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  • 101.
    Stehr, Jan Eric
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, Faculty of Science & Engineering.
    Chen, Shula
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Filippov, Stanislav
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, Faculty of Science & Engineering.
    Devika, M
    Gwangju Institute Science and Technology, South Korea .
    Koteeswara Reddy, N
    Gwangju Institute Science and Technology, South Korea .
    Tu, C W
    Gwangju Institute Science and Technology, South Korea University of Calif San Diego, CA 92093 USA .
    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.
    Defect properties of ZnO nanowires revealed from an optically detected magnetic resonance study2013In: Nanotechnology, ISSN 0957-4484, E-ISSN 1361-6528, Vol. 24, no 1, p. 015701-Article in journal (Refereed)
    Abstract [en]

    Optically detected magnetic resonance (ODMR) complemented by photoluminescence measurements is used to evaluate optical and defect properties of ZnO nanowires (NWs) grown by rapid thermal chemical vapor deposition. By monitoring visible emissions, several grown-in defects are revealed and attributed to Zn vacancies, shallow (but not effective mass) donor and exchange-coupled pairs of Zn vacancies and Zn interstitials. It is also found that the intensity of the donor-related ODMR signals is substantially lower in the NWs compared with that in bulk ZnO. This may indicate that formation of native donors is suppressed in NWs, which is beneficial for achieving p-type conductivity.

  • 102.
    Stehr, Jan Eric
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Chen, Shula
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Knutsen, K. E.
    Svensson, B. G.
    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.
    Defects in Electron Irradiated ZnO: An Electron Paramagnetic Resonance Study2013In: 2013 MRS Fall Meeting, 2013Conference paper (Refereed)
  • 103.
    Stehr, Jan Eric
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Wang, Xingjun
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Filippov, Stanislav
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Pearton, S J.
    University of Florida, FL USA .
    Gueorguiev Ivanov, Ivan
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    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.
    Defects in N, O and N, Zn implanted ZnO bulk crystals2013In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 113, no 10, p. 103509-Article in journal (Refereed)
    Abstract [en]

    Comprehensive characterization of defects formed in bulk ZnO single crystals co-implanted with N and Zn as well as N and O atoms is performed by means of optically detected magnetic resonance (ODMR) complemented by Raman and photoluminescence (PL) spectroscopies. It is shown that in addition to intrinsic defects such as Zn vacancies and Zn interstitials, several N-related defects are formed in the implanted ZnO. The prevailed configuration of the defects is found to depend on the choices of the co-implants and also the chosen annealing ambient. Specifically, co-implantation with O leads to the formation of (i) defects responsible for local vibrational modes at 277, 511, and 581 cm−1; (ii) a N-related acceptor with the binding energy of 160 ± 40 meV that is involved in the donor-acceptor pair emission at 3.23 eV; and (iii) a deep donor and a deep NO acceptor revealed from ODMR. Activation of the latter defects is found to require post-implantation annealing in nitrogen ambient. None of these defects are detected when N is co-implanted with Zn. Under these conditions, the dominant N-induced defects include a deep center responsible for the 3.3128 eV PL line, as well as an acceptor center of unknown origin revealed by ODMR. Formation mechanisms of the studied defects and their role in carrier recombination are discussed.

  • 104.
    Chen, Shula
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    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.
    Dynamics of donor bound excitons in ZnO2013In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 102, no 12, p. 121103-Article in journal (Refereed)
    Abstract [en]

    Comprehensive time-resolved photoluminescence measurements are performed on shallow neutral donor bound excitons (D0Xs) in bulk ZnO. It is found that transients of the no-phonon D0X transitions (I6-I9 lines) are largely affected by excitation conditions and change from a bi-exponential decay with characteristic fast (τf) and slow (τs) time constants under above-bandgap excitation to a single exponential one, determined by τs, under two-photon excitation. The slow decay also dominates transients of longitudinal optical phonon-assisted and two-electron-satellite D0X transitions, and is attributed to “bulk” D0X lifetime. The fast component is tentatively suggested to represent effects of surface recombination.

  • 105.
    Dagnelund, Daniel
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    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.
    Effect of hydrogen on defects in dilute nitride2013In: Hydrogenated dilute nitride semiconductors: theory, properties, applications / [ed] G. Ciatto, Pan Stanford Publishing, 2013, p. 75-98Chapter in book (Other academic)
  • 106.
    Puttisong, Yuttapoom
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Wang, X J.
    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.
    Chen, Weimin
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Effect of hyperfine-induced spin mixing on the defect-enabled spin blockade and spin filtering in GaNAs2013In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 87, no 12Article in journal (Refereed)
    Abstract [en]

    The effect of hyperfine interaction (HFI) on the recently discovered room-temperature defect-enabled spin-filtering effect in GaNAs alloys is investigated both experimentally and theoretically based on a spin Hamiltonian analysis. We provide direct experimental evidence that the HFI between the electron and nuclear spin of the central Ga atom of the spin-filtering defect, namely, the Ga-i interstitials, causes strong mixing of the electron spin states of the defect, thereby degrading the efficiency of the spin-filtering effect. We also show that the HFI-induced spin mixing can be suppressed by an application of a longitudinal magnetic field such that the electronic Zeeman interaction overcomes the HFI, leading to well-defined electron spin states beneficial to the spin-filtering effect. The results provide a guideline for further optimization of the defect-engineered spin-filtering effect. DOI: 10.1103/PhysRevB.87.125202

