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  • 301.
    Chen, Weimin
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Buyanova, Irina
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Nishibayashi, K.
    Kayanuma, K.
    Seo, K.
    Murayama, A.
    Oka, Y.
    Thaler, G.
    Frazier, R.
    Abernathy, C.R.
    Ren, F.
    Pearton, S.J.
    Pan, C.-C.
    Chen, G.-T.
    Chyi, J.-I
    Efficient spin relaxation in InGaN/GaN and InGaN/GaMnN quantum wells: An obstacle to spin detection2005In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 87, no 19, p. 192107-Article in journal (Refereed)
    Abstract [en]

    Transient magneto-optical spectroscopy of InGaNGaN and InGaNGaMnN quantum wells reveals a spin relaxation process with a characteristic time of 50 ps. We show that the observed spin relaxation is mediated by spin flips of individual carriers rather than by direct exciton spin flips, and is proposed to occur near the bottom of the exciton band (K=0). Nearly complete thermalization between spin sublevels of the excitons, observed immediately after the pulsed photoexcitation, is attributed to even faster spin relaxation of photogenerated hot carriers/excitons accompanying momentum and energy relaxation at high K vectors. © 2005 American Institute of Physics.

  • 302.
    Chen, Wei Min
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Buyanova, Irina
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Nishibayashi, K.
    Kay, K.
    Seo, K.
    Murayama, A.
    Oka, Y.
    Thaler, G.
    Frazier, R.
    Abernathy, C.R.
    Ren, F.
    Pearton, S.J.
    Pan, C.-C.
    Chen, G.-T.
    Chyi, J.-I.
    Zavada, J.M.
    Fast spin relaxation in InGaN/GaMnN spin LEDs: an obstacle to spin detection for future spintronics applications2005In: 3rd annual Nano Materials for Defense Applications Symposium,2005, 2005, p. 31-31Conference paper (Other academic)
    Abstract [en]

    Abstract Book of the 3rd annual Nano Materials for Defense Applications Symposium

  • 303.
    Syväjärvi, Mikael
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Nasi, L.
    Yazdi, Gholamreza
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Salviati, G.
    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.
    Yakimova, Rositsa
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Formation of ferromagnetic SiC: Mn phases2005In: Materials Science Forum, Vols. 483-485, 2005, Vol. 483-485, p. 241-244Conference paper (Refereed)
    Abstract [en]

    Ferromagnetic phases in as-grown SiC have been studied. An interpretation about the formation based on details of the phase appearance in the layers from optical microscopy, AFM, and TEM investigations is related to the growth. Some phases were found to have a nucleation at the edge of the phase and detailed TEM investigations show that the phases have an increased grain density at the edge while the main part of the phase is monocrystalline.

  • 304.
    Thinh, N.Q.
    et al.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Vorona, Igor
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Buyanova, Irina
    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, Semiconductor Materials. Linköping University, The Institute of Technology.
    Hong, Y.G.
    Department of Electrical and Computer Engineering, University of California, La Jolla, CA, USA.
    Tu, C.W.
    Department of Electrical and Computer Engineering, University of California, La Jolla, CA, USA.
    Limpijumnong, S.
    School of Physics, Institute of Science, Suranaree University of Technology, Nakhon Ratchasima, Thailand .
    Zhang, S.B.
    National Renewable Energy Laboratory, Golden, Colorado, USA.
    Ga-interstitial related defects in Ga(Al)NP2005In: 27th Int. Conf. on the Physics of Semicond,2004, American Institute of Physics (AIP), 2005, p. 259-260Conference paper (Other academic)
    Abstract [en]

    Twogrown-in Ga interstitial (Gai) defects in Ga(Al)NP are identified byoptically detected magnetic resonance (ODMR), from the characteristic hyperfine (HF)structure associated with the nuclear spin I=3/2 of the Gai.Both defects are concluded to be Gai-related complexes. Effects ofAl and N compositions on the HF structure shed lighton local surrounding of the Gai. ©2005 American Institute ofPhysics

  • 305.
    Izadifard, Morteza
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Bergman, Peder
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Vorona, Igor
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Chen, Weimin
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Buyanova, Irina
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Utsumi, A.
    Furukawa, Y.
    Moon, S.
    Wakahara, A.
    Yonezu, H.
    GaNxP1-x Alloys Lattice Matched to Si: A Novel Material System for Nano- Applications2005In: 3rd annual Nano Materials for Defense Applications Symposium,2005, 2005, p. 26-Conference paper (Other academic)
  • 306.
    Felici, M
    et al.
    INFM, Università “La Sapienza”, Roma, Italy .
    Polimeni, A.
    INFM, Università “La Sapienza”, Roma, Italy .
    Capizzi, M.
    INFM, Università “La Sapienza”, Roma, Italy .
    Dudiy, S.V.
    National Renewable Energy Laboratory, Golden, CO, USA.
    Zunger, A.
    National Renewable Energy Laboratory, Golden, CO, USA.
    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.
    Xin, H.P.
    Department of Electrical and Computer Engineering, University of California, La Jolla, CA, USA.
    Tu, C.W.
    Department of Electrical and Computer Engineering, University of California, La Jolla, CA, USA.
    High Energy Optical Transitions in Ga(PN): Contribution from Perturbed Valence Band2005In: AIP Conference Proceedings / Volume 772: PHYSICS OF SEMICONDUCTORS: 27th International Conference on the Physics of Semiconductors - ICPS-27 / [ed] José Menéndez, Chris G. Van de Walle, American Institute of Physics (AIP), 2005, p. 265-Conference paper (Refereed)
    Abstract [en]

    The GaP1–xNx conduction band is investigated experimentally (by excitation photoluminescence) andtheoretically (by pseudopotential supercells) for N concentrations up to x=3.5%and photon energies ranging from the optical absorption edge to3.2 eV. With increasing x: (i) a direct-like absorption edgedevelops smoothly and red-shifts rapidly overtaking energy-pinned cluster states; (ii)a broad absorption plateau appears between the X1c and the1c critical points of GaP; (iii) the 1c absorption edgebroadens and gradually disappears. Empirical pseudopotential calculations for GaP1-xNx randomalloy supercells account well for all the PLE results byconsidering N induced changes in the valence band overlooked sofar. ©2005 American Institute of Physics

  • 307.
    Chen, Weimin
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Buyanova, Irina
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Kayanuma, K.
    Nishibayashi, K.
    Seo, K.
    Murayama, A.
    Oka, Y.
    Toropov, A.A.
    Lebedev, A.V.
    Sorokin, S.V.
    Identification of a dominant mechanism for optical spin injection from a diluted magnetic semiconductor: Spin-conserving energy transfer via localized excitations2005In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 72, no 7, p. 73206-Article in journal (Refereed)
    Abstract [en]

    We provide compelling experimental evidence for a spin-conserving energy-transfer process via localized excitations as being responsible for the observed optical spin injection in ZnMnSe ZnCdSe quantum structures. We show that such a process is common and inherent to a diluted magnetic semiconductor because of strong potential fluctuations. © 2005 The American Physical Society.

