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  • 251.
    Palmgren, Susanna
    et al.
    Ecole Polytechnique Fédérale de Lausanne .
    Weman, Helge
    Ecole Polytechnique Fédérale de Lausanne .
    Schoenberg, A.
    Ecole Polytechnique Fédérale de Lausanne .
    Karlsson, Fredrik
    Ecole Polytechnique Fédérale de Lausanne .
    Dupertuis, M.-A.
    Ecole Polytechnique Fédérale de Lausanne .
    Leifer, K.
    Ecole Polytechnique Fédérale de Lausanne .
    Rudra, A.
    Ecole Polytechnique Fédérale de Lausanne .
    Kapon, E.
    Ecole Polytechnique Fédérale de Lausanne .
    Polarization-resolved optical absorption in single V-groove quantum wires2006In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 89, p. 191111-Article in journal (Refereed)
    Abstract [en]

    Optical transitions associated with all three linear polarization directions were investigated in single GaAs V-groove quantum wires of different wire thicknesses. This was accomplished by combining absorption measurements in V-groove waveguide geometry with surface-excited photoluminescence excitation spectroscopy. The observed transitions were identified with the aid of model calculations. It is shown that excitonic intersubband coupling should be accounted for in order to explain the optical transitions associated with confined light-hole-like states. The results are relevant for the design of efficient quantum wire waveguide modulators and lasers.

  • 252.
    Palmquist, J.-P.
    et al.
    Uppsala University, Department of Materials Chemistry, Ångström Laboratory, P.O. Box 538, SE-751 21 Uppsala, Sweden.
    Jansson, U.
    Uppsala University, Department of Materials Chemistry, Ångström Laboratory, P.O. Box 538, SE-751 21 Uppsala, Sweden.
    Seppänen, Timo
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics.
    Persson, Per
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics.
    Birch, Jens
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics.
    Hultman, Lars
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics.
    Isberg, P.
    ABB Group Services Center AB, Corporate Research, SE-721 78 Västerås, Sweden.
    Magnetron sputtered epitaxial single-phase Ti3SiC2 thin films2002In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 81, no 5, p. 835-Article in journal (Refereed)
    Abstract [en]

    [No abstract available]

  • 253.
    Palonen, H.
    et al.
    Uppsala Univ, Sweden.
    Mukhamedov, B. O.
    Natl Univ Sci and Technol MISIS, Russia.
    Ponomareva, A. V.
    Natl Univ Sci and Technol MISIS, Russia.
    Palsson, G. K.
    Uppsala Univ, Sweden.
    Abrikosov, Igor
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering.
    Hjorvarsson, B.
    Uppsala Univ, Sweden.
    The magnetization profile induced by the double magnetic proximity effect in an Fe/Fe0.30V0.70 superlattice2019In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 115, no 1, article id 012406Article in journal (Refereed)
    Abstract [en]

    The double magnetic proximity effect (MPE) in an Fe/Fe0.30V0.70 superlattice is studied by a direct measurement of the magnetization profile using polarized neutron reflectivity. The experimental magnetization profile is shown to qualitatively agree with a profile calculated using density functional theory. The profile is divided into a short range interfacial part and a long range tail. The interfacial part is explained by charge transfer and induced magnetization, while the tail is attributed to the inhomogeneous nature of the FeV alloy. The long range tail in the magnetization persists up to 170% above the intrinsic ordering temperature of the FeV alloy. The observed effects can be used to design systems with a direct exchange coupling between layers over long distances through a network of connected atoms. When combined with the recent advances in tuning and switching, the MPE with electric fields and currents, the results can be applied in spintronic devices. Published under license by AIP Publishing.

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  • 254.
    Paskov, Plamen
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Holtz, Per-Olof
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Monemar, Bo
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Schoenfeld, W.
    Garcia, J.M.
    Petroff, P.M.
    Photoluminescence up-conversion in InAs/GaAs self-assembled quantum dots2000In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 77, no 6, p. 812-814Article in journal (Refereed)
    Abstract [en]

    We report up-converted photoluminescence in a structure with InAs quantum dots embedded in GaAs. An efficient emission from the GaAs barrier is observed with resonant excitation of both the dots and the wetting layer. The intensity of the up-converted luminescence is found to increase superlinearly with the excitation density. The results suggest that the observed effect is due to a two-step two-photon absorption process involving quantum dot states. ⌐ 2000 American Institute of Physics.

  • 255. Paskova, T.
    et al.
    Hommel, D.
    Paskov, Plamen
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Darakchieva, Vanya
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Monemar, Bo
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Bockowski, M.
    Suski, T.
    Grzegory, I.
    Tuomisto, T.
    Saarinen, K.
    Ashkenov, N.
    Schubert, M.
    Effect of high-temperature annealing on the residual strain and bending of freestanding GaN films grown by hydride vapor phase epitaxy2006In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 88, no 14, p. 141909-Article in journal (Refereed)
    Abstract [en]

    The effect of high-temperature high-pressure annealing on the residual strain, bending, and point defect redistribution of freestanding hydride vapor phase epitaxial GaN films was studied. The bending was found to be determined by the difference in the in-plane lattice parameters in the two faces of the films. The results showed a tendency of equalizing the lattice parameters in the two faces with increasing annealing temperature, leading to uniform strain distribution across the film thickness. A nonmonotonic behavior of structural parameters with increasing annealing temperature was revealed and related to the change in the point defect content under the high-temperature treatment. © 2006 American Institute of Physics.

  • 256. Paskova, T.
    et al.
    Kroeger, R.
    Figge, S.
    Hommel, D.
    Darakchieva, Vanya
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Monemar, Bo
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Preble, E.
    Hanser, A.
    Williams, N.M.
    Tutor, M.
    High-quality bulk a-plane GaN sliced from boules in comparison to heteroepitaxially grown thick films on r-plane sapphire2006In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 89, no 5, p. 051914-Article in journal (Refereed)
    Abstract [en]

    Thick GaN bars with [1120] orientation have been sliced from GaN boules grown on freestanding films by hydride vapor phase epitaxy (HVPE) in the [0001] direction. High-resolution x-ray diffraction and transmission electron microscopy have been used to study the structural quality and defect distribution in the material in comparison to heteroepitaxially grown thick HVPE-GaN films grown in the [1120] direction on (1102)-plane sapphire. It is demonstrated that while the heteroepitaxial material possesses a high density of stacking faults and partial dislocations, leading to anisotropic structural characteristics, the (1120)-plane bulk GaN, sliced from boules, exhibits low dislocation density and narrow rocking curves with isotropic in-plane character. © 2006 American Institute of Physics.

  • 257.
    Paskova, Tanja
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Goldys, E.M.
    Div. of Info. and Commun. Sciences, Macquarie University, Sydney, NSW 2109, Australia.
    Paskov, Plamen
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Wahab, Qamar Ul
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Wilzén, Lars
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    de Jong, Michel P
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry .
    Monemar, Bo
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Mass transport growth and optical emission properties of hydride vapor phase epitaxy GaN2001In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 78, no 26, p. 4130-4132Article in journal (Refereed)
    Abstract [en]

    The optical emission properties of mass-transport regions of GaN grown by hydride vapor phase epitaxy are studied by cathodoluminescence imaging and spectroscopy. A strong donor-acceptor pair emission is observed from the mass-transport regions. Spatially resolved cathodoluminescence reveals a strong intensity contrast between the exciton and donor-acceptor bands from mass-transport and nontransport regions. Focused Auger electron and x-ray photoelectron spectroscopies were employed to investigate the impurity incorporation in the different regions. A preferential moderate increase of residual impurity incorporation or redistribution in mass-transport regions is suggested to be responsible for the observed change of the dominant radiative mechanism. © 2001 American Institute of Physics.