  • 107.
    Tveritinova, E. A.
    et al.
    Moscow State University, Faculty of Chemistry, Moscow, Russia.
    Kulakova, I. I.
    Moscow State University, Faculty of Chemistry, Moscow, Russia.
    Zhitnev, Yu. N.
    Moscow State University, Faculty of Chemistry, Moscow, Russia.
    Kharlanov, A. N.
    Moscow State University, Faculty of Chemistry, Moscow, Russia.
    Fionov, A. V.
    Moscow State University, Faculty of Chemistry, Moscow, Russia.
    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.
    Lunin, V. V.
    Moscow State University, Faculty of Chemistry, Moscow, Russia.
    Effect of the detonation nanodiamond surface on the catalytic activity of deposited nickel catalysts in the hydrogenation of acetylene2013In: Russian Journal of Physical Chemistry, ISSN 0036-0244, E-ISSN 1531-863X, Vol. A 87, no 7, p. 1114-1120Article in journal (Refereed)
    Abstract [en]

    A comparative study is performed of the catalytic activity of nanosized nickel deposited on deto nation synthesis nanodiamond (DND) and coal (CSUG) produced by burning sugar and crystalline quartz in the hydrogenation of acetylene. Nanosized nickel is obtained through the thermal decomposition of nickel formate under a dynamic vacuum. The catalysts are studied by means of scanning electron and transmission electron microscopy, Xray fluorescence, IRspectroscopy, Xray diffraction, and pulse microcatalytic method. It is shown that Ni/DND is an active catalyst of acetylene hydrogenation, considerably surpassing Ni/quartz and Ni/CSUG. The apparent activation energy of the hydrogenation of acetylene is calculated, and the region of the reaction are determined for all catalysts. It is found that the influence of the structure and nature of a functional coating of nanodiamond on the catalytic activity of Ni/DND deposited catalyst in the hydrogenation of acetylene. The ability of Ni/DND to hold active hydrogen is detected.

  • 108.
    Dagnelund, Daniel
    et al.
    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, San Diego, La Jolla, California, USA .
    Polimeni, A.
    INFM and Dipartimento di Fisica, Università di Roma “La Sapienza”, Roma, Italy.
    Capizzi, M.
    INFM and Dipartimento di Fisica, Università di Roma “La Sapienza,” Roma, Italy .
    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.
    Effect of thermal annealing on defects in post-growth hydrogenated GaNP2013In: Physica Status Solidi. C, Current topics in solid state physics, ISSN 1610-1634, E-ISSN 1610-1642, Vol. 10, no 4, p. 561-563Article in journal (Refereed)
    Abstract [en]

    Effect of thermal annealing on paramagnetic centers in post-growth hydrogenated GaN0.0081P0.9919 epilayer is examined by means of photoluminescence and optically detected magnetic resonance (ODMR) techniques. In recent studies, several Ga-interstitial (Gai) related centers were found to be activated by the presence of hydrogen in the hydrogenated GaNP alloys. These centers compete with near-band edge radiative recombination. Annealing at 400 ºC in Ar-ambient is found to cause quenching of the Gai-related ODMR signals that were activated by post-growth hydrogenation. We tentatively ascribe this effect to dissociation of the H-Gai complexes and subsequent out-diffusion of H.

  • 109.
    Dobrovolsky, Alexandr
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Kuang, Y. J.
    Department of Physics, University of California, La Jolla, California, USA.
    Sukrittanon, S.
    Graduate Program of Materials Science and Engineering, La Jolla, California, USA .
    Tu, C. W.
    Department of Electrical and Computer Engineering, University of California, San Diego, La Jolla, California, USA .
    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.
    Effects of N incorporation on Raman properties and band structure of GaP/GaNP core/shell nanowires2013In: Int. Conf. Nanowires (ICON2013), 2013, p. P2.31-Conference paper (Refereed)
  • 110.
    Filippov, Stanislav
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Wang, X. J.
    National Laboratory for Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai, China .
    Devika, M.
    Department of Nanobio Materials and Electronics, Gwangju Institute of Science and Technology, Gwangju, Republic of Korea .
    Koteeswara Reddy, N.
    Department of Nanobio Materials and Electronics, Gwangju Institute of Science and Technology, Gwangju 500712, Republic of Korea.
    Tu, C. W.
    Department of Electrical and Computer Engineering, University of California, San Diego, La Jolla, California, USA .
    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.
    Effects of Ni-coating on ZnO nanowires: A Raman scattering study2013In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 113, no 21, p. 214302-1-214302-6Article in journal (Refereed)
    Abstract [en]

    Structural properties of ZnO/Ni core/shell nanowires (NWs) are studied in detail by means of Raman spectroscopy. It is shown that formation of the Ni shell leads to passivation of surface states responsible for the observed enhanced intensity of the A1(LO) Raman mode of the bare ZnO NWs. It also causes appearance of 490 cm−1 and 710 cm−1 modes that are attributed to local vibrational modes of a defect/impurity (or defects/impurities). This defect is concluded to be preferably formed in annealed ZnO/Ni NWs and is unlikely to contain a Ni atom, as the same Raman modes were also reported for the Ni-free ZnO nanostructures. From our resonant Raman studies, we also show that the ZnO/Ni core/shell NWs exhibit an enhanced Raman signal with a multiline structure involving A1(LO). This observation is attributed to combined effects of an enhanced Fröhlich interaction at the ZnO/Ni heterointerface and coupling of the scattered light with local surface plasmons excited in the Ni shell. The plasmonic effect is also suggested to allow detection of carbon-related species absorbed at the surface of a single ZnO/Ni NW, promising for applications of such structures as efficient nano-sized gas sensors.

