liu.seSearch for publications in DiVA
Change search
Refine search result
2345678 201 - 250 of 431
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • oxford
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 201.
    Lee, Sun-Kyun
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Chen, Shula L
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Hongxing, D
    Fudan University, Shanghai.
    Chen, Z
    Fudan University, Shanghai.
    Chen, Weimin
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Buyanova, Irina A
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Long lifetime of free excitons in ZnO tetrapod structures2010Conference paper (Other academic)
  • 202.
    Buyanova, Irina A
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Magnetic Resonance Studies of Oxygen and Zinc-Vacancy Native Defects in Bulk ZnO Crystals2010In: Bulletin of the American Physical Society, 2010, p. A25.00001-Conference paper (Other academic)
    Abstract [en]

    ZnO is currently attracting increasing attention as a key material for a wide variety of electronic and optoelectronic applications. Optical, electrical, and magnetic properties of ZnO are believed to be strongly influenced by native defects. However, unambiguous experimental evidence confirming the formation of these defects in as-grown ZnO as well as evaluations of defect densities is currently sparse. In this talk we shall review our recent results from comprehensive defect characterization of as-grown bulk ZnO. By using electron paramagnetic resonance (EPR) and optically detected magnetic resonance (ODMR) spectroscopies, we show that both oxygen and zinc vacancies are formed in ZnO grown from melt without subjecting to irradiation. Defect concentrations are also determined. Based on spectral dependences of its EPR and ODMR signals, the VZn- defect is concluded to act as a deep acceptor responsible for the red emission peaking at around 1.6 eV, but does not participate in the green emission as commonly believed. The energy level position of the VZn corresponding to the (2-/-) transition is determined to be at Ev+1.0 eV. The center is also shown to exhibit a strong JT distortion with a JT energy of 0.8 eV. On the other hand, oxygen vacancies are probably less important in carrier recombination since they were only detected in EPR but not in ODMR. Annealing properties of both defects were also studied and higher thermal stability of the Zn vacancy was concluded. It was also suggested that annealing of the VZn centers is facilitated by thermally-activated diffusion of impurity atoms to the VZn sites. The obtained results are of importance for a better understanding of the defects in ZnO. They also provide useful information on control of electrical properties and defect-reaction induced degradation during device processing and operation, in the material that is commonly used as a substrate for epitaxial growth of layered device structures based on ZnO.

  • 203.
    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.
    Magneto-optical spectroscopy of spin injection and spin relaxation in spin light-emitting structures2010In: Handbook of Spintronic Semiconductors, Singapore: Pan Stanford Publishing , 2010, p. 289-323Chapter in book (Other academic)
    Abstract [en]

    This book provides an in-depth review of the rapidly developing field of spintronic semiconductors. It covers a broad range of topics, including growth and basic physical properties of diluted magnetic semiconductors based on II-VI, III-V and IV semiconductors, recent developments in theory and experimental techniques and potential device applications; its aim is to provide postgraduate students, researchers and engineers a comprehensive overview of our present knowledge and future perspectives of spintronic semiconductors.

  • 204.
    Chen, Shula
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Kyun Lee, Sun
    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.
    Dong, H X
    Fudan University.
    Sun, L
    Fudan University.
    Chen, Z H
    Fudan University.
    Buyanova, Irina
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    On the origin of suppression of free exciton no-phonon emission in ZnO tetrapods2010In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 96, no 3, p. 033108-Article in journal (Refereed)
    Abstract [en]

    Temperature dependent photoluminescence and cathodoluminescence (CL) spectroscopies are employed to investigate free exciton (FX) emissions in ZnO tetrapods. The intensity of the no-phonon line is found to be largely suppressed as compared with longitudinal optical phonon assisted transitions, in sharp contrast to bulk ZnO. From spatially resolved CL studies, this suppression is shown to strongly depend on structural morphology of the ZnO tetrapods and becomes most significant within areas with faceted surfaces. A model based on reabsorption due to multiple internal reflections in the vicinity of the FX resonance is suggested to account for the observed effect.

  • 205.
    Fionov, A.V.
    et al.
    Moscow MV Lomonosov State University.
    Lund, Anders
    Linköping University, Department of Physics, Chemistry and Biology, Chemical Physics . 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.
    Rozhkova, N.N.
    RAS.
    Buyanova, Irina
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Emelyanova, G.I.
    Moscow MV Lomonosov State University.
    Gorlenko, L.E.
    Moscow MV Lomonosov State University.
    Golubina, E.V.
    Moscow MV Lomonosov State University.
    Lokteva, E.S.
    Moscow MV Lomonosov State University.
    Osawa, E.
    Shinshu University.
    Lunin, V.V.
    Moscow MV Lomonosov State University.
    Paramagnetic centers in detonation nanodiamonds studied by CW and pulse EPR2010In: Chemical Physics Letters, ISSN 0009-2614, E-ISSN 1873-4448, Vol. 493, no 04-Jun, p. 319-322Article in journal (Refereed)
    Abstract [en]

    Dispersed detonation nanodiamonds have been studied by continuous-wave (CW) and pulse EPR techniques. The spectrum of bulk radicals (g = 2.0025 +/- 0.0002, a Lorentz line shape with Delta H-pp = 0.95 +/- 0.05 mT) dominated in CW EPR and prevented to record spectra from other paramagnetic species. The pulse EPR-spectrum was the superposition of the distorted P1-center spectrum with parameters (g = 2.0025, A(xx) = 2.57 mT, A(yy) = 3.08 mT, A(zz) = 4.07 mT), the H1-center spectrum (g = 2.0028) and the single line (g = 2.0025, DHpp = 0.40 +/- 0.05 mT) from other centers which may be assigned to surface radicals. The concentration of P1-centers has been estimated by CW EPR as 2 +/- 1 ppm N.

  • 206.
    Dagnelund, Daniel
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Vorona, Igor P
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Vlasenko, Leonid S
    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.
    Utsumi, A
    University of Technology, Toyohashi, Aichi, Japan.
    Furukawa, Y
    University of Technology, Toyohashi, Aichi, Japan.
    Wakahara, A
    University of Technology, Toyohashi, Aichi, Japan.
    Yonezu, H
    University of Technology, Toyohashi, Aichi, Japan.
    Buyanova, Irina A
    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.
    Phosphorus-related interfacial defect complex at a GaP/GaNP heterojunction2010Conference paper (Other academic)
    Abstract [en]

    For full exploration of dilute nitrides in device applications, a better understanding and control of defects located at interfaces involving e.g. Ga(In)NP are required. In this work we report on the first identification of a point defect situated at an interface between two semiconductors: GaNP and GaP. The defect is concluded to be a complex involving a P antisite or a P interstitial in its core, partnered with a neighboring impurity/defect aligned along a <111> direction, from detailed angular dependence studies of the optically detected magnetic resonance (ODMR) spectra at both X- and Q-band microwave frequencies. The principal g and A values, g=2.013, g=2.002, A=130x10-4 cm-1 and A=330x10-4 cm-1, are obtained from a spin Hamiltonian analysis. The interface nature of the defect is clearly evident from the absence of the ODMR lines originating from two out of four equivalent <111> orientations. Defect formation is shown to be facilitated by severe nitrogen ion bombardment under non-equilibrium growth conditions during solid-source molecular beam epitaxy and the defect is thermally stable upon post-growth thermal annealing.