  • 258.
    Paul, D.J.
    et al.
    Cavendish Laboratory, University of Cambridge, Madingley Road, Cambridge, CB3 0HE, United Kingdom.
    See, P.
    Cavendish Laboratory, University of Cambridge, Madingley Road, Cambridge, CB3 0HE, United Kingdom.
    Bates, R.
    Cavendish Laboratory, University of Cambridge, Madingley Road, Cambridge, CB3 0HE, United Kingdom.
    Griffin, N.
    Natl. Microlectron. Research Centre, University College Cork, Lee Maltings, Prospect Row, Cork, Ireland.
    Coonan, B.P.
    Natl. Microlectron. Research Centre, University College Cork, Lee Maltings, Prospect Row, Cork, Ireland.
    Redmond, G.
    Natl. Microlectron. Research Centre, University College Cork, Lee Maltings, Prospect Row, Cork, Ireland.
    Crean, G.M.
    Natl. Microlectron. Research Centre, University College Cork, Lee Maltings, Prospect Row, Cork, Ireland.
    Zozoulenko, Igor
    Linköping University, The Institute of Technology. Linköping University, Department of Science and Technology.
    Berggren, Karl-Fredrik
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics .
    Hollander, B.
    Holländer, B., Inst. fur Schicht und Ionentechnik, Forschungszentrum Jülich, D-52425 Jülich, Germany.
    Mantl, S.
    Inst. fur Schicht und Ionentechnik, Forschungszentrum Jülich, D-52425 Jülich, Germany.
    Si/SiGe electron resonant tunneling diodes with graded spacer wells2001In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 78, no 26, p. 4184-4186Article in journal (Refereed)
    Abstract [en]

    Resonant tunneling diodes have been fabricated using graded Si1 - xGex (x = 0.3?0.0) spacer wells and strained Si0.4Ge0.6 barriers on a relaxed Si0.7Ge0.3 n-type substrate which demonstrates negative differential resistance at up to 100 K. This design is aimed at reducing the voltage at which the peak current density is achieved. Peak current densities of 0.08 A/cm2 with peak-to-valley current ratios of 1.67 have been achieved for a low peak voltage of 40 mV at 77 K. This represents an improvement of over an order of magnitude compared to previous work. © 2001 American Institute of Physics.

  • 259.
    Paul, DJ
    et al.
    Univ Cambridge, Cavendish Lab, Cambridge CB3 0HE, England Linkoping Univ, Dept Phys & Measurement Sci, S-58183 Linkoping, Sweden LEO Elektronenmikroskopie GmbH, D-73446 Oberkochen, Germany KFA Julich GmbH, Forschungszentrum, Inst Schicht & Ionentech, D-52425 Julich, Germany Linkoping Univ, Dept Sci & Technol, S-60174 Norrkoping, Sweden.
    See, P
    Univ Cambridge, Cavendish Lab, Cambridge CB3 0HE, England Linkoping Univ, Dept Phys & Measurement Sci, S-58183 Linkoping, Sweden LEO Elektronenmikroskopie GmbH, D-73446 Oberkochen, Germany KFA Julich GmbH, Forschungszentrum, Inst Schicht & Ionentech, D-52425 Julich, Germany Linkoping Univ, Dept Sci & Technol, S-60174 Norrkoping, Sweden.
    Zozoulenko, Igor
    Linköping University, The Institute of Technology. Linköping University, Department of Science and Technology.
    Berggren, Karl-Fredrik
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics .
    Kabius, B
    Univ Cambridge, Cavendish Lab, Cambridge CB3 0HE, England Linkoping Univ, Dept Phys & Measurement Sci, S-58183 Linkoping, Sweden LEO Elektronenmikroskopie GmbH, D-73446 Oberkochen, Germany KFA Julich GmbH, Forschungszentrum, Inst Schicht & Ionentech, D-52425 Julich, Germany Linkoping Univ, Dept Sci & Technol, S-60174 Norrkoping, Sweden.
    Hollander, B
    Univ Cambridge, Cavendish Lab, Cambridge CB3 0HE, England Linkoping Univ, Dept Phys & Measurement Sci, S-58183 Linkoping, Sweden LEO Elektronenmikroskopie GmbH, D-73446 Oberkochen, Germany KFA Julich GmbH, Forschungszentrum, Inst Schicht & Ionentech, D-52425 Julich, Germany Linkoping Univ, Dept Sci & Technol, S-60174 Norrkoping, Sweden.
    Mantl, S
    Univ Cambridge, Cavendish Lab, Cambridge CB3 0HE, England Linkoping Univ, Dept Phys & Measurement Sci, S-58183 Linkoping, Sweden LEO Elektronenmikroskopie GmbH, D-73446 Oberkochen, Germany KFA Julich GmbH, Forschungszentrum, Inst Schicht & Ionentech, D-52425 Julich, Germany Linkoping Univ, Dept Sci & Technol, S-60174 Norrkoping, Sweden.
    Si/SiGe electron resonant tunneling diodes2000In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 77, no 11, p. 1653-1655Article in journal (Refereed)
    Abstract [en]

    Resonant tunneling diodes have been fabricated using strained-Si wells and strained Si0.4Ge0.6 barriers on a relaxed Si0.8Ge0.2 n-type substrate, which demonstrate negative differential resistance at 298 K. Peak current densities of 5 kA/cm(2) with peak-to-valley current ratios of 1.1 have been achieved. Theoretical modeling of the structure demonstrates that the major current peak results from the tunneling of light-mass electrons from the relaxed substrate and not from the heavy-mass electrons in the emitter accumulation layer. (C) 2000 American Institute of Physics. [S0003- 6951(00)02337-8].

  • 260.
    Peng, Ru
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Engineering Materials.
    D Y, Cong
    Key Laboratory of Electromagnetic Processin gof Materials Notheastern University, Shenyang.
    Zetterström, P
    The Studsvik Neutron Research Laboratory Uppsala University.
    Wang, Y D
    Dept of Mateials Science Engineering Northeastern University, Sheyang.
    Delaplane, R
    The Studsvik Neutron Research Laboratory Uppsala University.
    Zhao, X
    Key Laboratory of Electromagnetic Processing of Materials Northeastern University, Shenyang.
    Zuo, L
    Key Laboratory of Electromagnetic Processing of Materials Northeastern University, Shenyang.
    Crystal structure and phase transformation in Ni53Mn 25Ga22 shape memory alloy from 20 K to 473 K2005In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 87, no 11Article in journal (Refereed)
    Abstract [en]

    The crystal structures, magnetic structures, and phase transformation of the off-stoichiometric Ni53 Mn25 Ga22 were studied by neutron powder diffraction at different temperatures. It is shown that Ni53 Mn25 Ga22 has a tetragonal I4/mmm structure from 20 K to 403 K. An abrupt jump in unit-cell volume around room temperature, corresponding to an endothermic peak in the differential scanning calorimetry curve, was observed. This indicates a pretransformation in the martensitic phase of Ni53 Mn25 Ga22, which is completely different from the phase transformation in the stoichiometric Ni2 MnGa. The sequence of structural transformation in Ni53 Mn25 Ga22 is closely related to its intrinsic temperature-dependent magnetic structure. © 2005 American Institute of Physics.

  • 261.
    Persson, Nils-Krister
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Wang, Xiangjun
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Optical limitations in thin-film low-band-gap polymer/fullerene bulk heterojunction devices2007In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 91, no 8, p. 083503-Article in journal (Refereed)
    Abstract [en]

    Photovoltaic devices from the low-band-gap alternating copolymer APFO-Green1, blended with the fullerene derivative BTPF70 as electron acceptor, show a pronounced variation of the external quantum efficiency with varying thickness. Device simulation, based on ellipsometric characterization, reveals that this behavior is to be expected and valid also for most low-band-gap polymers and that it can be explained by optical interference. Requirements for materials suitable for wide spectral coverage in thin-film organic solar cells are delineated. Furthermore, the internal quantum efficiency is calculated to be ≈ 0.4.

