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  • 351.
    Valcheva, E
    et al.
    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.
    Tungasmita, Sukkaneste
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Persson, Per
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics.
    Birch, Jens
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics.
    Svedberg, EB
    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 .
    Interface structure of hydride vapor phase epitaxial GaN grown with high-temperature reactively sputtered AlN buffer2000In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 76, no 14, p. 1860-1862Article in journal (Refereed)
    Abstract [en]

    Thick hydride vapor phase epitaxy GaN layers have been grown on a-plane sapphire using high-temperature ion-assisted reactively sputtered AlN as a buffer layer. Transmission electron microscopy and atomic force microscopy were carried out to study the formation of the two interfaces sapphire/AlN and AlN/GaN, and their influence on the microstructure of both the buffer layer and the main GaN layer. It was demonstrated that the high-temperature reactively sputtered buffer layer provides a good alternative for hydride vapor phase epitaxy growth of GaN layers. In particular, the buffer promotes a specific interface ordering mechanism different from that observed on low-temperature buffers. (C) 2000 American Institute of Physics. [S0003-6951(00)00314-4].

  • 352.
    van den Berg, J. J.
    et al.
    University of Groningen, Netherlands.
    Yakimova, Rositsa
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    van Wees, B. J.
    University of Groningen, Netherlands.
    Spin transport in epitaxial graphene on the C-terminated (000(1)over-bar)-face of silicon carbide2016In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 109, no 1, p. 012402-Article in journal (Refereed)
    Abstract [en]

    We performed a temperature dependent study of the charge and spin transport properties of epitaxial graphene on the C-terminated (000 (1) over bar) face of silicon carbide (SiC), a system without a carbon buffer layer between the graphene and the SiC. Using spin Hanle precession in the nonlocal geometry, we measured a spin relaxation length of lambda(S) = 0.7 lm at room temperature, lower than in exfoliated graphene. We show that the charge and spin diffusion coefficient, D-C and D-S, respectively, increasingly deviate from each other during electrical measurements up to a difference of a factor 4. Thus, we show that a model of localized states that was previously used to explain D-C not equal D-S, can also be applied to epitaxial graphene systems without a carbon buffer layer. We attribute the effect to charge trap states in the interface between the graphene and the SiC. Published by AIP Publishing.

  • 353.
    Virojanadara, Chariya
    et al.
    Max-Planck-Institut für Festkörperforschung, Stuttgart, Germany.
    Hetzel, M
    Max-Planck-Institut für Festkörperforschung, Stuttgart, Germany.
    Starke, Ulrich
    Max-Planck-Institut für Festkörperforschung, Stuttgart, Germany.
    A diagonal cut through the SiC bulk unit cell: Structure and composition of the 4H-SiC(1-102) surface2008In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 92, no 6, p. 061902-Article in journal (Refereed)
    Abstract [en]

    The atomic and electronic structure of 4H-SiC(102) surfaces was investigated using low-energy electron diffraction, scanning tunneling microscopy, and photoelectron spectroscopy. Three well ordered phases can be prepared by Si deposition and annealing. The (2×1) phase is Si enriched and terminated by an ordered array of Si-adatom chains which contribute an anisotropic electronic surface state. The c(2×2) phase has a surface composition close to SiC bulk and possesses adatoms in the periodicity of the superlattice. At high temperatures, a (1×1) phase develops with a graphitelike composition.

  • 354.
    Von, Bardeleben H.J.
    et al.
    Von Bardeleben, H.J., Groupe de Physique des Solides, Universités Paris 6 And 7, UMR 75-88 au CNRS, 2 place Jussieu, 75251 Paris Cedex 05, France.
    Cantin, J.L.
    Groupe de Physique des Solides, Universités Paris 6 And 7, UMR 75-88 au CNRS, 2 place Jussieu, 75251 Paris Cedex 05, France.
    Zeinert, A.
    Université de Picardie, LPMC, 33rue St. Leu, F-80038 Amiens, France.
    Racine, B.
    Université de Picardie, LPMC, 33rue St. Leu, F-80038 Amiens, France, Ctr. for Interdisc. Plasma Science, Max Planck Inst. fur Plasmaphysik, D-85748 Garching, Germany.
    Zellama, K.
    Université de Picardie, LPMC, 33rue St. Leu, F-80038 Amiens, France.
    Hai, P.N.
    Spins and microstructure of hydrogenated amorphous carbon: A multiple frequency electron paramagnetic resonance study2001In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 78, no 19, p. 2843-2845Article in journal (Refereed)
    Abstract [en]

    Polymer-like and diamond-like hydrogenated amorphous carbon films, characterized by high spin concentrations of 1020 cm-3, have been studied by multiple frequency electron paramagnetic resonance (EPR) spectroscopy at 9, 35, and 94 GHz. Whereas the low-frequency measurements show only one single symmetric EPR line, the high-frequency measurements reveal the anisotropic nature of the g tensor. They show the presence of two different paramagnetic centers with anisotropic g tensors of g?(1) = 2.005, g?(1) ˜ 2.003, and g?(2) = 2.010, g?(2) ˜ 2.003. We attribute both to localized p states on nanosized sp2 graphitic clusters. The g? values of the g tensors, which are correlated to the size of the graphite like carbon clusters, indicate two different cluster sizes with values below 50 Å. © 2001 American Institute of Physics.

  • 355.
    Vorona, Igor
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Mtchedlidze, T.
    Izadifard, Morteza
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Buyanova, Irina
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Chen, Weimin
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Hong, Y.G.
    Xin, H.P.
    Tu, C.W.
    Magnetic resonance signatures of grown-in defects in GaInNP alloys grown on a GaAs substrate2005In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 86, no 22, p. 222110-Article in journal (Refereed)
    Abstract [en]

    Dilute-nitride Ga0.44In0.56NyP1-y alloys with y=0-0.02, grown on a GaAs substrate using gas-source molecular beam epitaxy, are studied by the optically detected magnetic resonance (ODMR) technique. Grown-in paramagnetic defects were found to act as centers of nonradiative recombination. Resolved hyperfine structure for one of the detected ODMR signals suggests involvement of a Ga-interstitial or an As-antisite in the structure of the related defect. © 2005 American Institute of Physics.