  • 207.
    Buyanova, Irina
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Murayama, A
    Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai, Japan.
    Furuta, T
    Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai, Japan.
    Oka, Y
    Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai, Japan.
    Norton, D P
    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.
    Osinsky, A
    SVT Associates, Eden Prairie, MN, USA.
    Dong, J W
    SVT Associates, Eden Prairie, MN, USA.
    Tu, C W
    Department of Electrical and Computer Engineering, UC California, La Jolla, USA.
    Chen, Weimin
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Spin dynamics in ZnO-based materials2010In: Journal of Superconductivity and Novel Magnetism, ISSN 1557-1939, Vol. 23, no 1, p. 161-165Article in journal (Refereed)
    Abstract [en]

    In this work, we address the issue of spin relaxation and its relevance to spin detection in ZnO-based materials, by spin-polarized, time-resolved magneto-optical spectroscopy. We have found that spin relaxation is very fast, i.e. about 100 ps for donor bound excitons in wurtzite ZnO, despite of a weak spin–orbit interaction. We also reveal that alloying of ZnO with Cd enhances spin relaxation, prohibiting ZnCdO/ZnO structures for efficient optical spin detection. On the other hand, a variation in strain field induced by lattice mismatch with substrates does not seem to lead to a noticeable change in spin relaxation. The observed fast spin relaxation, together with the limitation imposed by the band structure, are thus identified as the two most important factors that limit the efficiency of optical spin detection in the studied ZnO-based materials.

  • 208.
    Wang, Xingjun
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Puttisong, Yuttapoom
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Tu, Charles W
    Ptak, Aaron J
    Kalevich, Vladimir K
    Egorov, A Y
    Geelhaar, L
    Riechert, H
    Buyanova, Irina A
    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.
    Spin-blockade of dominant non-radiative carrier recombination channels via defects in Ga(In)NAs alloys2010In: Abstract Book of the MRS Spring Meeting, San Francisco, USA, April 5-9, 2010, 2010, p. EE6.6-Conference paper (Other academic)
  • 209.
    Wang, Xingjun
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Puttisong, Yuttapoom
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Tu, Charles W
    Ptak, Aaron J
    Kalevich, Vladimir K
    Egorov, A Y
    Geelhaar, L
    Riechert, H
    Buyanova, Irina A
    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.
    Spin-engineered suppression of dominant non-radiative shunt paths in Ga(In)NAs relevant to photovoltaic applications2010In: Abstract Book of the Materials Challenges in Alternative & Renewable Energy conference, 2010, p. 36-Conference paper (Other academic)
  • 210.
    Buyanova, Irina A
    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.
    Vacancy-related defects in ZnO2010In: Abstract book of the AVS International Symposium and Exhibition, Albuquerque, USA, October 17-22, 2010, 2010, p. 72-Conference paper (Other academic)
  • 211.
    Dagnelund, Daniel
    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.
    Furuta, T
    Institute of multidisciplinary Research for Advanced Materials, Tohoku University, Sendai, 980-8577, Japan.
    Hyomi, K
    Institute of multidisciplinary Research for Advanced Materials, Tohoku University, Sendai, 980-8577, Japan.
    Suoma, I
    Institute of multidisciplinary Research for Advanced Materials, Tohoku University, Sendai, 980-8577, Japan.
    Murayama, A
    n/a.
    Chen, Weimin
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Carrier and spin injection from ZnMnSe to CdSe quantum dots2009Conference paper (Other academic)
    Abstract [en]

    Optical carrier/exction and spin injection processes from a ZnMnSe dilute magnetic semiconductor (DMS) to CdSe quantum dots (QD’s) are studied in detail by means of spinpolarized magneto- photoluminescence (PL) and PL excitation spectroscopies. Efficiency of carrier/exciton transfer is found to be practically independent of width (Lb) of a ZnSe barrier layer inserted between the DMS and QD’s. This is tentatively explained in terms of photonexchange energy transfer. In sharp contrast, spin injection efficiency is found to be largely suppressed in the structures with large Lb, pointing towards increasing spin loss.

  • 212.
    Wang, Xingjun
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Puttisong, Yuttapoom
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Tu, C. W.
    Department of Electrical and Computer Engineering, University of California, La Jolla, California 92093, USA.
    Ptak, Aaron J.
    National Renewable Energy Laboratory, Golden, Colorado 80401, USA.
    Kalevich, V. K.
    A. F. Ioffe Physico-Technical Institute, St. Petersburg 194021, Russia.
    Egorov, A. Yu.
    A. F. Ioffe Physico-Technical Institute, St. Petersburg 194021, Russia.
    Geelhaar, L.
    Paul-Drude-Institut für Festkörpelektronik, 10117 Berlin, Germany.
    Riechert, H.
    Paul-Drude-Institut für Festkörpelektronik, 10117 Berlin, Germany.
    Chen, Weimin
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Buyanova, Irina
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Dominant recombination centers in Ga(In)NAs alloys: Ga interstitials2009In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 95, p. 241904-Article in journal (Refereed)
    Abstract [en]

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

  • 213.
    Buyanova, Irina A
    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.
    Wang, W M
    University of California.
    Tu, C W
    University of California.
    Chen, Weimin
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Effects of Ga doping on optical and structural properties of ZnO epilayers2009In: Superlattices and Microstructures, ISSN 0749-6036, E-ISSN 1096-3677, Vol. 45, no 4-5, p. 413-420Article in journal (Refereed)
    Abstract [en]

    Effects of Ga incorporation on electrical, structural and optical properties of ZnO epilayers are systematically studied by employing structural and optical characterization techniques combined with electrical and secondary ion mass spectrometry measurements. A non-monotonous dependence of free electron concentrations on Ga content is observed and is attributed to defect formation and phase separation. The former process is found to dominate for Ga concentrations of around 2-3x1020 cm-3. corresponding defects are suggested to be responsible for a broad red emission, which peaks at around 1.8 eV at K. Characteristic properties of this emission are well accounted for by assuming intracenter transitions at a deep center, of which the associated Huang-Rhys factor and mean phonon energy are determined. For higher Ga doping levels, the phase separation is found to be significant. It is that under these conditions only a minor fraction of incorporated Ga atoms form shallow donors, which leads to the observed dramatic decrease of carrier concentration.