  • 308. Thinh, N.Q.
    et al.
    Vorona, Igor
    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.
    Limpijumnong, S.
    Zhang, S.B.
    Hong, Y.G.
    Xin, H.P.
    Tu, C.W.
    Utsumi, A.
    Furukawa, Y.
    Moon, S.
    Wakahara, A.
    Yonezu, H.
    Important grown-in defects in novel dilute nitride (Al,In)GaNP: Ga interstitials2005In: 2005 MRS Spring Meeting,2005, 2005, p. 105-Conference paper (Other academic)
  • 309.
    Chen, Weimin
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Buyanova, Irina
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Nishibayashi, K.
    Kayanuma, K.
    Seo, K.
    Murayama, A.
    Oka, Y.
    Thaler, G.
    Frazier, R.
    Abernathy, C.R.
    Ren, F.
    Pearton, S.J.
    Pan, C.-C.
    Chen, G.-T.
    Chyi, J.-I.
    Zavada, J.M.
    InGaN quantum wells for spin detection: obstacles and prospects2005In: Workshop on Semiconductor Materials for Room Temperature Spintronic Applications,2005, 2005Conference paper (Other academic)
  • 310.
    Kyrychenko, F.V.
    et al.
    Department of Physics, University of Florida, Gainesville, FL, USA.
    Stanton, C.J.
    Department of Physics, University of Florida, Gainesville, FL, USA.
    Abernathy, C.R.
    Department of Materials Science and Engineering, University of Florida, Gainesville, FL, USA.
    Pearton, S.J.
    Department of Materials Science and Engineering, University of Florida, Gainesville, FL, USA.
    Ren, F.
    Department of Chemical Engineering, University of Florida, Gainesville, FL, USA.
    Thaler, G.
    Department of Materials Science and Engineering, University of Florida, Gainesville, FL, USA.
    Frazier, R.
    Department of Materials Science and Engineering, University of Florida, Gainesville, FL, USA.
    Buyanova, Irina
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Bergman, J. P:
    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, Semiconductor Materials. Linköping University, The Institute of Technology.
    Investigation of a GaMnN/GaN/InGaN structure for spinLED2005In: 27th Int. Conf. on the Physics of Semicond,2004 / [ed] José Menéndez, Chris G. Van de Walle, American Institute of Physics (AIP), 2005, p. 1319-1320Conference paper (Other academic)
    Abstract [en]

    Theoreticaland experimental studies of GaMnN/GaN/InGaN structure for a spin LEDdevice were performed. Strong electron spin relaxation was experimentally observedin a InGaN/GaN quantum well. It is shown that thestrong spin relaxation might result from the built-in piezoelectric fieldin strained wurzite heterostructures. A five level k · pmodel was used for microscopic calculations of the structure inversionasymmetry induced spin-orbit interaction. The magnitude of this interaction isshown to be comparable with that in InGaAs/GaAs quantum structures.©2005 American Institute of Physics

  • 311.
    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.

  • 312.
    Buyanova, Irina
    et al.
    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, Materials Science .
    New insight on electronic properties of GaNP alloy2005In: 27th Int. Conf. on the Physics of Semicond,2004, 2005, p. 271-Conference paper (Other academic)
  • 313.
    Kayanuma, K.
    et al.
    Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai, Japan .
    Tomita, T.
    Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai, Japan .
    Murayama, A.
    Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai, Japan .
    Oka, Y.
    Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai, Japan .
    Toropov, A.A.
    A.F. Ioffe Physico‐Technical Institute, Russian Academy of Sciences, St. Petersburg, Russia .
    Ivanov, S.V.
    A.F. Ioffe Physico‐Technical Institute, Russian Academy of Sciences, St. Petersburg, Russia .
    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.
    Optical study of spin injection dynamics in double quantum wells of II-VI diluted magnetic semiconductors2005In: AIP Conf. Proc. 772: PHYSICS OF SEMICONDUCTORS: 27th International Conference on the Physics of Semiconductors - ICPS-27 Date: 26-30 July 2004, American Institute of Physics (AIP), 2005, p. 1387-1388Conference paper (Other academic)
    Abstract [en]

    The spin injection process is studied in double quantum wells ofZnMnSe and ZnCdSe with a tunneling barrier by circularly-polarized transientphotoluminescence spectroscopy. The result shows two types of spin injectionsin the time ranges of 30 and 1000 ps. Theobserved spin injection processes are quantitatively interpreted by the individualtunneling of electrons and holes based on the rate equationanalysis. ©2005 American Institute of Physics

  • 314. Thinh, N.Q.
    et al.
    Vorona, Igor
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    Buyanova, Irina A.
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Chen, Weimin
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    Limpijumnong, S.
    School of Physics, Institute of Science, Suranaree University of Technology, Nakhon Ratchasima 30000, Thailand.
    Zhang, S.B.
    National Renewable Energy Laboratory, Golden, CO 80401, United States.
    Hong, Y.G.
    Department of Electrical and Computer Engineering, University of California, San Diego, CA 92093-0407, United States.
    Xin, H.P.
    Department of Electrical and Computer Engineering, University of California, San Diego, CA 92093-0407, United States.
    Tu, C.W.
    Department of Electrical and Computer Engineering, University of California, San Diego, CA 92093-0407, United States.
    Utsumi, A.
    Department of Electrical and Electronic Engineering, Toyohashi University of Technology, Toyohashi, Aichi, 441-8580, Japan.
    Furukawa, Y.
    Department of Electrical and Electronic Engineering, Toyohashi University of Technology, Toyohashi, Aichi, 441-8580, Japan.
    Moon, S.
    Department of Electrical and Electronic Engineering, Toyohashi University of Technology, Toyohashi, Aichi, 441-8580, Japan.
    Wakahara, A.
    Department of Electrical and Electronic Engineering, Toyohashi University of Technology, Toyohashi, Aichi, 441-8580, Japan.
    Yonezu, H.
    Department of Electrical and Electronic Engineering, Toyohashi University of Technology, Toyohashi, Aichi, 441-8580, Japan.
    Properties of Ga-interstitial defects in AlxGa 1-xNyP1-y2005In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 71, no 12Article in journal (Refereed)
    Abstract [en]