  • 356.
    Wagemans, W.
    et al.
    Eindhoven University of Technology, Netherlands.
    Janssen, P.
    Eindhoven University of Technology, Netherlands.
    van der Heijden, E. H. M.
    Eindhoven University of Technology, Netherlands.
    Kemerink, M.
    Eindhoven University of Technology, Netherlands.
    Koopmans, B.
    Eindhoven University of Technology, Netherlands.
    Frequency dependence of organic magnetoresistance2010In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 97, no 12, article id 123301Article in journal (Refereed)
    Abstract [en]

    To identify the microscopic mechanisms of organic magnetoresistance (OMAR), the dependency on the frequency of the applied magnetic field is explored, which consists of a dc and ac component. The measured magnetoconductance decreases when the frequency is increased. The decrease is stronger for lower voltages, which is shown to be linked to the presence of a negative capacitance, as measured with admittance spectroscopy. The negative capacitance disappears when the frequency becomes comparable to the inverse transit time of the minority carriers. These results are in agreement with recent interpretations that magnetic field effects on minority carrier mobility dominate OMAR. (C) 2010 American Institute of Physics. [doi: 10.1063/1.3491217]

  • 357.
    Wagner, Matthias
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Ivanov, Ivan Gueorguiev
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Storasta, Liutauras
    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 .
    Magnusson, Björn
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Chen, Weimin
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    Janzén, Erik
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Photoluminescence upconversion in 4H-SiC2002In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 81, no 14, p. 2547-Article in journal (Refereed)
    Abstract [en]

     Efficient photoluminescence upconversion is observed in 4H-SiC samples containing both the UD-3 defect and the titanium impurity. In this process, the titanium photoluminescence emission with no-phonon (NP) lines at 2.848 eV (A0) and 2.789 eV (B0) can be excited by tuning the laser to the NP line of UD-3 at 1.356 eV. In samples containing either only UD-3 or only titanium, a different photoluminescence upconversion process can be observed, which occurs at photon energies higher than ~1.5 eV without exhibiting sharp features. At least one of the two processes generates both free electrons and free holes and can, therefore, be a candidate for an important recombination channel.

  • 358.
    Wahab, Qamar Ul
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Ellison, A
    Linkoping Univ, Dept Phys & Measurement Technol, S-58183 Linkoping, Sweden ABB Corp Res, S-72178 Vasteras, Sweden Univ Sci & Tech Lille Flandres Artois, F-59665 Villeneuve Dascq, France.
    Henry, Anne
    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 .
    Hallin, Christer
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Di Persio, J
    Linkoping Univ, Dept Phys & Measurement Technol, S-58183 Linkoping, Sweden ABB Corp Res, S-72178 Vasteras, Sweden Univ Sci & Tech Lille Flandres Artois, F-59665 Villeneuve Dascq, France.
    Martinez, R
    Linkoping Univ, Dept Phys & Measurement Technol, S-58183 Linkoping, Sweden ABB Corp Res, S-72178 Vasteras, Sweden Univ Sci & Tech Lille Flandres Artois, F-59665 Villeneuve Dascq, France.
    Influence of epitaxial growth and substrate-induced defects on the breakdown of 4H-SiC Schottky diodes2000In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 76, no 19, p. 2725-2727Article in journal (Refereed)
    Abstract [en]

    Morphological defects and elementary screw dislocations in 4H-SiC were studied by high voltage Ni Schottky diodes. Micropipes were found to severely limit the performance of 4H-SiC power devices, whereas carrot-like defects did not influence the value of breakdown voltage. The screw dislocation density as determined by x-ray topography analysis under the active area of the diode was also found to directly affect the breakdown voltage. Only diodes with low density of screw dislocations and free from micropipes could block 2 kV or higher. (C) 2000 American Institute of Physics. [S0003-6951(00)01119-0].

  • 359.
    Wang, Jianpu
    et al.
    University of Cambridge, England.
    Gao, Feng
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Greenham, Neil C.
    University of Cambridge, England.
    Low-power write-once-read-many-times memory devices2010In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 97, no 5, article id 053301Article in journal (Refereed)
    Abstract [en]

    We introduce low-power write-once-read-many-times memory devices fabricated from solution. These devices are based on an electron-only structure using colloidal ZnO semiconductor nanoparticles and the doped conjugated polymer polyethylenedioxythiophene doped with polystyrene sulfonic acid (PEDOT:PSS). The conductive p-doped conjugated polymer is permanently dedoped by injected electrons, producing an insulating state. This demonstration provides a class of memory devices with the potential for extremely low-cost, low-power-consumption applications, such as radio-frequency identification tags. (C) 2010 American Institute of Physics.

  • 360.
    Wang, Xiangjun
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics . Linköping University, The Institute of Technology.
    Perzon, Erik
    Materials and Surface Chemistry, Chalmers University of Technology, Göteborg, Sweden.
    Delgado, Juan Luis
    Facultad de Ciencias del Medio Ambiente, Universidad de Castilla—La Mancha, Toledo, Spain.
    de la Cruz, Pilar
    Facultad de Ciencias del Medio Ambiente, Universidad de Castilla—La Mancha, Toledo, Spain.
    Zhang, Fengling
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics . Linköping University, The Institute of Technology.
    Langa, Fernando
    Facultad de Ciencias del Medio Ambiente, Universidad de Castilla—La Mancha, Toledo, Spain.
    Andersson, Mats
    Materials and Surface Chemistry, Chalmers University of Technology, Göteborg, Sweden.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics . Linköping University, The Institute of Technology.
    Infrared photocurrent spectral response from plastic solar cell with low-bandgap polyfluorene and fullerene derivative2004In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 85, no 21, p. 5081-5083Article in journal (Refereed)
    Abstract [en]

    Plastic solar cells were fabricated using a low-band-gap alternating copolymer of fluorene and a donor–acceptor–donor moiety (APFO-Green1), blended with [6,6]-phenyl-C61-butyric acid methylester or 3-(3,5-Bis-trifluoromethylphenyl)-1-(4-nitrophenyl)pyrazolino[60]fullerene as electron acceptors. The polymer shows optical absorption in two wavelength ranges from 300<<500  nm and 650<<1000  nm. Devices based on APFO-Green1 blended with the later fullerene exhibit an outstanding photovoltaic behavior at the infrared range, where the external quantum efficiency is as high as 8.4% at 840  nm and 7% at 900  nm, while the onset of photogeneration is found at 1  µm. A photocurrent density of 1.76  mA/cm2, open-circuit voltage of 0.54  V, and power conversion efficiency of 0.3% are achieved under the illumination of AM1.5 (1000  W/m2) from a solar simulator.

  • 361.
    Wang, Xiaodong
    et al.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Laiho, Ari
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Berggren, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Crispin, Xavier
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Remanent polarization in a cryptand-polyanion bilayer implemented in an organic field effect transistor2012In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 100, no 2, p. 023305-Article in journal (Refereed)
    Abstract [en]

    We investigate the possibility to maintain an electric polarization in an organic bilayer via ion trapping, i.e., without any external bias. In the cryptand-polyanion bilayer, ions of specific size can be strongly coordinated with organic macrocyclic molecules. Cations move from the polyanion layer to the cryptand layer upon applying a bias and are trapped in this layer. As a result, the voltage dependence of the polarization displays a hysteresis. The bilayer is then advantageously used as an electronic insulating layer in an organic field effect transistor. The ions trapping and de-trapping can be followed by the amplitude of the threshold voltage (V(th)) shift as well as its temporal evolution.