  • 262.
    Persson, Per
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics.
    Hultman, Lars
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics.
    Jacobson, H.
    Bergman, Peder
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Janzén, Erik
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Molina-Aldareguia, J.M.
    Department of Materials Science and Metallurgy, University of Cambridge, Pembroke Street, Cambridge, CB2 3QZ, United Kingdom.
    Clegg, W.J.
    Department of Materials Science and Metallurgy, University of Cambridge, Pembroke Street, Cambridge, CB2 3QZ, United Kingdom.
    Tuomi, T.
    Optoelectronics Laboratory, Helsinki University of Technology, P.O. Box 3000, 02015 TKK, Finland.
    Structural defects in electrically degraded 4H-SiC p+/n-/n+ diodes2002In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 80, no 25, p. 4852-Article in journal (Refereed)
    Abstract [en]

    [No abstract available]

  • 263.
    Peto, G
    et al.
    KFKI Research Institute for Technical and Materials Science.
    Molnar, G
    KFKI Research Institute for Technical and Materials Science.
    Kotai, E
    KFKI Research Institute for Technical and Materials Science .
    Dezsi, I
    KFKI Research Institute for Technical and Materials Science.
    Karsteen, M
    Chalmers University and Technology.
    Sodervall, U
    Chalmers University and Technology.
    Willander, Magnus
    Chalmers University and Technology.
    Caymax, M
    IMEC.
    Loo, R
    IMEC.
    Formation of epitaxial CoSi2 films on Si and on Si/Si80Ge20 (100) by reactive deposition epitaxy2002In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 81, no 1, p. 37-39Article in journal (Refereed)
    Abstract [en]

    CoxTi1-x layers were deposited on Si (100) and on Si/Si80Ge20 (100) capped with 30- or 40-nm-thick Si at 650 degreesC substrate temperature at 1x10(-6) Pa pressure. The Co-silicide films grown by reactive deposition epitaxy were characterized by Rutherford backscattering-channeling, x-ray difraction, by depth profile analysis of the components, and by sheet resistance measurements. The Ti content of the deposited Co layers was between 0.1 and 8 at. %. The epitaxy of the layers on Si and on Si/Si80Ge20 improved by increasing the Ti concentration. The minimum yield of the channeling and the full width at half maximum value of the rocking curve of CoSi2 decreased. The sheet resisitance of the formed layers was also minimal in these cases. The method applied is promising to form epitaxial CoSi2 layers on SixGe1-x substrates.

  • 264.
    Petoral, Rodrigo Jr
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Molecular Surface Physics and Nano Science. Linköping University, Faculty of Science & Engineering.
    Yazdi, Gholamreza
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Lloyd-Spets, Anita
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Physics.
    Yakimova, Rositsa
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Uvdal, Kajsa
    Linköping University, Department of Physics, Chemistry and Biology, Molecular Surface Physics and Nano Science. Linköping University, Faculty of Science & Engineering.
    Organosilane-functionalized wide band gap semiconductor surfaces2007In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 90, no 22Article in journal (Refereed)
    Abstract [en]

    Surface functionalization of wide band gap semiconductors, SiC, ZnO, and GaN, with organosilane is reported. Formation of self-assembled monolayers of mercaptopropyltrimethoxysilane is confirmed by x-ray photoelectron spectroscopy and atomic force microscopy. The molecules are adsorbed on the surfaces through the silane groups with the free thiol groups molecularly oriented away from the surface. Moreover, chemisorption via the thiolate is observed for the ZnO surface. Immobilization of a model biomolecule to the functionalized surface is demonstrated. An amino acid derivative, i.e., phosphotyrosine derived thiol, is linked on the functionalized ZnO and GaN surfaces via formation of disulfide bridges. © 2007 American Institute of Physics.

  • 265.
    Philipps, Jan M.
    et al.
    Justus Liebig University of Giessen, Germany.
    Stehr, Jan Eric
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    Hofmann, Detlev M.
    Justus Liebig University of Giessen, Germany.
    Buyanova, Irina
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    Eickhoff, Martin
    University of Bremen, Germany.
    Study of the carrier transfer across the GaNP nanowire electrolyte interface by electron paramagnetic spin trapping2017In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 110, no 22, article id 222101Article in journal (Refereed)
    Abstract [en]

    We investigate the transfer of photoexcited charge carriers from GaP and GaNP nanowires to an electrolyte by bias-dependent photocurrent and electron paramagnetic resonance experiments using 5,5-dimethyl-1-pyrroline-N-oxide as a spin trap. The results of the latter show that hydroxyl radicals are created over the entire applied bias range from -1000mV to +1300mV by hole transfer. In contrast, the photocurrent changes from cathodic to anodic at the open circuit potential of the three-electrode setup with the nanowire sample acting as the working electrode. The experiments show that the photoelectrochemical response of GaNP nanowires is significantly stronger compared to that of the GaP nanowires. Published by AIP Publishing.

  • 266.
    Pilch, Iris
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics. Linköping University, The Institute of Technology.
    Söderström, Daniel
    Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics. Linköping University, The Institute of Technology.
    Brenning, N
    Royal Institute Technology, Sweden .
    Helmersson, Ulf
    Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics. Linköping University, The Institute of Technology.
    Size-controlled growth of nanoparticles in a highly ionized pulsed plasma2013In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 102, no 3Article in journal (Refereed)
    Abstract [en]

    Copper nanoparticles (NPs) were synthesized using a high power pulsed hollow cathode technique and the produced NPs were studied as a function of pulse parameters, i.e., frequency, peak current, and pulse width. It was found that the particle size can be altered in a range from 10 to 40 nm by changing any one of the pulse parameters. The mechanisms of NP synthesis with respect to a pulsed discharge and a high degree of ionization of the sputtered material are discussed.

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  • 267.
    Pilch, Iris
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics. Linköping University, The Institute of Technology.
    Söderström, Daniel
    Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics. Linköping University, The Institute of Technology.
    Hasan, M I
    University of Liverpool, England .
    Helmersson, Ulf
    Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics. Linköping University, The Institute of Technology.
    Brenning, N
    KTH Royal Institute Technology, Sweden .
    Fast growth of nanoparticles in a hollow cathode plasma through orbit motion limited ion collection2013In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 103, no 19, p. 193108-Article in journal (Refereed)
    Abstract [en]

    Plasma-based nanoparticle synthesis techniques are attractive in many respects but suffer from a major drawback-low productivity. We demonstrate a technique by which the growth rate of copper nanoparticles has been substantially increased by collection of copper ions. A growth rate as high as 470 nm/s was obtained as compared to a growth rate of less than 3 nm/s in the case of growth by neutrals. The increased trapping of copper is explained as orbital motion limited (OML) collection of ions. Experimentally obtained nanoparticle growth rates are in good agreement with theoretical estimates of the OML ion collection rates.

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    fulltext
  • 268.
    Pozina, Galia
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Bergman, JP
    Linkoping Univ, Dept Phys & Measurement Technol, S-58183 Linkoping, Sweden Meijo Univ, Dept Elect Engn & Elect, Tempaku Ku, Nagoya, Aichi 4688502, Japan Meijo Univ, High Tech Res Ctr, Tempaku Ku, Nagoya, Aichi 4688502, Japan.
    Monemar, Bo
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Iwaya, M
    Linkoping Univ, Dept Phys & Measurement Technol, S-58183 Linkoping, Sweden Meijo Univ, Dept Elect Engn & Elect, Tempaku Ku, Nagoya, Aichi 4688502, Japan Meijo Univ, High Tech Res Ctr, Tempaku Ku, Nagoya, Aichi 4688502, Japan.
    Nitta, S
    Linkoping Univ, Dept Phys & Measurement Technol, S-58183 Linkoping, Sweden Meijo Univ, Dept Elect Engn & Elect, Tempaku Ku, Nagoya, Aichi 4688502, Japan Meijo Univ, High Tech Res Ctr, Tempaku Ku, Nagoya, Aichi 4688502, Japan.
    Amano, H
    Linkoping Univ, Dept Phys & Measurement Technol, S-58183 Linkoping, Sweden Meijo Univ, Dept Elect Engn & Elect, Tempaku Ku, Nagoya, Aichi 4688502, Japan Meijo Univ, High Tech Res Ctr, Tempaku Ku, Nagoya, Aichi 4688502, Japan.
    Akasaki, I
    Linkoping Univ, Dept Phys & Measurement Technol, S-58183 Linkoping, Sweden Meijo Univ, Dept Elect Engn & Elect, Tempaku Ku, Nagoya, Aichi 4688502, Japan Meijo Univ, High Tech Res Ctr, Tempaku Ku, Nagoya, Aichi 4688502, Japan.
    InGaN/GaN multiple quantum wells grown by metalorganic vapor phase epitaxy with mass transport2000In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 77, no 11, p. 1638-1640Article in journal (Refereed)
    Abstract [en]

    We report on studies of In0.12Ga0.88N/GaN heterostructures with three 35-Angstrom-thick quantum wells (QWs) grown on sapphire substrates by metalorganic vapor phase epitaxy with employment of mass transport. The structure is demonstrated to show good structural and optical properties. The threading dislocation density is less than 10(7) cm(-2) for the mass-transport regions. The photoluminescence (PL) spectrum is dominated by the rather narrow near-band gap emission at 2.97 eV with a linewidth of 40 meV. This emission has a typical PL decay time about 5 ns at 2 K within the PL contour. With increasing excitation intensity, an additional transition with longer decay time (about 200 ns) is enhanced at energy about 2.85 eV. The position of this line depends strongly on the excitation power. We explain the data in terms of a model, where the PL is a result of contribution from at least two nonequivalent QWs, which could be realized due to a potential gradient across the layers. (C) 2000 American Institute of Physics. [S0003- 6951(00)04337-0].