    A detailed account of the experimental results from optically detected magnetic resonance (ODMR) studies of grown-in defects in (Al)GaNP alloys, prepared by molecular beam epitaxy, is presented. The experimental procedure and an in-depth analysis by a spin Hamiltonian lead to the identification of two Gai defects (Gai-A and Gai-B). New information on the electronic properties of these defects and the recombination processes leading to the observation of the ODMR signals will be provided. These defects are deep-level defects. In conditions when the defect is directly involved in radiative recombination of the near-infrared photoluminescence band, the energy level of the Gai-B defect was estimated to be deeper than ~1.2 eV from either the conduction or valence band edge. In most cases, however, these defects act as nonradiative recombination centers, reducing the efficiency of light emission from the alloys. They can thus undermine the performance of potential photonic devices. High thermal stability is observed for these defects. ©2005 The American Physical Society.

  • 315.
    Buyanova, Irina
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Izadifard, Morteza
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Chen, Wei Min
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Kim, J.
    Ren, F.
    Thaler, G.
    Abernathy, C.R.
    Pearton, S.J.
    Pan, C.-C.
    Chen, G.-T.
    Chyi, J.-I.
    Zavada, J.M.
    Spin injection and spin loss in GaMnN/InGaN Light-Emitting Diodes2005In: AIP Conference Proceedings, ISSN 0094-243X, E-ISSN 1551-7616, Vol. 772, p. 1399-1400Article in journal (Refereed)
  • 316.
    Chen, Weimin
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Buyanova, Irina
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Nishibayashi, K.
    Kayanuma, K.
    Seo, K.
    Murayama, A.
    Oka, Y.
    Thaler, G.
    Frazier, R.
    Abernathy, C.R.
    Pearton, S.J.
    Kim, Jihyun
    Ren, F.
    Kyrychenko, F.V.
    Stanton, C.
    Pan, C.-C.
    Chen, G.T.
    Chyi, J.I.
    Zavada, J.M.
    Spin relaxation in InGaN/Ga(Mn)N quantum wells2005In: Bulletin of the American physical society, ISSN 0003-0503, Vol. 50, p. 609-609Article in journal (Refereed)
    Abstract [en]

    Proc. 2005 APS March Meeting, March 21-25, 2005; Los Angeles, CA, USA

  • 317.
    Buyanova, Irina
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    Chen, Weimin
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    Kayanuma, K.
    Murayama, A.
    Oka, Y.
    Lebedev, A. V.
    Toropov, A. A.
    Sorokin, S. V.
    Ivanov, S. V.
    Transient Spectroscopy of Optical Spin Injection in ZnMnSe/ZnCdSe Quantum Structures2005Conference paper (Refereed)
    Abstract [en]

    We show, by time-resolved magneto-photoluminescence (PL) spectroscopy in combination with selective laser excitation, that optical polarization of the ZnCdSe spin detector induced by spin injection from the ZnMnSe spin injector persists over a much longer time scale than the lifetime of the ZnMnSe excitons. This finding provides compelling experimental evidence that the dominant mechanism for the observed spin injection in the ZnMnSe/ZnCdSe structures should not be due to injection of the excitonic spins of the diluted magnetic semiconductor (DMS). It is rather due to e.g. a delayed spin injection arising from tunneling of individual carriers or/and trapped spins in ZnMnSe.

  • 318.
    Buyanova, Irina
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Izadifard, Morteza
    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 .
    Birch, Jens
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics.
    Chen, Wei Min
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Felici, M.
    Polimeni, A.
    Capizzi, M.
    Hong, Y.G.
    Xin, H.P.
    Tu, C.W.
    Unusual effects of hydrogen in GaNP alloys: A general property of dilute nitrides2005In: 2005 MRS Spring Meeting,2005, 2005, p. 135-Conference paper (Other academic)
  • 319.
    Buyanova, Irina
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    Izadifard, Morteza
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Kasic, A.
    Arwin, Hans
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Optics.
    Chen, Weimin
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    Xin, H. P.
    Hong, Y. G.
    Tu, C. W.
    Analysis of band anticrossing in GaNxP1-x alloys2004In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 70, p. 085209-Article in journal (Refereed)
    Abstract [en]

     Temperature-dependent absorption, photoluminescence excitation, and spectroscopic ellipsometry measurements are employed to accurately determine compositional and temperature dependences of the conduction band (CB) states in GaNP alloys. The CB edge and the higher lying Γc CB minimum (CBM) are shown to exhibit an apparently anticrossing behavior, i.e., the N-induced redshift of the bandgap energy is accompanied by a matching blueshift of the Γc CBM. The obtained data can be phenomenologically described by the band anticrossing model. By considering strong temperature dependence of the energy of the interacting N level, which has largely been overlooked in earlier studies of GaNP, the interacting N level can be attributed to the isolated substitutional NP and the coupling parameter is accurately determined.

  • 320.
    Syväjärvi, Mikael
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Stanciu, V.
    Izadifard, Morteza
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Chen, Weimin
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    Buyanova, Irina
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    Svedlindh, P.
    Yakimova, Rositsa
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    As-grown 4H-SiC epilayers with magnetic properties2004In: SILICON CARBIDE AND RELATED MATERIALS 2003, PRTS 1 AND 2, 2004, p. 747-750Conference paper (Refereed)
    Abstract [en]

    A growth process for diluted magnetic SiC has been explored for as-grown epitaxiallayers by introducing Mn ions. Depending on the growth conditions, either high Mn doping orexcess concentrations with second phases may form in the layers. Under those conditions wherecompound phases appear, there is a magnetic response in the material as demonstrated usingSQUID measurements with a transition temperature of 160K in the as-grown material. There is noresponse in layers for which the second phases have been removed by etching.