  • 214.
    Beyer, Jan
    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.
    Suraprapapich, S
    n/a.
    Tu, C W
    n/a.
    Chen, Weimin
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Efficiency of spin injection in novel InAs quantum dots structures2009In: Abstract Book of the 14th International Conference on Modulated Semiconductor structures (MSS-14), Kobe, Japan, July 19 - 24, 2009, 2009, p. 164-Conference paper (Other academic)
  • 215.
    Wang, Xingjun
    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.
    Zhao, F
    n/a.
    Balocchi, A
    n/a.
    Marie, X
    Tu, C W
    Harmand, J C
    Chen, Weimin
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Efficient room temperature spin filter based on a non-magnetic semiconductor at zero magnetic field2009In: Abstract Book of the 2009 Electronic Materials Conference, University Park, Pennsylvania, USA, June 24-26 2009, 2009, p. 78-Conference paper (Other academic)
  • 216.
    Wang, Xingjun
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Puttisong, Yuttapoom
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Buyanova, Irina
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Carrère, Hélène
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Zhao, F
    n/a.
    Balocchi, A
    n/a.
    Marie, X
    n/a.
    Tu, C W
    n/a.
    Chen, Weimin
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Efficient room temperature spin filter based on GaNAs quantum wells2009In: Abstract Book of the 14th International Conference on Modulated Semiconductor structures (MSS-14), Kobe, Japan, July 19 - 24, 2009, 2009, p. 161-Conference paper (Other academic)
  • 217.
    Wang, Xingjun
    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.
    Zhao, F
    n/a.
    Lagarde, D
    n/a.
    Balocchi, A
    n/a.
    Marie, X
    n/a.
    Tu, C W
    n/a.
    Harmand, J C
    n/a.
    Chen, Weimin
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Efficient Spin Filter Based on Non-Magnetic Semiconductor GaNAs2009In: Integrated Photonics and Nanophotonics Research and Applications/Nonlinear Optics/Slow and Fast Light: Conference “Integrated Photonics and Nanophotonics Research and Applications”, Honolulu, Hawaii, USA, July 12‐17, 2009, 2009, p. IWD4-Conference paper (Refereed)
    Abstract [en]

    We provide experimental demonstration of a novel defect-engineered, efficient and switchable spin filter from GaNAs to generate, amplify and detect electron spin polarization at room temperature without a magnetic material or external magnetic fields.

  • 218.
    Zhao, F
    et al.
    University of Toulouse.
    Balocchi, A
    University of Toulouse.
    Truong, G
    University of Toulouse.
    Amand, T
    University of Toulouse.
    Marie, X
    University of Toulouse.
    Wang, Xingjun
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Buyanova, Irina A
    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.
    Harmand, J C
    CNRS.
    Electron spin control in dilute nitride semiconductors2009In: JOURNAL OF PHYSICS-CONDENSED MATTER, ISSN 0953-8984, Vol. 21, no 17, p. 174211-Article in journal (Refereed)
    Abstract [en]

    We report on a study of spin-dependent recombination processes (SDR) for conduction band electrons on deep paramagnetic centers in a series of GaAs1-yNy epilayers by time-resolved optical orientation experiments. We demonstrate that this dilute nitride compound can be used as an effective electron spin filter under a polarized optical excitation of appropriate intensity. This optimum intensity can moreover be controlled by adjusting the nitrogen composition in the layer.

  • 219.
    Beyer, Jan
    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.
    Suraprapapich, Suwaree
    Department of Electrical and Computer Engineering, University of California at San Diego, La Jolla, USA.
    Tu, Charles
    Department of Electrical and Computer Engineering, University of California at San Diego, La Jolla, USA.
    Chen, Weimin
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Free-carriers beat excitons in spin-injection contest2009Other (Other (popular science, discussion, etc.))
    Abstract [en]

    Quantum dots (QDs) are a promising building block for future spin-functional devices with applications in spintronics and quantum information processing. Essential to the success of these devices is the ability to create a desired spin orientation of charge carriers (electrons and holes) in QDs via the injection of spin-polarized carriers. Researchers have now shown that this can be done most efficiently using independent (free) carriers rather than electron-hole pairs (excitons).

  • 220.
    Wang, Xingjun
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Vlasenko, Leonid
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Pearton, S. J.
    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.
    Identification of native defects in as-grown ZnO single crystals2009In: Abstract Book of the 2009 Electronic Materials Conference, University Park, Pennsylvania, USA, June 24-26 2009, 2009, p. 78-Conference paper (Other academic)
  • 221.
    Lee, Sun Kyun
    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.
    Chen, Weimin
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Hongxing, D
    n/a.
    Chen, Z
    n/a.
    Buyanova, Irina
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Optical Characterizations of ZnO Tetrapod Nanostructures2009In: Proc. of 33rd Workshop on Compound Semiconductor Devices and Integrated Circuits, Malaga, Spain, May 17-20 2009, 2009, p. 4-7Conference paper (Other academic)
  • 222.
    Wang, Xingjun
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Vlasenko, Leonid
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Pearton, S J
    University of Florida.
    Chen, Weimin
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Buyanova, Irina A
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Oxygen and zinc vacancies in as-grown ZnO single crystals2009In: JOURNAL OF PHYSICS D-APPLIED PHYSICS, ISSN 0022-3727, Vol. 42, no 17, p. 175411-Article in journal (Refereed)
    Abstract [en]

    Oxygen and zinc vacancies are unambiguously shown to be formed in as-grown ZnO bulk crystals grown from melt without being subjected to irradiation, from electron paramagnetic resonance (EPR) and optically detected magnetic resonance (ODMR) studies. Concentrations of the defects in their paramagnetic charge states V-O(+) and V-Zn(-) are estimated to be similar to 2 x 10(14) cm(-3) and similar to 10(15) cm(-3), respectively. The V-Zn(-) defect is concluded to act as a deep acceptor and to exhibit large Jahn-Teller distortion by 0.8 eV. The energy level of the defect corresponding to the (2-/-) transition is E-v + 1.0 eV. The isolated Zn vacancy is found to be an important recombination centre and is concluded to be responsible for the red luminescence centred at around 1.6 eV. On the other hand, the oxygen vacancy seems to be less important in carrier recombination as it could be detected only in EPR but not in ODMR measurements. Neither isolated V-Zn(-) nor V-O(+) centres participate in the so-called green emission. It is also shown that whereas the concentrations of both defects can be reduced by post-growth annealing, the Zn vacancy exhibits higher thermal stability. The important role of residual contaminants such as Li in the annealing process is underlined.