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  • 362.
    Wang, Xingjun
    et al.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Buyanova, Irina
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Chen, Weimin
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Izadifard, M.
    Department of Physics, Shahrood University of Technology, Shahrood, Iran .
    Rawal, S.
    Department of Materials Science and Engineering, University of Florida, Gainesville, Florida.
    Norton, D.P.
    Department of Materials Science and Engineering, University of Florida, Gainesville, Florida.
    Pearton, S.J.
    Department of Materials Science and Engineering, University of Florida, Gainesville, Florida.
    Osinsky, A.
    SVT Associates, Eden Prairie, Minnesota.
    Dong, J.W.
    SVT Associates, Eden Prairie, Minnesota.
    Dabiran, A.
    SVT Associates, Eden Prairie, Minnesota.
    Band gap properties of Zn1−xCdxO alloys grown by molecular-beam epitaxy2006In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 89, p. 151909-Article in journal (Refereed)
    Abstract [en]

    Optical absorption and reflectance measurements are performed to evaluate compositional and temperature dependences of band gap energies of Zn1−xCdxO alloys grown by molecular-beam epitaxy. The compositional dependence of the band gap energy, determined by taking into account excitonic contributions, is shown to follow the trend Eg(x) = 3.37−2.82x+0.95x2. Incorporation of Cd was also shown to somewhat slow down thermal variation of the band gap energies, beneficial for future device applications.

  • 363.
    Wang, Xingjun
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Puttisong, Yuttapoom
    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.
    Ptak, Aaron J.
    National Renewable Energy Laboratory, Golden, Colorado 80401, USA.
    Kalevich, V. K.
    A. F. Ioffe Physico-Technical Institute, St. Petersburg 194021, Russia.
    Egorov, A. Yu.
    A. F. Ioffe Physico-Technical Institute, St. Petersburg 194021, Russia.
    Geelhaar, L.
    Paul-Drude-Institut für Festkörpelektronik, 10117 Berlin, Germany.
    Riechert, H.
    Paul-Drude-Institut für Festkörpelektronik, 10117 Berlin, Germany.
    Chen, Weimin
    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.
    Dominant recombination centers in Ga(In)NAs alloys: Ga interstitials2009In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 95, p. 241904-Article in journal (Refereed)
    Abstract [en]

    Opticallydetected magnetic resonance measurements are carried out to study formationof Ga interstitial-related defects in Ga(In)NAs alloys. The defects, whichare among dominant nonradiative recombination centers that control carrier lifetimein Ga(In)NAs, are unambiguously proven to be common grown-in defectsin these alloys independent of the employed growth methods. Thedefects formation is suggested to become thermodynamically favorable because ofthe presence of nitrogen, possibly due to local strain compensation.

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  • 364. Wang, Ying
    et al.
    Gao, Weiying
    Braun, Slawomir
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry .
    Salaneck, William R
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry .
    Fabrice, Amy
    Calvin, Chan
    Kahn, Antoine
    Enhancement of iridium-based organic light-emitting diodes by spatial doping of the hole transport layer2005In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 87, no 19, p. 193501-Article in journal (Refereed)
    Abstract [en]

    The electroluminescence efficiency of Ir-based green emitter devices is very sensitive to the nature of the hole transport layer used. We show that by inserting a 1 nm layer of bis[4-(N,N-diethylamino)-2-methylphenyl](4- methylphenyl)methane (MPMP) in a 4, 4′ - bis- (carbazol-9-yl) biphenyl (CBP) hole transport layer, a device that combines the positive attributes of both MPMP (high efficiency) and CBP (low injection voltage) is obtained. These results can be understood based on a combined ultraviolet photoemission spectroscopy/inverse photoemission spectroscopy study, which reveals the very low electron affinity and superior electron blocking capability of MPMP. © 2005 American Institute of Physics.

  • 365. Wang, Z.
    et al.
    Kugler, Veronika Mozhdeh
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Helmersson, Ulf
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics .
    Konofaos, N.
    Applied Physics Laboratory, Department of Physics, University of Ioannina, 451 10 Ioannina, Greece.
    Evangelou, E.K.
    Applied Physics Laboratory, Department of Physics, University of Ioannina, 451 10 Ioannina, Greece.
    Nakao, S.
    Natl. Inst. Adv. Indust. Sci. T., Nagoya 462-8510, Japan.
    Jin, P.
    Natl. Inst. Adv. Indust. Sci. T., Nagoya 462-8510, Japan.
    Electrical properties of SrTiO3 thin films on Si deposited by magnetron sputtering at low temperature2001In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 79, no 10, p. 1513-1515Article in journal (Refereed)
    Abstract [en]

    Deposition of SrTiO3 (STO) thin films by radio-frequency magnetron sputtering in an ultrahigh vacuum system at a low substrate temperature (~200°C) was performed in order to produce high-quality STO/p-Si (100) interfaces and STO insulator layers with dielectric constants of high magnitude. The STO films were identified as polycrystalline by x-ray diffraction, and were approximated with a layered structure according to the best fitting results of raw data from both Rutherford backscattering spectroscopy and variable angle spectroscopic ellipsometry. Room-temperature current-voltage and capacitance-voltage (C-V) measurements on Al/STO/p-Si diodes clearly revealed metal-insulator-semiconductor behavior, and the STO/p-Si interface state densities were of the order of 1011 eV-1 cm-2. The dielectric constant of the STO film was 65, and the dielectric loss factor varied between 0.05 and 0.55 for a frequency range of 1 kHz-10 MHz. For a 387 nm thick STO film, the dielectric breakdown field was 0.31 MV cm-1, and the charge storage capacity was 2.1 µC cm-2. These results indicate that STO films are suitable for applications as insulator layers in dynamic random access memories or as cladding layers in electroluminescent devices. © 2001 American Institute of Physics.

  • 366.
    Webb, Matthew J.
    et al.
    Uppsala University, Sweden.
    Polley, Craig
    Lund University, Sweden.
    Dirscherl, Kai
    DFM, Denmark.
    Burwell, Gregory
    Swansea University, Wales.
    Palmgren, Pal
    VG Scienta Science AB, Sweden.
    Niu, Yuran
    Lund University, Sweden.
    Lundstedt, Anna
    Uppsala University, Sweden.
    Zakharov, Alexei A.
    Lund University, Sweden.
    Guy, Owen J.
    Swansea University, Wales.
    Balasubramanian, Thiagarajan
    Lund University, Sweden.
    Yakimova, Rositsa
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Grennberg, Helena
    Uppsala University, Sweden.
    Effects of a modular two-step ozone-water and annealing process on silicon carbide graphene2014In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 105, no 8, p. 081602-Article in journal (Refereed)
    Abstract [en]

    By combining ozone and water, the effect of exposing epitaxial graphene on silicon carbide to an aggressive wet-chemical process has been evaluated after high temperature annealing in ultra high vacuum. The decomposition of ozone in water produces a number of oxidizing species, however, despite long exposure times to the aqueous-ozone environment, no graphene oxide was observed after the two-step process. The systems were comprehensively characterized before and after processing using Raman spectroscopy, core level photoemission spectroscopy, and angle resolved photoemission spectroscopy together with low energy electron diffraction, low energy electron microscopy, and atomic force microscopy. In spite of the chemical potential of the aqueous-ozone reaction environment, the graphene domains were largely unaffected raising the prospect of employing such simple chemical and annealing protocols to clean or prepare epitaxial graphene surfaces.