  • 111.
    Puttisong, Yuttapoom
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Wang, X. J.
    National Laboratory for Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai, China .
    Buyanova, Irina
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Geelhaar, L.
    Paul-Drude-Institut fur Festkörpelektronik, Berlin, Germany.
    Ptak, A. J.
    National Renewable Energy Laboratory, Golden, Colorado, USA.
    Tu, C. W.
    Department of Electrical and Computer Engineering, University of California, San Diego, La Jolla, California, USA .
    Chen, Weimin
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Efficient room-temperature nuclear spin hyperpolarization of a defect atom in a semiconductor2013In: Nature Communications, ISSN 2041-1723, E-ISSN 2041-1723, Vol. 4, no 1751Article in journal (Refereed)
    Abstract [en]

    Nuclear spin hyperpolarization is essential to future solid-state quantum computation using nuclear spin qubits and in highly sensitive magnetic resonance imaging. Though efficient dynamic nuclear polarization in semiconductors has been demonstrated at low temperatures for decades, its realization at room temperature is largely lacking. Here we demonstrate that a combined effect of efficient spin-dependent recombination and hyperfine coupling can facilitate strong dynamic nuclear polarization of a defect atom in a semiconductor at room temperature. We provide direct evidence that a sizeable nuclear field (~150 Gauss) and nuclear spin polarization (~15%) sensed by conduction electrons in GaNAs originates from dynamic nuclear polarization of a Ga interstitial defect. We further show that the dynamic nuclear polarization process is remarkably fast and is completed in <5 μs at room temperature. The proposed new concept could pave a way to overcome a major obstacle in achieving strong dynamic nuclear polarization at room temperature, desirable for practical device applications.

  • 112.
    Stehr, Jan Eric
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Chen, S. L.
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Knutsen, K. E.
    Svensson, B. G.
    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.
    Electron Paramagnetic Resonance Investigations of Defects in Electron Irradiated ZnO2013Conference paper (Other academic)
  • 113.
    Ren, Q. J.
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Chen, S. L.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    Devika, M.
    Department of Nanobio Materials and Electronics, Gwangju Institute of Science and Technology, Gwangju, Republic of Korea .
    Koteeswara Reddy, N.
    Department of Nanobio Materials and Electronics, Gwangju Institute of Science and Technology, Gwangju 500712, Republic of Korea.
    Tu, C. W.
    Department of Electrical and Computer Engineering, University of California, San Diego, La Jolla, California, USA .
    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.
    Enhanced Efficiency of Light Emission From from ZnO/Ni Core/shell Nanowires: Effects of Surface Plasmons.2013Conference paper (Refereed)
    Abstract [en]

    Enhancement of light emission mediated via surface plasmons is shown in ZnO/Ni core/shell nanowires, based on time-resolved photoluminescence measurements. The obtained results are promising for future light emitters with spin-enabling functionality.

  • 114.
    Buyanova, Irina
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Chen, Weimin
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Excitonic and defect properties of nanostructured ZnO2013Conference paper (Refereed)
  • 115.
    Chen, Weimin
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Wang, X. J.
    National Laboratory for Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai, China .
    Puttisong, Yuttapoom
    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, San Diego, La Jolla, California, USA .
    Ptak, A. J.
    National Renewable Energy Laboratory, Golden, Colorado.
    Geelhaar, Lutz
    Paul-Drude-Institut für Festkörpelektronik, Berlin, Germany.
    Riechert, Henning
    Paul-Drude-Institut für Festkörpelektronik, Berlin, Germany.
    Exploring room-temperature spin functionality in non-magnetic semiconductor nanostructures.: Invited talk at the 5th IEEE International Nanoelectronics Conference (IEEE INEC 2013), Singapore, Jan.2-4, 2013.2013Conference paper (Other academic)
  • 116.
    Chen, Weimin
    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.
    Wang, X. J.
    National Laboratory for Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai, China .
    Buyanova, Irina
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Extraordinary Room-Temperature Spin Functionality In A Non-Magnetic Semiconductor2013Conference paper (Other academic)
  • 117.
    Chen, Weimin
    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.
    Wang, X. J.
    National Laboratory for Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai, China .
    Buyanova, Irina
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Ptak, Aaron J.
    National Renewable Energy Laboratory, Golden, Colorado, USA.
    Tu, C. W.
    Department of Electrical and Computer Engineering, University of California, San Diego, La Jolla, California, USA .
    Geelhaar, L.
    Paul-Drude-Institut für Festkörpelektronik, Berlin, Germany.
    Riechert, H.
    Paul-Drude-Institut für Festkörpelektronik, Berlin, Germany.
    Ga interstitials: usual grown-in defects with unusual room-temperature spin functionality in dilute nitrides2013Conference paper (Other academic)
  • 118.
    Dobrovolsky, Alexander
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Chen, Shula
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Kuang, Y. J.
    Department of Physics, University of California, La Jolla, California, USA.
    Sukrittanon, S.
    Graduate Program of Materials Science and Engineering, La Jolla, California, USA.
    Tu, C. W.
    Department of Electrical and Computer Engineering, University of California, San Diego, La Jolla, California, USA.
    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.
    Optical properties of GaP/GaNP core/shell nanowires: a temperature-dependent study2013In: Nanoscale Research Letters, ISSN 1931-7573, E-ISSN 1556-276X, Vol. 8, no 1, p. 239-Article in journal (Refereed)
    Abstract [en]

    Recombination processes in GaP/GaNP core/shell nanowires (NWs) grown on Si are studied by employing temperature-dependent continuous wave and time-resolved photoluminescence (PL) spectroscopies. The NWs exhibit bright PL emissions due to radiative carrier recombination in the GaNP shell. Though the radiative efficiency of the NWs is found to decrease with increasing temperature, the PL emission remains intense even at room temperature. Two thermal quenching processes of the PL emission are found to be responsible for the degradation of the PL intensity at elevated temperatures: (a) thermal activation of the localized excitons from the N-related localized states and (b) activation of a competing non-radiative recombination (NRR) process. The activation energy of the latter process is determined as being around 180 meV. NRR is also found to cause a significant decrease of carrier lifetime.