  • 223.
    Murayama, A.
    et al.
    Institute of Multidisciplinar Research for Advanced Materials.
    Furuta, T.
    Institute of Multidisciplinar Research for Advanced Materials.
    Oshino, S.
    Institute of Multidisciplinar Research for Advanced Materials.
    Hyomi, K.
    Institute of Multidisciplinar Research for Advanced Materials.
    Sakuma, M.
    Institute of Multidisciplinar Research for Advanced Materials.
    Souma, I.
    Institute of Multidisciplinar Research for Advanced Materials.
    Dagnelund, Daniel
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Buyanova, Irina A.
    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.
    Propagation dynamics of exciton spins in a high-density semiconductor quantum dot system2009Conference paper (Refereed)
    Abstract [en]

    We study propagation dynamics of exciton spins in a system composed of high-density self-assembled quantum dots (QDs) of CdSe and a diluted magnetic semiconductor (DMS) layer of ZnMnSe, where spin-polarized excitons are generated in the DMS layer and are subsequently injected into the QDs. The degree of circular polarization, P, of excitonic photoluminescence at 5 T in the coupled QDs shows a rapid increase with increasing delay time after a linearly polarized pulsed excitation, indicating the exciton-spin injection from the ZnMnSe to CdSe-QDs. The P value tends to decay gradually because of the exciton-spin relaxation in the QDs after the injection. The spin-polarized excitons in the QD ensemble migrate simultaneously from the QDs with higher exciton energies to those with lower exciton energies, where the exciton-spins relax inside each dot during the migration. Therefore, the observed P values in the QD emission band are affected by this feeding of the relaxed spins.

  • 224.
    Wang, Xingjun
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Buyanova, Irina A
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Zhao, F
    Université de Toulouse.
    Lagarde, D
    Université de Toulouse.
    Balocchi, A
    Université de Toulouse.
    Marie, X
    Université de Toulouse.
    Tu, C W
    University of California.
    Harmand, J C
    LPN, France.
    Chen, Weimin
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Room-temperature defect-engineered spin filter based on a non-magnetic semiconductor.2009In: Nature Materials, ISSN 1476-1122, E-ISSN 1476-4660, Vol. 8, no 3, p. 198-202Article in journal (Refereed)
    Abstract [en]

    Generating, manipulating and detecting electron spin polarization and coherence at room temperature is at the heart of future spintronics and spin-based quantum information technology. Spin filtering, which is a key issue for spintronic applications, has been demonstrated by using ferromagnetic metals, diluted magnetic semiconductors, quantum point contacts, quantum dots, carbon nanotubes, multiferroics and so on. This filtering effect was so far restricted to a limited efficiency and primarily at low temperatures or under a magnetic field. Here, we provide direct and unambiguous experimental proof that an electron-spin-polarized defect, such as a Ga(i) self-interstitial in dilute nitride GaNAs, can effectively deplete conduction electrons with an opposite spin orientation and can thus turn the non-magnetic semiconductor into an efficient spin filter operating at room temperature and zero magnetic field. This work shows the potential of such defect-engineered, switchable spin filters as an attractive alternative to generate, amplify and detect electron spin polarization at room temperature without a magnetic material or external magnetic fields.

  • 225.
    Beyer, Jan
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Buyanova, Irina A
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Suraprapapich, Suwaree
    UC San Diego, USA.
    Tu, Charles
    UC San Diego, USA.
    Chen, Weimin
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Spin injection in lateral InAs quantum dot structures by optical orientation spectroscopy2009In: Nanotechnology, ISSN 0957-4484, E-ISSN 1361-6528, Vol. 20, no 37, p. 375401-Article in journal (Refereed)
    Abstract [en]

    Optical spin injection is studied in novel laterally-arranged self-assembled InAs/GaAs quantum dot structures, by using optical orientation measurements in combination with tunable laser spectroscopy. It is shown that spins of uncorrelated free carriers are better conserved during the spin injection than the spins of correlated electrons and holes in an exciton. This is attributed to efficient spin relaxation promoted by the electron–hole exchange interaction of the excitons. Our finding suggests that separate carrier injection, such as that employed in electrical spin injection devices, can be advantageous for spin conserving injection. It is also found that the spin injection efficiency decreases for free carriers with high momentum, due to the acceleration of spin relaxation processes.

  • 226.
    Murayama, A
    et al.
    Tohoku University.
    Furuta, T
    Tohoku University.
    Oshino, S
    Tohoku University.
    Hyomi, K
    Tohoku University.
    Sakuma, M
    Tohoku University.
    Souma, I
    Tohoku University.
    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.
    Chen, Weimin
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Transfer dynamics of spin-polarized excitons into semiconductor quantum dots2009In: Journal of Luminescence, ISSN 0022-2313, E-ISSN 1872-7883, Vol. 129, p. 1927-1930Article in journal (Refereed)
    Abstract [en]

    We study on the transfer dynamics of spin-polarized excitons into self-assembled quantum dots (QDs) of CdSe coupled with a diluted magnetic semiconductor (DMS) layer of ZnMnSe through a ZnSe barrier layer. A variation in the degree of circular polarization P of excitonic photoluminescence in the coupled QDs was observed between samples with different thicknesses (LB) of the non-magnetic barrier. Relatively high values of P (0.3) were obtained in the samples with LB=1 or 2 nm, and the time dependences of the P value indicate the spin-transfer dynamics. From the LB dependence of the spin-transfer time, the spin-transfer mechanism is discussed, namely spin-conserving energy transfer.

  • 227.
    Dagnelund, Daniel
    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.
    Furuta, T.
    Institute of multidisciplinary Research for Advanced Materials, Tohoku University, Sendai, 980-8577, Japan.
    Hyomi, K.
    Institute of multidisciplinary Research for Advanced Materials, Tohoku University, Sendai, 980-8577, Japan.
    Souma, I.
    Institute of multidisciplinary Research for Advanced Materials, Tohoku University, Sendai, 980-8577, Japan.
    Murayama, A.
    Institute of multidisciplinary Research for Advanced Materials, Tohoku University, Sendai, 980-8577, Japan.
    Chen, Weimin
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    Carrier and spin injection from ZnMnSe to CdSe quantum dots2008Conference paper (Other academic)
    Abstract [en]

    Optical carrier/exction and spin injection processes from a ZnMnSe dilute magnetic semiconductor (DMS) to CdSe quantum dots (QD’s) are studied in detail by means of spinpolarized magneto- photoluminescence (PL) and PL excitation spectroscopies. Efficiency of carrier/exciton transfer is found to be practically independent of width (Lb) of a ZnSe barrier layer inserted between the DMS and QD’s. This is tentatively explained in terms of photonexchange energy transfer. In sharp contrast, spin injection efficiency is found to be largely suppressed in the structures with large Lb, pointing towards increasing spin loss.