  • 269.
    Pozina, Galia
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Bergman, JP
    Linkoping Univ, Dept Phys & Measurement Technol, S-58183 Linkoping, Sweden Meijo Univ, Dept Elect Engn & Elect, Tempaku Ku, Nagoya, Aichi 4688502, Japan Meijo Univ, High Tech Res Ctr, Tempaku Ku, Nagoya, Aichi 4688502, Japan.
    Monemar, Bo
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Yamaguchi, S
    Linkoping Univ, Dept Phys & Measurement Technol, S-58183 Linkoping, Sweden Meijo Univ, Dept Elect Engn & Elect, Tempaku Ku, Nagoya, Aichi 4688502, Japan Meijo Univ, High Tech Res Ctr, Tempaku Ku, Nagoya, Aichi 4688502, Japan.
    Amano, H
    Linkoping Univ, Dept Phys & Measurement Technol, S-58183 Linkoping, Sweden Meijo Univ, Dept Elect Engn & Elect, Tempaku Ku, Nagoya, Aichi 4688502, Japan Meijo Univ, High Tech Res Ctr, Tempaku Ku, Nagoya, Aichi 4688502, Japan.
    Akasaki, I
    Linkoping Univ, Dept Phys & Measurement Technol, S-58183 Linkoping, Sweden Meijo Univ, Dept Elect Engn & Elect, Tempaku Ku, Nagoya, Aichi 4688502, Japan Meijo Univ, High Tech Res Ctr, Tempaku Ku, Nagoya, Aichi 4688502, Japan.
    Optical spectroscopy of GaN grown by metalorganic vapor phase epitaxy using indium surfactant2000In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 76, no 23, p. 3388-3390Article in journal (Refereed)
    Abstract [en]

    The effect of In surfactant during metalorganic vapor phase epitaxial growth on sapphire substructure on the properties of GaN layers is studied using time-resolved photoluminescence. cathodoluminescence. and scanning electron microscopy. The samples are divided into two groups. where hydrogen and nitrogen, respectively, have been used as a carrier gas during growth. It is shown that In-doped samples have a lower dislocation density, a narrower photoluminescence linewidth, and a longer foe exciton lifetime. The influence of indium is stronger for GaN layers grown in nitrogen-rich conditions. The improvements of structural and optical properties are attributed to the effect of In on dislocations. (C) 2000 American Institute of Physics. [S0003-6951(00)02723-6].

  • 270.
    Pozina, Galia
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Bergman, JP
    Linkoping Univ, Dept Phys & Measurement Technol, S-58183 Linkoping, Sweden.
    Paskova, Tanja
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Monemar, Bo
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Bound exciton dynamics in GaN grown by hydride vapor-phase epitaxy1999In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 75, no 26, p. 4124-4126Article in journal (Refereed)
    Abstract [en]

    Temperature-dependent time-resolved photoluminescence measurements were performed on thick GaN layers grown by hydride vapor-phase epitaxy on Al2O3 substrates. Radiative lifetimes were determined for the neutral-donor-bound exciton with position at 3.478 eV and for two neutral-acceptor-bound excitons at 3.473 and 3.461 eV. We report a value of 3600 ps for the radiative lifetime of the acceptor-bound exciton transition at 3.461 eV. The dominant mechanism responsible for the nonradiative recombination of the bound excitons is shown to be connected with dissociation of the bound excitons into free excitons. (C) 1999 American Institute of Physics. [S0003-6951(99)00752-4].

  • 271.
    Pozina, Galia
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Ciechonski, Rafal
    GLO AB, Sweden.
    Bi, Zhaoxia
    Lund University, Sweden.
    Samuelson, Lars
    GLO AB, Sweden; Lund University, Sweden.
    Monemar, Bo
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering. Lund University, Sweden; TokyoUniversity of Agriculture and Technology, Japan.
    Dislocation related droop in InGaN/GaN light emitting diodes investigated via cathodoluminescence2015In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 107, no 25, p. 251106-Article in journal (Refereed)
    Abstract [en]

    Todays energy saving solutions for general illumination rely on efficient white light emitting diodes (LEDs). However, the output efficiency droop experienced in InGaN based LEDs with increasing current injection is a serious limitation factor for future development of bright white LEDs. We show using cathodoluminescence (CL) spatial mapping at different electron beam currents that threading dislocations are active as nonradiative recombination centers only at high injection conditions. At low current, the dislocations are inactive in carrier recombination due to local potentials, but these potentials are screened by carriers at higher injection levels. In CL images, this corresponds to the increase of the dark contrast around dislocations with the injection (excitation) density and can be linked with droop related to the threading dislocations. Our data indicate that reduction of droop in the future efficient white LED can be achieved via a drastic reduction of the dislocation density by using, for example, bulk native substrates. (C) 2015 AIP Publishing LLC.

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  • 272.
    Pozina, Galia
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Edwards, N.V.
    Bergman, Peder
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Paskova, Tanja
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Monemar, Bo
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Bremser, M.D.
    Dept. of Mat. and Sci. and Eng., North Carolina State University, Raleigh, NC 27695, United States.
    Davis, R.F.
    Dept. of Mat. and Sci. and Eng., North Carolina State University, Raleigh, NC 27695, United States.
    Time-resolved spectroscopy of strained GaN/AIN/6H-SiC heterostructures grown by metalorganic chemical vapor deposition2001In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 78, no 8, p. 1062-1064Article in journal (Refereed)
    Abstract [en]

    Temperature-dependent time-resolved photoluminescence measurements were performed on GaN film/AlN buffer/6H-SiC substrate heterostructures grown by metalorganic chemical vapor deposition. The overlying GaN layers were under tension, as estimated from the free A exciton (FEA) position. The recombination lifetimes were determined for the FEA and for the neutral-donor-bound exciton (D0X). We observed that the recombination lifetime for the FEA has the same value of 40-50 ps in all the layers, whereas the recombination time for the D0X varies for different samples. We observed that the recombination lifetimes for D0X have a clear dependence on the position of FEA, i.e., the recombination lifetime increases with decreasing strain in the layers. We discuss the results in term of the hole states involved in the donor-bound exciton recombination. © 2001 American Institute of Physics.

  • 273.
    Pozina, Galia
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Hemmingsson, Carl
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Amano, H
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Monemar, Bo
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Surface potential effect on excitons in AlGaN/GaN quantum well structures2013In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 102, no 8Article in journal (Refereed)
    Abstract [en]

    AlGaN/GaN quantum well (QW) heterostructures grown by metalorganic chemical vapor deposition on sapphire and on free-standing GaN substrates have been studied by temperature dependent time-resolved photoluminescence. A dominant contribution of the exciton radiative lifetime is observed in homoepitaxial samples even at enhanced temperatures up to 100 K. The QW-related emission is found to be more sensitive to the near surface built-in electric field in the homoepitaxial samples, revealed as a red shift of the QW exciton energy with decreasing the cap layer thickness. Absence of such shift in the heteroepitaxial samples suggests, assuming a surface potential of 0.5 eV, an increased polarization field due to residual compressive stress.