  • 119.
    Stehr, Jan Eric
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Dobrovolsky, Alexandr
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Kuang, Y. J.
    Department of Physics, University of California, La Jolla, California, USA.
    Sukrittanon, S.
    Graduate Program of Materials Science and Engineering, La Jolla, California, USA .
    Tu, C. W.
    Department of Electrical and Computer Engineering, University of California, San Diego, La Jolla, California, USA .
    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.
    Optically detected magnetic resonance investigation of GaP and GaP/GaNP/GaNP Nanowires2013In: 2013 MRS Fall Meeting, 2013Conference paper (Refereed)
  • 120.
    Dagnelund, Daniel
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Stehr, Jan E.
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Yu Egorov, A
    St Petersburg Academic University, Russia .
    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.
    Optically detected magnetic resonance studies of point defects in quaternary GaNAsP epilayers grown by vapor phase epitaxy2013In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 102, no 2, p. 021910-Article in journal (Refereed)
    Abstract [en]

    Defect properties of quaternary GaNAsP/GaP epilayers grown by vapor phase epitaxy (VPE) are studied by photoluminescence and optically detected magnetic resonance techniques. Incorporation of more than 0.6% of nitrogen is found to facilitate formation of several paramagnetic defects which act as competing carrier recombination centers. One of the defects (labeled as Ga-i-D) is identified as a complex defect that has a Ga interstitial (Ga-i) atom residing inside a Ga tetrahedron as its core. A comparison of Ga-i-D with other Ga-i-related defects known in ternary GaNP and GaNAs alloys suggests that this defect configuration is specific to VPE-grown dilute nitrides.

  • 121.
    Stehr, Jan Eric
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Chen, S. L.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    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.
    Photo-EPR and Photoluminescence Excitation Studies of Defects/Impurities Responsible for Upconversion Effects in Bulk ZnO crystals.2013Conference paper (Refereed)
  • 122.
    Ren, Q. J.
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Chen, Weimin
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Devika, M.
    Department of Nanobio Materials and Electronics, Gwangju Institute of Science and Technology, Gwangju, Republic of Korea .
    Koteeswara Reddy, N.
    Department of Nanobio Materials and Electronics, Gwangju Institute of Science and Technology, Gwangju 500712, Republic of Korea.
    Tu, C. W.
    Department of Electrical and Computer Engineering, University of California, San Diego, La Jolla, California, USA .
    Buyanova, Irina
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Plasmonic effects in ZnO/Ni core-shell nanowires.2013Conference paper (Refereed)
  • 123.
    Ren, Q. J.
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Chen, Weimin
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Devika, M.
    Department of Nanobio Materials and Electronics, Gwangju Institute of Science and Technology, Gwangju, Republic of Korea .
    Koteeswara Reddy, N.
    Department of Nanobio Materials and Electronics, Gwangju Institute of Science and Technology, Gwangju 500712, Republic of Korea.
    Tu, C. W.
    Department of Electrical and Computer Engineering, University of California, San Diego, La Jolla, California, USA .
    Buyanova, Irina
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Plasmonic effects in ZnO/Ni core-shell nanowires.2013Conference paper (Refereed)
  • 124.
    Koval'chuk, Andrii
    et al.
    V. Lashkaryov Institute of Semiconductor Physics of National Academy of Sciences of Ukraine, Kiev, Ukraine.
    Rudko, Galyna
    V. Lashkaryov Institute of Semiconductor Physics of National Academy of Sciences of Ukraine, Kiev, Ukraine.
    Fediv, Volodymyr
    Department of Biophysics and Medical Informatics, Bukovinian State Medical University, Chernivtsi, Ukraine.
    Ren, Qijun
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    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.
    Polymer Matrix Role in Light Absorption and Emission by Nano-CdS/PVA Composite2013Conference paper (Refereed)
    Abstract [en]

    Influence of a polymeric medium on the light absorption and emissionprocesses of composite nano-CdS/polyvinyl alcohol is studied by activating different absorption-emission routes via changing of excitation wavelengths. The mechanisms are analyzed by employing the time-resolved photoluminescence spectroscopy. It is shown that thepolymeric component of the composite contributes mainly to the excitation processes of photoluminescence via absorption of external laser excitation and its following transfer to the CdS nanoparticles that are incorporated into polymer matrix. The composite emission occurs mostly within the nanoparticles. It is also shown that time-decays of the photoluminescence emission from the CdS nanoparticles embedded in the composite depend on the excitation wavelength. Such behavior is ascribed to the interplay between the intrinsic nanoparticles excitation and extrinsic feeding of the nanoparticles via energy transfer from the excited polymer matrix. Possible mechanisms of the observed energy transfer are also discussed.