  • 228.
    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.
    Murayama, A.
    Furuta, T.
    Oka, Y.
    Norton, D. P.
    Pearton, S. J.
    Osinsky, A.
    Dong, J. W.
    Dominant factors limiting efficiency of optical spin detection in ZnO-based materials2008In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 92, p. 092103-Article in journal (Refereed)
    Abstract [en]

    Two dominant factors limiting efficiency of optical spin detection in ZnO-based materials system are identified from time-resolved optical orientation and magneto-optical studies. The first is related to the fundamental band structure of the materials characterized by a weak spin-orbit interaction. It leads to cancellation of circular polarization from the optical transitions between the conduction band and the A and B valence band states, which would otherwise carry the desired information on spin polarization of carriers. The second limiting factor is shown to be efficient carrier/exciton spin relaxation, i.e., about 45-80 ps.

  • 229.
    Dagnelund, Daniel
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    Wang, Xingjun
    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.
    Utsumi, A.
    Department of Electrical and Electronic Engineering, Toyohashi University of Technology, Toyohashi, Aichi, Japan.
    Furukawa, Y.
    Department of Electrical and Electronic Engineering, Toyohashi University of Technology, Toyohashi, Aichi, Japan.
    Wakahara, A.
    Department of Electrical and Electronic Engineering, Toyohashi University of Technology, Toyohashi, Aichi, Japan.
    Yonezu, H.
    Department of Electrical and Electronic Engineering, Toyohashi University of Technology, Toyohashi, Aichi, Japan.
    Effect of growth conditions on grown-in defect formation and luminescence efficiency in GaInNP epilayers grown by molecular-beam epitaxy.2008In: Physica status solidi (c)Special Issue: E-MRS 2007 Spring Meeting – Symposium F and Conference on Photonic Materials, Weinheim: Wiley-VCH Verlagsgesellschaft, 2008, Vol. 5, p. 460-463Conference paper (Refereed)
    Abstract [en]

    A detailed study of the impact of different growth conditions (i.e. ion bombardment, nitrogen flow and In content) on the defect formation in Ga(In)NP epilayers grown on GaP substrates by solid-source molecular beam epitaxy is performed. Reduced nitrogen ion bombardment during the growth is shown to significantly reduce formation of defects acting as competing recombination centers, such as a Ga interstitial defect and other unidentified defects revealed by optically detected magnetic resonance. Further, high nitrogen flow is found to be even more effective than the ion bombardment in introducing the defects. The incorporation of In by 5.1% is, on the other hand, found not to affect the introduction of defects. The results provide a useful insight into the formation mechanism of the defects that will hopefully shed light on a control of the defect introduction in the alloys by optimizing growth conditions.

  • 230.
    Wang, Xingjun
    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.
    Chen, Weimin
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    Hong, Y. G.
    Department of Electrical and Computer Engineering Univeristy of California, La Jolla, California 92093, USA.
    Tu, C. W.
    Department of Electrical and Computer Engineering University of California, La Jolla, California 92093, USA.
    Effects of grown-in defects on electron spin polarization in dilute nitride alloys2008In: 7th International Conference on Nitride Semiconductors ICNS-7,2007, phys. stat. sol. (c) vol. 5: WILEYVCH Verlag GmbH & Co. KGaA, Weinheim , 2008, p. 1529-Conference paper (Refereed)
    Abstract [en]

    Strong electron spin polarization in GaNAs epilayers and multiple quantum well structures is observed upon optical orientation at room temperature. The effect is explained in terms of spin dependent recombination (SDR) involving deep paramagnetic defects formed upon N incorporation in GaNAs. Concentration of the corresponding defects is shown to be enhanced during growth at low temperatures but is suppressed by post-growth annealing. Optically detected magnetic resonance (ODMR) measurements performed in the studied structures reveal two paramagnetic defects participating in carrier recombination. One of them is identified as a complex involving AsGa antisite. Correlation between concentrations of the defects monitored via ODMR and in optical orientation measurements is observed which suggests that the same defects may be involved in both processes.

  • 231.
    Buyanova, Irina
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    Wang, Xingjun
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    Pozina, G.
    Department of Materials Science and Engineering University of Florida, Gainesville, Florida 32611, USA.
    Chen, Weimin
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    Lim, W.
    Department of Materials Science and Engineering University of Florida, Gainesville, Florida 32611, USA.
    Norton, D. P.
    Department of Materials Science and Engineering University of Florida, Gainesville, Florida 32611, USA.
    Pearton, S. J.
    Department of Materials Science and Engineering University of Florida, Gainesville, Florida 32611, USA.
    Osinsky, A.
    SVT Associates Eden Prairie, Minnesota 55344, USA.
    Dong, J. W.
    SVT Associates Eden Prairie, Minnesota 55344, USA.
    Hertog, B.
    SVT Associates Eden Prairie, Minnesota 55344, USA.
    Effects of hydrogen on the optical properties of ZnCdO/ZnO quantum wells grown by molecular beam epitaxy2008In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 92, p. 261912-Article in journal (Refereed)
    Abstract [en]

    Temperature-dependent cw- and time-resolved photoluminescence (PL), as well as optically detected magnetic resonance (ODMR) measurements are employed to evaluate effects of deuterium (2H) doping on optical properties of ZnCdO/ZnO quantum well structures grown by molecular beam epitaxy. It is shown that incorporation of 2H from a remote plasma causes a substantial improvement in radiative efficiency of the investigated structures. Based on transient PL measurements, the observed improvements are attributed to efficient passivation by hydrogen of competing nonradiative recombination centers via defects. This conclusion is confirmed from the ODMR studies.

  • 232.
    Wang, Xingjun
    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.
    Chen, Weimin
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    Pan, C.J.
    Tu, C.W.
    Effects of stoichiometry on defect formation in ZnO epilayers grown by molecular-beam epitaxy: An optically detected magnetic resonance study2008In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 103, no 2, p. 023712-Article in journal (Refereed)
    Abstract [en]

    Photoluminescence (PL) and optically detected magnetic resonance are employed to study effects of nonstoichiometry during the growth on defect formation in ZnO epilayers grown by molecular-beam epitaxy (MBE). Several defects are revealed via monitoring the yellow PL emission (∼2.17 eV) and their magnetic resonance signatures are obtained. The defects are concluded to be common for the MBE growth and are facilitated during the off-stoichiometric growth conditions, especially under excess of oxygen. © 2008 American Institute of Physics.