  • 274.
    Pozina, Galia
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Hemmingsson, Carl
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Bergman, Peder
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Trinh, David
    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.
    Monemar, Bo
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Dynamics of bound excitons versus thickness in freestanding GaN wafers grown by halide vapor phase epitaxy2007In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 90, no 22Article in journal (Refereed)
    Abstract [en]

    The bound exciton recombination properties in freestanding GaN layers of various thicknesses grown by halide vapor phase epitaxy have been characterized by time-resolved spectroscopy. Improvement of the donor bound exciton (D0 X) lifetime was observed with increasing GaN layer thickness up to ∼400 μm, while for thicker layers the recombination time of D0 X shows a tendency to saturate. The thickness-dependent behavior of the D0 X decay can be understood in terms of competition between two nonradiative mechanisms: one of which is connected to structural defects, and consequently more important for thinner layers, while for layers with thickness above 400 μm with low structural defect density the recombination time is limited by point defects such as impurities and vacancies. © 2007 American Institute of Physics.

  • 275.
    Pozina, Galia
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Materials Science . Linköping University, The Institute of Technology.
    Hemmingsson, Carl
    Linköping University, Department of Physics, Chemistry and Biology, Materials Science . Linköping University, The Institute of Technology.
    Paskov, Plamen P.
    Linköping University, Department of Physics, Chemistry and Biology, Materials Science . Linköping University, The Institute of Technology.
    Bergman, Peder
    Linköping University, Department of Physics, Chemistry and Biology, Materials Science . Linköping University, The Institute of Technology.
    Monemar, Bo
    Linköping University, Department of Physics, Chemistry and Biology, Materials Science . Linköping University, The Institute of Technology.
    Kawashima, T.
    Meijo University.
    Amano, H.
    Meijo University.
    Akasaki, I.
    Meijo University.
    Usui, A.
    Furukawa Co. Ltd.
    Effect of annealing on metastable shallow acceptors in Mg-doped GaN layers grown on GaN substrates2008In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 92, no 15, p. 151904-Article in journal (Refereed)
    Abstract [en]

    Mg-doped GaN layers grown by metal-organic vapor phase epitaxy on GaN substrates produced by the halide vapor phase technique demonstrate metastability of the near-band-gap photoluminescence (PL). The acceptor bound exciton (ABE) line possibly related to the C acceptor vanishes in as-grown samples within a few minutes under UV laser illumination. Annealing activates the more stable Mg acceptors and passivates C acceptors. Consequently, only the ABE line related to Mg is dominant in PL spectra for the annealed samples. The temporal changes in PL are permanent at low temperatures; however, they can be recovered after heating to 100 K or higher.

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    FULLTEXT01
  • 276.
    Pozina, Galia
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Paskov, Plamen
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Bergman, Peder
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Hemmingsson, Carl
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Hultman, Lars
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics.
    Monemar, Bo
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Amano, H.
    Usui, A.
    Metastable behavior of the UV luminescence in Mg-doped GaN layers grown on quasibulk GaN templates2007In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 91, no 22Article in journal (Refereed)
    Abstract [en]

    Metastability of near band gap UV emissions in Mg-doped GaN layers grown by metal-organic vapor phase epitaxy on thick GaN templates grown by halide vapor phase epitaxy has been studied by cathodoluminescence (CL). The CL spectrum changes its initial shape within a few minutes under electron irradiation. The acceptor bound exciton line vanishes while the emissions related to the stacking faults (SFs) of different geometry rise significantly. The increase of the defect-related luminescence is likely caused by recombination enhanced SF formation under electron irradiation. The CL spectrum transformation is permanent at low temperatures, however, the metastable process is reversible if samples are heated to room temperature. © 2007 American Institute of Physics.

  • 277.
    Puttisong, Yuttapoom
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, Faculty of Science & Engineering.
    Dagnelund, Daniel
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Buyanova, Irina
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Tu, C W
    Department of Electrical and Computer Engineering, University of California, La Jolla, California 92093, USA.
    Polimeni, A
    INFM and Dipartimento di Fisica, Universita` di Roma “La Sapienza,” Piazzale A. Moro 2, I-00185 Roma, Italy.
    Capizzi, M
    INFM and Dipartimento di Fisica, Universita` di Roma “La Sapienza,” Piazzale A. Moro 2, I-00185 Roma, Italy.
    Chen, Weimin
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Room temperature spin filtering effect in GaNAs: Role of hydrogen2011In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 99, no 15, p. 152109-Article in journal (Refereed)
    Abstract [en]

    Effects of hydrogen on the recently discovered defect-engineered spin filtering in GaNAs are investigated by optical spin orientation and optically detected magnetic resonance. Post-growth hydrogen treatments are shown to lead to nearly complete quenching of the room-temperature spin-filtering effect in both GaNAs epilayers and GaNAs/GaAs multiple quantum wells, accompanied by a reduction in concentrations of Ga(i) interstitial defects. Our finding provides strong evidence for efficient hydrogen passivation of these spin-filtering defects, likely via formation of complexes between Gai defects and hydrogen, as being responsible for the Observed strong suppression of the spin-filtering effect after the hydrogen treatments.

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  • 278.
    Puttisong, Yuttapoom
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Huang, Yuqing
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Buyanova, Irina
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Yang, X. J.
    Hokkaido University, Japan.
    Subagyo, A.
    Hokkaido University, Japan.
    Sueoka, K.
    Hokkaido University, Japan.
    Murayama, A.
    Hokkaido University, Japan.
    Chen, Weimin
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Anomalous spectral dependence of optical polarization and its impact on spin detection in InGaAs/GaAs quantum dots2014In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 105, no 13, p. 132106-Article in journal (Refereed)
    Abstract [en]

    We show that circularly polarized emission light from InGaAs/GaAs quantum dot (QD) ensembles under optical spin injection from an adjacent GaAs layer can switch its helicity depending on emission wavelengths and optical excitation density. We attribute this anomalous behavior to simultaneous contributions from both positive and negative trions and a lower number of photo-excited holes than electrons being injected into the QDs due to trapping of holes at ionized acceptors and a lower hole mobility. Our results call for caution in reading out electron spin polarization by optical polarization of the QD ensembles and also provide a guideline in improving efficiency of spin light emitting devices that utilize QDs.

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    fulltext
  • 279.
    Puttisong, Yuttapoom
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    Wang, Xingjun
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Buyanova, Irina
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Carrere, H
    Université de Toulouse, LPCNO: INSA, UPS, CNRS, 135 avenue de Rangueil, 31077 Toulouse Cedex, France.
    Zhao, F
    Université de Toulouse, LPCNO: INSA, UPS, CNRS, 135 avenue de Rangueil, 31077 Toulouse Cedex, France.
    Balocchi, A
    Université de Toulouse, LPCNO: INSA, UPS, CNRS, 135 avenue de Rangueil, 31077 Toulouse Cedex, France.
    Marie, X
    Université de Toulouse, LPCNO: INSA, UPS, CNRS, 135 avenue de Rangueil, 31077 Toulouse Cedex, France.
    Tu, C W
    Department of Electrical and Computer Engineering, University of California, La Jolla, California 92093, USA.
    Chen, Weimin
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Electron spin filtering by thin GaNAs/GaAs multiquantum wells2010In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 96, no 5, p. 052104-Article in journal (Refereed)
    Abstract [en]

    Effectiveness of the recently discovered defect-engineered spin-filtering effect is closely examined in GaNAs/GaAs multiquantum wells (QWs) as a function of QW width. In spite of narrow well widths of 3-9 nm, rather efficient spin filtering is achieved at room temperature. It leads to electron spin polarization larger than 18% and an increase in photoluminescence intensity by 65% in the 9 nm wide QWs. A weaker spin filtering effect is observed in the narrower QWs, mainly due to a reduced sheet concentration of spin-filtering defects (e.g., Ga-i interstitial defects).

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    SpinFiltering
  • 280.
    Puttisong, Yuttapoom
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, Faculty of Science & Engineering.
    Wang, Xingjun
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Buyanova, Irina
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Tu, C W
    University California San Diego.
    Geelhaar, L
    Paul Drude Institut für Festkörperelektronik.
    Riechert, H
    Paul Drude Institut für Festkörperelektronik.
    Chen, Weimin
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Room-temperature spin injection and spin loss across a GaNAs/GaAs interface2011In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 98, no 1, p. 012112-Article in journal (Refereed)
    Abstract [en]

    Recently discovered effect of spin-filtering and spin amplification in GaNAs enables us to reliably obtain detailed information on the degree of spin loss during optical spin injection across a semiconductor heterointerface at room temperature. Spin polarization of electrons injected from GaAs into GaNAs is found to be less than half of what is generated in GaNAs by optical orientation. We show that the observed reduced spin injection efficiency is not only due to spin relaxation in GaAs, but more importantly due to spin loss across the interface due to structural inversion asymmetry and probably also interfacial point defects.