  • 367.
    Weidemann, O.
    et al.
    Walter Schottky Institute, Technical University Munich, Am Coulombwall 3, D-85748 Garching, Germany.
    Hermann, M.
    Walter Schottky Institute, Technical University Munich, Am Coulombwall 3, D-85748 Garching, Germany.
    Steinhoff, G.
    Walter Schottky Institute, Technical University Munich, Am Coulombwall 3, D-85748 Garching, Germany.
    Wingbrant, Helena
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Physics .
    Lloyd-Spets, Anita
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Physics .
    Stutzmann, M.
    Walter Schottky Institute, Technical University Munich, Am Coulombwall 3, D-85748 Garching, Germany.
    Eickhoff, M.
    Walter Schottky Institute, Technical University Munich, Am Coulombwall 3, D-85748 Garching, Germany.
    Influence of surface oxides on hydrogen-sensitive Pd: GaN Schottky diodes2003In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 83, no 4, p. 773-775Article in journal (Refereed)
    Abstract [en]

    Influence of surface oxides on hydrogen-sensitive Pd:GaN Schottky diodes was studied. Ex-situ fabricated devices show a sensitivity towards molecular hydrogen, which is about 50 times higher than for in situ deposited diodes. In situ deposited Pd Schottky contacts reveal lower barrier heights and drastically higher reverse currents.

  • 368.
    Weman, Helge
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Sirigu, L.
    Karlsson, Fredrik
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Leifer, K.
    Rudra, A.
    Kapon, E.
    High internal quantum efficiency, narrow linewidth emission InGaAs/GaAs/AlGaAs quantum wire light-emitting diode2002In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 81, no 15, p. 2839-2841Article in journal (Refereed)
    Abstract [en]

    High internal quantum efficiency (similar to60%), narrow linewidth (as narrow as 14 meV) exciton emission at room temperature has been obtained using strained InGaAs V-groove quantum wire (QWR) light-emitting diodes (LEDs). The high efficiency is achieved with the aid of selective carrier injection through self-ordered AlGaAs vertical quantum wells (VQWs), where the VQWs are separated from the InGaAs QWRs by thin GaAs spacer layers in order to reduce nonradiative recombination and inhomogeneous alloy broadening. Evidence for excitonic recombination in these LEDs up to RT is provided by measurements of the emission energy shifts at high magnetic fields.

  • 369.
    Westlund, A.
    et al.
    Chalmers, Dept Microtechnol & Nanosci MC2, SE-41296 Gothenburg, Sweden.
    Winters, M.
    Chalmers, Dept Microtechnol & Nanosci MC2, SE-41296 Gothenburg, Sweden.
    Ivanov, Ivan Gueorguiev
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Ul-Hassan, Jawad
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Nilsson, P. -A.
    Chalmers, Dept Microtechnol & Nanosci MC2, SE-41296 Gothenburg, Sweden.
    Janzén, Erik
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Rorsman, N.
    Chalmers, Dept Microtechnol & Nanosci MC2, SE-41296 Gothenburg, Sweden.
    Grahn, J.
    Chalmers, Dept Microtechnol & Nanosci MC2, SE-41296 Gothenburg, Sweden.
    Correction: Graphene self-switching diodes as zero-bias microwave detectors (vol 106, 093116, 2015)2015In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 106, no 15, article id 159902Article in journal (Other academic)
    Abstract [en]

    n/a

  • 370.
    Westlund, A.
    et al.
    Chalmers, Sweden.
    Winters, M.
    Chalmers, Sweden.
    Ivanov, Ivan Gueorguiev
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Ul-Hassan, Jawad
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Nilsson, P. -A.
    Chalmers, Sweden.
    Janzén, Erik
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Rorsman, N.
    Chalmers, Sweden.
    Grahn, J.
    Chalmers, Sweden.
    Graphene self-switching diodes as zero-bias microwave detectors2015In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 106, no 9, p. 093116-Article in journal (Refereed)
    Abstract [en]

    Self-switching diodes (SSDs) were fabricated on as-grown and hydrogen-intercalated epitaxial graphene on SiC. The SSDs were characterized as zero-bias detectors with on-wafer measurements from 1 to 67 GHz. The lowest noise-equivalent power (NEP) was observed in SSDs on the hydrogen-intercalated sample, where a flat NEP of 2.2 nW/Hz(1/2) and responsivity of 3.9 V/W were measured across the band. The measured NEP demonstrates the potential of graphene SSDs as zero-bias microwave detectors. (C) 2015 AIP Publishing LLC.

  • 371.
    Widmann, Matthias
    et al.
    Univ Stuttgart, Germany.
    Niethammer, Matthias
    Univ Stuttgart, Germany.
    Makino, Takahiro
    Natl Inst Quantum and Radiol Sci and Technol, Japan.
    Rendler, Torsten
    Univ Stuttgart, Germany.
    Lasse, Stefan
    Univ Stuttgart, Germany.
    Ohshima, Takeshi
    Natl Inst Quantum and Radiol Sci and Technol, Japan.
    Ul-Hassan, Jawad
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Nguyen, Son Tien
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Lee, Sang-Yun
    Korea Inst Sci and Technol, South Korea.
    Wrachtrup, Joreg
    Univ Stuttgart, Germany.
    Bright single photon sources in lateral silicon carbide light emitting diodes2018In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 112, no 23, article id 231103Article in journal (Refereed)
    Abstract [en]

    Single-photon emitting devices have been identified as an important building block for applications in quantum information and quantum communication. They allow us to transduce and collect quantum information over a long distance via photons as so-called flying qubits. In addition, substrates like silicon carbide provide an excellent material platform for electronic devices. In this work, we combine these two features and show that one can drive single photon emitters within a silicon carbide p-i-n-diode. To achieve this, we specifically designed a lateral oriented diode. We find a variety of new color centers emitting non-classical lights in the visible and near-infrared range. One type of emitter can be electrically excited, demonstrating that silicon carbide can act as an ideal platform for electrically controllable single photon sources. Published by AIP Publishing.

  • 372.
    Wilhelmsson, Ola
    et al.
    Department of Materials Chemistry, the Ångström Laboratory, Uppsala University, Uppsala, Sweden.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Giuliani, Finn
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Högberg, Hans
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Jansson, Ulf
    Department of Materials Chemistry, the Ångström Laboratory, Uppsala University, Uppsala, Sweden.
    Intrusion-type deformation in epitaxial Ti3SiC2/TiCx nanolaminates2007In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 91, no 12, p. 123124-Article in journal (Refereed)
    Abstract [en]

    We investigate the deformation of epitaxial Ti3 Si C2 (0001) Ti Cx (111) (x∼0.67) nanolaminates deposited by magnetron sputtering. Nanoindentation and transmission electron microscopy show that the Ti3 Si C2 layers deform via basal plane slip and intrusion into the TiC layers, suppressing kink-band and pile-up deformation behaviors analogous with monolithic Ti3 Si C2. This remarkable response to indentation is due to persistent slip in the TiC layers and prevention of gross slip throughout the nanolaminate by the interleaving Ti3 Si C2 layers. Hardness and Young's modulus were measured as ∼15 and ∼240 GPa, respectively.