  • 233.
    Dagnelund, Daniel
    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.
    Chen, Weimin
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    Murayama, A.
    Furuta, T.
    Hyomi, K.
    Souma, I.
    Oka, Y.
    Efficiency of optical spin injection and spin loss from a diluted magnetic semiconductor ZnMnSe to CdSe nonmagnetic quantum dots2008In: Physical Review B Condensed Matter, ISSN 0163-1829, E-ISSN 1095-3795, Vol. 77, no 3, p. 035437-Article in journal (Refereed)
    Abstract [en]

    Magneto-optical spectroscopy in combination with tunable laser spectroscopy is employed to study optical spin injection from a diluted magnetic semiconductor (DMS) ZnMnSe into nonmagnetic CdSe quantum dots (QDs). Observation of a DMS feature in the excitation spectra of the QD photoluminescence polarization provides clear evidence for optical spin-injection from the DMS to the QDs. By means of a rate equation analysis, the injected spin polarization is deduced to be about 32% at 5 T, decreasing from 100% before the injection. The observed spin loss is shown to occur during the spin injection process including crossing the heterointerfaces and energy relaxation within the QDs. © 2008 The American Physical Society.

  • 234.
    Dagnelund, Daniel
    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.
    Wang, Xingjun
    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.
    Utsumi, A.
    Furukawa, Y.
    Wakahara, A.
    Yonezu, H.
    Formation of grown-in defects in molecular beam epitaxial Ga(In)NP: effects of growth conditions and post-growth treatments2008In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 103, p. 063519-Article in journal (Refereed)
    Abstract [en]

    Effects of growth conditions and post-growth treatments, such as presence of N ions, N2 flow, growth temperature, In alloying, and postgrowth rapid thermal annealing (RTA), on formation of grown-in defects in Ga(In)NP prepared by molecular beam epitaxy are studied in detail by the optically detected magnetic resonance (ODMR) technique. Several common residual defects, such as two Ga-interstitial defects (i.e., Gai-A and Gai-B) and two unidentified defects with a g factor around 2 (denoted by S1 and S2), are closely monitored. Bombardment of impinging N ions on grown sample surface is found to facilitate formation of these defects. Higher N2 flow is shown to have an even more profound effect than a higher number of ions in introducing these defects. Incorporation of a small amount of In (e.g., 5.1%) in GaNP seems to play a minor role in the formation of the defects. In GaInNP with 45% of In; however, the defects were found to be abundant. Effect of RTA on the defects is found to depend on initial configurations of Gai-related defects formed during the growth. In the alloys where the Gai-A and Gai-B defects are absent in the as-grown samples (i.e., GaNP grown at a low temperature of 460 °C), the concentrations of the two Gai defects are found to increase after postgrowth RTA. This indicates that the defects originally introduced in the as-grown alloys have been transformed into the more thermally stable Gai-A and Gai-B during RTA. On the other hand, when the Gai-A and Gai-B are readily abundant (e.g., at higher growth temperatures (>=500 °C), RTA leads to a slight reduction of the Gai-A and Gai-B ODMR signals. The S2 defect is also shown to be thermally stable upon the RTA treatment.

  • 235.
    Wang, Xingjun
    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.
    Chen, Weimin
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    Zhao, F.
    Universit 769; de Toulouse, LPCNO: INSA, UPS, CNRS, 135 avenue de e Rangueil, 31077 Toulouse cedex, France.
    Lagarde, D.
    Université de Toulouse, LPCNO: INSA, UPS, CNRS, 135 avenue de e Rangueil, 31077 Toulouse cedex, France.
    Balocchi, A.
    Université de Toulouse, LPCNO: INSA, UPS, CNRS, 135 avenue de e Rangueil, 31077 Toulouse cedex, France.
    Marie, X.
    Université de Toulouse, LPCNO: INSA, UPS, CNRS, 135 avenue de e Rangueil, 31077 Toulouse cedex, France.
    Hong, Y. G.
    Department of Electrical and Computer Engineering University of California, La Jolla, CA92093, USA.
    Tu, C. W.
    Department of Electrical and Computer Engineering University of California, La Jolla, CA92093, USA.
    Harmand, J. C.
    LPN, route de Noazay, 91460 Marcoussis, France.
    Generating strong electron spin polarization at room temperature in GaNAs via spin-dependent recombination2008In: 5th International Conference on Physics and Applications of Spin-related Phenomena in Semiconductors PASPS V,2008, 2008Conference paper (Other academic)
    Abstract [en]

    The issues of generating and maintaining carrier spin polarization in semiconductors have attracted intense research efforts, not only due to their importance for future applications in spintronics but also due to the intriguing physics underpinning spin-dependent phenomena. Entering the family of semiconductors that exhibit attractive spin-dependent properties, Ga(In)NAs was most recently found to exhibit strong spin polarization of conducting electrons at room temperature upon N incorporation with an extremely long apparent spin lifetime. In this work we have uncovered the origin of the astonishing effect as being due to strong spin dependent recombination (SDR) via defects, by a combination of optical orientation and optically detected magnetic resonance (ODMR) studies. We were able to identify Ga self-interstitials and an As antisite complex to be the dominant defects participating in the SDR process. The involvement of these defects were unambiguously established by their unique spin-resonance signatures derived from the hyperfine interaction between the localized unpaired electron spin and nuclear spins (I=3/2) of the As and Ga atom - the core of the defects. These defects dominate in carrier capture and recombination leading to the observed strong dynamic polarization of electron spins. Further confirmation was found by the effects of growth conditions and post-growth treatments on the defect density that were closely correlated with the electron spin polarization.

  • 236.
    Dagnelund, Daniel
    et al.
    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.
    Murayama, A.
    Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai, 980-8577, Japan.
    Furuta, T.
    Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai, 980-8577, Japan.
    Hyomi, K.
    Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai, 980-8577, Japan.
    Souma, I.
    Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai, 980-8577, Japan.
    Oka, Y.
    Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai, 980-8577, Japan.
    Magneto-optical and tunable laser excitation spectroscopy of spin-injection and spin loss from Zn(Cd)MnSe diluted magnetic quantum well to CdSe non-magnetic quantum dots2008Conference paper (Refereed)
    Abstract [en]

    Magneto-optical spectroscopy in combination with tunable laser spectroscopy is employed to study the effect of sample design on optical spin-injection efficiency from a Zn(Cd)MnSe diluted magnetic semiconductor (DMS) into non-magnetic CdSe quantum dots (QDs). Two samples with inverted growth sequence of the DMS and QD layers were grown for this purpose. Despite observation of clear evidence for exciton/carrier-injection from the DMS to the QDs in both structures, their spin-injection efficiency is markedly different. The structure grown with the QD layer topmost exhibits rather efficient spin-injection, while the structure grown with the DMS layer topmost does not show any sign of spin-injection. Even in the former case, the spin-polarization of the injected excitons/carriers is deduced to be about 32%, decreasing from 100% before the injection. The observed spin loss is shown to occur during the spin-injection across the heterointerfaces. © 2007 Elsevier B.V. All rights reserved.