  • 321.
    Buyanova, Irina
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Izadifard, Morteza
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Kasic, A.
    Arwin, Hans
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Optics .
    Chen, Weimin
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Xin, H.P.
    Hong, Y.G.
    Tu, C.W.
    Compositional Dependence of conduction band states in GaNP alloys2004In: 5th International Conference on Low Dimensional Structures and Devices,2004, 2004, p. 64-Conference paper (Other academic)
  • 322.
    Buyanova, Irina
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    Chen, Weimin
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    Tu, C. W.
    Defects in dilute nitrides2004In: Journal of Physics: Condensed Matter, ISSN 0953-8984, E-ISSN 1361-648X, Vol. 16, p. S3027-S3035Article, review/survey (Refereed)
    Abstract [en]

    An overview of our present knowledge and understanding of defects in dilute nitrides will be provided and their important roles in determining the success of dilute nitrides for optoelectronic device applications will be underlined. A brief summary of experimental results of defects by various techniques reported so far in the literature will be given. Our recent results from optically detected magnetic resonance studies of grown-in non-radiative defects in Ga(In)NAs and Ga(Al, In)NP will be discussed in some detail, in an effort to provide chemical identification and experimental signatures of defects. Among them, intrinsic defects such as antisites and self-interstitials have been positively identified, and the effects of growth conditions, chemical compositions and post-growth processing on the formation of the defects were studied. The information retrieved from the experimental findings is expected to provide useful guidance for designing strategies to eliminate defects that are harmful to device performance.

  • 323.
    Chen, Weimin
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    Buyanova, Irina
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    Tu, C. W.
    Defects in dilute nitrides: significance and experimental signatures2004Conference paper (Refereed)
    Abstract [en]

    A brief review of experimental results of defects in dilute nitrides studied by various techniques reported so far in the literature is given. The emphasis is on experimental signatures of grown-in defects in Ga(In)NAs and Ga(Al)NP, which are expected to play important roles in device performance and in determining the success of this novel material system for applications in optoelectronics. The authors' recent results from optically detected magnetic resonance studies of grown-in intrinsic defects, i.e. AsGa antisite in Ga(In)NAs and Ga self-interstitials in Ga(Al,In)NP, are discussed in more detail, in an effort to provide detailed information on the chemical identification and the formation mechanism of the defects as well as to reveal their role in degrading the optical quality of the materials. The review aims not only to provide an overview of the present knowledge and understanding of defects in dilute nitrides, but also to stress the urgent need for concerted efforts to positively identify the most important defects that are harmful to device performance and to design strategies to suppress them during growth or to eliminate them by post-growth treatments.

  • 324.
    Buyanova, Irina
    et al.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Izadifard, Morteza
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Ivanov, Ivan Gueorguiev
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Birch, Jens
    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.
    Felici, M.
    Dipartimento di Fisica, Università di Roma “La Sapienza,” Roma, Italy .
    Polimeni, A.
    Dipartimento di Fisica, Università di Roma “La Sapienza,” Roma, Italy .
    Capizzi, M.
    Dipartimento di Fisica, Università di Roma “La Sapienza,” Roma, Italy .
    Hong, Y. G.
    Department of Electrical and Computer Engineering, University of California, La Jolla, California, USA .
    Xin, H. P.
    Department of Electrical and Computer Engineering, University of California, La Jolla, California, USA .
    Tu, C. W.
    Department of Electrical and Computer Engineering, University of California, La Jolla, California, USA .
    Direct experimental evidence for unusual effects of hydrogen on the electronic and vibrational properties of GaNxP1−x alloys: a proof for a general property of dilute nitrides2004In: Physical Review B Condensed Matter, ISSN 0163-1829, E-ISSN 1095-3795, Vol. 70, no 24, p. 245215-245219Article in journal (Refereed)
    Abstract [en]

    Direct experimental evidence for dramatic effects of hydrogen incorporation on the electronic structure and lattice properties of GaNxP1−x alloys is presented. By employing photoluminescence excitation spectroscopy, postgrowth hydrogenation is shown to reopen the band gap of the GaNP alloys and to efficiently reduce the N-induced coupling between the conduction band states. By Raman spectroscopy, these effects are shown to be accompanied by hydrogen-induced breaking of the Ga-P bond in the alloy, evident from disappearance of the corresponding vibrational mode. According to the performed Raman and x-ray diffraction measurements, the hydrogenation is also found to cause a strong expansion of the GaNP lattice, which changes the sign of strain from tensile in the as-grown GaNP epilayers to compressive in the posthydrogenated structures, due to the formation of complexes between N and H.

  • 325. Kayanuma, K.
    et al.
    Tomita, T.
    Murayama, A.
    Oka, Y.
    Buyanova, Irina
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    Chen, Weimin
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    Dynamical study of optical spin injection in ZnMnSe/ZnCdSe double quantum wells2004In: 10th Symposium on the Physics and Application of Spin-Related Phenomena in Semiconductors,2004, 2004, p. 88-91Conference paper (Other academic)
  • 326.
    Buyanova, Irina
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    Izadifard, Morteza
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Ivanov, Ivan Gueorguiev
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Birch, Jens
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics.
    Chen, Weimin
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    Polimeni, A.
    Capizzi, M.
    Hong, Y. G.
    Tu, C. W.
    Effects of hydrogen on electronic and crystalline structure of GaNP2004In: EMRS-2004 Spring Meeting,2004, 2004Conference paper (Other academic)
  • 327.
    Izadifard, Morteza
    et al.
    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, Functional Electronic Materials.
    Bergman, Peder
    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, Functional Electronic Materials.
    Utsumi, A.
    Furukawa, Y.
    Wakahara, A.
    Yonezu, H.
    Effects of rapid thermal annealing on optical quality of GaNP alloys2004In: EMRS-2004 Spring Meeting,2004, 2004, Vol. 151, p. 335-Conference paper (Refereed)
    Abstract [en]

    Significant improvements in radiative efficiency of GaNP epilayers grown on GaP substrates by solid-source molecular beam epitaxy (MBE) are achieved by post-growth rapid thermal annealing (RTA). From temperature-dependent CW and time-resolved photoluminescence (PL) spectroscopies combined with PL excitation measurements, the observed improvements are attributed to annealing out of competing nonradiative centres. This conclusion is supported by the following experimental evidence: reduced thermal quenching of the PL intensity resulting in a substantial (up to 18 times) increase at room temperature (RT) after RTA, and simultaneous improvements in carrier lifetime at RT deduced from time-resolved PL measurements.