  • 373.
    Wingqvist, Gunilla
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Tasnadi, Ferenc
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics . Linköping University, The Institute of Technology.
    Zukauskaite, Agne
    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.
    Arwin, Hans
    Linköping University, Department of Physics, Chemistry and Biology, Applied Optics . Linköping University, The Institute of Technology.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Increased electromechanical coupling in w-ScxAl1-xN2010In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 97, no 11, p. 112902-Article in journal (Refereed)
    Abstract [en]

    AlN is challenged as the material choice in important thin film electroacoustic devices for modern wireless communication applications. We present the promise of superior electromechanical coupling (kt2), in w−ScxAl1−xN by studying its dielectric properties. w−ScxAl1−xN (0≤x≤0.3) thin films grown by dual reactive magnetron sputtering exhibited low dielectric losses along with minor increased dielectric constant (ε). Ellipsometry measurements of the high frequency ε showed good agreement with density function perturbation calculations. Our data show that kt2 will improve from 7% to 10% by alloying AlN with up to 20 mol % ScN.

     

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  • 374.
    Winquist, Fredrik
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Spetz, Anita
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Armgarth, M.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Nylander, Claes
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Lundström, Ingemar
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Modified palladium metal‐oxide‐semiconductor structures with increased ammonia gas sensitivity1983In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 43, no 9, p. 839-841Article in journal (Refereed)
    Abstract [en]

    It is known that palladium metal‐oxide‐semiconductor (Pd‐MOS) structures are sensitive detectors for hydrogen gas. We show that the evaporation of a thin film of catalytically active metals on top of the structure can increase the sensitivity towards ammonia considerably. It was found that the thin metal must be in contact with the oxide to cause the increased sensitivity. The largest increase was observed with the transition metals Ir and Pt. The ammonia sensitivity could be enhanced about 60 times compared to that of an unmodified structure

  • 375.
    Yager, Tom
    et al.
    Chalmers, Sweden.
    Webb, Matthew J.
    Uppsala University, Sweden.
    Grennberg, Helena
    Uppsala University, Sweden.
    Yakimova, Rositsa
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Lara-Avila, Samuel
    Chalmers, Sweden.
    Kubatkin, Sergey
    Chalmers, Sweden.
    High mobility epitaxial graphene devices via aqueous-ozone processing2015In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 106, no 6, p. 063503-Article in journal (Refereed)
    Abstract [en]

    We find that monolayer epitaxial graphene devices exposed to aggressive aqueous-ozone processing and annealing became cleaner from post-fabrication organic resist residuals and, significantly, maintain their high carrier mobility. Additionally, we observe a decrease in carrier density from inherent strong n-type doping to extremely low p-type doping after processing. This transition is explained to be a consequence of the cleaning effect of aqueous-ozone processing and annealing, since the observed removal of resist residuals from SiC/G enables the exposure of the bare graphene to dopants present in ambient conditions. The resulting combination of charge neutrality, high mobility, large area clean surfaces, and susceptibility to environmental species suggest this processed graphene system as an ideal candidate for gas sensing applications.

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  • 376.
    Yang, Rong
    et al.
    Nanjing Technical University, Peoples R China.
    Zhang, Li
    Nanjing Technical University, Peoples R China.
    Cao, Yu
    Nanjing Technical University, Peoples R China.
    Miao, Yanfeng
    Nanjing Technical University, Peoples R China.
    Ke, You
    Nanjing Technical University, Peoples R China.
    Wei, Yingqiang
    Nanjing Technical University, Peoples R China.
    Guo, Qiang
    Nanjing Technical University, Peoples R China.
    Wang, Ying
    Nanjing Technical University, Peoples R China.
    Rong, Zhaohua
    Nanjing Technical University, Peoples R China.
    Wang, Nana
    Nanjing Technical University, Peoples R China.
    Li, Renzhi
    Nanjing Technical University, Peoples R China.
    Wang, Jianpu
    Nanjing Technical University, Peoples R China.
    Huang, Wei
    Nanjing Technical University, Peoples R China; Nanjing University of Posts and Telecommun, Peoples R China; Nanjing University of Posts and Telecommun, Peoples R China.
    Gao, Feng
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Inhomogeneous degradation in metal halide perovskites2017In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 111, no 7, article id 073302Article in journal (Refereed)
    Abstract [en]

    Although the rapid development of organic-inorganic metal halide perovskite solar cells has led to certified power conversion efficiencies of above 20%, their poor stability remains a major challenge, preventing their practical commercialization. In this paper, we investigate the intrinsic origin of the poor stability in perovskite solar cells by using a confocal fluorescence microscope. We find that the degradation of perovskite films starts from grain boundaries and gradually extend to the center of the grains. Firmly based on our findings, we further demonstrate that the device stability can be significantly enhanced by increasing the grain size of perovskite crystals. Our results have important implications to further enhance the stability of optoelectronic devices based on metal halide perovskites. Published by AIP Publishing.

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  • 377.
    Yang, S.
    et al.
    National Synchrotron Radiation Research Center, Hsinchu, Taiwan .
    Hsu, H. C.
    National Cheng Kung University, Taiwan.
    Liu, W-R.
    National Synchrotron Radiation Research Center, Hsinchu, Taiwan.
    Lin, B. H.
    National Synchrotron Radiation Research Center, Hsinchu, Taiwan.
    Kuo, C. C.
    National Chiao Tung University, Hsinchu, Taiwan .
    Hsu, C-H.
    National Synchrotron Radiation Research Center, Hsinchu, Taiwan .
    Eriksson, Martin
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Holtz, Per-Olof
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Hsieh, W. F.
    National Chiao Tung University, Hsinchu, Taiwan .
    Recombination dynamics of a localized exciton bound at basal stacking faults within the m-(p)lane ZnO film2014In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 105, no 1, p. 011106-Article in journal (Refereed)
    Abstract [en]

    We investigated the carrier dynamics near basal stacking faults (BSFs) in m-plane ZnO epitaxial film. The behaviors of the type-II quantum wells related to the BSFs are verified through time-resolved and time-integrated photoluminescence. The decay time of the emission of BSFs is observed to have a higher power law value and longer decay time than the emission of the donor-bound excitons. The spectral-dependent decay times reveal a phenomenon of carriers migrating among band tail states, which are related to the spatial distribution of the type-II quantum wells formed by the BSFs. A high density of excited carriers leads to a band bending effect, which in turn causes a blue-shift of the emission peak of BSFs with a broadened distribution of band tail states.

