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  • 301.
    Pozina, Galia
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Ciechonski, Rafal
    GLO AB, Sweden.
    Bi, Zhaoxia
    Lund University, Sweden.
    Samuelson, Lars
    GLO AB, Sweden; Lund University, Sweden.
    Monemar, Bo
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten. Lund University, Sweden; TokyoUniversity of Agriculture and Technology, Japan.
    Dislocation related droop in InGaN/GaN light emitting diodes investigated via cathodoluminescence2015Ingår i: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 107, nr 25, s. 251106-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

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

  • 302.
    Pozina, Galia
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Materiefysik.
    Edwards, NV
    Linkoping Univ, Dept Phys & Measurement Technol, S-58183 Linkoping, Sweden N Carolina State Univ, Dept Mat Sci & Engn, Raleigh, NC 27695 USA.
    Bergman, JP
    Linkoping Univ, Dept Phys & Measurement Technol, S-58183 Linkoping, Sweden N Carolina State Univ, Dept Mat Sci & Engn, Raleigh, NC 27695 USA.
    Monemar, Bo
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Materiefysik.
    Bremser, MD
    Linkoping Univ, Dept Phys & Measurement Technol, S-58183 Linkoping, Sweden N Carolina State Univ, Dept Mat Sci & Engn, Raleigh, NC 27695 USA.
    Davis, RF
    Linkoping Univ, Dept Phys & Measurement Technol, S-58183 Linkoping, Sweden N Carolina State Univ, Dept Mat Sci & Engn, Raleigh, NC 27695 USA.
    Time-resolved photoluminescence in strained GaN layers2001Ingår i: Physica status solidi. A, Applied research, ISSN 0031-8965, E-ISSN 1521-396X, Vol. 183, nr 1, s. 151-155Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A set of GaN epilayers grown by metalorganic chemical vapor deposition on 6H-SiC substrates was studied by time-resolved photoluminescence (PL) spectroscopy. The PL spectra are dominated by the free A exciton (FEA) and by the neutral-donor-bound exciton (D0X) transitions. The position of FEA indicates that the GaN layers are under tension. We observe that the recombination lifetime for the FEA is about 40-50 ps in all the layers, whereas the recombination time for the D0X varies for different samples. We found that the recombination lifetimes for D0X have a clear dependence on the position of FEA, i.e. the recombination lifetime increases with decreasing strain in the layers. The results can be explained in terms of the character of the hole states involved in the donor-bound exciton recombination.

  • 303.
    Pozina, Galia
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Materiefysik.
    Edwards, N.V.
    Bergman, Peder
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Materiefysik.
    Paskova, Tanja
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Monemar, Bo
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Materiefysik.
    Bremser, M.D.
    Dept. of Mat. and Sci. and Eng., North Carolina State University, Raleigh, NC 27695, United States.
    Davis, R.F.
    Dept. of Mat. and Sci. and Eng., North Carolina State University, Raleigh, NC 27695, United States.
    Time-resolved spectroscopy of strained GaN/AIN/6H-SiC heterostructures grown by metalorganic chemical vapor deposition2001Ingår i: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 78, nr 8, s. 1062-1064Artikel i tidskrift (Refereegranskat)
    Abstract [en]

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

  • 304.
    Pozina, Galia
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Hemmingsson, Carl
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Amano, H
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska högskolan.
    Monemar, Bo
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Surface potential effect on excitons in AlGaN/GaN quantum well structures2013Ingår i: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 102, nr 8Artikel i tidskrift (Refereegranskat)
    Abstract [en]

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

  • 305.
    Pozina, Galia
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Hemmingsson, Carl
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Bergman, J.Peder
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Kawashimab, T.
    Shiogamaguchi, Tempaku‐ku, Nagoya 468‐8502, Japan .
    Amanob, H.
    Shiogamaguchi, Tempaku‐ku, Nagoya 468‐8502, Japan .
    Akasaki, I
    Shiogamaguchi, Tempaku‐ku, Nagoya 468‐8502, Japan .
    Usuic, A.
    Tsukuba, Ibaraki 305‐0856, Japan .
    Monemar, Bo
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Optical Properties Of Metastable Shallow Acceptors In Mg‐Doped GaN Layers Grown By Metal‐Organic Vapor Phase Epitaxy2010Ingår i: AIP Conference Proceedings / [ed] M. J. Caldas and N. Studart, American Institute of Physics (AIP), 2010, Vol. 1199, s. 110-111Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    GaN layers doped by Mg show a metastable behavior of the near-band-gap luminescence caused by electron irradiation or UV excitation. At low temperatures < 30 K the changes in luminescence are permanent. Heating to room temperature recovers the initial low temperature spectrum shape completely. Two acceptors are involved in the recombination process as confirmed by transient PL. In as-grown samples a possible candidate for the metastable acceptor is CN, while after annealing a second more stable acceptor related to Mg became active.

  • 306.
    Pozina, Galia
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik.
    Hemmingsson, Carl
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial.
    Bergman, Peder
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial.
    Kawashima, T.
    Department of Materials Science and Engineering, Meijo University, 1-501 Shiogamaguchi, Tempaku-ku, Nagoya.
    Amano, H.
    Department of Materials Science and Engineering, Meijo University, 1-501 Shiogamaguchi, Tempaku-ku, Nagoya.
    Akasaki, I.
    Department of Materials Science and Engineering, Meijo University, 1-501 Shiogamaguchi, Tempaku-ku, Nagoya.
    Usui, A.
    R&D Division, Furukawa Co. Ltd., Tsukuba, Ibaraki 305-0856, Japan.
    Monemar, Bo
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial.
    Optical properties of metastable shallow acceptors in Mg-doped GaN layers grown by metal-organic vapor phase epitaxy2010Ingår i: AIP Conference Proceedings, AIP , 2010, Vol. 1199, s. 110-111Konferensbidrag (Refereegranskat)
    Abstract [en]

    GaN layers doped by Mg show a metastable behavior of the near-band-gap luminescence caused by electron irradiation or UV excitation. At low temperatures &lt; 30 K the changes in luminescence are permanent. Heating to room temperature recovers the initial low temperature spectrum shape completely. Two acceptors are involved in the recombination process as confirmed by transient PL. In as-grown samples a possible candidate for the metastable acceptor is C-N, while after annealing a second more stable acceptor related to Mg became active.

  • 307.
    Pozina, Galia
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Hemmingsson, Carl
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial.
    Bergman, Peder
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial.
    Trinh, David
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik.
    Hultman, Lars
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik.
    Monemar, Bo
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial.
    Dynamics of bound excitons versus thickness in freestanding GaN wafers grown by halide vapor phase epitaxy2007Ingår i: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 90, nr 22Artikel i tidskrift (Refereegranskat)
    Abstract [en]

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

  • 308.
    Pozina, Galia
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Hemmingsson, Carl
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Bergman, Peder
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Trinh, David
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Monemar, Bo
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Time-resolved spectroscopy of freestanding GaN layers grown by halide vapour phase epitaxy2008Ingår i: Superlattices and Microstructures, ISSN 0749-6036, E-ISSN 1096-3677, Vol. 43, nr 5-6, s. 605-609Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Freestanding GaN layers of various thicknesses grown by HVPE have been studied by time-resolved spectroscopy combined with structural and electrical measurements. We have observed an increase of the PL lifetime with increasing layer thickness, however, a saturation of the recombination times has been detected for the GaN layers thicker than 400 µm. We explain the observed thickness-dependent behavior of the decay times by competition of two nonradiative mechanisms, namely, for layers with thickness less than 400 µm the main nonradiative channel is related to the structural defects, while in thicker layers the recombination decay time is limited by impurities and/or vacancies. © 2007 Elsevier Ltd. All rights reserved.

  • 309.
    Pozina, Galia
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial.
    Hemmingsson, Carl
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial.
    Forsberg, Urban
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial.
    Lundskog, Anders
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial.
    Kakanakova-Georgieva, Anelia
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial.
    Ivanov, Ivan Gueorguiev
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial.
    Monemar, Bo
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial.
    Hultman, Lars
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik.
    Janzén, Erik
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial.
    Time-resolved photoluminescence properties of AlGaN/AlN/GaN high electron mobility transistor structures grown on 4- SiC substrate2008Ingår i: 8th International Conference on Physics of Light-Matter Coupling in Nanostructures,2008, 2008Konferensbidrag (Övrigt vetenskapligt)
  • 310.
    Pozina, Galia
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Hemmingsson, Carl
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Forsberg, Urban
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Lundskog, Anders
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Kakanakova-Georgieva, Anelia
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial.
    Monemar, Bo
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Janzén, Erik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Time-resolved photoluminescence properties of AlGaN/AlN/GaN high electron mobility transistor structures grown on 4H-SiC substrate2008Ingår i: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 104, nr 11, s. 113513-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    AlGaN/AlN/GaN high electron mobility transistor heterostructures grown by metal-organic chemical vapor deposition have been studied by temperature dependent time-resolved photoluminescence. The AlGaN-related emission is found to be sensitive to the excitation power and to the built-in internal electric field. In addition, this emission shows a shift to higher energy with the reduction in the excitation density, which is rather unusual. Using a self-consistent calculation of the band potential profile, we suggest a recombination mechanism for the AlGaN-related emission involving electrons confined in the triangular AlGaN quantum well and holes weakly localized due to potential fluctuations.

  • 311.
    Pozina, Galia
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Materiefysik. Linköpings universitet, Tekniska högskolan.
    Hemmingsson, Carl
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Materiefysik. Linköpings universitet, Tekniska högskolan.
    Paskov, Plamen P.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Materiefysik. Linköpings universitet, Tekniska högskolan.
    Bergman, Peder
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Materiefysik. Linköpings universitet, Tekniska högskolan.
    Monemar, Bo
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Materiefysik. Linköpings universitet, Tekniska högskolan.
    Kawashima, T.
    Meijo University.
    Amano, H.
    Meijo University.
    Akasaki, I.
    Meijo University.
    Usui, A.
    Furukawa Co. Ltd.
    Effect of annealing on metastable shallow acceptors in Mg-doped GaN layers grown on GaN substrates2008Ingår i: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 92, nr 15, s. 151904-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

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

  • 312.
    Pozina, Galia
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Khromov, Sergey
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Hemmingsson, Carl
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Monemar, Bo
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Effect of silicon and oxygen doping on donor bound excitons in bulk GaN2011Ingår i: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 84, nr 16, s. 165213-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Freestanding n-type intentionally doped GaN layers grown by halide vapor phase epitaxy (HVPE) were studied by transient photoluminescence (PL). Concentrations of silicon and oxygen were varied in the range between 10(17) and 10(18) cm(-3), as confirmed by secondary ion mass spectroscopy (SIMS). We show that a reduction of the background silicon concentration by one order of magnitude compared to the background level in undoped samples can be achieved by incorporation of oxygen during the growth. A strong band gap narrowing (BGN) of similar to 6 meV was observed with increasing doping in the studied samples. The low temperature PL recombination time for donor-bound excitons (DBEs) was found to depend significantly on donor concentration. A model assuming generation of DBEs by capturing of free excitons by neutral donors explains the experimental results at low temperature. From fitting the experimental DBE lifetime to the model, the donor concentration dependence for O and Si donors could be reproduced. An effective exciton capture cross-section was found to be similar to 9.4 x 10(-15) and 1.2 x 10(-14) cm(2) for silicon and oxygen donors, respectively.

  • 313.
    Pozina, Galia
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Materiefysik.
    Monemar, Bo
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Materiefysik.
    Amano, H.
    Akasaki, I.
    Usui, A.
    Metastable UV luminescence in Mg-doped GaN layers grown on freestanding GaN substrates2008Ingår i: International Symposium on Semiconductor Light Emitting Devices,2008, 2008Konferensbidrag (Övrigt vetenskapligt)
  • 314.
    Pozina, Galia
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Materiefysik.
    Monemar, Bo
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Materiefysik.
    Paskov, Plamen
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Materiefysik.
    Hemmingsson, Carl
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Materiefysik.
    Hultman, Lars
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik.
    Amano, H.
    Akasaki, I.
    Paskova, Tanja
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Figge, S.
    Hommel, D.
    Usui, A.
    Metastability of the UV luminescence in Mg-doped GaN layers grown by MOVPE on quasi-bulk GaN templates2007Konferensbidrag (Refereegranskat)
  • 315.
    Pozina, Galia
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Materiefysik.
    Paskov, Plamen
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Materiefysik.
    Bergman, Peder
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Materiefysik.
    Hemmingsson, Carl
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Materiefysik.
    Hultman, Lars
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik.
    Monemar, Bo
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Materiefysik.
    Amano, H.
    Usui, A.
    Metastable behavior of the UV luminescence in Mg-doped GaN layers grown on quasibulk GaN templates2007Ingår i: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 91, nr 22Artikel i tidskrift (Refereegranskat)
    Abstract [en]

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

  • 316.
    Ratnikov, V
    et al.
    Linkoping Univ, S-58183 Linkoping, Sweden Russian Acad Sci, Ioffe Inst, St Petersburg 194021, Russia Univ Sofia, Fac Phys, BU-1164 Sofia, Bulgaria.
    Kyutt, R
    Linkoping Univ, S-58183 Linkoping, Sweden Russian Acad Sci, Ioffe Inst, St Petersburg 194021, Russia Univ Sofia, Fac Phys, BU-1164 Sofia, Bulgaria.
    Shubina, Tatiana
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Paskova, Tanja
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Valcheva, E
    Linkoping Univ, S-58183 Linkoping, Sweden Russian Acad Sci, Ioffe Inst, St Petersburg 194021, Russia Univ Sofia, Fac Phys, BU-1164 Sofia, Bulgaria.
    Monemar, Bo
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Materiefysik.
    Bragg and Laue x-ray diffraction study of dislocations in thick hydride vapor phase epitaxy GaN films2000Ingår i: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 88, nr 11, s. 6252-6259Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The dislocation structure of hydride vapor phase epitaxial thick GaN layers grown on sapphire is studied by analysis of the microdistortion tensor components. Symmetrical reflections (including reflections from planes forming a large angle with the basal plane) with two modes of scanning (theta and theta -2 theta) in two geometries (Bragg and Laue) are used to obtain the tensor components. The instant connections between the tensor components and major dislocation types are specified. Different types of dislocation distributions have been identified in the thick GaN films grown on sapphire with and without undoped and Si-doped metalorganic chemical vapor deposited templates. Transmission electron microscopy was used to confirm the x-ray results by direct visualization of defect rearrangements. (C) 2000 American Institute of Physics. [S0021-8979(00)06023-0].

  • 317.
    Ratnikov, VV
    et al.
    RAS, Ioffe Inst, St Petersburg 194021, Russia Linkoping Univ, S-58183 Linkoping, Sweden.
    Kyutt, RN
    RAS, Ioffe Inst, St Petersburg 194021, Russia Linkoping Univ, S-58183 Linkoping, Sweden.
    Shubina, Tatiana
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Paskova, Tanja
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Monemar, Bo
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Materiefysik.
    Determination of microdistortion components and their application to structural characterization of HVBE GaN epitaxial layers2001Ingår i: Journal of Physics D: Applied Physics, ISSN 0022-3727, E-ISSN 1361-6463, Vol. 34, nr 10A, s. A30-A34Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The dislocation structure of hydride vapour phase epitaxial thick GaN layers grown on sapphire is studied by analysis of the microdistortion tenser components. Symmetrical reflections (including reflections from planes forming large angles with the basal plane) with two modes of scanning (theta and theta -2 theta) in two geometries (Bragg and Lane) are used to obtain the tenser components. The instant connections between the tenser components and major dislocation types are specified. Different types of dislocation distributions have been identified in the thick GaN films grown on sapphire without and with undoped and Si-doped metal-organic chemical vapour deposited templates.

  • 318.
    Reginski, K
    et al.
    Inst Electr Mat Technol, Dept Phys & Technol Low Dimens Struct, PL-02668 Warsaw, Poland Linkoping Univ, Dept Phys & Measurement Technol, S-58183 Linkoping, Sweden.
    Ochalski, T
    Inst Electr Mat Technol, Dept Phys & Technol Low Dimens Struct, PL-02668 Warsaw, Poland Linkoping Univ, Dept Phys & Measurement Technol, S-58183 Linkoping, Sweden.
    Muszalski, J
    Inst Electr Mat Technol, Dept Phys & Technol Low Dimens Struct, PL-02668 Warsaw, Poland Linkoping Univ, Dept Phys & Measurement Technol, S-58183 Linkoping, Sweden.
    Bugajski, M
    Inst Electr Mat Technol, Dept Phys & Technol Low Dimens Struct, PL-02668 Warsaw, Poland Linkoping Univ, Dept Phys & Measurement Technol, S-58183 Linkoping, Sweden.
    Bergman, JP
    Inst Electr Mat Technol, Dept Phys & Technol Low Dimens Struct, PL-02668 Warsaw, Poland Linkoping Univ, Dept Phys & Measurement Technol, S-58183 Linkoping, Sweden.
    Holtz, Per-Olof
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Materiefysik.
    Monemar, Bo
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Materiefysik.
    Investigations of optical properties of active regions in vertical cavity surface emitting lasers grown by MBE2002Ingår i: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 412, nr 1-2, s. 107-113Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The design of the vertical cavity surface emitting lasers (VCSELs) needs proper tuning of many different optical parameters of those structures. So, the optimisation of the VCSELs requires deep understanding of optical processes occurring in the active regions of such lasers. In a series of MBE processes, active regions of VCSELs as well as the whole VCSELs were grown. The active regions of the VCSEL structures were designed for lambda = 1000 nm and 980 nm emission. They consisted of a pair of distributed Bragg reflectors (DBRs) composed of AlAs and GaAs quarter wavelength layers and a cavity made of GaAs. The cavities contained one or several quantum wells (QWs) made of In0.2Ga0.8As. To optimise the optical characteristics of the active regions, several experimental methods have been applied. The Bragg reflectors and the whole microcavities were investigated by optical reflectivity. For selective excitation of a QW in a cavity active layer, a Ti-sapphire tuneable laser has been used. The fine tuning between the QW emission and the cavity Fabry-Perot resonance has been investigated by photoluminescence at varying temperatures of the sample. For monitoring the temporal evolution of the luminescence from the active region of the laser, time-resolved spectroscopy has been employed. The combination of many methods of optical investigations enabled a comprehensive characterisation and as a result an optimisation of the whole laser structure. (C) 2002 Elsevier Science B.V. All rights reserved.

  • 319.
    Rindermann, Jan Junis
    et al.
    University of Southampton.
    Pozina, Galia
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Monemar, Bo
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Amano, Hiroshi
    Nagoya University.
    Lagoudakis, Pavlos G.
    University of Southampton.
    The effect of exciton dimensionality on resonance energytransfer: advances for organic color converters in hybridinorganic/organic LEDs2012Ingår i: Proceedings of SPIE: PHYSICS AND SIMULATION OF OPTOELECTRONIC DEVICES XX, 2012, Vol. 8255, s. 82550I-01-82550I-10Konferensbidrag (Refereegranskat)
    Abstract [en]

    The dependence of resonance energy transfer from Wannier-Mott excitons to an organic overlayer on excitondimensionality is studied experimentally and by means of supporting simulations. The variation of temperatureeffectively tunes the balance between localized and free excitons, and allows to investigate the effect of theexcitonic potential disorder on resonance energy transfer. Our theoretical calculations give insight into theexperimentally observed temperature dependence of resonance energy transfer, and allow us to quantify thecontribution from localized and free excitons. It is shown that free excitons can undergo resonance energytransfer at a rate that is an order of magnitude higher compared to localized excitons. In planar geometriesnonradiative resonance energy transfer is dominating over radiative energy transfer and hence we propose hybridinorganic-organic LEDs which are optimized for resonance energy transfer to an organic or QD-based colorconverter.

  • 320.
    Roder, C.
    et al.
    Institute of Solid State Physics, University of Bremen, P.O. Box 330440, 28334 Bremen, Germany.
    Einfeldt, S.
    Institute of Solid State Physics, University of Bremen, P.O. Box 330440, 28334 Bremen, Germany, Ferdinand-Braun-Institut für Höchstfrequenztechnik, Gustav-Kirchhoff-Str. 4, 12489 Berlin, Germany.
    Figge, S.
    Institute of Solid State Physics, University of Bremen, P.O. Box 330440, 28334 Bremen, Germany.
    Hommel, D.
    Institute of Solid State Physics, University of Bremen, P.O. Box 330440, 28334 Bremen, Germany.
    Paskova, Tanja
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Monemar, Bo
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Materiefysik.
    Haskell, B.A.
    Materials Department, University of California, Santa Barbara, CA 93106-5050, United States, NICP/ERATO JST, UCSB Group, University of California, Santa Barbara, CA 93106-5050, United States.
    Fini, P.T.
    Materials Department, University of California, Santa Barbara, CA 93106-5050, United States, NICP/ERATO JST, UCSB Group, University of California, Santa Barbara, CA 93106-5050, United States.
    Speck, J.S.
    Materials Department, University of California, Santa Barbara, CA 93106-5050, United States, NICP/ERATO JST, UCSB Group, University of California, Santa Barbara, CA 93106-5050, United States.
    Nakamura, S.
    Materials Department, University of California, Santa Barbara, CA 93106-5050, United States, NICP/ERATO JST, UCSB Group, University of California, Santa Barbara, CA 93106-5050, United States.
    Strain in a-plane GaN layers grown on r-plane sapphire substrates2006Ingår i: Physica Status Solidi (A) Applications and Materials, ISSN 1862-6300, Vol. 203, nr 7, s. 1672-1675Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The strain in a-plane GaN layers of different thickness grown on r-plane sapphire substrates by hydride vapor phase epitaxy was studied by X-ray diffraction. The layers are found to be under compression in the growth plane and under tension in the growth direction. Therefore, the symmetry of the GaN unit cell is no longer hexagonal but orthorhombic. With increasing layer thickness the strain relaxes and the curvature of the wafer increases. Wafer bending is proposed to be the major strain relaxation mechanism. The anisotropic in-plane strain relaxation is attributed to the elastic and thermal anisotropy of GaN and sapphire. © 2006 WILEY-VCH Verlag GmbH & Co. KGaA.

  • 321.
    Roder, C.
    et al.
    Institute of Solid State Physics, University of Bremen, P.O. Box 330440, 28334 Bremen, Germany.
    Einfeldt, S.
    Institute of Solid State Physics, University of Bremen, P.O. Box 330440, 28334 Bremen, Germany, Ferdinand-Braun-Institut für Höchstfrequenztechnik, Gustav-Kirchhoff-Str. 4, 12489 Berlin, Germany.
    Figge, S.
    Institute of Solid State Physics, University of Bremen, P.O. Box 330440, 28334 Bremen, Germany.
    Paskova, T.
    Institute of Solid State Physics, University of Bremen, P.O. Box 330440, 28334 Bremen, Germany.
    Hommel, D.
    Institute of Solid State Physics, University of Bremen, P.O. Box 330440, 28334 Bremen, Germany.
    Paskov, Plamen
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Materiefysik.
    Monemar, Bo
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Materiefysik.
    Behn, U.
    Fachhochschule Schmalkalden, Blechhammer 4-9, 98574 Schmalkalden, Germany.
    Haskell, B.A.
    Haskell, B.A..
    Fini, P.T.
    Fini, P.T..
    Nakamura, S.
    Nakamura, S..
    Stress and wafer bending of a -plane GaN layers on r -plane sapphire substrates2006Ingår i: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 100, nr 10Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The stress and wafer bending of (11 2- 0) a -plane GaN layers of different thicknesses grown on (1 1- 02) r -plane sapphire substrates by hydride vapor phase epitaxy were studied by high-resolution x-ray diffraction and photoluminescence and photoreflectance spectroscopies. The layers are found to be under compression in the growth plane and under tension in the growth direction. The elastic and thermal anisotropies of the GaN and the sapphire crystal result in an in-plane stress and a wafer curvature, both of which are different in the two in-plane directions parallel and perpendicular to the GaN c axis. The GaN unit cell is no longer hexagonal but orthorhombic. The stress relaxes with increasing GaN layer thickness while the curvature of the wafer increases. Different stress relief mechanisms are considered, and the stresses in the layer and the curvature of the wafer are calculated using standard models on wafer bending. The results suggest that the wafer bending is the dominant stress relief mechanism. In addition, the redshift of the near-band-edge photoluminescence and the free exciton photoreflectance peaks with increasing layer thickness is correlated with the strain data determined by x-ray diffraction. © 2006 American Institute of Physics.

  • 322. Rudko, G. Yu.
    et al.
    Buyanova, Irina
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Funktionella elektroniska material.
    Monemar, Bo
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial.
    Chen, Weimin
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Funktionella elektroniska material.
    Toropov, A. A.
    Terentev, Y.
    Sorokin, S. V.
    Lebedev, A. V.
    Ivanov, S. V.
    Kopev, P. S.
    Hot exciton relaxation in diluted magnetic semiconductor ZnMnSe/CdSe superlattices2003Ingår i: 26th International Conference on the Physics of Semiconductors,2002, 2003, s. H245-Konferensbidrag (Övrigt vetenskapligt)
  • 323. Sabooni, M.
    et al.
    Esmaeili, M.
    Harati Zadeh, Hamid
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Monemar, Bo
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Materiefysik.
    Paskov, Plamen
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Materiefysik.
    Holtz, Per-Olof
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Materiefysik.
    Kamiyama, S.
    Iwaya, M.
    Amano, H.
    Akasaki, I.
    Exciton localization behaviour in different well width undoped GaN/Al 0.07Ga0.93N nanostructures2007Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We report results from optical spectroscopy such as photoluminescence (PL) and time resolved photo-luminescence (TRPL) techniques from different well width MOCVD grown GaN/Al0.07Ga0.93N MQW samples. There is evidence of localization at low temperature in all samples. The decay time of all samples becomes non-exponential when the detection energy is increased with respect to the peak of the emission. Localization of carriers (excitons) is demonstrated by the "S-shape" dependences of the PL peak energies on the temperature. The time-resolved PL spectra of the 3-nm well multi quantum wells reveal that the spectral peak position shifts toward lower energies as the decay time increases and becomes red-shifted at longer decay times. There is a gradient in the PL decay time across the emission peak profile, so that the PL process at low temperatures is a free electron-localized hole transition. © Association of Polish Electrical Engineers 2007.

  • 324. Sabooni, M.
    et al.
    Esmaeili, M.
    Haratizadeh, H.
    Monemar, Bo
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Materiefysik.
    Amano, H.
    Dynamical study of the radiative recombination processes in GaN/AlGaN QWs2008Ingår i: Journal of materials science. Materials in electronics, ISSN 0957-4522, E-ISSN 1573-482X, Vol. 19, nr SUPPL. 1Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The effects of the Si doping level on the recombination dynamics and carrier (exciton) localization in modulation-doped GaN/Al0.07 Ga0.93N multiple-quantum-well (MQW) structures were studied by means of photoluminescence (PL) and time-resolved PL measurements. All samples with different doping levels show a QW emission which is blue shifted with respect to the 3.48 eV PL peak from the GaN buffer layer. The decay time at the peak position remains nearly constant in the range of 320-420 ps at 2 K for all doping levels. For the undoped and low doped samples (3 × 1018 cm-3), which have less free electrons in the QWs, a non-exponential PL decay behaviour at 2 K is attributed to localized exciton recombination. The more highly doped samples (5 × 1018 cm-3 to 1020 cm-3) show almost exponential decay curves at 2 K, suggesting the recombination of free electrons and localized holes. The internal polarization-induced fields of the medium and highly-doped samples are partly screened by the electrons originating from the doping in the barriers. The emission peaks in time delayed PL spectra of these samples exhibit almost no shift as time evolves. Only the PL peak of the undoped and low-doped samples shows a redshift with time delay, related to the photogenerated carriers [1]. The decay time for the undoped sample shows non-exponential behaviour typical for localized excitons in III-N QWs. The same behaviour of decay time as a function of emission energy has been reported for InGaN QWs [2]. © Springer Science+Business Media, LLC 2008.

  • 325.
    Scholle, A
    et al.
    University of Paderborn.
    Greulich-Weber, S
    University of Paderborn.
    As, D J
    University of Paderborn.
    Mietze, Ch
    University of Paderborn.
    Nguyen, Tien Son
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Hemmingsson, Carl
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Monemar, Bo
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Janzén, Erik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska högskolan.
    Gerstmann, U
    University of Paderborn.
    Sanna, S
    University of Paderborn.
    Rauls, E
    University of Paderborn.
    Schmidt, W G
    University of Paderborn.
    Magnetic characterization of conductance electrons in GaN2010Ingår i: Physica Status Solidi, Vol. 247, John Wiley and Sons, Ltd , 2010, Vol. 247, nr 7, s. 1728-1731Konferensbidrag (Refereegranskat)
    Abstract [en]

    New electron paramagnetic resonance (EPR) measurements in hexagonal and cubic GaN intentionally doped with silicon are presented. In both type of samples the well-known EPR resonance of the dominant shallow donor is observed, whereby the g-tensors are determined to g(parallel to) = 1.9512, g(perpendicular to) = 1.9485 (free-standing hexagonal GaN) and g = 1.9533 (cubic GaN layer grown on 3C-SiC substrate). The spectra show an exceptionally small line width below 0.4 mT and contain no further signature. As a result, beside the line width itself, the EPR line is characterized by its g-tensor exclusively. With the help of a qualitative analysis of the Si donor wave function within effective mass theory (EMT) and a followed up calculation of the hyperfine (HF) splittings in the framework of density functional theory (DFT) the characteristic shape of the EPR lines can be explained by an enhanced delocalization of the unpaired electrons of shallow Si donors at the gallium sublattice due to overlapping impurity and conduction bands.

  • 326.
    Schubert, M.
    et al.
    University of Nebraska, NE 68588 USA; University of Nebraska, NE 68588 USA; Leibniz Institute Polymer Research Dresden, Germany.
    Korlacki, R.
    University of Nebraska, NE 68588 USA; University of Nebraska, NE 68588 USA.
    Knight, S.
    University of Nebraska, NE 68588 USA; University of Nebraska, NE 68588 USA.
    Hofmann, Tino
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten. University of Nebraska, NE 68588 USA; University of Nebraska, NE 68588 USA.
    Schoeche, S.
    JA Woollam Corp Inc, Japan.
    Darakchieva, Vanya
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Janzén, Erik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Monemar, Bo
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten. Tokyo University of Agriculture and Technology, Japan.
    Gogova, D.
    Bulgarian Academic Science, Bulgaria; Leibniz Institute Crystal Growth, Germany.
    Thieu, Q. -T.
    Tokyo University of Agriculture and Technology, Japan; Tokyo University of Agriculture and Technology, Japan.
    Togashi, R.
    Tokyo University of Agriculture and Technology, Japan.
    Murakami, H.
    Tokyo University of Agriculture and Technology, Japan.
    Kumagai, Y.
    Tokyo University of Agriculture and Technology, Japan.
    Goto, K.
    Tokyo University of Agriculture and Technology, Japan; Tamura Corp, Japan.
    Kuramata, A.
    Tamura Corp, Japan.
    Yamakoshi, S.
    Tamura Corp, Japan.
    Higashiwaki, M.
    National Institute Informat and Communicat Technology, Japan.
    Anisotropy, phonon modes, and free charge carrier parameters in monoclinic beta-gallium oxide single crystals2016Ingår i: PHYSICAL REVIEW B, ISSN 2469-9950, Vol. 93, nr 12, s. 125209-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We derive a dielectric function tensor model approach to render the optical response of monoclinic and triclinic symmetry materials with multiple uncoupled infrared and far-infrared active modes. We apply our model approach to monoclinic beta-Ga2O3 single-crystal samples. Surfaces cut under different angles from a bulk crystal, (010) and ((2) over bar 01), are investigated by generalized spectroscopic ellipsometry within infrared and far-infrared spectral regions. We determine the frequency dependence of 4 independent beta-Ga2O3 Cartesian dielectric function tensor elements by matching large sets of experimental data using a point-by-point data inversion approach. From matching our monoclinic model to the obtained 4 dielectric function tensor components, we determine all infrared and far-infrared active transverse optic phonon modes with A(u) and B-u symmetry, and their eigenvectors within the monoclinic lattice. We find excellent agreement between our model results and results of density functional theory calculations. We derive and discuss the frequencies of longitudinal optical phonons in beta-Ga2O3. We derive and report density and anisotropic mobility parameters of the free charge carriers within the tin-doped crystals. We discuss the occurrence of longitudinal phonon plasmon coupled modes in beta-Ga2O3 and provide their frequencies and eigenvectors. We also discuss and present monoclinic dielectric constants for static electric fields and frequencies above the reststrahlen range, and we provide a generalization of the Lyddane-Sachs-Teller relation for monoclinic lattices with infrared and far-infrared active modes. We find that the generalized Lyddane-Sachs-Teller relation is fulfilled excellently for beta-Ga2O3.

  • 327. Scott, K.
    et al.
    Butcher, A.
    Wintrebert-Fouquet, M.
    Chen, P.P.-T.
    Prince, K.E.
    Timmers, H.
    Shrestha, S.K.
    Shubina, Tatiana
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska högskolan.
    Ivanov, S.V.
    Wuhrer, R.
    Philips, M.R.
    Monemar, Bo
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial.
    Non-stoichiometry and non-homogeneity in InN2005Ingår i: Physica Status Solidi. C, Current topics in solid state physics, ISSN 1610-1634, E-ISSN 1610-1642, Vol. 2, s. 2263-2266Artikel i tidskrift (Refereegranskat)
  • 328.
    Sedrine, N. Ben
    et al.
    Instituto Tecnológico e Nuclear, 2686-953 Sacavèm, Portugal.
    Darakchieva, Vanya
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Lindgren, D
    Division of Solid State Physics, Lund University, 221 00 Lund, Sweden.
    Monemar, Bo
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Che, S. B.
    Graduate School of Electrical and Electronic Engineering, Chiba University, 263-8522 Chiba, Japan.
    Ishitani, Y
    Graduate School of Electrical and Electronic Engineering, Chiba University, 263-8522 Chiba, Japan.
    Yoshikawa, A
    Graduate School of Electrical and Electronic Engineering, Chiba University, 263-8522 Chiba, Japan.
    Optical properties of InN/In0.73Ga0.27N multiple quantum wells studied by spectroscopic ellipsometry2011Ingår i: Physica Status Solidi. C, Current topics in solid state physics, ISSN 1610-1634, E-ISSN 1610-1642, Vol. 8, nr 5, s. 1629-1632Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this work we study the optical properties of two high quality fifty-periods of In-polarity InN/In0.73Ga0.27N MQWs samples, grown by radio-frequency plasma-assisted molecular beam epitaxy, with different well (0.5-1 nm) and barrier thicknesses (3-4 nm). We employ spectroscopic ellipsometry at room temperature in the energy range from 0.6 to 6 eV, and incidence angles of 60 and 70°. Ellipsometric data were successfully modelled using the model dielectric function approach and a multilayer model assuming the MQWs as a homogeneous layer. The E0, A and E1 MQWs transition energies were determined and found to exhibit a blueshift with decreasing the well thickness.

  • 329.
    Shevchenko, E. A.
    et al.
    Russian Academic Science, Russia.
    Toropov, A. A.
    Russian Academic Science, Russia.
    Nechaev, D. V.
    Russian Academic Science, Russia.
    Jmerik, V. N.
    Russian Academic Science, Russia.
    Shubina, T. V.
    Russian Academic Science, Russia.
    Ivanov, S. V.
    Russian Academic Science, Russia.
    Yagovkina, M. A.
    Russian Academic Science, Russia.
    Pozina, Galia
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Bergman, Peder
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Monemar, Bo
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    AlGaN Quantum Well Heterostructures for Mid-Ultraviolet Emitters with Improved Room Temperature Quantum Efficiency2014Ingår i: Acta Physica Polonica. A, ISSN 0587-4246, E-ISSN 1898-794X, Vol. 126, nr 5, s. 1140-1142Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We report on optical studies of exciton localization and recombination kinetics in two single 2.2 nm thick AlxGa1-xN/Alx+0.1Ga0.9-xN quantum well structures (x = 0.55 and 0.6) grown by plasma assisted molecular beam epitaxy on a c-sapphire substrate. Strong localization potential inherent for both the quantum well and barrier regions results in merging of the quantum well and barrier emission spectra into a single broad line centered at 285 nm (x = 0.55) and 275 nm (x = 0.6). Time-resolved photoluminescence measurements revealed surprising temperature stability of the photoluminescence decay time constant (approximate to 400 ps) relevant to the recombination of the quantum well localized excitons. This observation implies nearly constant quantum efficiency of the quantum well emission in the whole range from 4.6 to 300 K.

  • 330.
    Shubina, T V
    et al.
    RAS.
    Glazov, M M
    RAS.
    Gippius, N A
    University of Clermont Ferrand.
    Toropov, A A
    RAS.
    Lagarde, D
    University of Clermont Ferrand.
    Disseix, P
    University of Clermont Ferrand.
    Leymarie, J
    University of Clermont Ferrand.
    Gil, B
    University of Montpellier 2.
    Pozina, Galia
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Bergman, J Peder
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Monemar, Bo
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Delay and distortion of slow light pulses by excitons in ZnO2011Ingår i: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 84, nr 7, s. 075202-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    istortion of light pulses in ZnO caused by both bound and free excitons is demonstrated by time-of-flight spectroscopy. Numerous lines of bound excitons dissect the pulse spectrum and induce slowdown of light propagation around the dips. Exciton-polariton resonances determine the overall pulse delay, which approaches 1.6 ns at 3.374 eV for a 0.3 mm propagation length, as well as the pulse curvature in the time-energy plane and its attenuation. Analysis of cw and time-resolved data yields the excitonic parameters inherent for bulk ZnO. A discrepancy is found between these bulk parameters and those given by surface-probing techniques.

  • 331.
    Shubina, T. V.
    et al.
    RAS.
    Toropov, A. .A.
    RAS.
    Pozina, Galia
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Bergman, Peder
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Glazov, M. M.
    RAS.
    Gippius, N. A.
    RAS.
    Disseix, P.
    CNRS UBP.
    Leymarie, J.
    CNRS UBP.
    Gil, B.
    University Montpellier 2.
    Monemar, Bo
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Excitonic parameters of GaN studied by time-of-flight spectroscopy2011Ingår i: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 99, nr 10, s. 101108-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We refine excitonic parameters of bulk GaN by means of time-of-flight spectroscopy of light pulses propagating through crystals. The influence of elastic photon scattering is excluded by using the multiple reflections of the pulses from crystal boundaries. The shapes of these reflexes in the time-energy plane depict the variation of the group velocity induced by excitonic resonances. Modeling of the shapes, as well as optical spectra, shows that a homogeneous width of the order of 10 mu eV characterizes the exciton-polariton resonances within the crystal. The oscillator strength of A and B exciton-polaritons is determined as 0.0022 and 0.0016, respectively.

  • 332.
    Shubina, Tatiana
    et al.
    Russian Acad Sci, AF Ioffe Physicotech Inst, St Petersburg 194021, Russia.
    Glazov, M. M.
    Russian Acad Sci, AF Ioffe Physicotech Inst, St Petersburg 194021, Russia.
    Toropov, A. A.
    Russian Acad Sci, AF Ioffe Physicotech Inst, St Petersburg 194021, Russia.
    Gippius, N. A.
    UBP, CNRS, UMR 6602, LASMEA, F-63177 Clermont Ferrand, France.
    Vasson, A.
    UBP, CNRS, UMR 6602, LASMEA, F-63177 Clermont Ferrand, France.
    Leymarie, J.
    UBP, CNRS, UMR 6602, LASMEA, F-63177 Clermont Ferrand, France.
    Kavokin, A.
    Univ Southampton, Southampton SO17 1BJ, Hants, England.
    Usui, A.
    Furukawa Co Ltd, R&D Div, Tsukuba, Ibaraki 3050856, Japan.
    Bergman, Peder
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Materiefysik.
    Pozina, Galia
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Materiefysik.
    Monemar, Bo
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Materiefysik.
    Resonant light delay in GaN with ballistic and diffusive propagation2008Ingår i: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 100, nr 8Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We report on a strong delay in light propagation through bulk GaN, detected by time-of-flight spectroscopy. The delay increases resonantly as the photon energy approaches the energy of a neutral-donor bound exciton (BX), resulting in a velocity of light as low as 2100 km/s. In the close vicinity of the BX resonance, the transmitted light contains both ballistic and diffusive components. This phenomenon is quantitatively explained in terms of optical dispersion in a medium where resonant light scattering by the BX resonance takes place in addition to the polariton propagation.

  • 333.
    Shubina, Tatiana
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Glazov, M.M.
    Ivanov, S.V.
    Vasson, A.
    Leymarie, J.
    Monemar, Bo
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Materiefysik.
    Araki, T.
    Naoi, H.
    Nanishi, Y.
    Effects of non-stoichiometry and compensation on fundamental parameters of heavily-doped InN2007Ingår i: Physica Status Solidi. C, Current topics in solid state physics, ISSN 1610-1634, E-ISSN 1610-1642, Vol. 4, nr 7, s. 2474-2477Artikel i tidskrift (Refereegranskat)
  • 334.
    Shubina, Tatiana
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Ivanov, SV
    Jmerik, VN
    Glazov, MM
    Kalvarskii, AP
    Tkachman, MG
    Vasson, A
    Leymarie, J
    Kavokin, A
    Amano, H
    Akasaki, I
    Butcher, KSA
    Guo, Q
    Monemar, Bo
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial.
    Kop'ev, PS
    Optical properties of InN with stoichoimetry violation and indium clustering2005Ingår i: Physica Status Solidi (a) applications and materials science, ISSN 1862-6300, E-ISSN 1862-6319, Vol. 202, nr 3, s. 377-382Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We demonstrate that nonstoichiometry is one of the main reason of strong deviation of the InN optical gap in the 0.7-2 eV range, with N/In < 1 and N/In > 1 corresponding to the lower and higher energies, respectively. The phenomenon is discussed in terms of atomic orbital energies, which are strongly different for indium and nitrogen, therefore both excess atom incorporation and elimination could change the optical gap. We estimate such trends using the approximation of the empirical nearest-neighbor tight binding theory. It is also demonstrated that resonant absorption in In-enriched regions is an additional factor lowering an effective absorption edge.

  • 335.
    Shubina, Tatiana
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska högskolan.
    Ivanov, SV
    Ioffe Physico-Technical Institute Polytekhnicheskaya 26 St. Petersburg 194021, Russia.
    Jmerik, VN
    Ioffe Physico-Technical Institute Polytekhnicheskaya 26 St. Petersburg 194021, Russia.
    Kop'ev, PS
    Ioffe Physico-Technical Institute Polytekhnicheskaya 26 St. Petersburg 194021, Russia.
    Vasson, A
    LASMEA-UMR 6602 CNRS-UBP 63177 AUBIERE CEDEX, France.
    Leymarie, J
    LASMEA-UMR 6602 CNRS-UBP 63177 AUBIERE CEDEX, France.
    Kavokin, A
    LASMEA-UMR 6602 CNRS-UBP 63177 AUBIERE CEDEX, France.
    Amano, H
    Meijo University, 1-501 Shiogamaguchi Tempaku-ku Nagoya 468-8502, Japan.
    Gil, B
    Université Montpellier II, 34095 Montpellier, France.
    Briot, O
    Université Montpellier II, 34095 Montpellier, France.
    Monemar, Bo
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Comment on "Mie resonances, infrared emission, and the band gap of InN" - Reply2004Ingår i: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 93, nr 26, s. 269702-Artikel i tidskrift (Övrigt vetenskapligt)
    Abstract [en]

    Abstract Not Available

  • 336.
    Shubina, Tatiana
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Ivanov, S.V.
    Jmerik, V.N.
    Mizerov, A.M.
    Leymarie, J.
    Vasson, A.
    Monemar, Bo
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Materiefysik.
    Kopev, P.S.
    Inhomogeneous InGaN and InN with In-enriched Nanostructures2007Ingår i: -,2007, 2007, s. 269-Konferensbidrag (Refereegranskat)
    Abstract [en]

      

  • 337.
    Shubina, Tatiana
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Ivanov, S.V.
    Jmerik, V.N.
    Solnyshkov, D.D.
    Vekshin, V.A.
    Kopev, P.S.
    Vasson, A
    Leymarie, J
    Kavokin, A
    Amano, H
    Shimono, K
    Monemar, Bo
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Materiefysik.
    Mie Resonances, Infrared Emission, and the Band Gap of InN2004Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The deviations on the band-gap of InN which were linked to the precipitation of indium in the metallic phase that leads to additional optical losses associated with Mie resonances were discussed. The two sets of InP epilayers were examined by both plasma-assisted molecular beam epitaxy (MBE) and metal-organic chemical vapor deposition (MOCVD) on sapphire. The Mie resonance for InN layers were important because of the activation in the In aggregation phenomena in the alloys. The results show that bright infrared emission arises in a close vicinity of In inclusions and was likely associated with surface states at the metal/InN interfaces.

  • 338.
    Shubina, Tatiana
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska högskolan.
    Ivanov, S.V.
    Mjerik, V.N.
    Solnyshkov, D.D.
    Kopev, P.D.
    Vasson, A.
    Leymaire, J.
    Kavokin, A.
    Amano, H.
    Kamiyama, S.
    Iwaya, M.
    Akasaki, I.
    Lu, H.
    Schaff, W.J.
    Kasic, A.
    Monemar, Bo
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial.
    Mie resonant Absorption and Infrared Emission in InN Related to Metallic In Clusters2005Ingår i: AIP Conference Proceedings, ISSN 0094-243X, E-ISSN 1551-7616, Vol. 772, s. 263-264Artikel i tidskrift (Refereegranskat)
  • 339.
    Shubina, Tatiana
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Ivanov, SV
    AF Ioffe Phys Tech Inst, St Petersburg 194021, Russia Linkoping Univ, Dept Phys & Measurement Technol, S-58183 Linkoping, Sweden Chalmers, S-41296 Gothenburg, Sweden Gothenburg Univ, S-41296 Gothenburg, Sweden Univ Ulm, Abt Halbleiterphys, D-89081 Ulm, Germany Univ Wurzburg, Inst Phys, D-97074 Wurzburg, Germany.
    Toropov, AA
    AF Ioffe Phys Tech Inst, St Petersburg 194021, Russia Linkoping Univ, Dept Phys & Measurement Technol, S-58183 Linkoping, Sweden Chalmers, S-41296 Gothenburg, Sweden Gothenburg Univ, S-41296 Gothenburg, Sweden Univ Ulm, Abt Halbleiterphys, D-89081 Ulm, Germany Univ Wurzburg, Inst Phys, D-97074 Wurzburg, Germany.
    Sorokin, SV
    AF Ioffe Phys Tech Inst, St Petersburg 194021, Russia Linkoping Univ, Dept Phys & Measurement Technol, S-58183 Linkoping, Sweden Chalmers, S-41296 Gothenburg, Sweden Gothenburg Univ, S-41296 Gothenburg, Sweden Univ Ulm, Abt Halbleiterphys, D-89081 Ulm, Germany Univ Wurzburg, Inst Phys, D-97074 Wurzburg, Germany.
    Lebedev, Alexander
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Kyutt, RN
    AF Ioffe Phys Tech Inst, St Petersburg 194021, Russia Linkoping Univ, Dept Phys & Measurement Technol, S-58183 Linkoping, Sweden Chalmers, S-41296 Gothenburg, Sweden Gothenburg Univ, S-41296 Gothenburg, Sweden Univ Ulm, Abt Halbleiterphys, D-89081 Ulm, Germany Univ Wurzburg, Inst Phys, D-97074 Wurzburg, Germany.
    Solnyshkov, DD
    AF Ioffe Phys Tech Inst, St Petersburg 194021, Russia Linkoping Univ, Dept Phys & Measurement Technol, S-58183 Linkoping, Sweden Chalmers, S-41296 Gothenburg, Sweden Gothenburg Univ, S-41296 Gothenburg, Sweden Univ Ulm, Abt Halbleiterphys, D-89081 Ulm, Germany Univ Wurzburg, Inst Phys, D-97074 Wurzburg, Germany.
    Pozina, Galia
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Materiefysik.
    Bergman, JP
    AF Ioffe Phys Tech Inst, St Petersburg 194021, Russia Linkoping Univ, Dept Phys & Measurement Technol, S-58183 Linkoping, Sweden Chalmers, S-41296 Gothenburg, Sweden Gothenburg Univ, S-41296 Gothenburg, Sweden Univ Ulm, Abt Halbleiterphys, D-89081 Ulm, Germany Univ Wurzburg, Inst Phys, D-97074 Wurzburg, Germany.
    Monemar, Bo
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Materiefysik.
    Willander, Magnus
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för teknik och naturvetenskap.
    Waag, A
    AF Ioffe Phys Tech Inst, St Petersburg 194021, Russia Linkoping Univ, Dept Phys & Measurement Technol, S-58183 Linkoping, Sweden Chalmers, S-41296 Gothenburg, Sweden Gothenburg Univ, S-41296 Gothenburg, Sweden Univ Ulm, Abt Halbleiterphys, D-89081 Ulm, Germany Univ Wurzburg, Inst Phys, D-97074 Wurzburg, Germany.
    Landwehr, G
    AF Ioffe Phys Tech Inst, St Petersburg 194021, Russia Linkoping Univ, Dept Phys & Measurement Technol, S-58183 Linkoping, Sweden Chalmers, S-41296 Gothenburg, Sweden Gothenburg Univ, S-41296 Gothenburg, Sweden Univ Ulm, Abt Halbleiterphys, D-89081 Ulm, Germany Univ Wurzburg, Inst Phys, D-97074 Wurzburg, Germany.
    Interface effects in type-II CdSe/BeTe quantum dots2002Ingår i: Physica status solidi. B, Basic research, ISSN 0370-1972, E-ISSN 1521-3951, Vol. 229, nr 1, s. 489-492Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We report on optical and structural studies of the interface symmetry in CdSe/BeTe multiple-layer structures containing self-assembled quantum dots. Temperature and decay behavior of the broad photoluminescence (PL) band is consistent with the type-II transitions involving deeply localized electron states. Large linear in-plane polarization of the PL (up to 80%) is observed, implying the C-2v (or lower) symmetry of the individual places of the electron localization.

  • 340.
    Shubina, Tatiana
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Jmerik, VN
    Ivanov, SV
    Kop'ev, PS
    Kavokin, A
    Karlsson, K Fredrik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Materiefysik. Linköpings universitet, Tekniska högskolan.
    Holtz, Per-Olof
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Materiefysik.
    Monemar, Bo
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Materiefysik.
    Narrow-line excitonic photoluminescence in GaN/AlxGa1-xN quantum well structures with inversion domains2003Ingår i: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 67, nr 24, s. 241306-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Microphotoluminescence studies reveal strong and narrow lines of similar to1-meV minimal width in GaN/AlxGa1-xN quantum well (QW) structures having inversion domains (IDs). These narrow lines coexist in the spectra with broad (10-15 meV) peaks. The features of both kinds are characteristic for intersections of the IDs with QWs, which provide either three- or one-dimensional carrier confinement, depending on both the ID diameter and well width.

  • 341.
    Shubina, Tatiana
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Jmerik, VN
    Tkachman, MG
    Vekshin, VA
    Ratnikov, VV
    Toropov, AA
    Sitnikova, AA
    Ivanov, SV
    Bergman, Peder
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Materiefysik.
    Karlsson, Fredrik
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Materiefysik.
    Holtz, Per-Olof
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Materiefysik.
    Monemar, Bo
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Materiefysik.
    Nanometric-scale fluctuations of intrinsic electric fields in GaN/AlGaN quantum wells with inversion domains2002Ingår i: Physica status solidi. B, Basic research, ISSN 0370-1972, E-ISSN 1521-3951, Vol. 234, nr 3, s. 919-923Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Strain and electric field fluctuations in regions of different polarities in GaN/AlGaN quantum well (QW) structures of dominant N-polarity with inversion domains (IDs) split the photoluminescence (PL) emission into two bands. Micro-PL and time-resolved PL studies reveal strong inhomogeneity of the array of the IDs, where essential parameters, such as strain, electric fields, and sizes are fluctuating quantities. We demonstrate also that the ID formation decreases the intrinsic electric field magnitudes.

  • 342.
    Shubina, Tatiana
    et al.
    Ioffe Physico-Technical Institute, Polytekhnicheskaya 26, St. Petersburg 194021, Russian Federation.
    Jmerik, V.N.
    Ioffe Physico-Technical Institute, Polytekhnicheskaya 26, St. Petersburg 194021, Russian Federation.
    Tkachman, M.G.
    Ioffe Physico-Technical Institute, Polytekhnicheskaya 26, St. Petersburg 194021, Russian Federation.
    Vekshin, V.A.
    Ioffe Physico-Technical Institute, Polytekhnicheskaya 26, St. Petersburg 194021, Russian Federation.
    Toropov, A.A.
    Ioffe Physico-Technical Institute, Polytekhnicheskaya 26, St. Petersburg 194021, Russian Federation.
    Ivanov, S.V.
    Ioffe Physico-Technical Institute, Polytekhnicheskaya 26, St. Petersburg 194021, Russian Federation.
    Kop'ev, P.S.
    Ioffe Physico-Technical Institute, Polytekhnicheskaya 26, St. Petersburg 194021, Russian Federation.
    Bergman, Peder
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Karlsson, Fredrik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Holtz, Per-Olof
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Monemar, Bo
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial.
    Optical properties of GaN/AlGaN quantum wells with inversion domains2003Ingår i: Physica status solidi. A, Applied research, ISSN 0031-8965, E-ISSN 1521-396X, Vol. 195, nr 3, s. 537-542Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Two-band photoluminescence (PL) and respective absorption and reflection features are observed in GaN/AlGaN MBE-grown quantum well (QW) structures of dominant N polarity with inversion domains (IDs). The PL bands are related to transitions in the regions of different polarity, characterized by different strain and electric fields. A micro-PL study reveals sharp and narrow (1.5-2.5 meV) PL lines placed between the bands, which are tentatively attributed to recombination at localization sites associated with intersections of the QWs with the domains. Additionally, we demonstrate that the ID formation decreases the overall strength of the intrinsic electric fields in the QW structures.

  • 343. Shubina, Tatiana
    et al.
    Karlsson, Fredrik
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Materiefysik.
    Jmerik, V.N.
    Ivanov, S.V.
    Kavokin, P.S.
    Holtz, Per-Olof
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Materiefysik.
    Kopev, P.S.
    Monemar, Bo
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Materiefysik.
    Narrow-line excitonic luminescence in GaN/AlGaN nanostructures based on inversion domains2003Ingår i: Physica Status Solidi. C, Current topics in solid state physics, ISSN 1610-1634, E-ISSN 1610-1642, Vol. 0, nr 7, s. 2716-2720Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Presented at: 5th International Conference on Nitride Semiconductors (ICNS-5), Nara, Japan, 25-30 May, 2003 

  • 344.
    Shubina, Tatiana
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska högskolan.
    Leymarie, J.
    Jmerik, V.N.
    Amano, H.
    Schaff, W.J.
    Monemar, Bo
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial.
    Ivanov, S.V.
    Optical properties of InN related to surface plasmons2005Ingår i: Physica Status Solidi (a) applications and materials science, ISSN 1862-6300, E-ISSN 1862-6319, Vol. 202, nr 14, s. 2633-2641Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We report on the complex nature of infrared luminescence and absorption in InN films, which cannot be entirely explained by the concept of a conventional narrow-gap semiconductor. In particular, it concerns the detection of peaks near absorption edges by both thermally detected optical absorption and photoluminescence excitation spectroscopy and the observation of extraordinarily strong resonant enhancement of emission. To describe the experimental data a model is proposed, which takes into account surface plasmons in metal-like inclusions, modifying the optical properties of InN. © 2005 WILEY-VCH Verlag GmbH & Co. KGaA,.

  • 345.
    Shubina, Tatiana
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Paskova, Tanja
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Toropov, AA
    Russian Acad Sci, AF Ioffe Phys Tech Inst, Ctr Nanoheterostruct Phys, St Petersburg 194021, Russia Linkoping Univ, Dept Phys & Measurement Technol, S-581833 Linkoping, Sweden.
    Lebedev, Alexander
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Ivanov, SV
    Russian Acad Sci, AF Ioffe Phys Tech Inst, Ctr Nanoheterostruct Phys, St Petersburg 194021, Russia Linkoping Univ, Dept Phys & Measurement Technol, S-581833 Linkoping, Sweden.
    Monemar, Bo
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Materiefysik.
    Micro-photoluminescence spectroscopy of exciton-polaritons in GaN with the wave vector k normal to the c-axis2001Ingår i: Physica status solidi. B, Basic research, ISSN 0370-1972, E-ISSN 1521-3951, Vol. 228, nr 2, s. 481-484Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We report on polarized micro-photoluminescence (mu -PL) and micro-reflectance (mu -R) studies of GaN layers grown by HVPE. A strong pi -polarized component in the vicinity of A exciton is observed in the mu -PL and attributed as a mixture of a bound B exciton, dominating at low temperature, and scattered A exciton-polariton states prevailing at higher temperatures. Temperature variation of exciton energies in the mu -R spectra reveals strain-induced difference between the top surface and the cleaved edges.

  • 346.
    Shubina, Tatiana
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Plotnikov, D.S.
    Terentev, Ya.V.
    Vinokurov, D.A.
    Pihtin, N.A.
    Tarasov, I.S.
    Ivanov, S.V.
    Leymarie, J.
    Kavokin, A.
    Vasson, A.
    Monemar, Bo
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Materiefysik.
    Lu, H.
    Schaff, W.J
    Kopev, P.S.
    Surface-plasmon-related enhancement of luminescence in InN2005Ingår i: 13 Int. Symposium Nanostructures: Physics and Technology,2005, 2005, s. 268-269Konferensbidrag (Refereegranskat)
  • 347. Shubina, Tatiana
    et al.
    Plotnikov, D.S.
    Vasson, A.
    Leymarie, J.
    Larsson, Mats
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Materiefysik.
    Holtz, Per-Olof
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Materiefysik.
    Monemar, Bo
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Materiefysik.
    Lu, H.
    Schaff, W.J.
    Kop¿ev, P.S.
    Surface-plasmon resonances in indium nitride with metal-enriched nano-particles2006Ingår i: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 288, nr 2, s. 230-235Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Plasmonic resonances in In-enriched nano-particles, spontaneously formed during growth, can dramatically modify optical properties of InN. Experimental support for this is provided from detailed studies of absorption and infrared emission in InN. In particular, thermally detected optical absorption and photoluminescence excitation spectroscopy reveal a peak below the region of strong absorption in InN. A higher-energy part of the infrared emission having a noticeable p-polarization is markedly enhanced with excitation along the surface. These peculiarities are discussed in terms of the Mie resonances, arising in metallic spheroids with different aspect ratio, and their coupling with recombining states, whose strength depends on energy separation between the states and the resonances. © 2005 Elsevier B.V. All rights reserved.

  • 348.
    Shubina, Tatiana
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Toropov, AA
    AF Ioffe Phys Tech Inst, St Petersburg 194021, Russia Linkoping Univ, Dept Phys & Measurement Technol, S-58183 Linkoping, Sweden.
    Ivanov, SV
    AF Ioffe Phys Tech Inst, St Petersburg 194021, Russia Linkoping Univ, Dept Phys & Measurement Technol, S-58183 Linkoping, Sweden.
    Bergman, JP
    AF Ioffe Phys Tech Inst, St Petersburg 194021, Russia Linkoping Univ, Dept Phys & Measurement Technol, S-58183 Linkoping, Sweden.
    Paskova, Tanja
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Holtz, Per-Olof
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Materiefysik.
    Monemar, Bo
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Materiefysik.
    Peculiarities of exciton-polaritons in GaN at different polarizations studied by mu-photoluminescence spectroscopy2002Ingår i: Physica status solidi. A, Applied research, ISSN 0031-8965, E-ISSN 1521-396X, Vol. 190, nr 1, s. 205-211Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We report on polariton properties in high quality thick GaN grown by hydride vapor phase epitaxy on c-sapphire. A strong fine is observed in the vicinity of the A exciton in T-polarization (k perpendicular to c, E parallel to the c-axis) by micro-photoluminescence (mu-PL). Comparison of the mu-PL and mu-reflectance spectra confirms the internal origin of the polariton emission. In the samples with low density of residual donors the enhancement of the a-polarized component is induced mostly by interbranch scattering which occurs, possibly., due to the complex structure of the exciton-polariton branches at k perpendicular to c. The Gamma(1)-Gamma(5) exciton splitting in the C band is determined by the mu-reflectance as similar to1 meV.

  • 349.
    Shubina, Tatiana
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Toropov, AA
    Jmerik, VN
    Tkachman, MG
    Lebedev, Alexander
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Ratnikov, VV
    Sitnikova, AA
    Vekshin, VA
    Ivanov, SV
    Kop'ev, PS
    Bigenwald, P
    Bergman, Peder
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Materiefysik.
    Holtz, Per-Olof
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Materiefysik.
    Monemar, Bo
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Materiefysik.
    Intrinsic electric fields in N-polarity GaN/AlxGa1-xN quantum wells with inversion domains2003Ingår i: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 67, nr 19Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    GaN/AlGaN quantum wells (QWs) of dominant N polarity with inversion domains (IDs), grown by molecular-beam epitaxy, have been studied. Two-band photoluminescence (PL), with the lower-energy band and an additional absorption edge related to the IDs, is observed in these QWs due to a difference in strain, electric field, and well width in the regions of different polarities. A time-resolved PL study reveals additionally strong inhomogeneity of the electric fields among the IDs. The intrinsic electric fields in the structures are relatively small-their maximal estimated value of 180 kV/cm is among the lowest ever reported. The low-scale electric fields indicate likely polarization deterioration in the N-polarity structures. These conditions are favorable for bright PL up to room temperature in 8-9-nm-wide wells.

  • 350. Shubina, Tatiana
    et al.
    Toropov, A.A.
    Lublinskaya, O.G.
    Kopev, P.S.
    Ivanov, S.V.
    El-Shaer, A.
    Al-Suleiman, M.
    Bakin, A.
    Waag, A.
    Voinilovich, A.
    Lutsenko, E.V.
    Yablonskii, G.P.
    Bergman, Peder
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Materiefysik.
    Pozina, Galia
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Materiefysik.
    Monemar, Bo
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Materiefysik.
    Recombination dynamics and lasing in ZnO/ZnMgO single quantum well structures2007Ingår i: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 91, nr 20Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We report a time-resolved study of the recombination dynamics in molecular beam epitaxy grown ZnOZnMgO single quantum wells (SQWs) of 1.0-4.5 nm width. The SQWs exhibit different emission properties, depending on both the well width and defect density. Stimulated emission has been achieved at room temperature in a separate confinement double heterostructure having a 3 nm wide SQW as an active region. It has been found that a critical parameter for the lasing is the inhomogeneous broadening of both QW and barrier emission bands. © 2007 American Institute of Physics.

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