  • 328.
    Chen, Weimin
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    Buyanova, Irina
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    Kayanuma, K.
    Chen, Z. H.
    Murayama, A.
    Oka, Y.
    Toropov, A. A.
    Sorokin, S. V.
    Ivanov, S. V.
    Kopev, P. S.
    Efficient spin depolarization in ZnCdSe spin detector: an important factor limiting optical spin injection efficiency in ZnMnSe/CdZnSe spin light-emitting structures2004In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 85, p. 5260-Article in journal (Refereed)
    Abstract [en]

     Spin depolarization of a ZnCdSe quantum-well spin detector (SD) in ZnMnSe/ZnCdSe light-emitting quantum structures is investigated by cw and time-resolved optical orientation spectroscopy. It is shown that spin depolarization is governed by three distinct spin relaxation processes with the corresponding polarization decay times of 850, 30, and <10 ps. The dominant and the fastest process is attributed to spin relaxation accompanying energy relaxation of hot excitons (and hot carriers) within the SD, providing evidence that it can be an important source of spin loss, leading to the observed limited efficiency of optical spin injection in the structures.

  • 329. Polyakov, A. Y.
    et al.
    Smirnov, N. B.
    Govorkov, A. V.
    Kim, J.
    Ren, F.
    Thaler, G. T.
    Frazier, R. M.
    Gila, B. P.
    Abernathy, C. R.
    Pearton, S. J.
    Buyanova, Irina
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    Rudko, G. Y.
    Chen, Weimin
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    Pan, C.-C.
    Chen, G.-T.
    Chyi, J.-I.
    Zavada, J. M.
    Electrical and luminescent properties and the spectra of deep centers in GaMnN/InGaN light-emitting diodes2004In: Journal of Electronic Materials, ISSN 0361-5235, E-ISSN 1543-186X, Vol. 33, no 3, p. 241-247Article in journal (Refereed)
    Abstract [en]

    Electrical and electroluminescent properties were studied for GaN/InGaN light-emitting diodes (LEDs) with the n-GaN layer up and with the top portion of the n layer made of undoped GaMnN to allow polarization modulation by applying an external magnetic field (so-called -spin-LEDs-). The contact annealing temperature was kept to 750°C, which is the thermal stability limit for retaining room-temperature magnetic ordering in the GaMnN layer. Measurable electroluminescence (EL) was obtained in these structures at threshold voltages of ∼15 V, with a lower EL signal compared to control LEDs without Mn. This is related to the existence of two parasitic junctions between the metal and the lower contact p-type layer and between the GaMnN and the n-GaN in the top contact layer.

  • 330.
    Chen, Weimin
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    Buyanova, Irina
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    Electron effective masses of dilute nitrides: Experiment2004In: Physics and Applications of Dilute Nitrides / [ed] Irina A. Buyanova and Weimin M. Chen, New York: Taylor & Francis , 2004, 1, p. 93-116Chapter in book (Other academic)
    Abstract [en]

    Since their development in the 1990s, it has been discovered that diluted nitrides have intriguing properties that are not only distinct from those of conventional semiconductor materials, but also are conducive to various applications in optoelectronics and photonics. The book examines these applications and presents a broad and in-depth look at the basic electronic and optical properties of diluted nitrides.

    The aim of Physics and Applications of Diluted Nitrides is to provide graduate students, researchers and engineers with a comprehensive overview of the present knowledge and future perspectives of diluted nitrides.

    Co-authored by a group of leading scientists in the field, this book brings the reader up to speed on the development and current state of diluted nitride applications, as well as the technologies to be developed in the near future.

  • 331.
    Izadifard, Morteza
    et al.
    Linköping University, Department of Physics, Chemistry and Biology.
    Bergman, Peder
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Vorona, Igor
    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.
    Buyanova, Irina
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Utsumi, A.
    Department of Electrical and Electronic Engineering, Toyohashi University of Technology, Hibarigaoka, Tempaku-cho, Toyohashi, Aichi, Japan .
    Furukawa, Y.
    Department of Electrical and Electronic Engineering, Toyohashi University of Technology, Hibarigaoka, Tempaku-cho, Toyohashi, Aichi, Japan .
    Moon, S.
    Department of Electrical and Electronic Engineering, Toyohashi University of Technology, Hibarigaoka, Tempaku-cho, Toyohashi, Aichi, Japan .
    Wakahara, A.
    Department of Electrical and Electronic Engineering, Toyohashi University of Technology, Hibarigaoka, Tempaku-cho, Toyohashi, Aichi, Japan .
    Yonezu, H.
    Department of Electrical and Electronic Engineering, Toyohashi University of Technology, Hibarigaoka, Tempaku-cho, Toyohashi, Aichi, Japan .
    Evaluation of optical quality and defect properties of GaNxP1−x alloys lattice matched to Si2004In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 85, p. 6347-Article in journal (Refereed)
    Abstract [en]

    By using a variety of optical characterization techniques, including cathodoluminescence, temperature-dependent cw- and time-resolved photoluminescence (PL), and PL excitation spectroscopies, high optical quality of the GaN0.018P0.982 epilayers lattice matched to Si substrates is demonstrated and is shown to be comparable to that of the “state-of-the-art” GaNP alloys grown on GaP substrates. The growth of GaNP on Si is, however, found to facilitate the formation of several point defects, including complexes involving Ga interstitial atoms (Gai).

  • 332.
    Toropov, A. A.
    et al.
    Ioffe Physico-Technical Institute of RAS, St. Petersburg, Russia.
    Terentev, Ya. V.
    Ioffe Physico-Technical Institute of RAS, St. Petersburg, Russia.
    Lebedev, A. V.
    Ioffe Physico-Technical Institute of RAS, St. Petersburg, Russia.
    Sorokin, S. V.
    Ioffe Physico-Technical Institute of RAS, St. Petersburg, Russia.
    Kaygorodov, V. A.
    Ioffe Physico-Technical Institute of RAS, St. Petersburg, Russia.
    Ivanov, S. V.
    Ioffe Physico-Technical Institute of RAS, St. Petersburg, Russia.
    Kopev, P. S.
    Ioffe Physico-Technical Institute of RAS, St. Petersburg, Russia.
    Buyanova, Irina
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    Bergman, Peder
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Monemar, Bo
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Chen, Weimin
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    Exciton magnetic polarons in a type II ZnMnSe/ZnSSe superlattice2004In: Physica status solidi (c)Special Issue: 11th International Conference on II–VI Compounds (II–VI 2003)Volume 1, Issue 4, physica status solidi (c), Vol. 1, Issue 4: WileyVCH , 2004, p. 847-850Conference paper (Refereed)
    Abstract [en]

    We present a time-resolved experimental study of excitonic magnetic polaron (EMP) dynamics in type II quantum wells ZnMnSe/ZnSSe. Two photoluminescence peaks were observed, which reflects coexistence of localized excitons and EMPs in the same sample. This was possible due to the competition of two localization mechanisms - magnetic localization of heavy holes in the ZnMnSe layers and non-magnetic localization of electrons in the ZnSSe layers.

  • 333.
    Buyanova, Irina
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    Izadifard, Morteza
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Chen, Weimin
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    Xin, H. P.
    Tu, C. W.
    Experimental evidence for N-induced strong coupling of host conduction band states in GaNP: insight into the dominant mechanism for giant band-gap bowing2004In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 69, p. 201303-Article in journal (Refereed)
    Abstract [en]

     Direct evidence for N-induced strong coupling of host conduction band (CB) states in GaNxP1-x is provided by photoluminescence excitation. It is manifested as: (1) a drastic change in the ratio of oscillator strengths between the optical transitions involving the CB minimum (CBM) and the high-lying Γ CB state; (2) a strong blueshift of the Γ CB state with increasing x accompanying a redshift of the CBM, (3) pinning of the localized N states and a newly emerging t2 (L or X3) CB state. These findings shed new light on the issue of the dominant mechanism responsible for the giant band-gap bowing of dilute nitrides.

  • 334. Thinh, N. Q.
    et al.
    Vorona, Igor
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    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, Functional Electronic Materials.
    Chen, Weimin
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    Hong, Y. G.
    Xin, H. P.
    Tu, C. W.
    Formation of Ga interstitials in (Al,In)yGa1-yNxP1-x alloys and their role in carrier recombination2004In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 85, p. 2827-Article in journal (Refereed)
    Abstract [en]

    Formation of complex defects involving a Ga interstitial (Gai) in (Al,In)yGa1-yNxP1-x alloys and their effects on optical quality are studied by photoluminescence (PL) and optically detected magnetic resonance spectroscopies. Introduction of these defects is shown to be largely promoted by incorporation of N. In quaternary alloys, concentrations of the defects are found to critically depend on the group III atoms that replace Ga, i.e., it is largely enhanced by the presence of Al in alloys, but is only marginally affected by In incorporation. The effect is attributed to differences in surface adatom mobilities of the group III atoms involved and their bonding strength with N. The revealed Gai complexes are shown to act as efficient nonradiative recombination centers degrading the PL efficiency. The defects exhibit high thermal stability and can only be partially removed by postgrowth rapid thermal annealing.

  • 335. Thinh, N. Q.
    et al.
    Vorona, Igor
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    Buyanova, Irina
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    Chen, Weimin
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    Limpijumnong, S.
    School of Physics, Institute of Science, Suranaree University of Technology, Nakhon Ratchasima, Thailand.
    Zhang, S. B.
    National Renewable Energy Laboratory, Golden, Colorado, USA.
    Hong, Y. G.
    Department of Electrical and Computer Engineering, University of California, La Jolla, California, USA.
    Tu, C. W.
    Department of Electrical and Computer Engineering, University of California, La Jolla, California, USA.
    Utsumi, A.
    Department of Electrical and Electronic Engineering, Toyohashi University of Technology, Toyohashi, Japan .
    Furukawa, Y.
    Department of Electrical and Electronic Engineering, Toyohashi University of Technology, Toyohashi, Japan .
    Moon, S.
    Department of Electrical and Electronic Engineering, Toyohashi University of Technology, Toyohashi, Japan .
    Wakahara, A.
    Department of Electrical and Electronic Engineering, Toyohashi University of Technology, Toyohashi, Japan .
    Yonezu, H.
    Department of Electrical and Electronic Engineering, Toyohashi University of Technology, Toyohashi, Japan .
    Identification of Ga-interstitial defects in GaNyP1−y and AlxGa1−xNyP1−y2004In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 70, no 12, p. 121201-Article in journal (Refereed)
    Abstract [en]

    Two Ga -interstitial (Gai) defects are identified by optically detected magnetic resonance as common grown-in defects in molecular beam epitaxial GaNyP1−y and AlxGa1−xNyP1−y. Characteristic hyperfine structure arising from spin interaction between an unpaired electron and a Ga nucleus is clearly resolved. The observed strong and nearly isotropic hyperfine interaction reveals an electron wave function of A1 symmetry that is highly localized at the Gai and thus a deep-level defect. Our analysis based on first-principles calculations suggests that these defects are complexes containing one Gai2+ .

  • 336. Toropov, A. A.
    et al.
    Terentev, Ya. V.
    Shubina, T. V.
    Sorokin, S. V.
    Sedova, I. V.
    Kaygorodov, V. A.
    Solovev, V. A.
    Meltser, B. Ya.
    Ivanov, S. V.
    Kopev, P. S.
    Buyanova, Irina
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    Chen, Weimin
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    InAs/Zn(Mn)Te/Cd(Mn)Se pseudomorphic quantum well structures for spintronic applications2004In: 11th International Conference on II-VI Compounds,2003, WileyVCH , 2004, p. 704-Conference paper (Refereed)
    Abstract [en]

    Zn(Mn)Te/Cd(Mn)Se quantum well heterostructures have been grown pseudomorphically on InAs(001) substrates using original InAs surface preparation techniques. The structures demonstrated bright PL in the 1-1.3 eV range and the effect of giant Zeeman splitting in the external magnetic field.

  • 337. Tomic, S.
    et al.
    OReilly, E. P.
    Klar, P. J.
    Gruning, H.
    Heimbrodt, W.
    Chen, Weimin
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    Buyanova, Irina
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    Influence of conduction-band nonparabolicity on electron confinement and effective mass in GaNxAs1−x∕GaAs quantum wells2004In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 69, p. 245305-Article in journal (Refereed)
    Abstract [en]

    We derive an analytical model to describe the conduction-band states of GaNAs-based quantum well structures, including the band anticrossing effect between N resonant states and the conduction-band edge. The predictions of the model are compared to those obtained using a full ten-band k·p model based on the same set of parameters. Both methods are then tested by comparison with the experimentally determined ground- and excited-state interband transition energies of GaNxAs1−x quantum wells of different well widths and N composition x obtained at 300 K and under hydrostatic pressures up to 2.0 GPa . We show that the transition energies can be described by a consistent set of material parameters in all the samples studied, and present how the conduction to valence-band offset ratio varies strongly with x in GaNxAs1−x∕GaAs quantum well structures. We conclude that the model presented can be used to predict the transition energies and electron subband structure of any GaNxAs1−x∕GaAs quantum well with well width between 2 and 25 nm , and N composition x between 1 and 4% , although further work is still required to confirm the optimum choice for the variation of band offset ratio with composition.