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  • 378.
    Yazdi, Gholamreza
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Materials Science . Linköping University, The Institute of Technology.
    Syväjärvi, Mikael
    Linköping University, Department of Physics, Chemistry and Biology, Materials Science . Linköping University, The Institute of Technology.
    Yakimova, Rositsa
    Linköping University, Department of Physics, Chemistry and Biology, Materials Science . Linköping University, The Institute of Technology.
    Aligned AlN nanowires and microrods by self-patterning2007In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 90, no 12, p. 123103-Article in journal (Refereed)
    Abstract [en]

    Self-patterned AlN microrods and nanowires were grown on 4H-SiC substrate by a physical vapor transport method. AlN hexagonal pyramids were found to be nucleation sites for the evolution of the observed morphological forms. The average diameter and length of the nanowires are about 200  nm and 90  µm, respectively. The density of microrods corresponds to the concentration of the pyramids, while the nanowires are less compact. Low-temperature cathodoluminescence spectra of microrods show band gap emission of AlN at 208  nm, which confirms that they are AlN single crystals. A formation mechanism of the AlN structures is suggested.

  • 379.
    Yin, Bin
    et al.
    Tianjin University of Technology.
    Yang, Liying
    Tianjin University of Technology.
    Liu, Yongsheng
    Nankai University.
    Chen, Yongsheng
    Nankai University.
    Qi, Qingjin
    Tianjin University of Technology.
    Zhang, Fengling
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics . Linköping University, The Institute of Technology.
    Yin, Shougen
    Tianjin University of Technology.
    Solution-processed bulk heterojunction organic solar cells based on an oligothiophene derivative2010In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 97, no 2, p. 023303-Article in journal (Refereed)
    Abstract [en]

    Organic bulk heterojunction (BHJ) solar cells based on a dicyanovinyl-substituted oligothiophene as a donor and [6,6]-phenyl C61 butyric acid methyl ester (PCBM) as an acceptor were fabricated and characterized. The oligothiophene derivative can absorb long wavelength photons of the solar radiation, which makes the solar cells with an optimized weight ratio of 1:1.4 have a decent short-circuit current density (12.4 mA/cm(2)) and open-circuit voltage (0.88 V) under AM 1.5G illumination with an intensity of 100 mW/cm(2). A power conversion efficiency (PCE) of 3.7% is achieved, which is among the best PCEs of solution processed small molecule BHJ solar cells.

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  • 380.
    Yukimune, M.
    et al.
    Ehime Univ, Japan.
    Fujiwara, R.
    Ehime Univ, Japan.
    Ikeda, H.
    Ehime Univ, Japan.
    Yano, K.
    Ehime Univ, Japan.
    Takada, K.
    Ehime Univ, Japan.
    Jansson, Mattias
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Chen, Weimin
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Buyanova, Irina
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Ishikawa, F.
    Ehime Univ, Japan.
    GaAs/GaNAs core-multishell nanowires with nitrogen composition exceeding 2%2018In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 113, no 1, article id 011901Article in journal (Refereed)
    Abstract [en]

    We report the growth of GaAs/GaNAs/GaAs core-multishell nanowires having N compositions exceeding 2%. The structures were grown by plasma-assisted molecular beam epitaxy using constituent Ga-induced vapor-liquid-solid growth on Si(111) substrates. The GaNAs shell nominally contains 0%, 2%, and 3% nitrogen. The axial cross-sectional scanning transmission electron microscopy measurements confirm the existence of core-multishell structure. The room temperature micro-photoluminescence measurements reveal a red-shift of the detected emission with increasing N content in the nanowires, consistent with the expected changes in the GaNAs bandgap energy due to the bowing effect. Published by AIP Publishing.

  • 381.
    Zhang, Bin
    et al.
    Chinese Acad Sci, Peoples R China; Univ Chinese Acad Sci, Peoples R China.
    Qiu, Weiyang
    Chinese Acad Sci, Peoples R China.
    Chen, Shula
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Chen, Pingping
    Chinese Acad Sci, Peoples R China.
    Chen, Weimin
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Buyanova, Irina
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Wang, Xingjun
    Chinese Acad Sci, Peoples R China.
    Effect of exciton transfer on recombination dynamics in vertically nonuniform GaAsSb epilayers2019In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 114, no 25, article id 252101Article in journal (Refereed)
    Abstract [en]

    Low-temperature photoluminescence (PL), photoreflectance (PR), and temperature dependent time-resolved PL spectroscopies are employed to investigate optical emission processes and exciton dynamics in graded GaAsSb epilayers. The nonuniformity in the Sb composition along the growth direction is disclosed by low-temperature PL and PR measurements. Furthermore, significant differences in PL dynamics are found at low temperatures for the PL emissions originating from spatial regions with the low and high Sb compositions, with a fast decay and a slow rise at the early stage of the PL transient, respectively. This finding is attributed to exciton transfer from the low Sb region to the high Sb region. The obtained results are important for a general understanding of optical transitions and exciton/carrier dynamics in material systems with a graded alloy composition.

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  • 382.
    Zhang, Fengling
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics .
    Gadisa, Abay
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics .
    Inganäs, Olle
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics .
    Svensson, M.
    Mat./Surf. Chem./Polymer Technology, Chalmers University of Technology, SE-412 96 Göteborg, Sweden.
    Andersson, M.R.
    Mat./Surf. Chem./Polymer Technology, Chalmers University of Technology, SE-412 96 Göteborg, Sweden.
    Influence of buffer layers on the performance of polymer solar cells2004In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 84, no 19, p. 3906-3908Article in journal (Refereed)
    Abstract [en]

    The study of the influence of different anode buffer layers on the performance of solar cells based on blends of polyfluorene copolymers, acting as electron donor, and [6,6]-phenyl-C61-butyric acid methylester (PCBM), acting as electron acceptor was presented. The construction of buffer later was done from different forms of poly(3, 4-ethylenedioxythiophene) poly-(styrenesulfonate) (PEDOT-PSS). Variations in open-circuit voltage, short-circuit current and fill factor were also observed. The anode buffer layer influences the photovoltage of polymer solar cells by controlling the conditions for charge injection at the anode.

  • 383.
    Zhao, QX
    et al.
    Göteborg University.
    Klason, P
    Göteborg University.
    Willander, Magnus
    Göteborg University.
    Zhong, HM
    Chinese Academy of Sciences.
    Lu, W
    Chinese Academy of Sciences.
    Yang, JH
    Chinese Academy of Sciences.
    Deep-level emissions influenced by O and Zn implantations in ZnO2005In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 87, no 21Article in journal (Refereed)
    Abstract [en]

    A set of bulk ZnO samples implanted with O and Zn at various densities were investigated by photoluminescence. The implantation concentration of O and Zn is varied between 1x10(17)/cm(3) and 5x10(19)/cm(3). The samples were thermally treated in an oxygen gas environment after the implantation. The results clearly show the influence of O and Zn implantations on the deep-level emission. By comparing the photoluminescence spectra for the samples with different implantations, we can conclude that the V-Zn is responsible to the observed deep-level emission. In addition, a novel transition at the emission energy of 3.08 eV at 77 K appears in the O-implanted sample with 5x10(19)/cm(3) implantation concentration. The novel emission is tentatively identified as O-antisite O-Zn.

  • 384.
    Zhao, Q.X.
    et al.
    Göteborg University.
    Wang, S.M.
    Göteborg University.
    Sadeghi, M.
    Göteborg University.
    Larsson, A.
    Göteborg University.
    Friesel, M.
    Göteborg University.
    Willander, Magnus
    Göteborg University.
    Nitrogen incorporation in GaNas layers grown by molecular beam epitaxy2006In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 89, no 3, p. 31907-1-31907-3Article in journal (Refereed)
    Abstract [en]

       GaNAs/GaAs quantum wells with high N concentrations, grown by molecular beam epitaxy, have been investigated by secondary-ion mass spectrometry (SIMS), high resolution x-ray diffraction (XRD), and photoluminescence (PL) measurements. The substitutional N concentration in an 18 nm thick strained GaNAs layer varies from 1.4% to 5.9% when the growth rate is reduced from 1 to 0.2 μm/h. By further reducing the growth rate, more N can be incorporated but relaxation occurs. Both the total N concentration, deduced from SIMS measurements, and the substitutional N concentration, deduced from XRD measurements, increase with reduced growth rate. By comparing the SIMS and XRD results, we found that a large amount of N was not in substitutional position when the substitutional N concentration is high (≫4%). The experimental results also show that there is no detectable change of total and substitutional N concentrations, within the instrument resolutions, after rapid thermal annealing at 700 °C for 30 s. However, PL measurements show a strong blueshift of the emission wavelength after annealing and the PL intensity increases by more than one order of magnitude.

  • 385.
    Zhao, QX
    et al.
    Chalmers University of Technology and Göteborg University.
    Wang, SM
    Chalmers University of Technology.
    Wei, YQ
    Chalmers University of Technology.
    Sadeghi, M
    Chalmers University of Technology.
    Larsson, A
    Chalmers University of Technology.
    Willander, Magnus
    Chalmers University of Technology and Göteborg University.
    Effect of growth temperature and post-growth thermal annealing on carrier localization and deep level emissions in GaNAs/GaAs quantum well structures2005In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 86, no 12Article in journal (Refereed)
    Abstract [en]

    We report results from investigation of the optical properties of GaNAs/GaAs quantum well structures. The structures were grown by molecular-beam epitaxy at different temperatures, and subsequently postgrowth thermal treatments at different temperature were performed. The results show that the carrier localization is smaller in a structure grown at a temperature of 580 degrees C in comparison with a structure grown at 450 degrees C. Both structures also show a broaden deep level emission band. Furthermore, the deep level emission band and the carrier localization effect can be removed by thermal annealing at 650 degrees C in the structure grown at 450 degrees C. The structure quality and radiative recombination efficiency are significantly improved after annealing. However, annealing under the same condition has a negligible effect on the structure grown at 580 degrees C. (C) 2005 American Institute of Physics.

  • 386.
    Zhao, QX
    et al.
    Chalmers University of Technology and Göteborg University.
    Willander, Magnus
    Chalmers University of Technology and Göteborg University.
    Morjan, RE
    Chalmers University of Technology and Göteborg University.
    Hu, QH
    Chalmers University of Technology and Göteborg University.
    Campbell, EEB
    Chalmers University of Technology and Göteborg University.
    Optical recombination of ZnO nanowires grown on sapphire and Si substrates2003In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 83, no 1, p. 165-167Article in journal (Refereed)
    Abstract [en]

    ZnO nanowires have been grown on sapphire and Si substrates using catalytic growth. A strong near-band-gap ultraviolet emission is observed at room temperature. By carefully studying the temperature dependence of ZnO wire emission, we found that the room-temperature UV emission contains two different transitions; one is related to the ZnO free exciton and the other is related to the free-to-bound transition. The bound state has a binding energy of about 124 meV. The results from optical measurements show that a high quality of ZnO nanowires grown on sapphire and Si substrates has been achieved.

  • 387.
    Zhen, Hongyu
    et al.
    Zhejiang Univ, Peoples R China.
    Li, Kan
    Zhejiang University, Peoples R China .
    Huang, Zhuoyin
    Zhejiang University, Peoples R China .
    Tang, Zheng
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Wu, Rengmao
    Zhejiang University, Peoples R China .
    Li, Guolong
    Zhejiang University, Peoples R China .
    Liu, Xu
    Zhejiang University, Peoples R China .
    Zhang, Fengling
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Inverted indium-tin-oxide-free cone-shaped polymer solar cells for light trapping2012In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 100, no 21, p. 213901-Article in journal (Refereed)
    Abstract [en]

    Based on the flexibility of polymer film, cone-shaped polymer solar cells (PSCs) are fabricated and studied. Effective light trapping is achieved due to multi-absorption in all 360 degrees directions. Monte Carlo ray tracing is used to simulate the absorption of cone-shaped PSCs with two variables: wavelength and half cone angle. With an inverted indium-tin-oxide-free device structure, a 43% enhanced light utilization without loss of material utilization is realized in the cone-shaped PSCs with a half cone angle of 45 degrees, compared with the planar PSCs.

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  • 388.
    Zhirkov, Igor
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Petruhins, Andrejs
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Näslund, Lars-Åke
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Kolozsvari, Szilard
    PLANSEE Composite Mat GmbH, Germany.
    Polcik, Peter
    PLANSEE Composite Mat GmbH, Germany.
    Rosén, Johanna
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Vacuum arc plasma generation and thin film deposition from a TiB2 cathode2015In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 107, no 18, p. 184103-Article in journal (Refereed)
    Abstract [en]

    We have studied the utilization of TiB2 cathodes for thin film deposition in a DC vacuum arc system. We present a route for attaining a stable, reproducible, and fully ionized plasma flux of Ti and B by removal of the external magnetic field, which leads to dissipation of the vacuum arc discharge and an increased active surface area of the cathode. Applying a magnetic field resulted in instability and cracking, consistent with the previous reports. Plasma analysis shows average energies of 115 and 26 eV, average ion charge states of 2.1 and 1.1 for Ti and B, respectively, and a plasma ion composition of approximately 50% Ti and 50% B. This is consistent with measured resulting film composition from X-ray photoelectron spectroscopy, suggesting a negligible contribution of neutrals and macroparticles to the film growth. Also, despite the observations of macroparticle generation, the film surface is very smooth. These results are of importance for the utilization of cathodic arc as a method for synthesis of metal borides. (C) 2015 AIP Publishing LLC.