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    FULLTEXT01
  • 281.
    Qiu, X. Y.
    et al.
    Nanjing University, Peoples R China.
    Liu, Q. M.
    Nanjing University, Peoples R China.
    Gao, Feng
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Lu, L. Y.
    Nanjing University, Peoples R China.
    Liu, J. -M.
    Nanjing University, Peoples R China.
    Room-temperature weak ferromagnetism of amorphous HfAlOx thin films deposited by pulsed laser deposition2006In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 89, no 24, p. 242504-Article in journal (Refereed)
    Abstract [en]

    The room-temperature weak ferromagnetism of amorphous HfAlOx thin films deposited by pulsed laser deposition on various substrates in oxygen-defective ambient is demonstrated. The magnetization is independent of film thickness, but depends on substrates and deposition temperatures. A magnetic moment of similar to 0.26 mu(B) per HfAlOx f.u. is recorded for HfAlOx films deposited under optimized conditions [deposited at 600 degrees C on (001) sapphire in high vacuum]. It is argued that interfacial defects are one of the possible sources of the weak ferromagnetism. (c) 2006 American Institute of Physics.

  • 282.
    Robinson, I.K.
    et al.
    Department of Physics, University of Illinois, Urbana, IL 61801, United States.
    Nilsson, P.O.
    Department of Physics, Chalmers University of Technology, SE-412 96 Gothenburg, Sweden.
    Debowska-Nilsson, D.
    Institute of Physics, Jagellonian University, ul. Reymonta 4, PL-30-059 Krakow, Poland.
    Ni, Wei-Xin
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface and Semiconductor Physics .
    Hansson, Göran
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface and Semiconductor Physics .
    Resonant scattering in delta-doped heterostructures2001In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 79, no 18, p. 2913-2915Article in journal (Refereed)
    Abstract [en]

    We demonstrate the utility of resonant x-ray scattering in probing the structure of doping layers at a heterostructure interface. The positions of germanium layers inserted at the interface of a silicon epitaxial film assert a strong influence of the phase of the scattered intensity along the crystal truncation rods. The phase of the scattering, and hence the internal structure of the layers, can be determined conveniently by analyzing its energy dependence in the vicinity of the Germanium absorption edge at 11.103 keV. © 2001 American Institute of Physics.

  • 283.
    Roelofs, W. S. C.
    et al.
    Eindhoven University of Technology, Netherlands; Philips Research Labs, Netherlands.
    Mathijssen, S. G. J.
    Philips Research Labs, Netherlands; University of Groningen, Netherlands.
    Bijleveld, J. C.
    Eindhoven University of Technology, Netherlands.
    Raiteri, D.
    Eindhoven University of Technology, Netherlands.
    Geuns, T. C. T.
    Philips Research Labs, Netherlands.
    Kemerink, M.
    Eindhoven University of Technology, Netherlands.
    Cantatore, E.
    Eindhoven University of Technology, Netherlands.
    Janssen, R. A. J.
    Eindhoven University of Technology, Netherlands.
    de Leeuw, D. M.
    Philips Research Labs, Netherlands; University of Groningen, Netherlands.
    Fast ambipolar integrated circuits with poly(diketopyrrolopyrrole-terthiophene)2011In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 98, no 20, article id 203301Article in journal (Refereed)
    Abstract [en]

    Ambipolar integrated circuits were prepared with poly (diketopyrrolopyrrole-terthiophene) as the semiconductor. The field-effect mobility of around 0.02 cm(2)/V s for both electrons and holes allowed for fabrication of functional integrated complementary metal-oxide semiconductor (CMOS)-like inverters and ring oscillators. The oscillation frequency was found to have a near quadratic dependence on the supply bias. The maximum oscillation frequency was determined to be 42 kHz, which makes this ring oscillator the fastest CMOS-like organic circuit reported to date. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3589986]

  • 284.
    Roelofs, W.S. Christian
    et al.
    Eindhoven University of Technology, The Netherlands; Philips Research Laboratories, Eindhoven, The Netherlands .
    Charrier, Dimitri S. H.
    Eindhoven University of Technology, The Netherlands .
    Dzwilewski, Andrzej
    Eindhoven University of Technology, The Netherlands .
    Janssen, Rene A. J.
    Eindhoven University of Technology, The Netherlands .
    de Leeuw, Dago M.
    Max Planck Institute Polymer Research, Mainz, Germany; King Abdulaziz University, Jeddah, Saudi Arabia .
    Kemerink, Martijn
    Linköping University, Department of Physics, Chemistry and Biology, Complex Materials and Devices. Linköping University, The Institute of Technology. Eindhoven University of Technology, The Netherlands .
    Scanning tunnelling microscopy on organic field-effect transistors based on intrinsic pentacene2014In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 104, no 26, p. 263301-Article in journal (Refereed)
    Abstract [en]

    The full potential of scanning tunnelling microscopy (STM) and scanning tunnelling spectroscopy for in-situ characterization of organic semiconductors has so far not been accessible. Here, we demonstrate that the underlying problem, the low intrinsic conductivity, can be overcome by working in a field-effect geometry. We present high resolution surface topographies obtained by STM on pentacene organic field-effect transistors (OFETs). By virtue of the OFET geometry, the hole accumulation layer that is present at sufficiently negative gate bias acts as back contact, collecting the tunnelling current. The presence of a true tunnelling gap is established, as is the need for the presence of an accumulation layer. The tunnelling current vs. tip bias showed rectifying behaviour, which is rationalized in terms of the tip acting as a second gate on the unipolar semiconductor. An explanatory band diagram is presented. The measurements shown indicate that intrinsic organic semiconductors can be in-situ characterized with high spatial and energetic resolution in functional devices.

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  • 285. Roman, L.S.
    et al.
    Berggren, Magnus
    Linköping University, The Institute of Technology. Linköping University, Department of Science and Technology.
    Inganäs, Olle
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics.
    Polymer diodes with high rectification1999In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 75, p. 3557-3557Article in journal (Refereed)
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  • 286.
    Rosen, Johanna
    et al.
    University of Sydney.
    Persson, P.O.A.
    University of Sydney.
    Ionescu, M.
    Australian Nuclear Science and Technology Organization.
    Kondyurin, A.
    University of Sydney.
    McKenzie, D.R.
    University of Sydney.
    Bilek, M.M.M.
    University of Sydney.
    Oxygen incorporation in Ti2AlC thin films2008In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 92, no 6, p. 064102-Article in journal (Refereed)
    Abstract [en]

    Thin films of Ti2AlC MAX phase have been deposited using a multiple cathode pulsed cathodic arc. Evidence for substantial oxygen incorporation in the MAX phase is presented, likely originating from residual gas present in the vacuum chamber during deposition. The characteristic MAX phase crystal structure is maintained, in agreement with ab initio calculations, supporting substitutional O in C lattice positions. On the basis of these results, we propose the existence of a MAX phase-like material with material properties tuned by the incorporation of oxygen. Additionally, possible unintentional O incorporation in previously reported MAX phase materials is suggested.

  • 287.
    Rosen, Johanna
    et al.
    University of Sydney.
    Schneider, Jochen M.
    University of Sydney.
    Anders, Andre
    University of Sydney.
    Charge state dependence of cathodic vacuum arc ion energy and velocity distributions2006In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 89, no 14, p. 141502-Article in journal (Refereed)
    Abstract [en]

    In the literature, conflicting conclusions are reported concerning the charge state dependence of cathodic arc ion energy and velocity distributions. It appears that data from electrostatic energy analyzers indicate charge state dependence of ion energy, whereas time-of-flight methods support charge state independence of ion velocity. Here the authors present charge-state-resolved ion energy distributions and calculate the corresponding ion velocity distributions in aluminum vacuum arc plasma. They show that the conflicting conclusions reported in the literature for the two different characterization techniques may originate from the commonly employed data interpretation of energy and velocity, in which peak values and average values are not carefully distinguished.

