to the non-doped situation (− 9.6 kJ/mol). For all situations in the present study, the graphene layer was found to remain its aromatic character. However, a minor charge transfer was observed to take place from the graphene adlayer towards the non-doped and doped diamond (111) substrates.

  • 44.
    Sundqvist, Bertil
    Umeå University, Faculty of Science and Technology, Department of Physics. State Key Laboratory of Superhard Materials, Jilin University, Changchun 130012, PR China.
    Raman identification of C70 monomers and dimers2017In: Diamond and related materials, ISSN 0925-9635, E-ISSN 1879-0062, Vol. 73, p. 143-147Article in journal (Refereed)
    Abstract [en]

    Fullerenes easily polymerize under high pressure by forming covalent intermolecular bonds. For C60 this reaction is easily monitored by Raman scattering, but for C70 no simple method to determine its bonding state is known. In this work C70 has been heated over a wide range of temperatures at a pressure of 1.6 GPa and the treated material has been studied by Raman spectroscopy, using 830 nm laser excitation to avoid photo-induced polymerization. By comparing the present data with earlier results for pure dimers, zig-zag chain polymers and pressure treated powders, characteristic fingerprint peaks can be found for the C70 monomer and the C140 dimer. The molecular stretching mode near 88 cm-1 is a clear fingerprint for dimers while the strong A1′ peak near 455 cm-1 clearly shows the presence of monomers. Several other new peaks appear in pressure-treated material and the relative intensities of many peaks change in a systematic way, but it is not clear whether these changes indicate the presence of dimers or of small oligomers in general. Simple strategies for semi-quantitative structural analysis of pressure-treated C70 material by Raman spectroscopy are briefly discussed.

  • 45.
    Talyzin, A V
    et al.
    Dept of Inorganic Chemistry , Ångström Lab Uppsala university.
    Dubrovinsky, L S
    Theoretical Geochemistry Program; Inst of Eart Sciences Uppsala university.
    Odén, Magnus
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Engineering Materials.
    Jansson, U
    Dept of Inorganic Chemistry, Ångström Lab Uppsala University.
    Superhard and superelastic films of polymeric C602001In: Diamond and related materials, ISSN 0925-9635, E-ISSN 1879-0062, Vol. 10, no 11, p. 2044-2048Article in journal (Refereed)
    Abstract [en]

    The C60 thin film deposited on steel substrate was transformed by high pressure-high temperature treatment to a superhard and superclastic material. The films were studied by Raman spectroscopy in situ at 20 GPa after heating at 300░C and ex situ after the quenching. The hardness and elastic properties of the high-pressure phases have been characterized with nanoindentation. The hardness of the films were determined to be 0.5 ▒ 0.1 GPa and 61.9 ▒ 9 GPa for unmodified C60 and HPHT treated films, respectively. The hardness of the pressurized film is higher than for cubic BN but lower than hardness values reported for ultrahard fullerite samples prepared from powders. An interesting observation was that the HPHT treated film showed an extreme elastic response with an elastic recovery of approximately 90%. ⌐ 2001 Elsevier Science B.V. All rights reserved.

  • 46.
    Van Regemorter, T.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry.
    Larsson, Karin
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry.
    Effect of substitutional N on the diamond CVD growth process: A theoretical approach2008In: Diamond and related materials, ISSN 0925-9635, E-ISSN 1879-0062, Vol. 17, no 7-10, p. 1076-1079Article in journal (Refereed)
    Abstract [en]

    For both (111) and (100) diamond surface orientations, one C atom within the first or second surface carbon layer has substitutionally been replaced by an N atom. The effects of this impurity on CH3 adsorption and H abstraction from a newly adsorbed CH3 have been carefully investigated by using ultra-soft pseudo-potential density functional theory (DFT) under periodic boundary conditions. The effects of N at various positions within the two atomic layers were especially studied. It was generally found that nitrogen in the first atomic layer will never affect the initial growth reactions. An exception exist for the dopant in one of the three studied positions within the (100) surface, where a beta-scission rearrangement is observed. When N is positioned within the second carbon layer for both surface orientations with all surface carbons H-terminated (i.e. no surface radicals), nitrogen is moving off-site and one of the N-C bonds is thereby broken. On the other hand, when a radical is present oil the surface (formed by the abstraction of one Surface H), N move back on-site and one electron is transferred from N to the surface C radical with a resulting electron lone pair fort-nation. When CH2 is bonded to the surface as a result of gaseous H abstraction from the adsorbed CH3 species and with N directly bonded to the surface carbon onto which CH3 is initially adsorbed, a beta-scission rearrangement is also observed.

  • 47.
    Van Regemorter, Tanguy
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry.
    Larsson, Karin
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry.
    Effect of co-adsorbed dopants on initial diamond growth steps: H abstraction from an adsorbed CH32009In: Diamond and related materials, ISSN 0925-9635, E-ISSN 1879-0062, Vol. 18, no 9, p. 1152-1156Article in journal (Refereed)
    Abstract [en]

    The effect induced by a neighbouring co-adsorbed dopant on H abstraction from an adsorbed CH3 species on diamond has been investigated by using an ultra-soft pseudo-potential density functional theory (DFT) method under periodic boundary conditions. Both the (100) and (111) diamond surface orientations were considered with various types of dopants in two different hydrogenated forms; AHx (A = N, B, S, or P; X = 0 or 1 for S; X = 1 or 2 for N, B and P, and X = 2 or 3 for C). The H abstraction by gaseous radical H was found to be energetically favoured by the presence of the dopants in all of their different hydrogenated forms. For NH2, SH, or PH2, this effect is induced by a destabilisation of the diamond surface by sterical repulsions between the adsorbed growth species CH3 and the co-adsorbed dopant. For BH2 and the dopants in their radical form, the abstraction reaction is favoured due to the formation of a new covalent bond between the dopant and the co-adsorbed CH2 (product of the abstraction reaction), which strongly stabilises the surface after the abstraction process.

  • 48.
    Vargas Catalan, Ernesto
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Forsberg, Pontus
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Absil, Olivier
    Université de Liège, Belgium.
    Karlsson, Mikael
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Controlling the profile of high aspect ratio gratings in diamond2016In: Diamond and related materials, ISSN 0925-9635, E-ISSN 1879-0062, Vol. 63, p. 60-68Article in journal (Refereed)
    Abstract [en]

    Diamond is an excellent material for infrared optics and for applications in harsh environments. Some of those desirable properties, i.e. hardness and chemical inertness, also make it a challenging material to machine and etch. In this study we have tested a wide range of etch parameters in an inductively coupled plasma etcher, in order to produce highly controlled, high aspect ratio gratings in diamond. We discuss the effects of pressure, bias power, and some gas mixture variation (pure oxygen and argon-oxygen) on the etch results and how it im- pacts the etch mask sputtering and redeposition. We also present a method for applying a fresh aluminum mask, in order to etch even deeper optical grating. Gratings with aspect ratios as high as 1:13.5 have been achieved with a 1.42 μm grating period. 

  • 49.
    Zhao, Jie
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics. Northwest Univ Xian, Key Lab Synthet & Nat Funct Mol Chem, Minist Educ, Coll Chem & Mat Sci, Xian 710069, Shaanxi, Peoples R China.
    Zeng, Shuangshuang
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Wu, Biao
    Northwest Univ Xian, Key Lab Synthet & Nat Funct Mol Chem, Minist Educ, Coll Chem & Mat Sci, Xian 710069, Shaanxi, Peoples R China.
    Zhang, Shi-Li
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Zhang, Zhi-Bin
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Re-organized graphene nanoplatelet thin films achieved by a two-step hydraulic method2018In: Diamond and related materials, ISSN 0925-9635, E-ISSN 1879-0062, Vol. 84, p. 141-145Article in journal (Refereed)
    Abstract [en]

    Film deposition of graphene nanoplatelets (GNPs) from dispersion via casting and printing approaches features cost- and material-efficiency, however, it usually suffers from poor uniformity, rough surface and loose flake stacking due to adverse effect of hydraulic force. Here, a simple two-step method exploiting hydraulic force is presented to readily deliver GNP films of improved quality from an aqueous dispersion. While as-deposited GNP films exhibit the aforementioned film defects, the hydraulic force in the subsequent step constituting soaking in water and drying leads to an efficient re-organization of the individual GNPs in the films, The majority of GNPs thus are oriented horizontally and closely stacked. As a result, densified, smoothened and homogenized GNP thin films can be readily achieved. The GNP re-organization reduces resistivity from > 1 Omega cm to 10(-2) Omega cm. The method developed is universally applicable to solution-phase film deposition of 2D materials.

  • 50.
    Zheng, W.T.
    et al.
    Department of Materials Science and National Key Laboratory of Superhard Materials, Jilin University, Changchun 130023, China, Department of Precision Engineering, Chiba Institute of Technology, 2-17-1 Tsudanuma, Narashino 275-0016, Japan, Department of Physics, Linkoping University, S-581 83 Linkoping, Sweden, National Key Laboratory of Materials Surface Modification by Laser, Ion, and Electron, Dalian University of Technology, Dalian 116024, China.
    Guo, J.H.
    Department of Physics, Uppsala University, Box 530, 751 21 Uppsala, Sweden.
    Sakamoto, Y.
    Department of Precision Engineering, Chiba Institute of Technology, 2-17-1 Tsudanuma, Narashino 275-0016, Japan.
    Takaya, M.
    Department of Precision Engineering, Chiba Institute of Technology, 2-17-1 Tsudanuma, Narashino 275-0016, Japan.
    Li, X.T.
    Department of Materials Science and National Key Laboratory of Superhard Materials, Jilin University, Changchun 130023, China.
    Chao, P.J.
    Department of Materials Science and National Key Laboratory of Superhard Materials, Jilin University, Changchun 130023, China.
    Jin, Z.S.
    Department of Materials Science and National Key Laboratory of Superhard Materials, Jilin University, Changchun 130023, China.
    Xing, K.Z.
    Department of Physics, Linkoping University, S-581 83 Linkoping, Sweden.
    Sundgren, J.-E.
    Department of Physics, Linkoping University, S-581 83 Linkoping, Sweden.
    Chemical bonding in carbon nitride films studied by X-ray spectroscopies2001In: Diamond and related materials, ISSN 0925-9635, E-ISSN 1879-0062, Vol. 10, no 9-10, p. 1897-1900Article in journal (Refereed)
    Abstract [en]

    Carbon nitride films are deposited using dc magnetron sputtering in a N2 discharge. The nature of chemical bonding of the films is investigated using X-ray photoelectron spectroscopy, near-edge X-ray absorption fine structure, and X-ray emission spectroscopy. X-Ray photoelectron spectroscopy spectra show that N1s binding states depend on substrate temperature, in which two pronounced peaks can be observed. The near edge X-ray absorption fine structure at C1s and N1s exhibits a similar absorption profile in the p* resonance region, but the s* resonance is sharper in the N1s spectra. Resonant N K-emission spectra show a strong dependence on excitation photo energies. Compared XPS N1s spectra with recent theoretical calculations by Johansson and Stafstrom, two main nitrogen sites are assigned in which N bound to sp3 hybridized C and sp2 hybridized C, respectively. The correlation of X-ray photoelectron, X-ray absorption, and X-ray emission spectra for N in carbon nitride films is also discussed. © 2001 Elsevier Science B.V. All rights reserved.

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