  • 338.
    Buyanova, Irina
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    Izadifard, Morteza
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Chen, Weimin
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    Kim, J.
    Ren, F.
    Thaler, G.
    Abernathy, C. R.
    Pearton, S. J.
    Pan, C.-C.
    Chen, G.-T.
    Chyi, J.-I.
    Zavada, J. M.
    On spin injection in GaMnN/InGaN Light-Emitting Diodes2004In: 3rd International Conference on Physics and Applications of Spin-Related Phenomena in Semiconductors PASPS III,2004, 2004Conference paper (Other academic)
  • 339.
    Buyanova, Irina
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    Izadifard, Morteza
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Chen, Weimin
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    Kim, J.
    Ren, F.
    Thaler, G.
    Abernathy, C. R.
    Pearton, S. J.
    Pan, C.-C.
    Chen, G.-T.
    Chyi, J. Y.
    Zavada, J. M.
    On the origin of spin loss in GaMnN/InGaN Light-Emitting Diodes2004In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 84, p. 2599-Article in journal (Refereed)
    Abstract [en]

     Spin polarization of GaMnN/InGaN light-emitting diodes grown by molecular beam epitaxy is analyzed. In spite of the ferromagnetic behavior of the GaMnN spin injector, the diodes are shown to exhibit very low efficiency of spin injection. Based on resonant optical orientation spectroscopy, the spin loss in the structures is shown to be largely due to fast spin relaxation within the InGaN spin detector, which itself destroys any spin polarization generated by optical spin orientation or electrical spin injection.

  • 340.
    Buyanova, Irina
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    Izadifard, Morteza
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Storasta, Liutauras
    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.
    Kim, J.
    Ren, F.
    Thaler, G.
    Abernathy, C. R.
    Pearton, S. J.
    Pan, C.-C.
    Chen, G.-T.
    Chyi, J.-I.
    Zavada, J. M.
    Optical and electrical characterization of (Ga,Mn)N/InGaN multiquantum well light-emitting diodes2004In: Journal of Electronic Materials, ISSN 0361-5235, E-ISSN 1543-186X, Vol. 33, no 5, p. 467-471Article in journal (Refereed)
    Abstract [en]

     (Ga,Mn)/N/InGaN multiquantum well (MQW) diodes were grown by molecular beam epitaxy (MBE). The current-voltage characteristics of the diodes show the presence of a parasitic junction between the (Ga,Mn)N and the n-GaN in the top contact layer due to the low conductivity of the former layer. Both the (Ga,Mn)N/InGaN diodes and control samples without Mn doping show no or very low (up to 10% at the lowest temperatures) optical (spin) polarization at zero field or 5 T, respectively. The observed polarization is shown to correspond to the intrinsic optical polarization of the InGaN MQW, due to population distribution between spin sublevels at low temperature, as separately studied by resonant optical excitation with a photon energy lower than the bandgap of both the GaN and (Ga,Mn)N. This indicates efficient losses in the studied structures of any spin polarization generated by optical spin orientation or electrical spin injection. The observed vanishing spin injection efficiency of the spin light-emitting diode (LED) is tentatively attributed to spin losses during the energy relaxation process to the ground state of the excitons giving rise to the light emission.

  • 341.
    Buyanova, Irina
    et al.
    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.
    Optical and electronic properties of GaInNP alloys - a new material for lattice matching to GaAs2004In: Physics and applications of dilute nitrides / [ed] Irina A. Buyanova and Weimin M. Chen, Kerala, India: Research Signpost , 2004, 1, p. -442Chapter in book (Other academic)
    Abstract [en]

    Since their development in the 1990s, it has been discovered that diluted nitrides have intriguing properties that are not only distinct from those of conventional semiconductor materials, but also are conducive to various applications in optoelectronics and photonics. The book examines these applications and presents a broad and in-depth look at the basic electronic and optical properties of diluted nitrides.

    The aim of Physics and Applications of Diluted Nitrides is to provide graduate students, researchers and engineers with a comprehensive overview of the present knowledge and future perspectives of diluted nitrides.

    Co-authored by a group of leading scientists in the field, this book brings the reader up to speed on the development and current state of diluted nitride applications, as well as the technologies to be developed in the near future.

  • 342.
    Buyanova, Irina
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    Bergman, Peder
    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.
    Thaler, G.
    Frazier, R.
    Abernathy, C. R.
    Pearton, S. J.
    Kim, J.
    Ren, F.
    Kyrychenko, F. V.
    Stanton, C. J.
    Pan, C.-C.
    Chen, G.-T.
    Chyi, J.-I.
    Zavada, J. M.
    Optical study of spin injection dynamics in InGaN/GaN quantum wells with GaMnN injection layers2004In: Journal of Vacuum Science & Technology B, ISSN 1071-1023, E-ISSN 1520-8567, Vol. 22, no 6, p. 2668-2672Article in journal (Refereed)
    Abstract [en]

     The spin injection dynamics of GaMnN/InGaN multiquantum well (MQW) light emitting diodes (LEDs) grown by molecular beam epitaxy were examined using picosecond-transient and circularly polarized photoluminescence (PL) measurements. Even with the presence of a room temperature ferromagnetic GaMnN spin injector, the LEDs are shown to exhibit very low efficiency of spin injection. Based on resonant optical orientation spectroscopy, the spin loss in the structures is shown to be largely due to fast spin relaxation within the InGaN MQW, which itself destroys any spin polarization generated by optical spin orientation or electrical spin injection. Typical photoluminescence decay times were 20-40 ns in both commercial GaN MQW LEDs with emission wavelengths between 420-470 nm and in the GaMnN/InGaN multi-quantum well MQW LEDs. In the wurtzite InGaN/GaN system, biaxial strain at the interfaces give rise to large piezoelectric fields directed along the growth axis. This built-in piezofield breaks the reflection symmetry of confining potential leading to the presence of a large Rashba term in the conduction band Hamiltonian which is responsible for the short spin relaxation times.

  • 343.
    Buyanova, Irina
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    Izadifard, Morteza
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Chen, Weimin
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    Xin, H. P.
    Tu, C. W.
    Origin of bandgap bowing in GaNP alloys2004Conference paper (Refereed)
    Abstract [en]

     By employing photoluminescence excitation (PLE) spectroscopy, the authors provide direct evidence for N-induced strong coupling and repelling of host conduction band (CB) states in GaNxP1-x. This strong coupling is manifested as (i) a drastic change in the ratio of oscillator strengths between the optical transition near Eg/rGamma and that near the CB minimum (CBM); (ii) a strong blue shift of the a1(Γ) state with increasing N composition accompanying a red shift of the CBM; (iii) pinning of the energies of the N-related levels; and (iv) the appearance of t2(L) or t2(X3) upon N incorporation of which the energy position is insensitive to N compositions. These findings shed new light on the controversial issue of the dominant mechanism responsible for the giant bandgap bowing of dilute nitrides.

  • 344.
    Buyanova, Irina
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    Izadifard, Morteza
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Chen, Weimin
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    Kim, J.
    Ren, F.
    Thaler, G.
    Abernathy, C. R.
    Pearton, S. J.
    Pan, C.-C.
    Chen, G.-T.
    Chyi, J.-I.
    Zavada, J. M.
    Origin of spin loss in GaMnN/InGaN Light-Emitting Diodes2004In: 2nd annual Nano Materials for Defense Applications Symposium,2004, 2004, p. 51-Conference paper (Other academic)
    Abstract [en]

      

  • 345.
    Chen, Weimin
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Buyanova, Irina
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Kayanuma, K.
    Murayama, A.
    Oka, Y.
    Toropov, A.A.
    Ivanov, S.V.
    Kop¿ev, P.S.
    Physics of optical spin injection in ZnMnSe/ZnCdSe Quantum Structures2004In: 5th International Conference on Low Dimensional Structures and Devices,2004, 2004, p. 18-Conference paper (Other academic)
  • 346.
    Buyanova, Irina
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    Chen, Weimin
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    Recombination processes in dilute nitrides2004In: Physics and Applications of Dilute Nitrides / [ed] Irina A. Buyanova and Weimin M. Chen, New York: Taylor & Francis , 2004, 1, p. 255-280Chapter in book (Other academic)
    Abstract [en]

    Since their development in the 1990s, it has been discovered that diluted nitrides have intriguing properties that are not only distinct from those of conventional semiconductor materials, but also are conducive to various applications in optoelectronics and photonics. The book examines these applications and presents a broad and in-depth look at the basic electronic and optical properties of diluted nitrides.

    The aim of Physics and Applications of Diluted Nitrides is to provide graduate students, researchers and engineers with a comprehensive overview of the present knowledge and future perspectives of diluted nitrides.

    Co-authored by a group of leading scientists in the field, this book brings the reader up to speed on the development and current state of diluted nitride applications, as well as the technologies to be developed in the near future.

  • 347. Pearton, SJ
    et al.
    Abernathy, CR
    Thaler, GT
    Frazier, RM
    Norton, DP
    Ren, F
    Park, YD
    Zavada, JM
    Buyanova, Irina A
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Chen, Weimin
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    Hebard, AF
    Wide bandgap GaN-based semiconductors for spintronics2004In: Journal of Physics: Condensed Matter, ISSN 0953-8984, E-ISSN 1361-648X, Vol. 16, no 7, p. R209-R245Article, review/survey (Refereed)
    Abstract [en]

    Recent results on achieving ferromagnetism in transition-metal-doped GaN, A1N and related materials are discussed. The field of semiconductor spintronics seeks to exploit the spin of charge carriers in new generations of transistors, lasers and integrated magnetic sensors. There is strong potential for new classes of ultra-low-power, high speed memory, logic and photonic devices based on spintronics. The utility of such devices depends on the availability of materials with practical magnetic ordering temperatures and most theories predict that the Curie temperature will be a strong function of bandgap. We discuss the current state-of-the-art in producing room temperature ferromagnetism in GaN-based materials, the origins of the magnetism and its potential applications.

  • 348.
    Buyanova, Irina
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    Rudko, G. Yu.
    Chen, Weimin
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    Toropov, A. A.
    Sorokin, S. V.
    Ivanov, S. V.
    Kopev, P. S.
    Control of spin functionality in ZnMnSe-based structures: Spin switching versus spin alignment2003In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 82, no 11, p. 1700-Article in journal (Refereed)
    Abstract [en]

     The ability of attaining desired spin functionality by adjusting structural design is demonstrated in diluted magnetic semiconductor (DMS) quantum structures based on II-VI semiconductors. The following spin enabling functions are achieved by tuning the ratio between the rates of exciton spin relaxation within the DMS and exciton escape from it to an adjacent nonmagnetic spin detector. Spin switching is realized when using a thin layer of Zn0.95Mn0.05Se as a spin manipulator and is attributed to a fast exciton escape from the DMS preceding the spin relaxation. Spin alignment is accomplished in tunneling structures where the presence of an energy barrier inserted between a spin manipulator (a DMS-based superlattice) and a spin detector ensures a slow escape rate from the DMS layer.

  • 349.
    Buyanova, Irina
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    Chen, Weimin
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    Kayanuma, K.
    Chen, Z. H.
    Murayama, A.
    Oka, Y.
    Toropov, A. A.
    Sorokin, S. V.
    Ivanov, S. V.
    Kopev, P. S.
    Efficiency Of Optical Spin Injection In ZnMnSe/CdZnSe Quantum Structures2003In: MRS Fall Meeting,2003, 2003, p. 258-Conference paper (Other academic)
  • 350.
    Buyanova, Irina
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    Chen, Weimin
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    Tu, C. W.
    Electronic structure of GaNP alloys: Insights from optical studies2003In: 204th Annual Meeting of the Electrochemical Society,2003, Proceedings - Electrochemical Society, Vol. 11: Electrochemical Society , 2003, p. 390-399Conference paper (Other academic)
    Abstract [en]

     In this paper we review our recent results from optical studies that have provided new insights into the N-induced modifications of the electronic structure of GaNP alloys. The near-band gap photoluminescence (PL) in the alloys is attributed to excitonic transitions at localized states likely related to N clusters. Their energy levels positions are found to be insensitive to N composition and thus unlikely contribute to the formation of the conduction band (CB) states in the alloys. Experimental evidence for a band crossover from an indirect to a direct band gap in GaNP at very low N compositions (∼0.5%) is provided from transient PL studies and absorption measurements. Admixing of the localized states with the extended CB states during alloy formation is shown to have counteracting effects on the temperature variation of the band gap of the GaNP alloys after the band crossover. It is also demonstrated that post-growth hydrogen implantation can reverse the N-induced effects.

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