  • 288.
    Rosen, Johanna
    et al.
    Rhein Westfal TH Aachen.
    Widenkvist, E
    Uppsala University.
    Larsson, K
    Uppsala University.
    Kreissig, U
    Research Center Rossendorf.
    Mraz, S
    Rhein Westfal TH Aachen.
    Martinez, C
    Rhein Westfal TH Aachen.
    Music, D
    Rhein Westfal TH Aachen.
    Schneider, JM
    Rhein Westfal TH Aachen.
    Reducing the impurity incorporation from residual gas by ion bombardment during high vacuum magnetron sputtering2006In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 88, no 19, p. 191905-Article in journal (Refereed)
    Abstract [en]

    The influence of ion energy on the hydrogen incorporation has been investigated for alumina thin films, deposited by reactive magnetron sputtering in an Ar/O-2/H2O environment. Ar+ with an average kinetic energy of similar to 5 eV was determined to be the dominating species in the plasma. The films were analyzed with x-ray diffraction, x-ray photoelectron spectroscopy, and elastic recoil detection analysis, demonstrating evidence for amorphous films with stoichiometric O/Al ratio. As the substrate bias potential was increased from -15 V (floating potential) to -100 V, the hydrogen content decreased by similar to 70%, from 9.1 to 2.8 at. %. Based on ab initio calculations, these results may be understood by thermodynamic principles, where a supply of energy enables surface diffusion, H-2 formation, and desorption [Rosen , J. Phys.: Condens. Matter 17, L137 (2005)]. These findings are of importance for the understanding of the correlation between ion energy and film composition and also show a pathway to reduce impurity incorporation during film growth in a high vacuum ambient.

  • 289.
    Rosén, Johanna
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics.
    Anders, A.
    Lawrence Berkeley National Laboratory, Berkeley, CA 94720, United States.
    Schneider, J.M.
    Materials Chemistry, RWTH-Aachen, D-52056 Aachen, Germany.
    Plasma chemistry fluctuations in a reactive arc plasma in the presence of magnetic fields2002In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 80, no 22, p. 4109-Article in journal (Refereed)
    Abstract [en]

    [No abstract available]

  • 290. Rudko, G. Yu.
    et al.
    Buyanova, Irina
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    Chen, Weimin
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    Xin, H. P.
    Tu, C. W.
    Temperature dependence of the GaNxP1-x band gap and effect of band crossover2002In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 81, no 21, p. 3984-Article in journal (Refereed)
    Abstract [en]

    The absorption edge of GaNxP1-x alloys (0.01<=x<=0.03) is shown to exhibit a direct-band gap-like behavior. Thermal variation of the band gap energy Eg, however, is found to be the same or even smaller than that for the indirect band gap of GaP and depends on the N content. The effect is tentatively attributed to the following counteracting contributions to the band edge formation. An interaction with N-related localized states, especially significant in the vicinity of band crossover (e.g., x = 0.013), causes a substantial slow down of the Eg shift with temperature. On the contrary, an increasing contribution of Γc states, which becomes predominant for the higher compositions, leads to the larger thermal variation in Eg.

  • 291.
    Saha, Bivas
    et al.
    University of Calif Berkeley, CA 94720 USA.
    Garbrecht, Magnus
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Perez-Taborda, Jaime A.
    CSIC, Spain.
    Fawey, Mohammed H.
    Karlsruhe Institute Technology, Germany; TUD, Germany.
    Rui Koh, Yee
    Purdue University, IN 47907 USA; Purdue University, IN 47907 USA.
    Shakouri, Ali
    Purdue University, IN 47907 USA; Purdue University, IN 47907 USA.
    Martin-Gonzalez, Marisol
    CSIC, Spain.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Sands, Timothy D.
    Virginia Tech, VA 24061 USA; Virginia Tech, VA 24061 USA.
    Compensation of native donor doping in ScN: Carrier concentration control and p-type ScN2017In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 110, no 25, article id 252104Article in journal (Refereed)
    Abstract [en]

    Scandium nitride (ScN) is an emerging indirect bandgap rocksalt semiconductor that has attracted significant attention in recent years for its potential applications in thermoelectric energy conversion devices, as a semiconducting component in epitaxial metal/semiconductor superlattices and as a substrate material for high quality GaN growth. Due to the presence of oxygen impurities and native defects such as nitrogen vacancies, sputter-deposited ScN thin-films are highly degenerate n-type semiconductors with carrier concentrations in the (1-6) x 10(20) cm(-3) range. In this letter, we show that magnesium nitride (MgxNy) acts as an efficient hole dopant in ScN and reduces the n-type carrier concentration, turning ScN into a p-type semiconductor at high doping levels. Employing a combination of high-resolution X-ray diffraction, transmission electron microscopy, and room temperature optical and temperature dependent electrical measurements, we demonstrate that p-type Sc1-xMgxN thin-film alloys (a) are substitutional solid solutions without MgxNy precipitation, phase segregation, or secondary phase formation within the studied compositional region, (b) exhibit a maximum hole-concentration of 2.2 x 10(20) cm(-3) and a hole mobility of 21 cm(2)/Vs, (c) do not show any defect states inside the direct gap of ScN, thus retaining their basic electronic structure, and (d) exhibit alloy scattering dominating hole conduction at high temperatures. These results demonstrate MgxNy doped p-type ScN and compare well with our previous reports on p-type ScN with manganese nitride (MnxNy) doping. Published by AIP Publishing.

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  • 292.
    Saha, Bivas
    et al.
    Purdue University, IN 47907 USA; Purdue University, IN 47907 USA.
    Lawrence, Samantha K.
    Purdue University, IN 47907 USA.
    Schroeder, Jeremy
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Birch, Jens
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Bahr, David F.
    Purdue University, IN 47907 USA.
    Sands, Timothy D.
    Purdue University, IN 47907 USA; Purdue University, IN 47907 USA; Purdue University, IN 47907 USA.
    Enhanced hardness in epitaxial TiAlScN alloy thin films and rocksalt TiN/(Al,Sc)N superlattices2014In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 105, no 15, p. 151904-Article in journal (Refereed)
    Abstract [en]

    High hardness TiAlN alloys for wear-resistant coatings exhibit limited lifetimes at elevated temperatures due to a cubic-AlN to hexagonal-AlN phase transformation that leads to decreasing hardness. We enhance the hardness (up to 46 GPa) and maximum operating temperature (up to 1050 degrees C) of TiAlN-based coatings by alloying with scandium nitride to form both an epitaxial TiAlScN alloy film and epitaxial rocksalt TiN/(Al,Sc)N superlattices on MgO substrates. The superlattice hardness increases with decreasing period thickness, which is understood by the Orowan bowing mechanism of the confined layer slip model. These results make them worthy of additional research for industrial coating applications.

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  • 293.
    Said, Elias
    et al.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Crispin, Xavier
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Herlogsson, Lars
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Elhag, Sami
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Robinson, Nathaniel D.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Berggren, Magnus
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Polymer field-effect transistor gated via a poly(styrenesulfonic acid) thin film2006In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 89, no 14, p. 143507-Article in journal (Refereed)
    Abstract [en]

    A polyanionic proton conductor, named poly(styrenesulfonic acid) (PSSH), is used to gate an organic field-effect transistor (OFET) based on poly(3-hexylthiophene) (P3HT). Upon applying a gate bias, large electric double layer capacitors (EDLCs) are formed quickly at the gate-PSSH and P3HT-PSSH interfaces due to proton migration in the polyelectrolyte. This type of robust transistor, called an EDLC-OFET, displays fast response (<1  ms) and operates at low voltages (<1  V). The results presented are relevant for low-cost printed polymer electronics.

  • 294. Sankin, V.I.
    et al.
    Shkrebiy, P. P.
    Yakimova, Rositsa
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Wannier-Stark ladder conditions in 4H-SiC p-n junctions grown on off axis substrates2006In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 89, no 23, p. 233508-Article in journal (Refereed)
    Abstract [en]

    4H-SiC p+ - n- - n+ junctions have been prepared on 8° off oriented plane aiming to investigate conditions of Wannier-Stark localization (WSL), and respectively the occurrence of a negative temperature coefficient of avalanche breakdown voltage (TCABV). A method is proposed that can enable obtaining important results without reaching the regime of destructive avalanche breakdown. By analyzing the photocurrent of light with different wavelengths and at strong electric fields, a negative differential photoconductance has been discovered testifying that the WSL is not suppressed at the field inclination in 8° off axis, and a negative TCABV is expected in commercial p-n junctions. © 2006 American Institute of Physics.