  • 237.
    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.
    Murayama, A.
    Oka, Y.
    Abernathy, C. R.
    Pearton, S. J.
    Magneto-optical properties and spin dynamics in novel II-VI and III-V semiconductor materials and nanostructures2008In: Progress in Electromagnetics Research Symposium,2008, 2008, p. 517-Conference paper (Other academic)
  • 238.
    Dagnelund, Daniel
    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.
    Chen, Weimin
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    Furuta, T.
    Hyomi, K.
    Souma, I.
    Murayama, A.
    Magneto-optical spectroscopy of spin injection from ZnMnSe to CdSe quantum dots2008In: Int. Scanning Probe Microscopy Conference,2008, 2008Conference paper (Other academic)
  • 239. Lim, W.
    et al.
    Norton, D. P.
    Pearton, S. J,
    Wang, Xingjun
    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.
    Buyanova, Irina
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    Osinsky, A.
    Dong, J. W.
    Hertog, B.
    Thompson, A. V.
    Schoenfeld, W. V.
    Wang, Y. L.
    Ren, F.
    Migration and Luminescence Enhancement Effects of Deuterium in ZnO/ZnCdO Quantum Wells2008In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 92, p. 032103-Article in journal (Refereed)
    Abstract [en]

    ZnO/ZnCdO/ZnO multiple quantum well samples grown on sapphire substrates by molecular beam epitaxy and annealed in situ were exposed to D2 plasmas at 150 °C. The deuterium showed migration depths of ~0.8 µm for 30 min plasma exposures, with accumulation of 2H in the ZnCdO wells. The photoluminescence (PL) intensity from the samples was increased by factors of 5 at 5 K and ~20 at 300 K as a result of the deuteration, most likely due to passivation of competing nonradiative centers. Annealing up to 300 °C led to increased migration of 2H toward the substrate but no loss of deuterium from the sample and little change in the PL intensity. The initial PL intensities were restored by annealing at >=400 °C as 2H was evolved from the sample (~90% loss by 500 °C). By contrast, samples without in situ annealing showed a decrease in PL intensity with deuteration. This suggests that even moderate annealing temperatures lead to degradation of ZnCdO quantum wells.

  • 240.
    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.
    Optical and electronic properties of GaInNP alloys - a new material for lattice matching to GaAs2008In: Dilute III-V Nitride Semiconductors and Material Systems: Physics and Technology, Berlin: Springer Verlag , 2008, 1, p. 301-316Chapter in book (Other academic)
    Abstract [en]

    A major current challenge for semiconductor devices is to develop materials for the next generation of optical communication systems and solar power conversion applications. Recently, extensive research has revealed that an introduction of only a few percentages of nitrogen into III-V semiconductor lattice leads to a dramatic reduction of the band gap. This discovery has opened the possibility of using these material systems for applications ranging from lasers to solar cells. "Physics and Technology of Dilute III-V Nitride Semiconductors and Novel Dilute Nitride Material Systems" reviews the current status of research and development in dilute III-V nitrides, with 24 chapters from prominent research groups covering recent progress in growth techniques, experimental characterization of band structure, defects carrier transport, transport properties, dynamic behavior of N atoms, device applications, modeling of device design, novel optoelectronic integrated circuits, and novel nitrogen containing III-V materials.

  • 241.
    Buyanova, Irina A.
    et al.
    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.
    Tu, C. W.
    Univ Calif, Dept Elect & Comp Engn, La Jolla, CA USA.
    Optical and electronic properties of GaInNP alloys - a new material system for lattice matching to GaAs2008In: Physica Status Solidi (a) applications and materials science, ISSN 1862-6300, E-ISSN 1862-6319, Vol. 205, no 1, p. 101-106Article in journal (Refereed)
    Abstract [en]

    In this paper we will review our recent results from optical characterization studies of GaInNP. We will show that N incorporation in these alloys affects their structural and defect properties, as well as the electronic structure. The main structural changes include (i) increasing carrier localization due to strong compositional fluctuations, which is typical for all dilute nitrides, and (ii) N-induced long range ordering effects, specific for GaInNP. The observed degradation of radiative efficiency of the alloys upon increasing N content is attributed to formation of several defects acting as centres of efficient non-radiative recombination. One of the defects is identified as a complex involving a Ga interstitial atom. N incorporation is also found to change the band line up from the type I in the GaInP/GaAs structures to the type 11 in the GaInNP/GaAs heterojunctions with [N] > 0.5%. For the range of N compositions studied ([N] <= 2%), a conduction band offset at the GaInNP/GaAs interface is found to nearly linearly depend on [N] at -0.10 eV/%, whereas the valence band offset remains unaffected. (c) 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  • 242.
    Wang, Xingjun
    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.
    Chen, Weimin
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    Wang, W. M.
    Tu, C. W.
    Optical and structural characterization of Ga-doped ZnO epilayers grown by plasma-assisted molecular-beam epitaxy2008In: 2nd Int. Conf. on Functional Materials and Devices ICFMD2008,2008, 2008Conference paper (Other academic)
  • 243.
    Wang, Xingjun
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    Norton, D. P.
    Pearton, S. J.
    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.
    Physical properties of ZnCdO alloys and quantum structures2008In: 2nd Int. Conf. on Functional Materials and Devices,2008, 2008, p. I-46-Conference paper (Other academic)
  • 244.
    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.
    Murayama, A.
    Oka, Y.
    Pearton, S. J.
    Norton, D. P.
    Abernathy, C. R.
    Osinsky, A.
    Dong, J. W.
    Spin injection and spin detection in semiconductor quantum structures2008In: First Nordic Workshop on Spintronics and Nanomagnetism,2008, 2008Conference paper (Other academic)
  • 245.
    Dagnelund, Daniel
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    Buyanova, Irina
    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.
    Murayama, A.
    Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai, 980-8577, Japan.
    Furuta, T.
    Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai, 980-8577, Japan.
    Hyomi, K.
    Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai, 980-8577, Japan.
    Souma, I.
    Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai, 980-8577, Japan.
    Oka, Y.
    Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai, 980-8577, Japan.
    Spin injection in a coupled system of a diluted magnetic semiconductor Zn0.80Mn0.20Se and self-assembled quantum dots of CdSe2008In: Proceedings of the 7th International Conference on Physics of Light-Matter Coupling in Nanostructures, 2008, Vol. 43, no 5-6, p. 615-619Conference paper (Refereed)
    Abstract [en]

    Spin injection processes from a Zn0.80Mn0.20Se diluted magnetic semiconductor (DMS) to adjacent self-assembled CdSe quantum dots (QDs) were investigated by cw and time-resolved magneto-optical spectroscopy in combination with tunable laser excitation. Direct experimental evidence for the spin injection was provided from the generation of the spin polarization in the QDs, which was opposite to their expected intrinsic polarization, by resonantly generating the spins in the DMS. The observed limited spin polarization generated by the spin injection, together with the sensitivity of the spin injection efficiency on structure design, indicates severe spin loss during the process and calls for further investigations to optimize spin injection efficiency in quantum structures. © 2007 Elsevier Ltd. All rights reserved.