  • 125.
    Koval'chuk, A. O.
    et al.
    V. Lashkaryov Institute of Semiconductor Physics of National Academy of Sciences of Ukraine, Kiev, Ukraine.
    Rudko, G. Yu,
    V. Lashkaryov Institute of Semiconductor Physics of National Academy of Sciences of Ukraine, Kiev, Ukraine.
    Fediv, V. I.
    Department of Biophysics and Medical Informatics, Bukovinian State Medical University, Chernivtsi, Ukraine.
    Ren, Q. J.
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Pozina, G.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics.
    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.
    Probing host-guest interactions in organic/inorganic nanocomposite by time-resolved photoluminescence2013In: 2013 EMRS Fall Meeting, 2013Conference paper (Refereed)
  • 126.
    Wang, X. J.
    et al.
    National Laboratory for Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai, China .
    Buyanova, Irina
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Chen, Weimin
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Promoting dynamic nuclear spin polarization of PIn in InP.2013Conference paper (Refereed)
  • 127.
    Dobrovolsky, Alexandr
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Stehr, Jan Eric
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Kuang, Y. J.
    Department of Physics, University of California, La Jolla, California, USA.
    Sukrittanon, S.
    Graduate Program of Materials Science and Engineering, La Jolla, California, USA .
    Tu, C. W.
    Department of Electrical and Computer Engineering, University of California, San Diego, La Jolla, California, USA .
    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.
    Recombination processes in GaP/GaNP core/shell nanowires.2013Conference paper (Refereed)
  • 128.
    Puttisong, Yuttapoom
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Wang, X. J.
    National Laboratory for Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai, China .
    Buyanova, Irina
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Chen, Weimin
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Role of hyperfine interaction on room room-temperature defect-enabled spin blockade and spin filtering functionalities in GaNAs alloys2013Conference paper (Other academic)
  • 129.
    Rudko, G. Yu,
    et al.
    V. Lashkaryov Institute of Semiconductor Physics of National Academy of Sciences of Ukraine, Kiev, Ukraine.
    Kovalchuk, A. O.
    V. Lashkaryov Institute of Semiconductor Physics of National Academy of Sciences of Ukraine, Kiev, Ukraine.
    Fediv, V. I.
    Department of Biophysics and Medical Informatics, Bukovinian State Medical University, Chernivtsi, Ukraine.
    Ren, Q. J.
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    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.
    Pozina, Galia
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Role of the host polymer matrix in light emission processes in nano-CdS/poly vinyl alcohol composite2013In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 543, p. 11-15Article in journal (Refereed)
    Abstract [en]

    Participation of a polymeric media in light-emitting processes of composite nano-CdS/polyvinyl alcohol is studied by probing different absorption-emission routes via adjustment of excitation wavelengths. It is shown that the polymeric constituent of the composite contributes chiefly to the photoluminescence excitation processes via absorption and excitation transfer to the embedded CdS nanoparticles while the composite emission occurs mostly within the nanoparticles.

  • 130.
    Puttisong, Yuttapoom
    et al.
    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.
    Ptak, Aaron J.
    National Renewable Energy Laboratory, Golden, Colorado, USA.
    Tu, C. W.
    Department of Electrical and Computer Engineering, University of California, San Diego, La Jolla, California, USA .
    Geelhaar, Lutz
    Paul-Drude-Institut für Festkörpelektronik, Berlin, Germany.
    Riechert, H.
    Paul-Drude-Institut für Festkörpelektronik, Berlin, Germany.
    Chen, Weimin
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Room-temperature defect-enabled electron spin amplifier in a non-magnetic semiconductor2013Conference paper (Other academic)
  • 131.
    Puttisong, Yuttapoom
    et al.
    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.
    Ptak, Aaron J.
    National Renewable Energy Laboratory, Golden, Colorado.
    Tu, C. W.
    Department of Electrical and Computer Engineering, University of California, San Diego, La Jolla, California, USA .
    Geelhaar, Lutz
    Paul-Drude-Institut für Festkörpelektronik, Berlin, Germany.
    Riechert, Henning
    Paul-Drude-Institut für Festkörpelektronik, Berlin, Germany.
    Chen, Weimin
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Room-Temperature Electron Spin Amplifier Base on Ga(In)NAs Alloys2013In: Advanced Materials, ISSN 0935-9648, E-ISSN 1521-4095, Vol. 25, no 5, p. 738-742Article in journal (Refereed)
    Abstract [en]

    The first experimental demonstration of a spin amplifier at room temperature is presented. An efficient, defect-enabled spin amplifier based on a non-magnetic semiconductor, Ga(In)NAs, is proposed and demonstrated, with a large spin gain (up to 2700% at zero field) for conduction electrons and a high cut-off frequency up to 1 GHz.

  • 132.
    Puttisong, Yuttapoom
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Wang, X. J.
    National Laboratory for Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai, China .
    Buyanova, Irina
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Ptak, Aaron J.
    National Renewable Energy Laboratory, Golden, Colorado, USA.
    Tu, C. W.
    Department of Electrical and Computer Engineering, University of California, San Diego, La Jolla, California, USA .
    Geelhaar, Lutz
    Paul-Drude-Institut für Festkörpelektronik, Berlin, Germany.
    Riechert, H.
    Paul-Drude-Institut für Festkörpelektronik, Berlin, Germany.
    Chen, Weimin
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Room-temperature spin functionality in non-magnetic semiconductor thin films and quantum structures2013Conference paper (Other academic)
  • 133.
    Dobrovolsky, Alexandr
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Persson, Per
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Kuang, Y. J.
    Department of Physics, University of California, La Jolla, California, USA.
    Sukrittanon, S.
    Graduate Program of Materials Science and Engineering, La Jolla, California, USA .
    Tu, C. W.
    Department of Electrical and Computer Engineering, University of California, San Diego, La Jolla, California, USA .
    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.
    Signatures of N incorporation in Raman and optical properties of GaP/GaNP core/shell nanowires2013In: 2013 MRS Fall Meeting, 2013Conference paper (Refereed)
    Abstract [en]

    GaP/GaNP core shell NWs is a novel material system that has been most recently suggested for applications in solar cells. Adding nitrogen not only allow to tune the bandgap energy of GaNP alloy but also causes splitting of conduction band (CB) states, promising for intermediate band solar cells with improved efficiency. The purpose of this work is to investigate effects of N incorporation on band structure of such GaP/GaNxP1-x core/shell NWs using photoluminescence (PL) and photoluminescence excitation (PLE) spectroscopies. Structural quality of the wires will be also evaluated from Raman measurements.The GaP/GaN0.009P0.991core/shell NWs studied in this work were grown on Si (111) substrates by gas-source molecular beam epitaxy (MBE). The GaP NW cores were grown under the vapor liquid-solid (VLS) mechanism, whereas the GaNP shell was formed via the step-mediated growth. The resulted core/shell NWs were found to have an axial length of about 2.5 μm, a total diameter of about 220 nm, and a typical diameter of the GaP core of ~110 nm. According to performed TEM measurements, the NWs predominantly have zincblende structure with some inclusions of the wurtzite crystal phase. Excellent structural quality of the wires was concluded based on the performed Raman measurements. The Raman scattering spectra were found to contain several first-order Raman modes including intense and sharp peaks at 366 and 403 cm-1 and weaker modes at 387, 397 and 499 cm-1. The first two modes are typical for zinc-blende GaP and are related to transverse-optic (TO) and longitudinal-optical (LO) phonons, respectively. The spectral positions of these modes were unaffected by the N incorporation indicating that the formed GaNP shell is unstrained. The Raman mode at 499 cm-1 peak is related to the Ga-N bond vibrations, confirming the formation of the GaNP alloy. The 397 cm-1 peak can be identify as a surface optical (SO) phonon mode due to its sensitivity to the dielectric constant of an external medium.It is also found that incorporation of N causes a dramatic increase of the PL intensity, which can be easily detected at room temperature even from a single wire. This is accompanied by a shortening of the PL decay time revealed from the performed transient PL measurements. We attribute these changes to the N-induced transformation of the band gap from the indirect one in GaP to a direct band gap in the GaNP alloy. Secondly, N incorporation causes a red shift of the fundament absorption edge revealed via the PLE measurements due to the bowing effect. The red shift of the conduction band (CB) edge is accompanied by a strong blue shift of the Γ CB state. This is ascribed to the splitting of the host CB states that are strongly perturbed by N. The revealed changes in the band structure are potentially beneficial for the applications of GaNP/GaP NWs in novel intermediate band solar cell structures with high efficiency.

  • 134.
    Chen, Weimin
    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.
    Wang, X. J.
    National Laboratory for Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai, China .
    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, San Diego, La Jolla, California, USA .
    Ptak, A. J.
    National Renewable Energy Laboratory, Golden, Colorado, USA.
    Geelhaar, Lutz
    Paul-Drude-Institut für Festkörpelektronik, Berlin, Germany.
    Riechert, H.
    Paul-Drude-Institut für Festkörpelektronik, Berlin, Germany.
    Spin functional non-magnetic semiconductors for future spintronics2013Conference paper (Other academic)
  • 135.
    Chen, Weimin
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Beyer, Jan
    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.
    Suraprapapich, S
    Department of Electrical and Computer Engineering, University of California at San Diego, La Jolla, USA .
    Tu, C. W.
    Department of Electrical and Computer Engineering, University of California, San Diego, La Jolla, California, USA .
    Spin properties of InAs/GaAs quantum dot structures relevant to room-temperature spintronics.2013Conference paper (Refereed)
  • 136.
    Chen, Weimin
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Beyer, Jan
    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.
    Suraprapapich, S
    Department of Electrical and Computer Engineering, University of California at San Diego, La Jolla, USA .
    Tu, C. W.
    Department of Electrical and Computer Engineering, University of California, San Diego, La Jolla, California, USA .
    Spin properties of InAs/GaAs quantum dot structures relevant to room-temperature spintronics2013In: XXII International Materials Research Congress, 2013Conference paper (Refereed)
  • 137.
    Dagnelund, Daniel
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Puustinen, J.
    Guina, M.
    Buyanova, Irina
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Chen, Weimin
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Study of grown-in defects in GaBiAs grown at low temperatures by molecular beam epitaxy2013In: : , 2013Conference paper (Other academic)
  • 138.
    Buyanova, Irina
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Chen, Weimin
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Understanding key properties of ZnO nanostructures relevant to advanced optoelectronic applications.2013Conference paper (Refereed)
  • 139.
    Dagnelund, Daniel
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Vorona, I.P.
    Institute of Semiconductor Physics, National Academy of Sciences of Ukraine, Kiev, Ukraine .
    Nosenko, G.
    Institute of Semiconductor Physics, National Academy of Sciences of Ukraine, Kiev 03028, Ukraine .
    Wang, X. J.
    National Laboratory for Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai, China .
    Tu, C. W.
    Department of Electrical and Computer Engineering, University of California, San Diego, La Jolla, California, USA .
    Yonezu, H.
    Department of Electrical and Electronic Engineering, Toyohashi University of Technology, Japan .
    Polimeni, A.
    INFM and Dipartimento di Fisica, Università di Roma “La Sapienza”, Roma, Italy.
    Capizzi, M.
    INFM and Dipartimento di Fisica, Università 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.
    Buyanova, Irina
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    An optically detected magnetic resonance study of effects of hydrogenation on non-radiative defects in GaNP and GaNAs alloys2012Conference paper (Other academic)
  • 140.
    Dagnelund, Daniel
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Ren, Q. J.
    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.
    Murayama, A.
    Graduate School of Information Science and Technology, Hokkaido University, Japan.
    Antiferromagnetic coupling in CdSe/ZnMnSe quantum dot structures2012In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 101, no 5, p. 052405-1-052405-Article in journal (Refereed)
    Abstract [en]

    Spin polarization of nonmagnetic CdSe quantum dots (QDs) coupled to adjacent ZnMnSe diluted magnetic semiconductor (DMS) is investigated by CW and time-resolved magneto-optical spectroscopy under tunable laser excitation. Efficient enhancement in the degree of σ circular polarization of photoluminescence from the CdSe QDs is observed under optical excitation at the σ+-active exciton state of the DMS. The fact that the enhancement persists much longer than the exciton lifetime of the DMS rules out a role of the DMS excitons. A possible explanation is discussed in terms of antiferromagnetic coupling between the excitons in QDs and aligned Mn ions in DMS.

  • 141.
    Tveritinova, E A
    et al.
    Moscow MV Lomonosov State University.
    Kulakova, I I
    Moscow MV Lomonosov State University.
    Zhitnev, Yu N
    Moscow MV Lomonosov State University.
    Fionov, A V
    Moscow MV Lomonosov State University.
    Lund, Anders
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    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.
    Lunin, V V
    Moscow MV Lomonosov State University.
    Catalytic conversion of C(2)-C(3) alcohols on detonation nanodiamond and its modifications2012In: Russian Journal of Physical Chemistry, ISSN 0036-0244, E-ISSN 1531-863X, Vol. 86, no 1, p. 26-31Article in journal (Refereed)
    Abstract [en]

    The catalytic activity of detonation nanodiamond and its modifications obtained through treatment with hydrogen or air at elevated temperatures is studied in the conversion of C(2)-C(3) alcohols. The catalysts were characterized by means of electron microscopy, optical (FTIR) spectroscopy, elemental analysis and pulse microcatalytic method. It has been established that nanodiamond exhibits high catalytic activity in the conversion of alcohols. The oxidizing and reducing treatment of nanodiamond changes its activity and selectivity, and the activity of oxidized nanodiamond is considerably higher than that of reduced nanodiamond.

  • 142.
    Puttisong, Yuttapoom
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    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.
    Ptak, Aaron J.
    National Renewable Energy Laboratory, Golden, Colorado, USA.
    Tu, Charles W.
    Department of Electrical and Computer Engineering, University of California, San Diego, La Jolla, California, USA .
    Geelhaar, Lutz
    Paul-Drude-Institut für Festkörpelektronik, Berlin, Germany.
    Riechert, Henning
    Paul-Drude-Institut für Festkörpelektronik, Berlin, Germany.
    Chen, Weimin
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Defect-enabled Room-temperature Spin Functionality in Ga(In)NAs2012Conference paper (Other academic)
    Abstract [en]

    Efficient generation, maintaining, manipulation and detection of electron spin polarization and coherence at room-temperature (RT) in semiconductors is a prerequisite for the success of future semiconductor spintronics. Potential spintronic devices are expected to be based on fundamental building blocks such as spin filters (or spin injectors or spin aligners), spin amplifiers and spin detectors. During the past decade spin filters and spin detectors have been a main focal point of intense research efforts in the field of semiconductor spintronics that have led to many innovative approaches and encouraging developments. In contrast, experimental developments in spin amplifiers have been extremely limited. At present, realization of efficient RT spin functionality remains to be a great challenge and a hotly pursued research topic.

    In this work, we explore a new and unconventional approach of defect-enabled spin functionality in a non-magnetic semiconductor without requiring a magnetic layer or external magnetic fields. We demonstrated efficient defect-engineered spin filtering in Ga(In)NAs, which is capable of generating a remarkably high spin polarization degree (> 40%) of conduction electrons at RT. The highest spin polarization achieved to date by using this approach is up to 90 %. We also proposed a conceptually new spin amplifier by defect engineering and provided the first experimental demonstration of an efficient RT spin amplifier based on Ga(In)NAs with a spin gain up to 2700%! Such a spin amplifier is shown to be capable of amplifying a fast-modulating input spin signal while truthfully maintaining its time variation of the spin-encoded information, and is predicted to remain functional up to 1 GHz. By taking advantage of the spin amplification effect, we further showed that Ga(In)NAs can be employed as an efficient RT spin detector, with spin detection efficiency well exceeding 100%. Applications of such a spin-functional semiconductor material could potentially provide an attractive and viable solution to the current and important issues on RT spin injection, spin amplification and spin detection in semiconductors for future spintronics.

  • 143.
    Chen, Weimin
    et al.
    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.
    Defect-engineered spin functionality in a non-magnetic semiconductor.: Invited talk at the 3rd Nordic Workshop on Spintronics and Nanomagnetism, Varberg Kurort, April 22-25, 2012.2012Conference paper (Refereed)
  • 144.
    Stehr, Jan
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Wang, X. J.
    National Laboratory for Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai, China .
    Ren, F.
    Pearton, S.
    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.
    Defects in N, O and N, Zn implanted ZnO single crystals.2012Conference paper (Other academic)
  • 145.
    Chen, Shula
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    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.
    Donor bound excitons involving a hole from the B valence band in ZnO: Time resolved and magneto-photoluminescence studies (vol 99, 091909, 2011)2012Other (Refereed)
    Abstract [en]

    n/a

  • 146.
    Beyer, Jan
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Wang, P. H.
    Buyanova, Irina
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Suraprapapich, S.
    Department of Electrical and Computer Engineering, University of California at San Diego, La Jolla, USA .
    Tu, C. W.
    Department of Electrical and Computer Engineering, University of California, San Diego, La Jolla, California, USA .
    Chen, Weimin
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Effect of in-plane anisotropy on spin injection efficiency in InAs/GaAs nanostructures revealed in a longitudinal magnetic field2012Conference paper (Other academic)
  • 147.
    Puttisong, Yuttapoom
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    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, Charles W.
    Department of Electrical and Computer Engineering, University of California, San Diego, La Jolla, California, USA .
    Polimeni, A.
    INFM and Dipartimento di Fisica, Università di Roma “La Sapienza”, Italy.
    Capizzi, M.
    INFM and Dipartimento di Fisica, Università di Roma, Italy .
    Chen, Weimin
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Effect of post-growth hydrogen treatment and annealing on spin filtering functionality in Ga(In)NAs alloys2012Conference paper (Other academic)
  • 148.
    Beyer, Jan
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Wang, P. H.
    Linköping University, Department of Physics, Chemistry and Biology. 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.
    Suraprapapich, S
    Department of Electrical and Computer Engineering, University of California at San Diego, La Jolla, USA .
    Tu, C. W.
    Department of Electrical and Computer Engineering, University of California, San Diego, La Jolla, California, USA .
    Chen, Weimin
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Effects of a longitudinal magnetic field on spin injection and detection in InAs/GaAs quantum dot structures2012In: Journal of Physics: Condensed Matter, ISSN 0953-8984, E-ISSN 1361-648X, Vol. 24, no 14, p. 145304-Article in journal (Refereed)
    Abstract [en]

    Effects of a longitudinal magnetic field on optical spin injection and detection in InAs/GaAs quantum dot (QD) structures are investigated by optical orientation spectroscopy. An increase in optical and spin polarization of the QDs is observed with increasing magnetic field in the range of 0-2 T, and is attributed to suppression of exciton spin depolarization within the QDs that is promoted by hyperfine interaction and anisotropic electron-hole exchange interaction. This leads to a corresponding enhancement in spin detection efficiency of the QDs by a factor of up to 2.5. At higher magnetic fields when these spin depolarization processes are quenched, electron spin polarization in anisotropic QD structures (such as double QDs that are preferably aligned along a specific crystallographic axis) still exhibits rather strong field dependence under non-resonant excitation. In contrast, such field dependence is practically absent in more "isotropic" QD structures (e.g. single QDs). We attribute the observed effect to stronger electron spin relaxation in the spin injectors (i.e. wetting layer and GaAs barriers) of the lower-symmetry QD structures, which also explains the lower spin injection efficiency observed in these structures.

  • 149.
    Dagnelund, Daniel
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Vorona, I.P.
    Institute of Semiconductor Physics, National Academy of Sciences of Ukraine, Kiev, Ukraine .
    Nosenko, G.
    Institute of Semiconductor Physics, National Academy of Sciences of Ukraine, Kiev, Ukraine .
    Wang, X. J.
    National Laboratory for Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai, China .
    Tu, C. W.
    Department of Electrical and Computer Engineering, University of California, San Diego, La Jolla, California, USA .
    Yonezu, H.
    Department of Electrical and Electronic Engineering, Toyohashi University of Technology, Japan .
    Polimeni, A.
    INFM and Dipartimento di Fisica, Università di Roma “La Sapienza”, Roma, Italy.
    Capizzi, M.
    INFM and Dipartimento di Fisica, Universita` di Roma “La Sapienza”, Piazzale A. Moro 2,.
    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.
    Effects of hydrogenation on non-radiative defects in GaNP and GaNAs alloys: An optically detected magnetic resonance study2012In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 111, no 023501Article in journal (Refereed)
    Abstract [en]

    Photoluminescence and optically detected magnetic resonance techniques are utilized to study defect properties of GaNP and GaNAs alloys subjected to post-growth hydrogenation by low-energy sub-threshold ion beam irradiation. It is found that in GaNP H incorporation leads to activation of new defects, which has a Ga interstitial (Ga-i) atom at its core and may also involve a H atom as a partner. The observed activation critically depends on the presence of N in the alloy, as it does not occur in GaP with a low level of N doping. In sharp contrast, in GaNAs hydrogen is found to efficiently passivate Ga-i-related defects present in the as-grown material. A possible mechanism responsible for the observed difference in the H behavior in GaNP and GaNAs is discussed.

  • 150.
    Ren, Qijun
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Chen, Weimin
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Koteeswara Reddy, N.
    Department of Nanobio Materials and Electronics, Gwangju Institute of Science and Technology, Gwangju 500712, Republic of Korea.
    Tu, C. W.
    Department of Electrical and Computer Engineering, University of California, San Diego, La Jolla, California, USA .
    Buyanova, Irina
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Effects of Ni-coating on optical properties of ZnO/Ni core-shell nanowires2012Conference paper (Other academic)
1234567 101 - 150 of 430
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