  • 295.
    Schneider, Jochen
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Anders, A
    Linkoping Univ, Dept Phys, Film Phys Div, SE-58183 Linkoping, Sweden Univ Calif Berkeley, Lawrence Berkeley Lab, Berkeley, CA 94720 USA Royal Inst Technol, Dept Mat Phys, SE-10044 Stockholm, Sweden Linkoping Univ, Dept Phys, Film Phys Div, S-58183 Linkoping, Sweden.
    Hjorvarsson, B
    Linkoping Univ, Dept Phys, Film Phys Div, SE-58183 Linkoping, Sweden Univ Calif Berkeley, Lawrence Berkeley Lab, Berkeley, CA 94720 USA Royal Inst Technol, Dept Mat Phys, SE-10044 Stockholm, Sweden Linkoping Univ, Dept Phys, Film Phys Div, S-58183 Linkoping, Sweden.
    Hultman, Lars
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics.
    Magnetic-field-dependent plasma composition of a pulsed arc in a high-vacuum ambient2000In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 76, no 12, p. 1531-1533Article in journal (Refereed)
    Abstract [en]

    The effect of a magnetic field on the plasma composition of a pulsed Au plasma stream in a high-vacuum ambient is described. The plasma was formed with a pulsed vacuum-arc-plasma source, and the time-resolved plasma composition was measured with time-of-flight charge-to-mass spectrometry. Plasma impurities due to ionization of nonmetallic species (H+, O+, and N+) were found to be below the detection limit in the absence of a magnetic field. However, in the presence of a magnetic field (0.4 T), the contribution of ionized nonmetal species to the plasma composition was up to 0.22 atomic ratio. These results are characteristic of plasma-based techniques where magnetic fields are employed in a high-vacuum ambient. In effect, the impurity incorporation during thin-film growth pertains to the present findings. (C) 2000 American Institute of Physics. [S0003-6951(00)00712-9].

  • 296.
    Schneider, Jochen
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Anders, A.
    Lawrence Berkeley Natl. Laboratory, Berkeley, CA 94720, United States.
    Yushkov, G.Yu.
    High Current Electronics Institute, Russian Academy of Sciences, 634055 Tomsk, Russian Federation.
    Magnetic-field-dependent plasma composition of a pulsed aluminum arc in an oxygen ambient2001In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 78, no 2, p. 150-152Article in journal (Refereed)
    Abstract [en]

    A variety of plasma-based deposition techniques utilize magnetic fields to affect the degree of ionization as well as for focusing and guiding of plasma beams. Here we use time-of-flight charge-to-mass spectrometry to describe the effect of a magnetic field on the plasma composition of a pulsed Al plasma stream in an ambient containing intentionally introduced oxygen as well as for high vacuum conditions typical residual gas. The plasma composition evolution was found to be strongly dependent on the magnetic field strength and can be understood by invoking two electron impact ionization routes: ionization of the intentionally introduced gas as well as ionization of the residual gas. These results are characteristic of plasma-based techniques where magnetic fields are employed in a high-vacuum ambient. In effect, the impurity incorporation during reactive thin-film growth pertains to the present findings. © 2001 American Institute of Physics.

  • 297.
    Schneider, Jochen
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Larsson, K
    Lu, J
    Olsson, E
    Hjorvarsson, B
    Role of hydrogen for the elastic properties of alumina thin films2002In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 80, no 7, p. 1144-1146Article in journal (Refereed)
    Abstract [en]

    We describe the role of the presence of hydrogen on the elastic properties of AlxOyHz (0.32less than or equal toxless than or equal to0.4, 0.54less than or equal toyless than or equal to0.6, 3x10(-4)less than or equal tozless than or equal to0.14) films. The films were deposited by reactive magnetron sputtering in an Ar/O-2/H2O discharge and were studied by Rutherford backscattering spectrometry, nuclear resonance analysis, selected area electron diffraction, as well as nanoindentation. As the hydrogen concentration is increased from 0.03% to 13.9% the measured elastic modulus value is reduced by approximately 53%. The measured elastic modulus is in excellent agreement with our electronic structure calculations. The large scattering in the reported values of the elastic properties of amorphous alumina thin films can readily be understood by hydrogen incorporation during synthesis. (C) 2002 American Institute of Physics.

  • 298.
    Schoeche, S
    et al.
    University of Nebraska, NE 68588 USA .
    Kuehne, P
    University of Nebraska, NE 68588 USA .
    Hofmann, T
    University of Nebraska, NE 68588 USA .
    Schubert, M
    University of Nebraska, NE 68588 USA .
    Nilsson, Daniel
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Kakanakova-Gueorguie, Anelia
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Janzén, Erik
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Darakchieva, Vanya
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Electron effective mass in Al0.72Ga0.28N alloys determined by mid-infrared optical Hall effect2013In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 103, no 21, p. 212107-Article in journal (Refereed)
    Abstract [en]

    The effective electron mass parameter in Si-doped Al0.72Ga0.28N is determined to be m* = (0.336 +/- 0.020) m(0) from mid-infrared optical Hall effect measurements. No significant anisotropy of the effective electron mass parameter is found supporting theoretical predictions. Assuming a linear change of the effective electron mass with the Al content in AlGaN alloys and m* = 0.232m(0) for GaN, an average effective electron mass of m* = 0.376m(0) can be extrapolated for AlN. The analysis of mid-infrared spectroscopic ellipsometry measurements further confirms the two phonon mode behavior of the E-1(TO) and one phonon mode behavior of the A(1)(LO) phonon mode in high-Al-content AlGaN alloys as seen in previous Raman scattering studies.

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  • 299.
    Schubert, Mathias
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering. University of Nebraska-Lincoln, Lincoln, Nebraska 68588, USA; Leibniz Institute for Polymer Research, Dresden 01069, Germany; .
    Mock, Alyssa
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Korlacki, Rafal
    Univ Nebraska, NE 68588 USA.
    Knight, Sean
    Univ Nebraska, NE 68588 USA.
    Galazka, Zbigniew
    Leibniz Inst Kristallzuchtung, Germany.
    Wagner, Guenther
    Leibniz Inst Kristallzuchtung, Germany.
    Wheeler, Virginia
    US Naval Res Lab, DC 20375 USA.
    Tadjer, Marko
    US Naval Res Lab, DC 20375 USA.
    Goto, Ken
    Novel Crystal Technol Inc, Japan.
    Darakchieva, Vanya
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Longitudinal phonon plasmon mode coupling in β-Ga2O32019In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 114, no 10, article id 102102Article in journal (Refereed)
    Abstract [en]

    In this letter, we investigate a set of n-type single crystals of monoclinic symmetry beta-Ga2O3 with different free electron concentration values by generalized far infrared and infrared spectroscopic ellipsometry. In excellent agreement with our previous model prediction, we find here by experiment that longitudinal-phonon-plasmon coupled modes are polarized either within the monoclinic plane or perpendicular to the monoclinic plane. As predicted, all modes change the amplitude and frequency with the free electron concentration. The most important observation is that all longitudinal-phonon-plasmon coupled modes polarized within the monoclinic plane continuously change their direction as a function of free electron concentration.

  • 300.
    Schubert, Mattias
    et al.
    Faculty of Physics and Geosciences, Inst. of Experimental Physics II University of Leipzig.
    Bundesmann, C.
    Faculty of Physics and Geosciences, Inst. of Experimental Physics II University of Leipzig.
    Jacopic, G.
    Institut für Nanostrukturierte Materialien und Photonik JOANNEUM Research Forschungsgesellschaft mbH.
    Maresch, H.
    Institut für Nanostrukturierte Materialien und Photonik JOANNEUM Research Forschungsgesellschaft mbH.
    Arwin, Hans
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Optics .
    Infrared dielectric function and vibrational modes of pentacene thin films2004In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 84, no 2, p. 200-202Article in journal (Refereed)
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