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  • 389.
    Zhirkov, Igor
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Petruhins, Andrejs
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Polcik, Peter
    PLANSEE Composite Mat GmbH, Germany.
    Kolozsvari, Szilard
    PLANSEE Composite Mat GmbH, Germany.
    Rosén, Johanna
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Generation of super-size macroparticles in a direct current vacuum arc discharge from a Mo-Cu cathode2016In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 108, no 5, p. 054103-Article in journal (Refereed)
    Abstract [en]

    An inherent property of cathodic arc is the generation of macroparticles, of a typical size ranging from submicrometer up to a few tens of mu m. In this work, we have studied macroparticle generation from a Mo0.78Cu0.22 cathode used in a dc vacuum arc discharge, and we present evidence for super-size macroparticles of up to 0.7mm in diameter. All analyzed particles are found to be rich in Mo (&gt;= 98 at. %). The particle generation is studied by visual observation of the cathode surface during arcing, by analysis of composition and geometrical features of the used cathode surface, and by examination of the generated macroparticles with respect to shape and composition. A mechanism for super-size macroparticle generation is suggested based on observed segregated layers of Mo and Cu identified in the topmost part of the cathode surface, likely due to the discrepancy in melting and evaporation temperatures of Mo and Cu. The results are of importance for increasing the fundamental understanding of macroparticle generation, which in turn may lead to increased process control and potentially provide paths for tuning, or even mitigating, macroparticle generation. (C) 2016 AIP Publishing LLC.

  • 390.
    Zhou, Yinhua
    et al.
    State Key Lab for Supramolecular Structure and Materials Jilin University.
    Zhang, Fengling
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics .
    Tvingstedt, Kristofer
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics .
    Barrau, Sophie
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Li, Fenghong
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Tian, Wenjing
    State Key Lab for Supramolecular Structure and Materials Jilin University.
    Inganäs, Olle
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics .
    Investigation on Polymer Anode Design for Flexible Polymer Solar Cells2008In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 92Article in journal (Refereed)
    Abstract [en]

       

  • 391.
    Zhou, Yinhua
    et al.
    State Key Lab for Supramolecular Structure and Materials Jilin University.
    Zhang, Fengling
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics .
    Tvingstedt, Kristofer
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics .
    Tian, Wenjing
    State Key Lab for Supramolecular Structure and Materials Jilin University.
    Inganäs, Olle
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics .
    Multifolded Polymer Solar Cells on Flexible Substrates2008In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 93, no 033302Article in journal (Refereed)
  • 392.
    Zhu, Hong
    et al.
    Massachusetts Institute of Technology, Cambridge, USA.
    Sun, Wenhao
    Massachusetts Institute of Technology, Cambridge, USA.
    Armiento, Rickard
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, The Institute of Technology.
    Lazić, Predrag
    Rudjer Boskovic Institute, Zagreb, Croatia.
    Ceder, Gerbrand
    Massachusetts Institute of Technology, Cambridge, USA.
    Band structure engineering through orbital interaction for enhanced thermoelectric power factor2014In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 104, p. 082107-1-082107-5Article in journal (Refereed)
    Abstract [en]

    Band structure engineering for specific electronic or optical properties is essential for the further development of many important technologies including thermoelectrics, optoelectronics, and microelectronics. In this work, we report orbital interaction as a powerful tool to finetune the band structure and the transport properties of charge carriers in bulk crystalline semiconductors. The proposed mechanism of orbital interaction on band structure is demonstrated for IV-VI thermoelectric semiconductors. For IV-VI materials, we find that the convergence of multiple carrier pockets not only displays a strong correlation with the s-p and spin-orbit coupling but also coincides with the enhancement of power factor. Our results suggest a useful path to engineer the band structure and an enticing solid-solution design principle to enhance thermoelectric performance.

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  • 393.
    Zhu, Xiaolong
    et al.
    Technical University of Denmark, Lyngby.
    Ou, Yiyu
    Technical University of Denmark, Lyngby.
    Jokubavicius, Valdas
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Syväjärvi, Mikael
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Hansen, Ole
    Technical University of Denmark, Lyngby.
    Ou, Haiyan
    Technical University of Denmark, Lyngby.
    Mortensen, N. Asger
    Technical University of Denmark, Lyngby.
    Xiao, Sanshui
    Technical University of Denmark, Lyngby.
    Broadband light-extraction enhanced by arrays of whispering gallery resonators2012In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 101, no 24Article in journal (Refereed)
    Abstract [en]

    We demonstrate a light-extraction approach using a whispering gallery resonators array. The wavelength-scale resonant dielectric nanospheres support whispering gallery modes, which can be coupled with the confined waveguide modes inside the bulk material, thus dramatically improving light extraction. Broadband light-extraction enhancement across the entire visible spectral range is achieved by exciting three low-order and low-quality-factor resonances. As an example, the broadband extraction enhancement of about 50% is obtained for the emission of fluorescent SiC at all the tested angles. The experimental results are supported by numerical simulations. Our light-extraction strategy could enable the manufacturing of high-throughput, nondestructive, and affordable optical coating in a variety of optical devices.

  • 394.
    Zozoulenko, Igor V.
    et al.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Evaldsson, Martin
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Quantum antidot as a controllable spin injector and spin filter2004In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 85, no 15, p. 3136-3138Article in journal (Refereed)
    Abstract [en]

    We propose a device based on an antidot embedded in a narrow quantum wire in the edge-state regime, that can be used to inject and/or control spin-polarized current. The operational principle of the device is based on the effect of resonant backscattering from one edge state into another through localized quasibound states, combined with the effect of Zeeman splitting of the quasibound states in sufficiently high magnetic field. We outline the device geometry, present detailed quantum-mechanical transport calculations, and suggest a possible scheme to test the device performance and functionality.

  • 395.
    Zuo, Guangzheng
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Complex Materials and Devices. Linköping University, Faculty of Science & Engineering.
    Andersson, Olof
    Linköping University, Department of Physics, Chemistry and Biology, Complex Materials and Devices. Linköping University, Faculty of Science & Engineering.
    Abdalla, Hassan
    Linköping University, Department of Physics, Chemistry and Biology, Complex Materials and Devices. Linköping University, Faculty of Science & Engineering.
    Kemerink, Martijn
    Linköping University, Department of Physics, Chemistry and Biology, Complex Materials and Devices. Linköping University, Faculty of Science & Engineering.
    High thermoelectric power factor from multilayer solution-processed organic films2018In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 112, no 8, article id 083303Article in journal (Refereed)
    Abstract [en]

    We investigate the suitability of the "sequential doping" method of organic semiconductors for thermoelectric applications. The method consists of depositing a dopant (F4TCNQ) containing solution on a previously cast semiconductor (P3HT) thin film to achieve high conductivity, while preserving the morphology. For very thin films (similar to 25 nm), we achieve a high power factor around 8 mu W/mK(-2) with a conductivity over 500 S/m. For the increasing film thickness, conductivity and power factor show a decreasing trend, which we attribute to the inability to dope the deeper parts of the film. Since thick films are required to extract significant power from thermoelectric generators, we developed a simple additive technique that allows the deposition of an arbitrary number of layers without significant loss in conductivity or power factor that, for 5 subsequent layers, remain at similar to 300 S/m and similar to 5 mu W/mK(-2), respectively, whereas the power output increases almost one order of magnitude as compared to a single layer. The efficient doping in multilayers is further confirmed by an increased intensity of (bi)polaronic features in the UV-Vis spectra. Published by AIP Publishing.

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