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  • 1. Audren, A.
    et al.
    Hallén, Anders
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Linnarsson, Margareta K.
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Possnert, G.
    Damage recovery in ZnO by post-implantation annealing2010In: Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, ISSN 0168-583X, E-ISSN 1872-9584, Vol. 268, no 11-12, p. 1842-1846Article in journal (Other academic)
    Abstract [en]

    ZnO bulk samples were implanted with 200 key-Co ions at room temperature with two fluences, 1 x 10(16) and 8 x 10(16) cm(-2), and then annealed in air for 30 min at different temperatures up to 900 degrees C. After the implantation and each annealing step, the samples were analyzed by Rutherford backscattering spectrometry (RBS) in random and channeling directions to follow the evolution of the disorder profile. The RBS spectra reveal that disorder is created during implantation in proportion to the Co fluence. The thermal treatments induce a disorder recovery, which is however, not complete after annealing at 900 degrees C, where about 15% of the damage remains. To study the Co profile evolution during annealing, the samples were, in addition to RBS, characterized by secondary ion mass spectrometry (SIMS). The results show that Co diffusion starts at 800 degrees C, but also that a very different behavior is seen for Co concentrations below and above the solubility limit. (C) 2010 Elsevier B.V. All rights reserved.

  • 2. Audren, A.
    et al.
    Hallén, Anders
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Possnert, G.
    Damage recovery in the oxygen sublattice of ZnO by post-implantation annealing2012In: Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, ISSN 0168-583X, E-ISSN 1872-9584, Vol. 272, p. 418-421Article in journal (Refereed)
    Abstract [en]

    Hydrothermally grown zinc oxide bulk samples were implanted with 200 key-Co ions with a fluence of 4.5 x 10(16) cm(-2) and then annealed in air during 30 min at different temperatures up to 900 degrees C. After the implantation and each annealing step, the samples were analyzed using the nuclear reaction O-16(alpha,alpha)O-16 at 3.045 MeV He in random and channeling directions to follow the annealing of the disorder profile in the O sublattice. For comparison, the disorder in the Zn sublattice was also observed by Rutherford backscattering spectrometry (RBS) in random and channeling directions. The results reveal that the disorder created during the Co implantation is slightly higher in the O sublattice than in the Zn sublattice. The disorder recovery induced by the thermal treatments, starts at 500 degrees C in the O sublattice and at 700 degrees C in the Zn sublattice. Although, the most part of the disorder recovery occurs between 700 and 800 degrees C in both sublattices.

  • 3. Azarov, A. Yu.
    et al.
    Hallén, Anders
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Svensson, B. G.
    Du, X. L.
    Kuznetsov, A. Yu.
    Damage accumulation and annealing behavior in high fluence implanted MgZnO2012In: Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, ISSN 0168-583X, E-ISSN 1872-9584, Vol. 272, p. 426-429Article in journal (Refereed)
    Abstract [en]

    Molecular beam epitaxy grown MgxZn1-xO (x <= 0.3) layers were implanted at room temperature with 150 keV Er-166(+) ions in a fluence range of 5 x 10(15-)3 x 10(16) cm(-2). Evolution of ion-induced damage and structural changes were studied by a combination of Rutherford backscattering spectrometry, nuclear reaction analysis and time-of-flight elastic recoil detection analysis. Results show that damage production enhances in both Zn- and O-sublattices with increasing the Mg content in the MgZnO. However, MgZnO as well as pure ZnO exhibits a high degree of dynamic annealing and MgZnO can not be amorphized even at the highest ion fluence used. Annealing of heavily damaged ZnO leads to a strong surface erosion and thinning of the film. Increasing the Mg content suppresses the surface evaporation in high fluence implanted MgZnO but leads to a strong surface decomposition accompanied with a Mg-rich surface layer formation during post-implantation annealing.

  • 4.
    Azarov, Alexander
    et al.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Titov, A. I.
    Karaseov, P. A.
    Hallén, Anders
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Effect of collision cascade density on radiation damage in SiC2009In: Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, ISSN 0168-583X, E-ISSN 1872-9584, Vol. 267, no 8-9, p. 1247-1250Article in journal (Refereed)
    Abstract [en]

    The damage accumulation in 6H-SiC bombarded at room temperature with 1.3 keV/amu atomic P+ ions and small cluster ions PFn+ (n = 2 and 4) have been studied by Rutherford backscattering spectrometry in channeling mode. Results show that collision cascade density strongly affects damage buildup in SiC. The cluster ion bombardment of SiC produces more stable defects both near the surface and in the region between the surface and bulk defect peaks than irradiation by atomic ions.

  • 5.
    Bergsåker, Henric
    et al.
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
    Bykov, Igor
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
    Petersson, Per
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
    Possnert, G.
    Likonen, J.
    Koivuranta, S.
    Coad, J. P.
    Widdowson, A. M.
    Microstructure and inhomogeneous fuel trapping at divertor surfaces in the JET tokamak2014In: Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, ISSN 0168-583X, E-ISSN 1872-9584, Vol. 332, p. 266-270Article in journal (Refereed)
    Abstract [en]

    The plasma deposited layers at divertor surfaces in the JET tokamak with carbon wall have been studied post mortem, using micro ion beam analysis (mu-IBA) methods, optical microscopy and scanning electron microscopy (SEM). The layers were formed during plasma operations over different periods through 1998-2009. They frequently have a columnar structure. For mu-IBA a 3 MeV He-3 beam was used, focused to about 5-15 mu m size. Nuclear reaction analysis was used to measure D, Be and C. Elemental mapping was carried out both at the original surface and on polished layer cross sections. Trapped deuterium is predominantly found in remote areas on the horizontal bottom divertor tiles and in regions with locally enhanced deuterium concentration on the vertical tiles. Pockets with enhanced deuterium concentration are found in the carbon fibre composite (CFC) substrate. Areas with dimensions of about 100 mu m with enhanced deuterium concentration are also found inside the deposited layers. The inhomogeneous fuel trapping is tentatively explained with co-deposition in partly protected pits in the substrate and by incorporation of dust particles in the growing layers.

  • 6.
    Bykov, Igor
    et al.
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
    Bergsaker, Henric
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
    Possnert, G.
    Zhou, Y.
    Heinola, K.
    Pettersson, J.
    Conroy, S.
    Likonen, J.
    Petersson, Per
    Widdowson, A.
    Studies of Be migration in the JET tokamak using AMS with Be-10 marker2016In: Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, ISSN 0168-583X, E-ISSN 1872-9584, Vol. 371, p. 370-375Article in journal (Refereed)
    Abstract [en]

    The JET tokamak is operated with beryllium limiter tiles in the main chamber and tungsten coated carbon fiber composite tiles and solid W tiles in the divertor. One important issue is how wall materials are migrating during plasma operation. To study beryllium redistribution in the main chamber and in the divertor, a Be-10 enriched limiter tile was installed prior to plasma operations in 2011-2012. Methods to take surface samples have been developed, an abrasive method for bulk Be tiles in the main chamber, which permits reuse of the tiles, and leaching with hot HCl to remove all Be deposited at W coated surfaces in the divertor. Quantitative analysis of the total amount of Be in cm(2) sized samples was made with inductively coupled plasma atomic emission spectroscopy (ICP-AES). The Be-10/Be-9 ratio in the samples was measured with accelerator mass spectrometry (AMS). The experimental setup and methods are described in detail, including sample preparation, measures to eliminate contributions in AMS from the B-10 isobar, possible activation due to plasma generated neutrons and effects of diffusive isotope mixing. For the first time marker concentrations are measured in the divertor deposits. They are in the range 0.4-1.2% of the source concentration, with moderate poloidal variation. (C) 2015 Elsevier B.V. All rights reserved.

  • 7.
    Bykov, Igor
    et al.
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
    Bergsåker, Henric
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
    Petersson, Per
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
    Likonen, Jari
    Possnert, G.
    Widdowson, C.
    Combined ion micro probe and SEM analysis of strongly non uniform deposits in fusion devices2015In: Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, ISSN 0168-583X, E-ISSN 1872-9584, Vol. 342, p. 19-28Article in journal (Refereed)
    Abstract [en]

    Conventional ion beam analysis (IBA) of deposited layers from fusion devices may have insufficient accuracy due to strongly uneven appearance of the layers. Surface roughness and spatial variation of the matrix composition make interpretation of broad beam spectra complex and non obvious. We discuss complications of applied IBA arising for fusion-relevant surfaces and demonstrate how quantification can be improved by employing micro IBA methods. The analysis is bound to pre-defined regions on the sample surface and can be extended by employing beams of several types, scanning electron microscopy (SEM) and stereo SEM techniques.

  • 8.
    Bykov, Igor
    et al.
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
    Bergsåker, Henric
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
    Petersson, Per
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
    Likonen, Jari
    Possnert, Göran
    Quantitative plasma-fuel and impurity profiling in thick plasma-deposited layers by means of micro ion beam analysis and SIMS2014In: Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, ISSN 0168-583X, E-ISSN 1872-9584, Vol. 332, p. 280-285Article in journal (Refereed)
    Abstract [en]

    The operation of the Joint European Torus (JET) with full-carbon wall during the last decades has proven the importance of material re-deposition processes in remote areas of the tokamak. The thickness of the deposits in shadowed areas can reach 1 mm. The main constituent is carbon, with little inclusion of Inconel components. Atomic fractions Be/C and D/C can locally reach 1. Three methods were used to study thick deposits on JET divertor surfaces: (i) NRA analysis with a 15 mu m wide, 3 MeV He-3 ion microbeam on a polished cross section of the layer to determine the concentration distribution of D, Be and C and the distribution of Ni by particle induced X-ray emission; (ii) elastic proton scattering (EPS) from the top of the layers with a broad proton beam at 3.5 and 4.6 MeV. These methods were absolutely calibrated using thick elemental targets. (iii) Depth profiling of D, Be and Ni was done with secondary ion mass spectrometry (SIMS), sputtering the layers from the surface. The three methods are complementary. The thickest layers are accessible only by microbeam mapping of the cross sections, albeit with limited spatial resolution. The SIMS has the best depth resolution, but is difficult for absolute quantification and is limited in accessible depth. The probed depth with proton backscattering is limited to about 30 mu m. The combination of all three methods provided a coherent picture of the layer composition. It was possible to correlate the SIMS profiling results to quantitative data obtained by the microbeam method.

  • 9.
    Bykov, Igor
    et al.
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
    Petersson, Per
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
    Bergsåker, Henric
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
    Hallén, A.
    Possnert, G.
    Investigation of tritium analysis methods for ion microbeam application2012In: Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, ISSN 0168-583X, E-ISSN 1872-9584, Vol. 273, p. 250-253Article in journal (Refereed)
    Abstract [en]

    The trapping and retention of tritium in deposited layers on plasma-facing components is a critical issue for the international tokamak experimental reactor (ITER) and for future power producing tokamak fusion reactors. Cross sections of deposited layers at surfaces in the JET tokamak divertor are being investigated using ion microbeam analysis. To include tritium analysis with high spatial resolution, a number of plausible ion beam techniques have been investigated. Calibration samples with 150 nm tritiated titanium films were used. Absolute concentrations were determined with classical ERD using 2.5-3.5 MeV C-12(+). Cross sections for non-Rutherford ERD and for the T(C-12,p)C-14 and T(C-12,alpha)B-11 nuclear reactions were measured for different angles in the energy range 2.5-15 MeV. Background spectra were collected from pure carbon, beryllium and deuterium enriched samples and the sensitivity for microbeam NRA measurements of the tritium concentration in thick targets with predominantly Be-C-D matrix was estimated.

  • 10.
    Chang, Zhongwen
    et al.
    KTH, School of Engineering Sciences (SCI), Physics, Reactor Physics.
    Olsson, Pär
    KTH, School of Engineering Sciences (SCI), Physics, Reactor Physics.
    Terentyev, D
    Nuclear Materials Science Institute, Belgium.
    Sandberg, N
    Swedish Radiation Safety Authority, Sweden.
    Multiscale calculation of dislocation bias in fcc Ni and bcc Fe model lattices2014In: Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, ISSN 0168-583X, E-ISSN 1872-9584Article in journal (Refereed)
    Abstract [en]

    In order to gain more insights on void swelling, dislocation bias is studied in this work. Molecular staticsimulations with empirical potentials are applied to map the dislocation–point defects interactionenergies in both fcc Ni and bcc Fe model lattices. The interaction energies are then used to numericallysolve the diffusion equation and obtain the dislocation bias. The importance of the dislocation core regionis studied under a the temperature range 573–1173 K and the dislocation densities 1012—1015 m-2. Theresults show that larger dislocation bias is found in the fcc Ni than in the bcc Fe under differenttemperatures and dislocation densities. The anisotropic interaction energy model is used to obtain thedislocation bias and the result is compared to that obtained using the atomistic interaction model, thecontribution from the core structure is then shown in both the Ni lattice and the Fe lattice.

  • 11. Chen, C. C.
    et al.
    Lindgren, A. C.
    Zhang, Shi-Li
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Zhu, D. Z.
    Vantomme, A.
    Different strain relaxation mechanisms in strained Si/Si1-xGex/Si heterostructures by high dose B+ and BF2+ doping2002In: Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, ISSN 0168-583X, E-ISSN 1872-9584, Vol. 198, no 02-jan, p. 57-63Article in journal (Refereed)
    Abstract [en]

    Strained Si/Si0.8Ge0.2/Si heterostructures are implanted at room temperature with 7.5 keV B+ and 33 keV BF2+ ions to a high dose of 2 x 10(15) ions/cm(2), respectively. The samples are subsequently subjected to three-step anneals (spacer anneal, oxidation anneal and rapid thermal anneal), which are used to simulate a real fabrication process of SiGe-based MOSFET devices. The damage induced by implantation and its recovery are characterized by 2 MeV He-4(+) RBS/ channeling spectrometry. A damage layer on the surface is induced by B+ implantation, but BF2+ ion implantation amorphizes the surface of Si/Si0.8Ge0.2/Si heterostructure. Channeling angular scans along the (110) axial direction demonstrate that the strain stored in the SiGe layer could be nearly completely retained for the B+ implantated and subsequently annealed sample. However, the strain in the BF2+ implanted/annealed SiGe layer has decreased drastically.

  • 12. Chiapetto, Monica
    et al.
    Messina, Luca
    KTH, School of Engineering Sciences (SCI), Physics, Reactor Physics. Université Paris-Saclay, Gif-sur-Yvette, France.
    Becquart, Charlotte S.
    Olsson, Pär
    KTH, School of Engineering Sciences (SCI), Physics, Reactor Physics.
    Malerba, Lorenzo
    Nanostructure evolution of neutron-irradiated reactor pressure vessel steels: Revised Object kinetic Monte Carlo model2017In: Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, ISSN 0168-583X, E-ISSN 1872-9584, Vol. 393, p. 105-109Article in journal (Refereed)
    Abstract [en]

    This work presents a revised set of parameters to be used in an Object kinetic Monte Carlo model to simulate the microstructure evolution under neutron irradiation of reactor pressure vessel steels at the operational temperature of light water reactors (∼300 °C). Within a “grey-alloy” approach, a more physical description than in a previous work is used to translate the effect of Mn and Ni solute atoms on the defect cluster diffusivity reduction. The slowing down of self-interstitial clusters, due to the interaction between solutes and crowdions in Fe is now parameterized using binding energies from the latest DFT calculations and the solute concentration in the matrix from atom-probe experiments. The mobility of vacancy clusters in the presence of Mn and Ni solute atoms was also modified on the basis of recent DFT results, thereby removing some previous approximations. The same set of parameters was seen to predict the correct microstructure evolution for two different types of alloys, under very different irradiation conditions: an Fe-C-MnNi model alloy, neutron irradiated at a relatively high flux, and a high-Mn, high-Ni RPV steel from the Swedish Ringhals reactor surveillance program. In both cases, the predicted self-interstitial loop density matches the experimental solute cluster density, further corroborating the surmise that the MnNi-rich nanofeatures form by solute enrichment of immobilized small interstitial loops, which are invisible to the electron microscope.

  • 13.
    Claisse, Antoine
    et al.
    KTH, School of Engineering Sciences (SCI), Physics, Reactor Physics.
    Olsson, Pär
    KTH, School of Engineering Sciences (SCI), Physics, Reactor Physics.
    First-principles calculations of (Y, Ti, O) cluster formation in body centred cubic iron-chromium2013In: Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, ISSN 0168-583X, E-ISSN 1872-9584, Vol. 303, p. 18-22Article in journal (Refereed)
    Abstract [en]

    In the present work, the ab initio parametrization necessary for a Monte Carlo study of the (Y, Ti, O) clusters in a FeCr matrix is done. The cohesive, binding and migration energies of all the solutes have been calculated in the dilute limit in the framework of density functional theory. The special case of the strong interaction between an Y atom and a vacancy has been considered. In the dilute limit, Cr is transparent with respect to Y, Ti, O or vacancies. On the contrary, Y binds O strongly in 2NN configuration while not in 1NN. Ti binds O in 1NN and 2NN configurations. A vacancy binds strongly with Y and O in 1NN position which is resulting in a low diffusion coefficient for Y. The peculiar case of the binding attraction between two interstitial oxygen atoms has been studied and is believed to be the main reason for the planar (2D) symmetry of the cluster nuclei. A preferential cluster shape is determined for the early nucleation stage, up to 12 atoms.

  • 14. Fedosseev, V. N.
    et al.
    Berg, Lars Erik
    KTH, School of Engineering Sciences (SCI), Applied Physics, Chemical Physics.
    Lebas, N.
    Launila, Olli J.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Chemical Physics.
    Lindroos, M.
    Losito, R.
    Marsh, B. A.
    Österdahl, Fabian K.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Chemical Physics.
    Pauchard, Thomas
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Tranströmer, Göran
    KTH, School of Engineering Sciences (SCI), Physics.
    Vannesjö, Johanna
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    ISOLDE RILIS: New beams, new facilities2008In: Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, ISSN 0168-583X, E-ISSN 1872-9584, Vol. 266, no 19-20, p. 4378-4382Article in journal (Refereed)
    Abstract [en]

    The resonance ionization laser ion source (RILIS) at the ISOLDE on-line isotope separator is based on the selective excitation of atomic transitions by tunable laser radiation. New ion beams have been produced with RILIS in recent years: Sb, Sc, Dy, Au, Hg and Po. In total, isotopes of 26 different elements have been selectively laser-ionized and separated at ISOLDE. In order to facilitate the work on development of atomic ionization schemes an off-line laser laboratory has been established at CERN. Operating independently of the on-line RI LIS setup, this laboratory will be capable of providing extensive data on atomic transitions, in particular between highly excited and auto-ionizing atomic states, which are required for the improvement of the RILIS efficiency. Additionally, the program gram of upgrading the on-line RI LIS system by the implementation of solid state lasers will be presented.

  • 15.
    Garcia-Carrasco, Alvaro
    et al.
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
    Petersson, Per
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
    Hallén, Anders
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Grzonka, J.
    Gilbert, M. R.
    Fortuna-Zalesna, E.
    Rubel, Marek
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
    Impact of helium implantation and ion-induced damage on reflectivity of molybdenum mirrors2016In: Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, ISSN 0168-583X, E-ISSN 1872-9584Article in journal (Refereed)
    Abstract [en]

    Molybdenum mirrors were irradiated with Mo and He ions to simulate the effect of neutron irradiation on diagnostic first mirrors in next-generation fusion devices. Up to 30 dpa were produced under molybdenum irradiation leading to a slight decrease of reflectivity in the near infrared range. After 3×1017 cm-2 of helium irradiation, reflectivity decreased by up to 20%. Combined irradiation by helium and molybdenum led to similar effects on reflectivity as irradiation with helium alone. Ion beam analysis showed that only 7% of the implanted helium was retained in the first 40nm layer of the mirror. The structure of the near-surface layer after irradiation was studied with scanning transmission electron microscopy and the extent and size distribution of helium bubbles was documented. The consequences of ion-induced damage on the performance of diagnostic components are discussed.

  • 16. Gubarev, M.
    et al.
    Ramsey, Brian D.
    Engelhaupt, D.
    Burgess, J. Michael
    Mildner, D.
    An evaluation of grazing-incidence optics for neutron imaging2007In: Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, ISSN 0168-583X, E-ISSN 1872-9584, Vol. 265, no 2, p. 626-630Article in journal (Refereed)
    Abstract [en]

    The focusing capabilities of neutron imaging optics based on the Wolter-1 geometry have been successfully demonstrated with a beam of long wavelength neutrons with low angular divergence. A test mirror was fabricated using an electroformed nickel replication process at Marshall Space Flight Center. The neutron current density gain at the focal spot of the mirror is found to be at least 8 for neutron wavelenaths in the range from 6 to 20 angstrom. Possible applications of the optics are briefly discussed.

  • 17.
    Hallén, Anders.
    et al.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Janson, M. S.
    Kuznetsov, A. Y.
    Aberg, D.
    Linnarsson, Margareta K
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Svensson, B. G.
    Persson, P. O.
    Carlsson, F. H. C.
    Storasta, L.
    Bergman, J. P.
    Sridhara, S. G.
    Zhang, Y.
    Ion implantation of silicon carbide2002In: Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, ISSN 0168-583X, E-ISSN 1872-9584, Vol. 186, p. 186-194Article in journal (Refereed)
    Abstract [en]

    Ion implantation is an important technique for a successful implementation of commercial SiC devices. Much effort has also been devoted to optimising implantation and annealing parameters to improve the electrical device characteristics. However, there is a severe lack of understanding of the fundamental implantation process and the generation and annealing kinetics of point defects and defect complexes. Only very few of the most elementary intrinsic point defects have been unambiguously identified so far. To reach a deeper understanding of the basic mechanisms SiC samples have been implanted with a broad range of ions, energies, doses, etc., and the resulting defects and damage produced in the lattice have been studied with a multitude of characterisation techniques. In this contribution we will review some of the results generated recently and also try to indicate where more research is needed. In particular, deep level transient spectroscopy (DLTS) has been used to investigate point defects at very low doses and transmission electron microscopy (TEM) and Rutherford backscattering spectrometry (RBS) are used for studying the damage build-up at high doses.

  • 18.
    Hallén, Anders.
    et al.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Keskitalo, N.
    Defect distributions in silicon implanted with low doses of MeV ions2002In: Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, ISSN 0168-583X, E-ISSN 1872-9584, Vol. 186, p. 344-348Article in journal (Refereed)
    Abstract [en]

    Deep level transient spectroscopy (DLTS) is used to study the distributions as a function of depth of the single negative divacancy complex in n-type FZ silicon implanted with low doses of H, He and O ions, The energies of the incoming ions are chosen to correspond to the same projected range, i.e. about 24 mum. The defect distribution is found to be relatively broad as compared to Monte Carlo simulations of the initially created vacancy distribution, particularly for the case of proton implantation. Furthermore, it is shown that the yield of divacancies, per generated vacancy, increases slightly with incoming ion mass and is three times higher at half the projected range than in the damage peak.

  • 19.
    Hallén, Anders
    et al.
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Moschetti, Giuseppe
    RBS channeling measurement of damage annealing in InAs/AlSb HEMT structures2014In: Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, ISSN 0168-583X, E-ISSN 1872-9584, Vol. 332, p. 172-175Article in journal (Refereed)
    Abstract [en]

    Electrical isolation of InAs/AlSb high electron mobility transistors has been achieved by the ion implantation isolation technique. The multilayered structures are grown by molecular beam epitaxy on GaAs substrates. The optimal isolation is provided by damaging patterned areas by 100 keV Ar ions implanted at room temperature using fluence of 2 x 10(15) cm(-2), and then annealing the samples in 365 degrees C for 30 min. The damage build-up and annealing is studied by channeling Rutherford backscattering spectrometry (RBS) and compared to sheet resistance measurements. Only a low level of damage annealing can be seen in RBS for the post-implant annealed samples, but for Ar fluence higher than 2 x 10(14) cm(-2), a strong electrical resistivity increase can still be achieved.

  • 20.
    Henriksson, Krister O. E.
    et al.
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Power Safety.
    Nordlund, K.
    Keinonen, J.
    Crater annihilation on silver by cluster ion impacts2007In: Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, ISSN 0168-583X, E-ISSN 1872-9584, Vol. 255, no 1, p. 259-264Article in journal (Refereed)
    Abstract [en]

    Using the MD/MC-CEM potential we have investigated the impacts of 20 keV Ag-13 cluster ions on (001) silver surfaces having one initial crater. This one was made in the zeroth ion impact. The degree of annihilation of the initial crater was investigated as a function of the lateral distance r(i) between the crater and the ion. The impact points were selected randomly inside a circular area with a radius of 75 angstrom centered on the crater. To reduce the total number of simulations, the circular area was divided into annuli. The initial and final atomic positions in the impact simulations were analyzed and the degree of annihilation of the initial crater was determined. The results indicate that for r <= 60 angstrom there is a net growth of the initial crater, and for distances r is an element of (60,80) angstrom there is a small net filling of the crater.

  • 21. Henriksson, Krister O. E.
    et al.
    Nordlund, K.
    Keinonen, J.
    Molecular dynamics simulations of helium cluster formation in tungsten2006In: Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, ISSN 0168-583X, E-ISSN 1872-9584, Vol. 244, no 2, p. 377-391Article in journal (Refereed)
    Abstract [en]

    Molecular dynamics simulations of helium implantation into single-crystalline tungsten at 0 and 300 K have been performed. Non-damaging ion energies of 50, 100 and 200 eV were used. Clusters containing up to the order of 100 He atoms were formed. These clusters were nucleated athermally, via the creation of (111) crowdion interstitials and interstitial dislocation loop punching. Ruptures of He clusters were observed, but no associated ejection of W atoms.

  • 22. Intarasiri, S.
    et al.
    Dangtip, S.
    Hallén, Anders.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Jensen, J.
    Yu, L. D.
    Possnert, G.
    Singkarat, S.
    Activation energy of the growth of ion-beam-synthesized nano-crystalline 3C-SiC2007In: Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, ISSN 0168-583X, E-ISSN 1872-9584, Vol. 257, p. 195-198Article in journal (Refereed)
    Abstract [en]

    In this experiment, carbon ions at 40 keV were implanted into (10 0) high-purity p-type silicon wafers at 400 degrees C to a fluence of 6.5 x 10(17) ions/cm(2). Subsequent thermal annealing of the implanted samples was performed in a vacuum furnace at 800-1000 degrees C. Glancing incidence X-ray diffraction (GIXRD) was used to characterize the crystalline quality and estimate the grain size of nano-crystalline 3C-SiC. Activation energy for the growth of 3C-SiC was evaluated following the annealing behaviour of the GIXRD-characteristic 3C-SiC (111) peaks. It was found that the 3C-SiC was directly formed during ion implantation at this substrate temperature and the activation energy of the process was about 0.05 eV. Such a low energy was explained in terms of ion beam induced precipitate formation.

  • 23. Intarasiri, S.
    et al.
    Hallén, Anders.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Kamwanna, T.
    Yu, L. D.
    Possnert, G.
    Singkarat, S.
    Characterization of the crystalline quality of beta-SiC formed by ion beam synthesis2006In: Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, ISSN 0168-583X, E-ISSN 1872-9584, Vol. 249, p. 851-855Article in journal (Refereed)
    Abstract [en]

    The ion beam synthesis (IBS) technique is applied to form crystalline silicon carbide (SiC) for future optoelectronics applications. Carbon ions at 80 and 40 keV were implanted into (100) high-purity p-type silicon wafers at room temperature and 400 degrees C, respectively, to doses in excess of 10(17) ions/cm(2). Subsequent thermal annealing of the implanted samples was performed in a vacuum furnace at temperatures of 800, 900 and 1000 degrees C, respectively. Elastic recoil detection analysis was used to investigate depth distributions of the implanted ions and infrared transmittance (IR) measurement was used to characterize formation of SiC in the implanted Si substrate. Complementary to IR, Raman scattering measurements were also carried out. Levels of the residual damage distribution of the samples annealed at different temperatures were compared with that of the as-implanted one by Rutherford backscattering spectrometry (RBS) in the channeling mode. The results show that C-ion implantation at the elevated temperature, followed by high-temperature annealing, enhances the synthesis of crystalline SiC.

  • 24. Intarasiri, S.
    et al.
    Kamwanna, T.
    Hallén, Anders.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Yu, L. D.
    Janson, M. S.
    Thongleum, C.
    Possnert, G.
    Singkarat, S.
    RBS and ERDA determinations of depth distributions of high-dose carbon ions implanted in silicon for silicon-carbide synthesis study2006In: Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, ISSN 0168-583X, E-ISSN 1872-9584, Vol. 249, p. 859-864Article in journal (Refereed)
    Abstract [en]

    For ion beam synthesis of silicon carbide (SiC), a knowledge of the depth distribution of implanted carbon ions in silicon is crucial for successful development. Based on its simplicity and availability, we selected Rutherford backscattering spectrometry (RBS) as an analysis technique for this purpose. A self-developed computer program dedicated to extract depth profiles of lighter impurities in heavier matrix is established. For control, calculated results are compared with an other ion beam analysis (IBA) technique superior for studying lighter impurity in heavier substrate i.e. elastic recoil detection analysis (ERDA). The RBS was performed with a 1.7-MV Tandetron accelerator using He2+ as the probe ions. The ERDA was performed with a 5-MV Pelletron accelerator using I8+ as the probe ions. This work shows that the RBS-extracted data had no significant deviations from those of ERDA and simulations by SRIM2003 and SIMPL computer codes. We also found that annealing at temperatures as high as 1000 degrees C had quite limited effect on the redistribution of carbon in silicon.

  • 25. Juslin, N.
    et al.
    Nordlund, K.
    Wallenius, Janne
    KTH, School of Engineering Sciences (SCI), Physics, Reactor Physics.
    Malerba, L.
    Simulation of threshold displacement energies in FeCr2007In: Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, ISSN 0168-583X, E-ISSN 1872-9584, Vol. 255, no 1, p. 75-77Article in journal (Refereed)
    Abstract [en]

    We have studied the role of chromium on threshold displacement energies in FeCr for the fusion reactor steel relevant concentration 10% Cr. We have used molecular dynamics simulations in order to determine whether the observed Cr-content dependence of macroscopic properties can be due to the defect production. We compare FeCr-alloys with pure iron and chromium, employing two different potential sets for the Fe-Cr system. We find that there are no significant differences between pure iron and FeCr with 10% Cr for the 100, 110 and 111 directions and the average threshold energy.

  • 26. Keskitalo, N.
    et al.
    Tiensuu, S.
    Hallén, Anders.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Characterization of hydrophobic bonded silicon wafers2002In: Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, ISSN 0168-583X, E-ISSN 1872-9584, Vol. 186, p. 66-70Article in journal (Refereed)
    Abstract [en]

    Direct bonding of silicon-to-silicon has been recognized as an interesting method for creating novel device geometries and structures and it has so far been used for the preparation of power devices and sensors. The influence of the bonded interface on electrical performance is then of great interest. In this contribution the interface region of hydrophobic bonded n-type silicon wafers have been studied and a comparison is made between samples before and after an exposure to low doses of 9.5 MeV protons to see the effect of the interface on point defect kinetics, The samples were studied using current-voltage (IV), capacitance-voltage (CV). deep level transient spectroscopy (DLTS). secondary ion mass spectrometry (SIMS) and scanning electron microscopy (SEM). During reverse bias there is a dramatic increase in leakage current when the depletion region reaches the bonded interface region. Due to the high leakage currents DLTS measurements could not be performed directly at the interface. However. in contrast to previous studies. no deep levels are discovered in the interface region of non-irradiated samples and, furthermore, no influence of the bonded interface on the concentration and depth distribution of irradiation induced defects could be detected. This suggests that the irradiation induced defects are unaffected by the bonded interlace, At the interface a boron peak is detected by SIMS.

  • 27. Leveque, P.
    et al.
    Hallén, Anders.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Pellegrino, P.
    Svensson, B. G.
    Privitera, V.
    Dose-rate influence on the defect production in MeV proton-implanted float-zone and epitaxial n-type silicon2002In: Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, ISSN 0168-583X, E-ISSN 1872-9584, Vol. 186, p. 375-379Article in journal (Refereed)
    Abstract [en]

    The production of stable vacancy-related point defects in proton-implanted float-zone and epitaxial silicon has been studied in the low dose range ( less than or equal to 10(10)/cm(2)) as a function of dose-rate. The well-known inverse dose-rate effect has been observed in both types of materials with a decrease in the concentration of vacancy-related defects as the dose-rate increases. The effect is less pronounced in oxygen lean epitaxial silicon. Moreover, a continuous decrease of the vacancy-related defect concentration as a function of the flux was measured while a threshold was expected according to previous studies. Both or these results can be explained by a simple calculation, taking into account the influence of the oxygen concentration as well as the influence of the diffusion coefficient of point defects on the inverse dose-rate effect.

  • 28. Leveque, P.
    et al.
    Pellegrino, P.
    Hallén, Anders.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Svensson, B. G.
    Privitera, V.
    Hydrogen-related defect centers in float-zone and epitaxial n-type proton implanted silicon2001In: Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, ISSN 0168-583X, E-ISSN 1872-9584, Vol. 174, no 3, p. 297-303Article in journal (Refereed)
    Abstract [en]

    Hydrogen-related defects in float zone (Fz) and epitaxial (Epi) n-type silicon crystals have been studied by means of deep level transient spectroscopy. These defects, as well as the characteristic vacancy-oxygen (VO) and divacancy (V-2) centers were introduced by proton implantation (1.3 MeV) using a dose of 1 x 10(10)/cm(2). A hydrogen-related defect level located at 0.45 eV below the conduction band edge (E-c) appears in both kind of samples. Another hydrogen-related defect appears predominantly in the Fz samples with a level at E-c - 0.32 eV. Depth profiling as well as annealing studies strongly suggest that the level at E-c - 0.45 eV is due to a complex involving hydrogen and V2 The level at E-c - 0.32 eV is strongly suppressed in the high purity Epi samples and the same holds for VO center. These results together with annealing data provide substantial evidence that the E-c - 0.32 eV level originates from a VO-center partly saturated with hydrogen (a VOH complex). Finally, in the Epi samples a new level at similar toE(c) - 0.31 eV is resolved, which exhibits a concentration Versus depth profile strongly confined to the damage peak region. The origin of this level is not known but the extremely narrow depth profile may indicate a higher-order defect of either vacancy or interstitial type,

  • 29.
    Linnarsson, Margareta K.
    et al.
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Hallén, Anders
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Manganese in silicon carbide2012In: Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, ISSN 0168-583X, E-ISSN 1872-9584, Vol. 273, p. 127-130Article in journal (Refereed)
    Abstract [en]

    Structural disorder and relocation of implanted Mn in semi-insulating 4H-SiC has been studied. Subsequent heat treatment of Mn implanted samples has been performed in the temperature range 1400-2000 degrees C. The depth distribution of manganese is recorded by secondary ion mass spectrometry. Rutherford backscattering spectrometry has been employed for characterization of crystal disorder. Ocular inspection of color changes of heat-treated samples indicates that a large portion of the damage has been annealed. However, Rutherford backscattering shows that after heat treatment, most disorder from the implantation remains. Less disorder is observed in the [0 0 0 1] channel direction compared to [1 1 (2) over bar 3] channel direction. A substantial rearrangement of manganese is observed in the implanted region. No pronounced manganese diffusion deeper into the sample is recorded.

  • 30.
    Linnarsson, Margareta K.
    et al.
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Khartsev, Sergiy
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Primetzhofer, D.
    Possnert, G.
    Hallén, Anders
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    ToF-MEIS stopping measurements in thin SiC films2014In: Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, ISSN 0168-583X, E-ISSN 1872-9584, Vol. 332, p. 130-133Article in journal (Refereed)
    Abstract [en]

    Electronic stopping in thin, amorphous, SiC films has been studied by time-of-flight medium energy ion scattering and conventional Rutherford backscattering spectrometry. Amorphous SiC films (8, 21 and 36 nm) were prepared by laser ablation using a single crystalline silicon carbide target. Two kinds of substrate films, one with a lower atomic mass (carbon) and one with higher atomic mass (iridium) compared to silicon has been used. Monte Carlo simulations have been used to evaluate electronic stopping from the shift in energy for the signal scattered from Ir with and without SiC. The two kinds of samples are used to illustrate the strength and challenges for ToF-MEIS compared to conventional RBS.

  • 31.
    Messina, Luca
    et al.
    KTH, School of Engineering Sciences (SCI), Physics, Reactor Physics.
    Chang, Zhongwen
    KTH, School of Engineering Sciences (SCI), Physics, Reactor Physics.
    Olsson, Pär
    KTH, School of Engineering Sciences (SCI), Physics, Reactor Physics.
    Ab initio modelling of vacancy-solute dragging in dilute irradiated iron-based alloys2013In: Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, ISSN 0168-583X, E-ISSN 1872-9584, Vol. 303, p. 28-32Article in journal (Refereed)
    Abstract [en]

    The formation of solute-defect nanoclusters in RPV steels is the main cause of radiation induced embrittlement. Solute atoms may diffuse in the alloy by a vacancy drag mechanism, depending on the strength of interaction with point defects. A multifrequency model based on ab initio computed migration barriers was applied in order to investigate the possibility of solute drag in iron-based bcc binary alloys containing Ni, Cr, Cu or Mn, and the obtained solute diffusion coefficients were compared with previous experiments. The results show that Ni is expected to be dragged at temperatures below approximately 900 K, while Cr and Mn are not involved in the dragging mechanism. As for Cu, the results are controversial because the computed migration barriers are strongly affected by the particular choice of the ab initio method.

  • 32.
    Messina, Luca
    et al.
    KTH, School of Engineering Sciences (SCI), Physics, Reactor Physics.
    Malerba, Lorenzo
    Olsson, Pär
    KTH, School of Engineering Sciences (SCI), Physics, Reactor Physics.
    Stability and mobility of small vacancy-solute complexes in Fe-MnNi and dilute Fe-X alloys: A kinetic Monte Carlo study2015In: Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, ISSN 0168-583X, E-ISSN 1872-9584, Vol. 352, p. 61-66Article in journal (Refereed)
    Abstract [en]

    Manganese and nickel solute atoms in irradiated ferritic steels play a major role in the nanostructural evolution of reactor pressure vessels (RPV), as they are responsible for the formation of embrittling nanofeatures even in the absence of copper. The stability and mobility of small vacancy solute clusters is here studied with an atomistic kinetic Monte Carlo approach based on ab initio calculations, in order to investigate the influence of Mn and Ni on the early life of small radiation-induced vacancy clusters, and to provide the necessary parameters for advanced object kinetic Monte Carlo simulations of the RPV long-term nanostructural evolution. Migration barriers are obtained by direct ab initio calculations or through a binding energy model based on ab initio data. Our results show a clear immobilizing and stabilizing effect on vacancy clusters as the solute content is increased, whereas the only evident difference between the two solute species is a somewhat longer elongation of the cluster mean free path in the presence of a few Mn atoms.

  • 33. Nordlund, K.
    et al.
    Wallenius, Janne
    KTH, School of Engineering Sciences (SCI), Physics, Reactor Physics.
    Malerba, L.
    Molecular dynamics simulations of threshold displacement energies in Fe2006In: Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, ISSN 0168-583X, E-ISSN 1872-9584, Vol. 246, no 2, p. 322-332Article in journal (Refereed)
    Abstract [en]

    We compare systematically the threshold displacement energy surface of 11 interatomic potentials in Fe. We discuss in detail different possible definitions of threshold displacement energies, and how they relate to different kinds of experimental threshold displacement energies. We compare the threshold results to experiments, and find that none of the 11 tested potentials agrees fully with experiments. However, all the potentials predict some qualitative features in the same way, most importantly that the threshold energy surface close to the 100 crystal direction is flat and that the largest threshold energies occur around very roughly the 123 crystal direction.

  • 34. Paneta, V.
    et al.
    Fluch, U.
    Petersson, Per
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
    Ott, S.
    Primetzhofer, D.
    Characterization of compositional modifications in metal-organic frameworks using carbon and alpha particle microbeams2017In: Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, ISSN 0168-583X, E-ISSN 1872-9584, Vol. 404, p. 198-201Article in journal (Refereed)
    Abstract [en]

    Zirconium-oxide based metal-organic frameworks (MOFs) were grown on p-type Si wafers. A modified linker molecule containing iodine was introduced by post synthetic exchange (PSE). Samples have been studied using Rutherford Backscattering Spectrometry (RBS) and Particle Induced X-ray Emission (PIXE) techniques, employing the 5 MV 15SDH-2 Pelletron Tandem accelerator at the Angstrom laboratory. The degree of post synthetic uptake of the iodine-containing linker has been investigated with both a broad beam and a focused beam of carbon and alpha particles targeting different kind of MOF crystals which were of similar to 1-10 mu m in size, depending on the linker used. Iodine concentrations in MOF crystallites were also measured by Nuclear Magnetic Resonance Spectroscopy (NMR) and are compared to the RBS results. In parallel to the ion beam studies, samples were investigated by Scanning Electron Microscopy (SEM) to quantify possible crystallite clustering, develop optimum sample preparation routines and to characterize the potential ion beam induced sample damage and its dependence on different parameters. Based on these results the reliability and accuracy of ion beam data is assessed.

  • 35. Pelicon, P.
    et al.
    Vavpetic, P.
    Grlj, N.
    Cadez, I.
    Markelj, S.
    Brezinsek, S.
    Kreter, A.
    Dittmar, T.
    Tsitrone, E.
    Pegourie, B.
    Languille, P.
    Rubel, Marek
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics. KTH, School of Electrical Engineering (EES), Centres, Alfvén Laboratory Centre for Space and Fusion Plasma Physics.
    Schwarz-Selinger, T.
    Fuel retention study in fusion reactor walls by micro-NRA deuterium mapping2011In: Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, ISSN 0168-583X, E-ISSN 1872-9584, Vol. 269, no 20, p. 2317-2321Article in journal (Refereed)
    Abstract [en]

    Nuclear Reaction Analysis (NRA) with a (3)He ion beam is a powerful analytical technique for analysis of light elements in thin films. The main motivation for 3He focused beam applications is lateral mapping of deuterium using the nuclear reaction D((3)He,p)(4)He in surfaces exposed to a tokamak plasma, where a lateral resolution in the pm-range provides unique information for fuel retention studies. At the microprobe at the Jozef Stefan Institute typical helium ion currents of 300 pA and beam dimensions of 4 x 4 mu m(2) can be obtained. This work is focused on micro-NRA studies of plasma-facing materials using a set-up consisting of a silicon partially depleted charge particle detector for NRA spectroscopy applied in parallel with a permanently installed X-ray detector, an RBS detector and a beam chopper for ion dose monitoring. A method for absolute deuterium quantification is described. In addition, plasma-deposited amorphous deuterated carbon thin films (a-C:D) with known D content were used as a reference. The method was used to study deuterium fuel retention in carbon fibre composite materials exposed to a deuterium plasma in the Tore Supra and TEXTOR tokamaks. The high lateral resolution of micro-NRA allowed us to make a detailed study of the influence of topography on the fuel retention process. We demonstrated that the surface topography plays a dominant role in the retention of deuterium. The deep surfaces inside the castellation gaps showed approximately two orders of magnitude lower deuterium concentrations than in areas close to the exposed surface.

  • 36. Pellegrino, P.
    et al.
    Leveque, P.
    Kortegaard-Nielsen, H.
    Hallén, Anders.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Wong-Leung, J.
    Jagadish, C.
    Svensson, B. G.
    Separation of vacancy and interstitial depth profiles in proton- and boron-implanted silicon2002In: Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, ISSN 0168-583X, E-ISSN 1872-9584, Vol. 186, p. 334-338Article in journal (Refereed)
    Abstract [en]

    A new experimental method of studying shifts between concentration-versus-depth profiles of vacancy-type and interstitial-type defects in ion-implanted silicon is demonstrated. The concept is based on deep level transient spectroscopy (DLTS) measurements utilizing the filling pulse variation technique. The vacancy profile. represented by the vacancy-oxygen center and the interstitial profile, represented by the substitutional carbon-interstitial carbon pair, are obtained at the same sample temperature by varying the duration of the filling pulse, Thus the two profiles can be recorded with a high relative depth resolution, Point defects have been introduced in low doped float zone n-type silicon by implantation with 6 MeV boron ions and 1.3 MeV protons at room temperature, using low doses. For each implantation condition the peak of the interstitial profile is shown to be displaced by similar to 0.5 mum towards larger depths compared to that of the vacancy profile. This shift is primarily attributed to the preferential forward momentum of recoiling Si atoms, in accordance with theoretical predictions.

  • 37. Perot, B.
    et al.
    Carasco, C.
    Klamra, Wlodzimierz
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Isaksson, P.
    Le Tourneur, P.
    Lhuissier, M.
    Colonna, A.
    Tintori, C.
    Peerani, P.
    Sequeira, V.
    Salvato, M.
    et al,
    Development of the EURITRACK tagged neutron inspection system2007In: Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, ISSN 0168-583X, E-ISSN 1872-9584, Vol. 261, no 02-jan, p. 295-298Article in journal (Refereed)
    Abstract [en]

    The EURopean Illicit TRAfficing Countermeasures Kit (EURITRACK) project is part of the 6th European Union Framework Program. It aims at developing a Tagged Neutron Inspection System (TNIS) to detect illicit materials, such as explosives and narcotics, in cargo containers. Fast neutron induced reactions produce specific gamma-rays used to determine the chemical composition of the inspected material. The associated particle technique is employed to precisely locate the interaction points of the neutrons. A new deuterium-tritium neutron generator has been developed, including a pixelized alpha particle detector. The TNIS also comprises high-efficiency fast neutron and gamma-ray detectors, a dedicated front-end electronics and an integrated software to entirely drive the system and automatically process the data. Most components have been integrated during last months at Institute Ruder Boskovic, in Zagreb, Croatia. An overview of the TNIS and of its preliminary performances is presented.

  • 38. Persson, L.
    et al.
    Whitlow, H. J.
    El Bouanani, M.
    Hult, M.
    Andersson, M.
    Bubb, I. F.
    Cohen, D. D.
    Dytlewski, N.
    Johnston, P. N.
    Walker, S. R.
    Zaring, C.
    Östling, Mikael
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Separation of mass-overlapped time of flight-energy elastic recoil detection analysis data using Ryan and Jamieson's dynamic analysis method2001In: Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, ISSN 0168-583X, E-ISSN 1872-9584, Vol. 179, no 3, p. 403-411Article in journal (Refereed)
    Abstract [en]

    Time of flight-energy (ToF-E) elastic recoil detection analysis (ERDA) data often contains mass signals with considerable overlap from adjacent isotopes in the mass-energy plane. An evaluation has been carried out of the suitability of the dynamic analysis method proposed by Ryan and Jamieson to decompose elemental signals with overlapping mass. This method is shown to work very well on generated test data and the result when it was applied to experimental data appears quite promising. Very accurate mass calibration and lineshape determination was found to be a prerequisite for the application of the method.

  • 39. Petersson, P.
    et al.
    Bergsåker, Henric
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
    Possnert, G.
    Coad, J. P.
    Koivuranta, S.
    Likonen, J.
    Ion beam micro analysis of deposits at tokamak divertor surfaces2010In: Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, ISSN 0168-583X, E-ISSN 1872-9584, Vol. 268, no 11-12, p. 1838-1841Article in journal (Refereed)
    Abstract [en]

    Cross sections of deposited layers in the Joint European Torus (JET) were analysed using the nuclear micro analysis at the Tandem Laboratory, Uppsala University. For deuterium and beryllium the nuclear reactions D-2(He-3,p)He-4 and Be-9(He-3,p(n))B-11 were exploited for analysis. Typically the analyses have been made with 10 mu m spatial resolution and a sensitivity of better than one atomic percent for beryllium or deuterium in carbon matrix. Comparing several different surface treatment techniques shows that polishing the sample surface give very good optical surface information but that some amount of deuterium and beryllium probably is removed. For good quantitative results the measurement can either be done on a rough surface or the top of the polished surface can be cut off. (C) 2010 Elsevier B.V. All rights reserved.

  • 40. Petersson, Per
    et al.
    Bergsåker, Henric
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics. KTH, School of Electrical Engineering (EES), Centres, Alfvén Laboratory Centre for Space and Fusion Plasma Physics.
    Hallén, Anders
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Jensen, Jens
    Possnert, Göran
    Mapping of hydrogen isotopes with a scanning nuclear microprobe2008In: Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, ISSN 0168-583X, E-ISSN 1872-9584, Vol. 266, no 10, p. 2429-2432Article in journal (Refereed)
    Abstract [en]

    Elastic recoil detection analysis using heavy ions with a scanning nuclear microprobe was applied to determine the content of hydrogen isotopes in carbon material facing fusion plasma in the JET fusion reactor. The hydrogen and deuterium concentrations in re-deposited material were obtained by mapping a cross sectional cut of a wall sample. De-trapping and hydrogen release caused by the primary ion beam were investigated. For both the deuterium and hydrogen concentration a drop of similar to 75% was observed from an extrapolated initial value to a final steady state region. A procedure was used to determine the initial concentration. In this way a mapping of the initial deuterium concentration could be obtained.

  • 41.
    Petersson, Per
    et al.
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
    Rubel, Marek
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
    Possnert, Göran
    Tandem labb, Uppsala Universitet.
    Brezinsek, S.
    Forschungszentrum Juelich, Germany .
    Pégourié, B.
    CEA Cadarache, France .
    Nuclear reaction and heavy ion ERD analysis of wall materials from controlled fusion devices: Deuterium and nitrogen-15 studies2012In: Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, ISSN 0168-583X, E-ISSN 1872-9584, Vol. 273, p. 113-117Article in journal (Refereed)
    Abstract [en]

    Time-of-flight HIERDA (26 MeV I-127(7+)) and micro-NRA (2.5 MeV He-3) were used to determine the composition of graphite and tungsten plasma-facing components (PFC) exposed at the TEXTOR and Tore Supra tokamaks. High sensitivity and resolution of HIERDA allowed, for the first time, for studies of nitrogen-15 showing that the gas injected during tokamak discharges is trapped on PFC, 3-7 x 10(15) N cm(-2). Also helium retention in tungsten has been identified: up to 8 x 10(15) He cm(-2). Deuterium distribution on the main limiters of Tore Supra is not uniform on tiles extracted from the erosion- and deposition-dominated areas. This is measured both on macro- (points 5 mm apart) and micro-scale (30 gm). The mapping with mu-NRA revealed the D content variation by a factor 40-50 in regions 1 x 2 mm(2): 1.2-40 x 10(17) D cm(-2) and 4-230 x 10(18) D cm(-2) in the erosion and deposition zones, respectively. In summary, the measurements of N-15 contributed to material mixing studies and improved understanding of deuterium retention on PFC.

  • 42. Pontikis, V.
    et al.
    Russier, V.
    Wallenius, Janne
    KTH, School of Engineering Sciences (SCI), Physics, Reactor Physics.
    An analytic n-body potential for bcc iron2007In: Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, ISSN 0168-583X, E-ISSN 1872-9584, Vol. 255, no 1, p. 37-40Article in journal (Refereed)
    Abstract [en]

    We have developed an analytic n-body phenomenological potential for bcc iron made of two electron-density functionals representing repulsion via the Thomas-Fermi free-electron gas kinetic energy term and attraction via a square root functional similar to the second moment approximation of the tight-binding scheme. Electron-density is given by radial, hydrogen-like orbitals with effective charges taken as adjustable parameters fitted on experimental and ab-initio data. Although the set of adjustable parameters is small, prediction of static and dynamical properties of iron is in excellent agreement with the experiments. Advantages and shortcomings of this model are discussed with reference to published works.

  • 43. Primetzhofer, D.
    et al.
    Dentoni Litta, Eugenio
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Hallén, Anders
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Linnarsson, Margareta K.
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Possnert, G.
    Ultra-thin film and interface analysis of high-k dielectric materials employing Time-Of-Flight Medium Energy Ion Scattering (TOF-MEIS)2014In: Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, ISSN 0168-583X, E-ISSN 1872-9584, Vol. 332, p. 212-215Article in journal (Refereed)
    Abstract [en]

    We explore the potential of Time-Of-Flight Medium Energy Ion Scattering (TOF-MEIS) for thin film analysis and analyze possible difficulties in evaluation of experimental spectra. As a model system high-k material stacks made from ultra-thin films of HfO2 grown on a p-type Si (100) substrate with a 0.5 nm SiO2 interface layer have been investigated. By comparison of experimental spectra and computer simulations TOF-MEIS was employed to establish a depth profile of the films and thus obtaining information on stoichiometry and film quality. Nominal film thicknesses were in the range from 1.8 to 12.2 nm. A comparison of the results with those from other MEIS approaches is made. Issues regarding different combinations of composition and stopping power as well as the influence of channeling are discussed. As a supporting method Rutherford-Backscattering spectrometry (RBS) was employed to obtain the areal density of Hf atoms in the films.

  • 44. Razpet, A.
    et al.
    Possnert, G.
    Johansson, A.
    Hallén, Anders.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Hjort, K.
    Ion transmission and characterization of ordered nanoporous alumina2004In: Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, ISSN 0168-583X, E-ISSN 1872-9584, Vol. 222, no 04-mar, p. 593-600Article in journal (Refereed)
    Abstract [en]

    Ordered nanoporous alumina samples with a pore diameter of 70 nm, an array period of 100 nm and several thicknesses were considered as possible masks for pattern transfer by MeV ion lithography. A simple procedure for the sample alignment using a 2 MeV He+ beam was utilized. The energy distributions of transmitted ions as well as backscattering spectra were studied in aligned and non-aligned orientations. The best transmission, comparable to the relative surface area covered by pores, was reached for 2 mum thick samples and was independent on ion species. Although the transmission for thicker membranes was generally lower, it significantly depended on the quality of each individual sample. The presented ion beam technique can therefore be used as a tool for the characterization of porous materials. The acceptance angle for transmission through pores and the effective atomic density of samples can be obtained from the experimental data and it is shown that nanoporous alumina can be used as a mask for MeV ion lithography.

  • 45.
    Rubel, Marek J.
    et al.
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
    Coad, J. P.
    Likonen, J.
    Philipps, V.
    Analysis of fuel retention in plasma-facing components from controlled fusion devices2009In: Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, ISSN 0168-583X, E-ISSN 1872-9584, Vol. 267, no 4, p. 711-717Article in journal (Refereed)
    Abstract [en]

    First wall components in controlled fusion devices undergo severe modification by various physical and chemical processes arising from plasma-wall interactions: material erosion, its transport in the plasma and re-deposition. The intention of this work is to give a concise overview of key issues in the characterization of plasma-facing materials and components in tokamaks. The importance of surface analysis in studies of fuel inventory and material migration is presented. Experimental procedures and analysis methods are briefly reviewed with emphasis on ion beam techniques which play a prominent role in studies of wall components exposed to hot plasmas. Practical aspects in the analytical approach are addressed and special instrumentation used in these studies is described.

  • 46.
    Rubel, Marek
    et al.
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
    Petersson, Per
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
    Alves, Eduardo
    Brezinsek, Sebastijan
    Coad, Joseph Paul
    Heinola, Kalle
    Mayer, Matej
    Widdowson, Anna
    The role and application of ion beam analysis for studies of plasma-facing components in controlled fusion devices2016In: Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, ISSN 0168-583X, E-ISSN 1872-9584, Vol. 371, p. 4-11Article in journal (Refereed)
    Abstract [en]

    First wall materials in controlled fusion devices undergo serious modification by several physical and chemical processes arising from plasma-wall interactions. Detailed information is required for the assessment of material lifetime and accumulation of hydrogen isotopes in wall materials. The intention of this work is to give a concise overview of key issues in the characterization of plasma-facing materials and components in tokamaks, especially in JET with an ITER-Like Wall. IBA techniques play a particularly prominent role here because of their isotope selectivity in the low-Z range (1-10), high sensitivity and combination of several methods in a single run. The role of He-3-based NRA, RBS (standard and micro size beam) and HIERDA in fuel retention and material migration studies is presented. The use of tracer techniques with rare isotopes (e.g. N-15) or marker layers on wall diagnostic components is described. Special instrumentation, development of equipment to enhance research capabilities and issues in handling of contaminated materials are addressed. (C) 2015 Published by Elsevier B.V.

  • 47. Schmid, F.
    et al.
    Sommer, Gerhard
    KTH, School of Engineering Sciences (SCI), Solid Mechanics (Dept.).
    Rappolt, M.
    Regitnig, P.
    Holzapfel, Gerhard A.
    KTH, School of Engineering Sciences (SCI), Solid Mechanics (Dept.).
    Laggner, P.
    Amenitsch, H.
    Bidirectional tensile testing cell for in situ small angle X-ray scattering investigations of soft tissue2006In: Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, ISSN 0168-583X, E-ISSN 1872-9584, Vol. 246, no 1, p. 262-268Article in journal (Refereed)
    Abstract [en]

    An X-ray cell for the acquisition of one-dimensional mechanical force-displacement diagrams of soft tissue samples has been developed. The combination of X-ray and mechanical data allows new insights into the coupling of the macroscopic behavior and nanoscopic structural changes during the application of load. Two linear mu-translation stages are used to symmetrically - i.e. bidirectionally - stretch the sample. A video-extensometer is installed to record geometrical changes of the sample during measurement which allows to determine true stresses and strains. The sample can be immersed in a liquid and heated. We demonstrate the advantages over common unidirectional tensile testing devices without length measurement systems by comparing different mechanical and diffraction data sets of human arterial tissue.

  • 48. Schwellnus, F.
    et al.
    Catherall, R.
    Crepieux, B.
    Fedosseev, V. N.
    Marsh, B. A.
    Mattolat, Ch.
    Menna, M.
    Österdahl, Fabian
    KTH, School of Engineering Sciences (SCI), Applied Physics, Chemical Physics.
    Raeder, S.
    Stora, T.
    Wendt, K.
    Study of low work function materials for hot cavity resonance ionization laser ion sources2009In: Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, ISSN 0168-583X, E-ISSN 1872-9584, Vol. 267, no 10, p. 1856-1861Article in journal (Refereed)
    Abstract [en]

    The selectivity of a hot cavity resonance ionization laser ion source (RILIS) is most often limited by contributions from competing surface ionization of the hot walls of the ionization cavity. In this article we present investigations on the properties of designated high temperature, low work function materials regarding their performance and suitability as cavity material for RILIS. Tungsten test cavities, impregnated with a mixture of barium oxide and strontium oxide (BaOSrO on W), or alternatively gadolinium hexaboride (GdB6) were studied in comparison to a standard tungsten RILIS cavity as being routinely used for hot cavity laser ionization at ISOLDE. Measurement campaigns took place at the off-line mass separators at ISOLDE/CERN, Geneva and RISIKO/University of Mainz.

  • 49.
    Skog, P.
    et al.
    Stockholm Universitet.
    Soroka, Inna L.
    Stockholm Universitet.
    Johansson, A.
    Uppsala Universitet.
    Schuch, R.
    Stockholm Universitet.
    Guiding of highly charged ions through Al2O3 nano-capillaries2007In: Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, ISSN 0168-583X, E-ISSN 1872-9584, Vol. 258, no 1, p. 145-149Article in journal (Refereed)
    Abstract [en]

    Over the past years, our group has performed expts. on ion guiding in nano-capillary membranes of polyethylene terephthalate (PET), SiO2 and Al2O3. We report the results from our recent expts. on guiding of 7 keV Ne7+-ions in Al2O3 nano-capillaries of about 1/200 aspect ratio. We will compare these exptl. findings with previously obtained and published results of different membrane materials. [on SciFinder(R)]

  • 50.
    Ström, Petter
    et al.
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
    Petersson, Per
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
    Rubel, Marek
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
    Primetzhofer, D.
    Brezinsek, S.
    Kreter, A.
    Unterberg, B.
    Sergienko, G.
    Sugiyama, K.
    Ion beam analysis of tungsten layers in EUROFER model systems and carbon plasma facing components2016In: Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, ISSN 0168-583X, E-ISSN 1872-9584, Vol. 371, p. 355-359Article in journal (Refereed)
    Abstract [en]

    The tungsten enriched surface layers in two fusion-relevant EUROFER steel model samples, consisting of an iron-tungsten mixture exposed to sputtering by deuterium ions, were studied by Rutherford backscattering spectrometry and medium energy ion scattering. Exposure conditions were the same for the two samples and the total amount of tungsten atoms per unit area in the enriched layers were similar (2e15 and 2.4e15 atoms/cm2 respectively), despite slightly different initial atomic compositions. A depth profile featuring exponential decrease in tungsten content towards higher depths with 10-20 atomic percent of tungsten at the surface and a decay constant between 0.05 and 0.08 Å-1 was indicated in one sample, whereas only the total areal density of tungsten atoms was measured in the other. In addition, two different beams, iodine and chlorine, were employed for elastic recoil detection analysis of the deposited layer on a polished graphite plate from a test limiter in the TEXTOR tokamak following experiments with tungsten hexafluoride injection. The chlorine beam was preferred for tungsten analysis, mainly because it (as opposed to the iodine beam) does not give rise to problems with overlap of forward scattered beam particles and recoiled tungsten in the spectrum.

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