  • 246.
    Dagnelund, Daniel
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    Wang, Xingjun
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    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, Functional Electronic Materials.
    Chen, Weimin
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    Utsumi, A.
    Furukawa, Y.
    Moon, S.
    Wakahara, A.
    Yonezu, H.
    Spin resonance spectroscopy of grown-in defects in Ga(In)NP alloys2008In: 7th International Conference on Physics of Light-Matter Coupling in Nanostructures, 2007, Elsevier Ltd. , 2008, p. 620-625Conference paper (Refereed)
    Abstract [en]

    We employ the optically detected magnetic resonance (ODMR) technique to study and identify important grown-in defects in Ga(In)NP grown by molecular-beam epitaxy (MBE). Several types of defects were revealed from ODMR studies. The dominant defects were found to be related to Ga interstitials, evident form their characteristic hyperfine interaction arising from the spin interaction between the electron and the Ga nucleus. Some other as yet unidentified intrinsic defects were also found to be commonly present in the alloys. The effects of growth conditions (ion bombardment, N2 gas flow, etc.) and post-growth rapid thermal annealing on the formation of these defects were studied in detail, shedding light on the formation mechanism of defects.

  • 247.
    Park, Jiho
    et al.
    Institute of Multidisciplinary Research for Advanced Materials Tohoku University, Sendai 980-8577, Japan.
    Murayama, Akihiro
    Institute of Multidisciplinary Research for Advanced Materials Tohoku University, Sendai 980-8577, Japan.
    Souma, Izuru
    Institute of Multidisciplinary Research for Advanced Materials Tohoku University, Sendai 980-8577, Japan.
    Oka, Yasuo
    Institute of Multidisciplinary Research for Advanced Materials Tohoku University, Sendai 980-8577, Japan.
    Dagnelund, Daniel
    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.
    Spin-Conserving Tunneling of Excitons in Diluted Magnetic Semiconductor Double Quantum Wells2008In: Japanese Journal of Applied Physics, ISSN 0021-4922, E-ISSN 1347-4065, Vol. 47, p. 3533-3536Article in journal (Refereed)
    Abstract [en]

    Spin polarization in carrier tunneling was studied in double quantum wells by the polarized photoluminescence-excitation spectroscopy. The double quantum wells consist of a diluted magnetic quantum well of Zn0.77Cd0.15Mn0.08Se and a nonmagnetic quantum well of Zn0.82Cd0.18Se. Efficient spin-conserving tunneling of an exciton as an entity was observed from the nonmagnetic quantum well to the magnetic well. The spin-reversing tunneling was suppressed by two orders of magnitude in high magnetic field. The spin-conserving tunneling time was determined as 20 ps by time resolved photoluminescence measurement.

  • 248. Furuta, T.
    et al.
    Hyomi, K.
    Souma, I.
    Oka, Y.
    Murayama, A.
    Dagnelund, Daniel
    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.
    Spin-injection dynamics and effects of spin relaxation in self-assembled quantum dots of CdSe2008In: Journal of the Korean Physical Society, ISSN 0374-4884, E-ISSN 1976-8524, Vol. 53, p. 163-166Article in journal (Refereed)
    Abstract [en]

    We study the spin injection dynamics and the effects of spin relaxation in self-assembled quantum dots (QDs) of CdSe coupled with a diluted magnetic semiconductor (DMS) layer of ZnMnSe, where spin-polarized excitons can be injected from the DMS into the QDs because of the potential difference. The degree of circular polarization, $P$, of excitonic photoluminescence (PL) at 5 T in the coupled QDs shows a rapid increase with increasing delay time after a linearly polarized pulse excitation, indicating the spin-injection dynamics. The $P$ value tends to decay gradually because of the exciton-spin relaxation in the QDs after the spin injection. The spin-polarized excitons in the QD ensemble migrate simultaneously from QDs with higher exciton energies to those with lower exciton energies. This inter-dot transfer of excitons also affects the $P$ value in the lower energy region of the QD-emission band because the excitons lose their spin polarizations due to the spin relaxation in the dots during the migration. The detailed analysis for the exciton-spin transfer is presented in a coupled QD system after spin injection.

  • 249. Park, J. H.
    et al.
    Souma, I.
    Oka, Y.
    Murayama, A.
    Dagnelund, Daniel
    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.
    Transfer dynamics of spin-polarized excitons in ZnCdMnSe/ZnCdSe double quantum wells2008In: Journal of the Korean Physical Society, ISSN 0374-4884, E-ISSN 1976-8524, Vol. 53, p. 167-170Article in journal (Refereed)
    Abstract [en]

    We study the transfer dynamics of spin-polarized excitons in diluted magnetic semiconductor (DMS) double quantum wells (QWs) of ZnCdMnSe/ZnCdSe, where the spin-polarized excitons tunnel from the non-magnetic ZnCdSe to DMS-ZnCdMnSe wells and subsequently relax to the ground state in the DMS well with phonon emissions. The exciton-transfer time decreases when the exciton-energy difference between both the wells is equal to the one-LO-phonon energy, indicating the LO-phonon-assisted acceleration of the spin transfer. Moreover, the exciton transfer alters into the separate transfer of the electron and the heavy hole when the electron potential difference becomes larger than the LO-phonon energy. This observation demonstrates the importance of energy-relaxation dynamics in the spatial transport of spins in semiconductor quantum structures.

  • 250.
    Buyanova, Irina
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    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, Materials Science .
    Izadifard, M.
    Hong, Y.G.
    Tu, C.W.
    Band alignment in novel GaInNP/GaAs heterostructures.2007In: 31th Workshop on Compound Semiconductor Devices and Integrated Circuits WOCSDICE 2007,2007, 2007, p. 183-186Conference paper (Other academic)
2345678 201 - 250 of 431
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • oxford
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf