Change search
Refine search result
456789 301 - 350 of 403
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • 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.
  • 301.
    Ren, Qijun
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Devika, A.
    Tu, C. W.
    Department of Electrical and Computer Engineering, University of California, San Diego, La Jolla, California, USA .
    Chen, Weimin
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Buyanova, Irina
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Localized surface plasmon mediated emission from Ni coated ZnO nanowires2012Conference paper (Refereed)
  • 302.
    Ren, Qijun
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Filippov, Stanislav
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Chen, Shula
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Devika, M.
    Department of Nanobio Materials and Electronics, Gwangju Institute of Science and Technology, Gwangju, Republic of Korea .
    Koteeswara Reddy, N.
    Department of Nanobio Materials and Electronics, Gwangju Institute of Science and Technology, Gwangju, Republic of Korea.
    Tu, C. W.
    Department of Electrical and Computer Engineering, University of California, San Diego, La Jolla, California, USA .
    Chen, Weimin
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Buyanova, Irina
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Evidence for coupling between exciton emissions and surface plasmon in Ni-coated ZnO nanowires2012In: Nanotechnology, ISSN 0957-4484, E-ISSN 1361-6528, Vol. 23, no 42, p. 425201-Article in journal (Refereed)
    Abstract [en]

    We show that coating ZnO nanowires (NWs) with a transition metal, such as Ni, can increase the efficiency of light emission at room temperature. Based on detailed structural and optical studies, this enhancement is attributed to energy transfer between near-band-edge emission in ZnO and surface plasmons in the Ni film which leads to an increased rate of the spontaneous emission. It is also shown that the Ni coating leads to an enhanced non-radiative recombination via surface states, which becomes increasingly important at low measurement temperatures and in annealed ZnO/Ni NWs.

  • 303. Rudko, G. Yu.
    et al.
    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.
    Toropov, A. A.
    Terentev, Y.
    Sorokin, S. V.
    Lebedev, A. V.
    Ivanov, S. V.
    Kopev, P. S.
    Energy relaxation and spin alignment in diluted magnetic semiconductor superlattices2002In: Electronic Materials Conference,2002, 2002Conference paper (Other academic)
  • 304. Rudko, G. Yu.
    et al.
    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.
    Xin, H. P.
    Tu, C. W.
    Temperature behavior of the GaNP band gap energy2003In: E-MRS 2002 Spring Meeting,2002, Elsevier , 2003, p. 493-496Conference paper (Refereed)
    Abstract [en]

    We report experimental results from temperature dependence studies of the optical absorption edge of the GaNP alloys with N compositions up to 3.1%. The observed increase in the absorption coefficient with increasing N content, as well as the spectral shape of the absorption edge incline a band crossover to a direct band gap for the alloy, in agreement with previous studies. Temperature variation of the GaNP band gap, however, is found to be rather similar to that in the parental GaP, except for the N composition of ~1% when a slow down in the thermally induced reduction of the band gap energy was observed due to a resonant interaction with the N-related defects. We thus suggest that both contributions from the interaction with the localized states and the increasing Γ character of the conduction band states are important for the alloy formation.

  • 305. Rudko, G. Yu.
    et al.
    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.
    Xin, H. P.
    Tu, C. W.
    Temperature dependence of the GaNxP1-x band gap and effect of band crossover2002In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 81, no 21, p. 3984-Article in journal (Refereed)
    Abstract [en]

    The absorption edge of GaNxP1-x alloys (0.01<=x<=0.03) is shown to exhibit a direct-band gap-like behavior. Thermal variation of the band gap energy Eg, however, is found to be the same or even smaller than that for the indirect band gap of GaP and depends on the N content. The effect is tentatively attributed to the following counteracting contributions to the band edge formation. An interaction with N-related localized states, especially significant in the vicinity of band crossover (e.g., x = 0.013), causes a substantial slow down of the Eg shift with temperature. On the contrary, an increasing contribution of Γc states, which becomes predominant for the higher compositions, leads to the larger thermal variation in Eg.

  • 306. Rudko, G. Yu.
    et al.
    Buyanova, Irina
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    Monemar, Bo
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Chen, Weimin
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    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 superlattices2003In: 26th International Conference on the Physics of Semiconductors,2002, 2003, p. H245-Conference paper (Other academic)
  • 307.
    Rudko, G. Yu.
    et al.
    V. Lashkaryov Institute of Semiconductor Physics of National Academy of Sciences of Ukraine, Kiev.
    Kovalchuk, A. O.
    V. Lashkaryov Institute of Semiconductor Physics of National Academy of Sciences of Ukraine, Kiev.
    Fediv, V. I.
    Bukovinian State Medical University, Chernivtsi, Ukraine.
    Beyer, Jan
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Chen, Weimin
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Buyanova, Irina
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Effects of ultraviolet light on optical properties of colloidal CdS nanoparticles embedded in a polymer PVA matrix2012In: Advanced Science, Engineering and Medicine, ISSN 2164-6627, Vol. 4, no 5, p. 394-400Article in journal (Refereed)
    Abstract [en]

    CdS nanoparticles have been synthesized in aqueous solution using polyvinyl alcohol (PVA) as a capping reagent. The effects of exposure by ultraviolet (UV) light on optical properties of nanocomposites consisting of colloidal CdS nanoparticles and a polymer PVA matrix were studied by employing photoluminescence (PL) spectroscopy. It is shown that UV-induced changes of the photoluminescence intensity in PVA are caused by creation and healing of non-radiative recombination centers. It is also concluded that in the nanocomposites, the UV-induced changes of the PL intensity are predominantly governed by processes at the NP/PVA interface.

  • 308.
    Rudko, G. Yu.
    et al.
    V. Lashkaryov Institute of Semiconductor Physics of National Academy of Sciences of Ukraine, Kiev.
    Kovalchuk, A. O.
    V. Lashkaryov Institute of Semiconductor Physics of National Academy of Sciences of Ukraine, Kiev.
    Fediv, V. I.
    Bukovinian State Medical University, Chernivtsi, Ukraine.
    Beyer, Jan
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Chen, Weimin
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Buyanova, Irina
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Nanocomposites properties variation under UV-exposure2012Conference paper (Other academic)
  • 309.
    Rudko, G. Yu,
    et al.
    V. Lashkaryov Institute of Semiconductor Physics of National Academy of Sciences of Ukraine, Kiev, Ukraine.
    Kovalchuk, A. O.
    V. Lashkaryov Institute of Semiconductor Physics of National Academy of Sciences of Ukraine, Kiev, Ukraine.
    Fediv, V. I.
    Department of Biophysics and Medical Informatics, Bukovinian State Medical University, Chernivtsi, Ukraine.
    Ren, Q. J.
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Chen, Weimin
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Buyanova, Irina
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Pozina, Galia
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Role of the host polymer matrix in light emission processes in nano-CdS/poly vinyl alcohol composite2013In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 543, p. 11-15Article in journal (Refereed)
    Abstract [en]

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

  • 310.
    Rudko, Galyna
    et al.
    National Academic Science Ukraine, Ukraine.
    Kovalchuk, Andrii
    National Academic Science Ukraine, Ukraine.
    Fediv, Volodymyr
    Bukovinian State Medical University, Ukraine.
    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.
    Enhancement of polymer endurance to UV light by incorporation of semiconductor nanoparticles2015In: Nanoscale Research Letters, ISSN 1931-7573, E-ISSN 1556-276X, Vol. 10, no 81, p. 1-6Article in journal (Refereed)
    Abstract [en]

    Improvement of polyvinyl alcohol stability against ultraviolet (UV) illumination is achieved by introducing cadmium sulfide (CdS) nanoparticles into the polymeric matrix. Enhancement of stability is analyzed by optical characterization methods. UV protection is achieved by diminishing the probability of photo-activated formation of defects in polymer. The sources of polymer protection are the lowering of the efficiency of polymer excitation via partial absorption of incident light by the embedded nanoparticles as well as the de-excitation of the macromolecules that have already absorbed UV quanta via energy drain to nanoparticles. Within the nanoparticles, the energy is either dissipated by conversion to the thermal energy or reemitted as visible-range photoluminescence quanta.

  • 311.
    Rudko, Galyna Yu
    et al.
    V. Lashkaryov Institute of Semiconductor Physics of National Academy of Sciences of Ukraine, 45, Pr. Nauky, Kiev 03028, Ukraine..
    Koval'chuk, Andrii O
    Nauky, Kiev 03028, Ukraine.
    Fediv, Volodymyr I
    Department of Biophysics and Medical Informatics, Bukovinian State Medical University, 42 Kobylyanska st., 58000 Chernivtsi, Ukraine..
    Chen, Weimin
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, Faculty of Science & Engineering.
    Buyanova, Irina A
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, Faculty of Science & Engineering.
    Interfacial bonding in a CdS/PVA nanocomposite: A Raman scattering study2015In: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 452, p. 33-37Article in journal (Refereed)
    Abstract [en]

    Raman spectroscopy is employed to characterize the bonding between CdS nanoparticles (NPs) and a polyvinyl alcohol (PVA) as well as structural changes in the polymeric matrix caused by incorporation of NPs. It is shown that after the formation of CdS NPs the vibrations of carbonyl groups in acetate residuals of PVA and of CO groups at the macromolecules ends disappear. Formation of NPs also leads to an increased degree of hydrogen bonding and crystallinity of the hybrid material as compared with the unloaded polymer. The observed changes are ascribed to the formation of coordinative bonds and hydrogen between the CdS nanoparticles and polymeric macromolecules. The scheme of this interfacial bonding is also proposed.

  • 312.
    Rudko, Galyna Yu.
    et al.
    National Academic Science Ukraine, Ukraine.
    Vorona, Igor P.
    National Academic Science Ukraine, Ukraine.
    Fediv, Volodymyr I.
    Bukovinian State Medical University, Ukraine.
    Kovalchuk, Andrii
    National Academic Science Ukraine, Ukraine.
    Stehr, Jan Eric
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    Shanina, Bela D.
    National Academic Science Ukraine, Ukraine.
    Chen, Weimin
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    Buyanova, Irina
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    Luminescent and Optically Detected Magnetic Resonance Studies of CdS/PVA Nanocomposite2017In: Nanoscale Research Letters, ISSN 1931-7573, E-ISSN 1556-276X, Vol. 12, article id 130Article in journal (Refereed)
    Abstract [en]

    A series of solid nanocomposites containing CdS nanoparticles in polymeric matrix with varied conditions on the interface particle/polymer was fabricated and studied by photoluminescence (PL) and optically detected magnetic resonance (ODMR) methods. The results revealed interface-related features in both PL and ODMR spectra. The revealed paramagnetic centers are concluded to be involved in the processes of photo-excited carriers relaxation.

  • 313.
    Stehr, Jan Eric
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Chen, S. L.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    Chen, Weimin
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Buyanova, Irina
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Photo-EPR and Photoluminescence Excitation Studies of Defects/Impurities Responsible for Upconversion Effects in Bulk ZnO crystals.2013Conference paper (Refereed)
  • 314.
    Stehr, Jan Eric
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Chen, S. L.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    Filippov, S.
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Devika, M.
    Department of Nanobio Materials and Electronics, Gwangju Institute of Science and Technology, Gwangju, Republic of Korea .
    Koteeswara Reddy, N.
    Department of Nanobio Materials and Electronics, Gwangju Institute of Science and Technology, Gwangju 500712, Republic of Korea.
    Tu, C. W.
    Department of Electrical and Computer Engineering, University of California, San Diego, La Jolla, California, USA .
    Chen, Weimin
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Buyanova, Irina
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Defect properties of ZnO nanowires2014In: AIP Conference Proceedings, ISSN 0094-243X, E-ISSN 1551-7616, Vol. 1583, p. 272-276Article in journal (Refereed)
    Abstract [en]

    In this work we examined optical and defect properties of as-grown and Ni-coated ZnO nanowires (NWs) grown by rapid thermal chemical vapor deposition by means of optically detected magnetic resonance (ODMR). Several grown-in defects are revealed by monitoring visible photoluminescence (PL) emissions and are attributed to Zn vacancies, O vacancies, a shallow (but not effective mass) donor and exchange-coupled pairs of a Zn vacancy and a Zn interstitial. It is also found that the same ODMR signals are detected in the as-grown and Ni-coated NWs, indicating that metal coatings does not significantly affect formation of the aforementioned defects and that the observed defects are located in the bulk of the NWs.

  • 315.
    Stehr, Jan Eric
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Chen, S. L.
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Knutsen, K. E.
    Svensson, B. G.
    Chen, Weimin
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Buyanova, Irina
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Electron Paramagnetic Resonance Investigations of Defects in Electron Irradiated ZnO2013Conference paper (Other academic)
  • 316.
    Stehr, Jan Eric
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, Faculty of Science & Engineering.
    Chen, Shula
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Filippov, Stanislav
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, Faculty of Science & Engineering.
    Devika, M
    Gwangju Institute Science and Technology, South Korea .
    Koteeswara Reddy, N
    Gwangju Institute Science and Technology, South Korea .
    Tu, C W
    Gwangju Institute Science and Technology, South Korea University of Calif San Diego, CA 92093 USA .
    Chen, Weimin
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Buyanova, Irina
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Defect properties of ZnO nanowires revealed from an optically detected magnetic resonance study2013In: Nanotechnology, ISSN 0957-4484, E-ISSN 1361-6528, Vol. 24, no 1, p. 015701-Article in journal (Refereed)
    Abstract [en]

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

  • 317.
    Stehr, Jan Eric
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, Faculty of Science & Engineering.
    Chen, Shula
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, Faculty of Science & Engineering.
    Jansson, Mattias
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, Faculty of Science & Engineering.
    Ishikawa, F.
    Ehime University, Japan.
    Chen, Weimin
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, Faculty of Science & Engineering.
    Buyanova, Irina
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, Faculty of Science & Engineering.
    Defect formation in GaAs/GaNxAs1-x core/shell nanowires2016In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 109, no 20, article id 203103Article in journal (Refereed)
    Abstract [en]

    Photoluminescence and optically detected magnetic resonance (ODMR) spectroscopies are used to investigate the formation and role of defects in GaAs/GaNxAs1-x core/shell nanowires (NWs) grown by molecular beam epitaxy on Si substrates. Gallium vacancies, which act as non-radiative recombination (NRR) centers, are identified by ODMR. It is shown that the defects are formed in bulk regions, i.e., not on the surface, of the GaNAs shell and that their concentration increases with increasing nitrogen content. Temperature dependent photoluminescence experiments reveal, on the other hand, suppressed thermal quenching of the near-band-edge emission with increasing [N]. This leads to the conclusion that the dominant NRR processes in the studied NWs are governed by surface defects, whereas the role of gallium vacancies in the observed thermally activated NRR is minor. Published by AIP Publishing.

  • 318.
    Stehr, Jan Eric
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Chen, Shula
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Knutsen, K. E.
    Svensson, B. G.
    Chen, Weimin
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Buyanova, Irina
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Defects in Electron Irradiated ZnO: An Electron Paramagnetic Resonance Study2013In: 2013 MRS Fall Meeting, 2013Conference paper (Refereed)
  • 319.
    Stehr, Jan Eric
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Chen, Shula
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Koteeswara Reddy, Nandanapalli
    Gwangju Institute Science and Technology, South Korea .
    Tu, Charles W.
    University of California, La Jolla, USA.
    Chen, Weimin
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Buyanova, Irina
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Turning ZnO into an Efficient Energy Upconversion Material by Defect Engineering2014In: Advanced Functional Materials, ISSN 1616-301X, E-ISSN 1616-3028, Vol. 24, no 24, p. 3760-3764Article in journal (Refereed)
    Abstract [en]

    Photon upconversion materials are attractive for a wide range of applications from medicine, biology, to photonics. Among them, ZnO is of particular interest owing to its outstanding combination of materials and physical properties. Though energy upconversion has been demonstrated in ZnO, the exact physical mechanism is still unknown, preventing control of the processes. Here, defects formed in bulk and nanostructured ZnO synthesized using standard growth techniques play a key role in promoting efficient energy upconversion via two-step two-photon absorption (TS-TPA). From photoluminescence excitation of the anti-Stokes emissions, the threshold energy of the TS-TPA process is determined as being 2.10-2.14 eV in all studied ZnO materials irrespective of the employed growth techniques. This photo-electron paramagnetic resonance studies show that this threshold closely matches the ionization energy of the zinc vacancy (a common grown-in intrinsic defect in ZnO), thereby identifying the zinc vacancy as being the dominant defect responsible for the observed efficient energy upconversion. The upconversion is found to persist even at a low excitation density, making it attractive for photonic and photovoltaic applications.

  • 320.
    Stehr, Jan Eric
    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.
    Koteeswawa Reddy, Nandanapalli
    Humboldt University, Institute of Chemistry, Berlin, Germany.
    Tu, Charles W.
    University of California, Department of Electrical and Computer Engineering, La Jolla, CA, USA.
    Buyanova, Irina
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Efficient nitrogen incorporation in ZnO nanowires2015In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 5, article id 13406Article in journal (Refereed)
    Abstract [en]

    One-dimensional ZnO nanowires (NWs) are a promising materials system for a variety of applications. Utilization of ZnO, however, requires a good understanding and control of material properties that are largely affected by intrinsic defects and contaminants. In this work we provide experimental evidence for unintentional incorporation of nitrogen in ZnO NWs grown by rapid thermal chemical vapor deposition, from electron paramagnetic resonance spectroscopy. The incorporated nitrogen atoms are concluded to mainly reside at oxygen sites (NO). The NO centers are suggested to be located in proximity to the NW surface, based on their reduced optical ionization energy as compared with that in bulk. This implies a lower defect formation energy at the NW surface as compared with its bulk value, consistent with theoretical predictions. The revealed facilitated incorporation of nitrogen in ZnO nanostructures may be advantageous for realizing p-type conducting ZnO via N doping. The awareness of this process can also help to prevent such unintentional doping in structures with desired n-type conductivity.

  • 321.
    Stehr, Jan Eric
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, Faculty of Science & Engineering.
    Chen, Weimin
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, Faculty of Science & Engineering.
    Reddy, N. K.
    Humboldt University, Institute of Chemistry, Berlin, Germany .
    Tu, C. W.
    Department of Electrical and Computer Engineering, University of California, La Jolla, CA, USA .
    Buyanova, Irina
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, Faculty of Science & Engineering.
    Unintentional nitrogen incorporation in ZnO nanowires detected by electron paramagnetic resonance spectroscopy2016In: Physica Status Solidi. C, Current topics in solid state physics, ISSN 1610-1634, E-ISSN 1610-1642, Vol. 13, no 7-9, p. 572-575Article in journal (Refereed)
    Abstract [en]

    Unintentional incorporation of nitrogen in ZnO nanowires (NWs) grown by rapid thermal chemical vapor deposition is unambiguously proven by electron paramagnetic resonance spectroscopy. The nitrogen dopants are suggested to be provided from contaminations in the source gases. The majority of incorporated nitrogen atoms are concluded to reside at oxygen sites, i.e. in the atomic configuration of nitrogen substituting for oxygen (NO). The NO centers are suggested to be located in proximity to the NW surface, based on their reduced optical ionization energy as compared with that in a bulk material. This implies that the defect formation energy at the NW surface could be lower than its bulk value, consistent with previous theoretical predictions. The obtained results underline that nitrogen can be easily incorporated in ZnO nanostructures which may be of advantage for realizing p-type conducting ZnO via N doping. On the other hand, the awareness of this process can help to prevent such unintentional doping in structures with desired n-type conductivity.

  • 322.
    Stehr, Jan Eric
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, Faculty of Science & Engineering.
    Chen, Weimin
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, Faculty of Science & Engineering.
    Reddy, Nandanapalli Koteeswara
    Humboldt University, Institute of Chemistry, Berlin, 12489, Germany.
    Tu, Charles W
    University of California, Department of Electrical and Computer Engineering, La Jolla, CA 92093, USA.
    Buyanova, Irina
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, Faculty of Science & Engineering.
    Efficient Nitrogen Incorporation in ZnO Nanowires by Unintentional Doping2015Conference paper (Refereed)
    Abstract [en]

    One-dimensional ZnO nanowires (NWs) are a promising materials system for a variety of applications. Utilization of ZnO, however, requires a good understanding and control of material properties that are largely affected by intrinsic defects and contaminants. In this work we provide experimental evidence for unintentional incorporation of nitrogen in ZnO NWs grown by rapid thermal chemical vapor deposition, from electron paramagnetic resonance spectroscopy. The incorporated nitrogen atoms are concluded to mainly reside at oxygen sites (NO). The NO centers are suggested to be located in proximity to the NW surface, based on their reduced optical ionization energy as compared with that in bulk. This implies a lower defect formation energy at the NW surface as compared with its bulk value, consistent with theoretical predictions. The revealed facilitated incorporation of nitrogen in ZnO nanostructures may be advantageous for realizing p-type conducting ZnO via N doping. The awareness of this process can also help to prevent such unintentional doping in structures with desired n-type conductivity.

  • 323.
    Stehr, Jan Eric
    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.
    Reddy, Nandanapalli Koteeswara
    Tu, C.W.
    Buyanova, Irina
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Efficient Nitrogen Incorporation in ZnO Nanowires by Unintentional Doping2015Conference paper (Refereed)
  • 324.
    Stehr, Jan Eric
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, Faculty of Science & Engineering.
    Chen, Weimin
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, Faculty of Science & Engineering.
    Svensson, B. G.
    University of Oslo, Norway.
    Buyanova, Irina
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, Faculty of Science & Engineering.
    Thermal stability of the prominent compensating (Al-Zn-V-Zn) center in ZnO2016In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 119, no 10, p. 105702-Article in journal (Refereed)
    Abstract [en]

    Electron paramagnetic resonance spectroscopy is used to investigate the thermal stability of the Aluminum-Zinc vacancy (Al-Zn-V-Zn) complex created in bulk single crystalline ZnO by room temperature electron irradiation with an energy of 1.2 MeV. Two different stages in the annealing process at 160 and 250 degrees C with apparent activation energies of E-A1 = 1.5 +/- 0.2 eV and E-A2 = 1.9 +/- 0.2 eV, respectively, are observed. The second stage leads to the complete annealing out of the (Al-Zn-V-Zn) complex and is accompanied by restoration of the concentration of the AlZn shallow donor centers to its initial value in as-grown (i.e., not irradiated) material. The obtained results prove that the (Al-Zn-V-Zn) complex is the dominant acceptor responsible for compensation of n-type-dopants in the studied Al-containing ZnO samples. (C) 2016 AIP Publishing LLC.

  • 325.
    Stehr, Jan Eric
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, Faculty of Science & Engineering.
    Chen, Weimin
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Svensson, Bengt
    Buyanova, Irina
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    The zinc vacancy – donor complex: A relevant compensating center in n-type ZnO (invited talk)2016Conference paper (Refereed)
  • 326.
    Stehr, Jan Eric
    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.
    Tu, C. W.
    Department of Electrical and Computer Engineering, University of California, San Diego, La Jolla, California, USA .
    Buyanova, Irina
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Unintentional Nitrogen Doping in ZnO Nanowires Revealed by Electron Paramagnetic Resonance Spectroscopy2014In: Abstract Book of the 56th Electronic Materials Conference, 2014, p. 113-Conference paper (Refereed)
  • 327.
    Stehr, Jan Eric
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, Faculty of Science & Engineering.
    Dobrovolskiy, Alexander
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Kuang, Y. J.
    Department of Physics, University of California, La Jolla, San Diego, California, 92093, USA.
    Sukrittanon, S.
    Graduate Program of Material Science and Engineering, University of California, La Jolla, San Diego, California, 92093, USA.
    Tu, C. W.
    Department of Electrical and Computer Engineering, University of California, La Jolla, San Diego, California, 92093, USA.
    Chen, Weimin
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, Faculty of Science & Engineering.
    Bouyanova, Irina
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, Faculty of Science & Engineering.
    Novel GaP/GaNP Core/Shell Nanowires for Optoelectronics and Photonics2015In: Abstract Book, 2015, p. S8.03-Conference paper (Refereed)
  • 328.
    Stehr, Jan Eric
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Dobrovolsky, Alexander
    Filippov, Stanislav
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Kuang, Y. J.
    Department of Physics, University of California, La Jolla, California, USA.
    Sukrittanon, S.
    Graduate Program of Materials Science and Engineering, La Jolla, California, USA .
    Tu, C. W.
    Department of Electrical and Computer Engineering, University of California, San Diego, La Jolla, California, USA .
    Chen, Weimin
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Buyanova, Irina
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    GaP/GaNP core/shell nanowires - a novel material system for optoelectronics and photonics2014In: Abstract Book of the 3rd Int. Conf. on Nanostructures, Nanomaterials and Nanoengineering, 2014, p. 31-Conference paper (Refereed)
  • 329.
    Stehr, Jan Eric
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, Faculty of Science & Engineering.
    Dobrovolsky, Alexander
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    Kuang, K. J.
    Sukrittanon, Supanee
    Tu, Charles W.
    Department of Electrical and Computer Engineering, University of California.
    Chen, Weimin
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, Department of Thematic Studies. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Buyanova, Irina A
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, Department of Thematic Studies. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Defect formation and optical properties of coaxial GaP/GaNP core/shell Nanowires (invited talk)2016Conference paper (Refereed)
  • 330.
    Stehr, Jan Eric
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Dobrovolsky, Alexander
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Sukrittanon, S.
    Kuang, Y.
    Tu, C.W.
    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.
    Fabry-Perot Microcavity Modes in Single GaP/GaNP Core/Shell Nanowires.2015Conference paper (Refereed)
  • 331.
    Stehr, Jan Eric
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Dobrovolsky, Alexander
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Sukrittanon, S.
    Graduate Program of Materials Science and Engineering, La Jolla, California, USA .
    Kuang, Yanjin
    Department of Physics, University of California—San Diego, La Jolla, California 92093, United States.
    Tu, C. W.
    Department of Electrical and Computer Engineering, University of California, San Diego, La Jolla, California, USA .
    Chen, Weimin
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Buyanova, Irina
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Optimizing GaNP Coaxial Nanowires for Efficient Light Emission by Controlling Formation of Surface and Interfacial Defects2015In: Nano letters (Print), ISSN 1530-6984, E-ISSN 1530-6992, Vol. 15, no 1, p. 242-247Article in journal (Refereed)
    Abstract [en]

    We report on identification and control of important nonradiative recombination centers in GaNP coaxial nanowires (NWs) grown on Si substrates in an effort to significantly increase light emitting efficiency of these novel nanostructures promising for a wide variety of optoelectronic and photonic applications. A point defect complex, labeled as DD1 and consisting of a P atom with a neighboring partner aligned along a crystallographic ⟨111⟩ axis, is identified by optically detected magnetic resonance as a dominant nonradiative recombination center that resides mainly on the surface of the NWs and partly at the heterointerfaces. The formation of DD1 is found to be promoted by the presence of nitrogen and can be suppressed by reducing the strain between the core and shell layers, as well as by protecting the optically active shell by an outer passivating shell. Growth modes employed during the NW growth are shown to play a role. On the basis of these results, we identify the GaP/GaNyP1–y/GaNxP1–x (x < y) core/shell/shell NW structure, where the GaNyP1–y inner shell with the highest nitrogen content serves as an active light-emitting layer, as the optimized and promising design for efficient light emitters based on GaNP NWs.

  • 332.
    Stehr, Jan Eric
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, Faculty of Science & Engineering.
    Dobrovolsky, Alexandr
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Kuang, Y. J.
    Sukrittanon, S.
    Tu, C. W.
    Chen, Weimin
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, Faculty of Science & Engineering.
    Bouyanova, Irina
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Surface and interfacial defects in coaxial GaNP nanowires2015Conference paper (Refereed)
  • 333.
    Stehr, Jan Eric
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Dobrovolsky, Alexandr
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Kuang, Y. J.
    Department of Physics, University of California, La Jolla, California, USA.
    Sukrittanon, S.
    Graduate Program of Materials Science and Engineering, La Jolla, California, USA .
    Tu, C. W.
    Department of Electrical and Computer Engineering, University of California, San Diego, La Jolla, California, USA .
    Chen, Weimin
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Buyanova, Irina
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Defects in GaNP Nanowires2014In: Abstract Book of the 56th Electronic Materials Conference, 2014, p. 114-Conference paper (Refereed)
  • 334.
    Stehr, Jan Eric
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Dobrovolsky, Alexandr
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Kuang, Y. J.
    Department of Physics, University of California, La Jolla, California, USA.
    Sukrittanon, S.
    Graduate Program of Materials Science and Engineering, La Jolla, California, USA .
    Tu, C. W.
    Department of Electrical and Computer Engineering, University of California, San Diego, La Jolla, California, USA .
    Chen, Weimin
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Buyanova, Irina
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Optically detected magnetic resonance investigation of GaP and GaP/GaNP/GaNP Nanowires2013In: 2013 MRS Fall Meeting, 2013Conference paper (Refereed)
  • 335.
    Stehr, Jan Eric
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Hofmann, D. M.
    University of Giessen, Germany .
    Meyer, B. K.
    University of Giessen, Germany .
    Electron paramagnetic resonance and photo-electron paramagnetic resonance investigation on the recharging of the substitutional nitrogen acceptor in ZnO2012In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 112, no 10, p. 103511-Article in journal (Refereed)
    Abstract [en]

    We investigated the substitutional nitrogen center in ZnO single crystals by electron paramagnetic resonance (EPR) and photo-EPR spectroscopy. Aside the three principle hyperfine lines due to the interaction of the N-0 (2p5) electron spin with the nitrogen nucleus (I = 1, natural abundance 99.6%), we identify additional satellite lines which arise from Delta m(S) = +/- 1 and Delta m(I) = +/- 1, +/- 2 transitions becoming allowed due to quadrupole interaction. The quadrupole coupling constant e(2)qQ/h is determined to -5.9 MHz with an asymmetry parameter of eta = 0.05. These values are somewhat different from those obtained for the nitrogen center in ZnO powders, but are closer to the theoretical calculations of Gallino et al. We further carefully investigated the photon induced recharging of the N centers. We determine the energy h nu required for the process N-O(-) + h nu -andgt; N-O(0) + e(cb)(-) to 2.1 +/- 0.05 eV, the dependence of the EPR signal intensity on the illumination time shows a mono-exponential behavior which gives evidence that a direct ionization process is monitored.

  • 336.
    Stehr, Jan Eric
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Johansen, K. M.
    University of Oslo, Norway.
    Bjørheim, T. S.
    University of Oslo, Norway.
    Vines, L.
    University of Oslo, Norway.
    Svensson, B. G.
    University of Oslo, Norway.
    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.
    Zinc-Vacancy–Donor Complex: A Crucial Compensating Acceptor in ZnO2014In: Physical Review Applied, ISSN 2331-7019, Vol. 2, no 021001Article in journal (Refereed)
    Abstract [en]

    The aluminum–zinc-vacancy (Al Zn −V Zn ) complex is identified as one of the dominant defects in Al-containing n -type ZnO after electron irradiation at room temperature with energies above 0.8 MeV. The complex is energetically favorable over the isolated V Zn , binding more than 90% of the stable V Zn ’s generated by the irradiation. It acts as a deep acceptor with the (0/− ) energy level located at approximately 1 eV above the valence band. Such a complex is concluded to be a defect of crucial and general importance that limits the n -type doping efficiency by complex formation with donors, thereby literally removing the donors, as well as by charge compensation.

  • 337.
    Stehr, Jan Eric
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Johansen, K. M.
    Borheim, T. S.
    Vines, L.
    Svensson, B. G.
    Chen, Weimin
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, Faculty of Science & Engineering.
    Bouianova, Irina
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    The Aluminum - zinc vacancy complex in ZnO: An EPR study2015Conference paper (Refereed)
  • 338.
    Stehr, Jan Eric
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Wang, Xingjun
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Filippov, Stanislav
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Pearton, S J.
    University of Florida, FL USA .
    Gueorguiev Ivanov, Ivan
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Chen, Weimin
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Buyanova, Irina
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Defects in N, O and N, Zn implanted ZnO bulk crystals2013In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 113, no 10, p. 103509-Article in journal (Refereed)
    Abstract [en]

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

  • 339.
    Stehr, Jan
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Wang, X. J.
    National Laboratory for Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai, China .
    Ren, F.
    Pearton, S.
    Chen, Weimin
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Buyanova, Irina
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Defects in N, O and N, Zn implanted ZnO single crystals.2012Conference paper (Other academic)
  • 340.
    Sukrittanon, S.
    et al.
    Graduate Program of Materials Science and Engineering, La Jolla, California, USA .
    Dobrovolsky, Alexandr
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Kuang, Y. J.
    Department of Physics, University of California, La Jolla, USA.
    Chen, Weimin
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Buyanova, Irina
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Tu, C. W.
    Department of Electrical and Computer Engineering, University of California, San Diego, La Jolla, USA .
    Growth and Optical Properties of GaNxP1-x/GaNyP1-y Core/Shell Nanowires Grown by Gas-Source Molecular Beam Epitaxy2014In: Abstract Book of the 56th Electronic Materials Conference, 2014, p. 130-Conference paper (Refereed)
  • 341.
    Sukrittanon, S.
    et al.
    University of California, San Diego, La Jolla, USA .
    Kuang, Y. J.
    University of California, San Diego, La Jolla, USA .
    Dobrovolsky, Alexandr
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Kang, Won-Mo
    Gwangju institute of Science and Technology (GIST), South Korea .
    Jang, Ja-Soon
    Yeungnam University, Daegu, South Korea .
    Kim, Bong-Joong
    DGwangju institute of Science and Technology (GIST), South Korea.
    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.
    Tu, C. W.
    University of California, San Diego, La Jolla, USA .
    Growth and characterization of dilute nitride GaNxP1−x nanowires and GaNxP1−x/GaNyP1−y core/shell nanowires on Si (111) by gas source molecular beam epitaxy2014In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 105, no 7, p. 072107-Article in journal (Refereed)
    Abstract [en]

    We have demonstrated self-catalyzed GaN xP1−x and GaN xP1−x/GaNyP1−y core/shell nanowire growth by gas-source molecular beam epitaxy. The growth window for GaN xP1−x nanowires was observed to be comparable to that of GaP nanowires (∼585 °C to ∼615 °C). Transmission electron microscopy showed a mixture of cubic zincblende phase and hexagonal wurtzite phase along the [111] growth direction in GaN xP1−x nanowires. A temperature-dependent photoluminescence (PL) study performed on GaN xP1−x/GaNyP1−y core/shell nanowires exhibited an S-shape dependence of the PL peaks. This suggests that at low temperature, the emission stems from N-related localized states below the conduction band edge in the shell, while at high temperature, the emission stems from band-to-band transition in the shell as well as recombination in the GaN xP1−x core.

  • 342.
    Sun, Jianwu
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Jokubavicius, Valdas
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Gao, L.
    Department of Chemical Engineering and Chemistry, Eindhoven University of of Technology, P.O. Box 513, Eindhoven, Netherlands.
    Booker, Ian Don
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Jansson, Mattias
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, Faculty of Science & Engineering.
    Liu, Xinyu
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, Faculty of Science & Engineering.
    Hofmann, J.P.
    Department of Chemical Engineering and Chemistry, Eindhoven University of of Technology, P.O. Box 513, Eindhoven, Netherlands.
    Hensen, E.J.M.
    Department of Chemical Engineering and Chemistry, Eindhoven University of of Technology, P.O. Box 513, Eindhoven, Netherlands.
    Linnarsson, M.
    School of Information and Communication Technology, KTH Royal Institute of Technology, Kista, Sweden.
    Wellmann, P.
    Department of Materials Science 6, University of of Erlangen-Nuremberg, Martensstr. 7, Erlangen, Germany.
    Ramiro, I.
    Instituto de Energía Solar, Universidad Politécnica de Madrid, E.T.S.I. Telecomunicación, Av. De la Complutense 30, Madrid, Spain.
    Marti, A.
    Instituto de Energía Solar, Universidad Politécnica de Madrid, E.T.S.I. Telecomunicación, Av. De la Complutense 30, Madrid, Spain.
    Yakimova, Rositsa
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Syväjärvi, Mikael
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Solar driven energy conversion applications based on 3C-SiC2016In: Materials Science Forum, Trans Tech Publications Ltd , 2016, Vol. 858, p. 1028-1031Conference paper (Refereed)
    Abstract [en]

    There is a strong and growing worldwide research on exploring renewable energy resources. Solar energy is the most abundant, inexhaustible and clean energy source, but there are profound material challenges to capture, convert and store solar energy. In this work, we explore 3C-SiC as an attractive material towards solar-driven energy conversion applications: (i) Boron doped 3C-SiC as candidate for an intermediate band photovoltaic material, and (ii) 3C-SiC as a photoelectrode for solar-driven water splitting. Absorption spectrum of boron doped 3C-SiC shows a deep energy level at ~0.7 eV above the valence band edge. This indicates that boron doped 3C-SiC may be a good candidate as an intermediate band photovoltaic material, and that bulk like 3C-SiC can have sufficient quality to be a promising electrode for photoelectrochemical water splitting. © 2016 Trans Tech Publications, Switzerland.

  • 343.
    Syväjärvi, Mikael
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Ma, Quanbao
    University of Oslo, Norway.
    Jokubavicius, Valdas
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Galeckas, Augustinas
    University of Oslo, Norway.
    Sun, Jianwu
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Liu, Xinyu
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Jansson, Mattias
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, Faculty of Science & Engineering.
    Wellmann, Peter
    University of Erlangen Nurnberg, Germany.
    Linnarsson, Margareta
    KTH Royal Institute Technology, Sweden.
    Runde, Paal
    St Gobain Ceram Mat AS, Norway.
    Andre Johansen, Bertil
    St Gobain Ceram Mat AS, Norway.
    Thogersen, Annett
    SINTEF Mat and Chemistry, Norway.
    Diplas, Spyros
    SINTEF Mat and Chemistry, Norway.
    Almeida Carvalho, Patricia
    SINTEF Mat and Chemistry, Norway.
    Martin Lovvik, Ole
    SINTEF Mat and Chemistry, Norway.
    Nilsen Wright, Daniel
    SINTEF ICT, Norway.
    Yu Azarov, Alexander
    University of Oslo, Norway.
    Svensson, Bengt G.
    University of Oslo, Norway.
    Cubic silicon carbide as a potential photovoltaic material2016In: Solar Energy Materials and Solar Cells, ISSN 0927-0248, E-ISSN 1879-3398, Vol. 145, p. 104-108Article in journal (Refereed)
    Abstract [en]

    In this work we present a significant advancement in cubic silicon carbide (3C-SiC) growth in terms of crystal quality and domain size, and indicate its potential use in photovoltaics. To date, the use of 3C-SiC for photovoltaics has not been considered due to the band gap of 2.3 eV being too large for conventional solar cells. Doping of 3C-SiC with boron introduces an energy level of 0.7 eV above the valence band. Such energy level may form an intermediate band (IB) in the band gap. This IB concept has been presented in the literature to act as an energy ladder that allows absorption of sub-bandgap photons to generate extra electron-hole pairs and increase the efficiency of a solar cell. The main challenge with this concept is to find a materials system that could realize such efficient photovoltaic behavior. The 3C-SiC bandgap and boron energy level fits nicely into the concept, but has not been explored for an IB behavior. For a long time crystalline 3C-SiC has been challenging to grow due to its metastable nature. The material mainly consists of a large number of small domains if the 3C polytype is maintained. In our work a crystal growth process was realized by a new approach that is a combination of initial nucleation and step-flow growth. In the process, the domains that form initially extend laterally to make larger 3C-SiC domains, thus leading to a pronounced improvement in crystalline quality of 3C-SiC. In order to explore the feasibility of IB in 3C-SiC using boron, we have explored two routes of introducing boron impurities; ion implantation on un-doped samples and epitaxial growth on un-doped samples using pre-doped source material. The results show that 3C-SiC doped with boron is an optically active material, and thus is interesting to be further studied for IB behavior. For the ion implanted samples the crystal quality was maintained even after high implantation doses and subsequent annealing. The same was true for the samples grown with pre-doped source material, even with a high concentration of boron impurities. We present optical emission and absorption properties of as-grown and boron implanted 3C-SiC. The low-temperature photoluminescence spectra indicate the formation of optically active deep boron centers, which may be utilized for achieving an IB behavior at sufficiently high dopant concentrations. We also discuss the potential of boron doped 3C-SiC base material in a broader range of applications, such as in photovoltaics, biomarkers and hydrogen generation by splitting water. (C) 2015 Elsevier B.V. All rights reserved.

  • 344.
    Syväjärvi, Mikael
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Stanciu, V.
    Izadifard, Morteza
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Chen, Weimin
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    Buyanova, Irina
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    Svedlindh, P.
    Yakimova, Rositsa
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    As-grown 4H-SiC epilayers with magnetic properties2004In: SILICON CARBIDE AND RELATED MATERIALS 2003, PRTS 1 AND 2, 2004, p. 747-750Conference paper (Refereed)
    Abstract [en]

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

  • 345. Sörman, E.
    et al.
    Nguyen, Son Tien
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Chen, Weimin
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    Kordina, O.
    Hallin, Christer
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Janzén, Erik
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Silicon vacancy related defect in 4H and 6H SiC2000In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 61, no 4, p. 2613-2620Article in journal (Refereed)
    Abstract [en]

    We report on an irradiation-induced photoluminescence (PL) band in 4H and 6H SiC and the corresponding optically detected magnetic resonance (ODMR) signals from this band. The deep PL band has the same number of no-phonon lines as there are inequivalent sites in the respective polytype. These lines are at 1352 and 1438 meV in the case of 4H and at 1366, 1398, and 1433 meV in the case of 6H. The intensity of the PL lines is reduced after a short anneal at 750░C. ODMR measurements with above-band-gap excitation show that two spin-triplet (S=1) states with a weak axial character are detected via each PL line in these bands. One of these two triplet states can be selectively excited with the excitation energy of the corresponding PL line. These triplet signals can therefore be detected separately and only then can the well documented and characteristic hyperfine interaction of the silicon vacancy in SiC be resolved. Considering the correlation between the irradiation dose and the signal strength, the well established annealing temperature and the characteristic hyperfine pattern, we suggest that this PL band is related to the isolated silicon vacancy in 4H and 6H SiC. The spin state (S=1) implies a charge state of the vacancy with an even number of electrons. By combining the knowledge from complementary electron-spin resonance measurements and theoretical calculations we hold the neutral charge state for the strongest candidate. ⌐2000 The American Physical Society.

  • 346. Terentev, Ya. V.
    et al.
    Toropov, A. A.
    Sorokin, S. V.
    Lebedev, A. V.
    Ivanov, S. V.
    Kopev, P. S.
    Buyanova, Irina
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    Chen, Weimin
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    Monemar, Bo
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Semimagnetic ZnMnSe/CdSe Fractional Monolayer Superlattice as an Injector of Spin-Polarized Carriers2002In: Physica status solidi. B, Basic research, ISSN 0370-1972, E-ISSN 1521-3951, Vol. 229, no 2, p. 765-768Article in journal (Refereed)
    Abstract [en]

    We report on effective injection of spin-oriented carriers from a semimagnetic semiconductor structure to a non-magnetic ZnCdSe/ZnSe quantum well (QW). A short-period ZnMnSe/CdSe fractional monolayer superlattice was used as a spin injector. The carriers are photo-generated in the semimagnetic region, spin-polarized via the effect of giant Zeeman splitting and then injected into the non-magnetic QW. The spin injection efficiency was estimated by circular polarization measurements of recombination emission from the QW. The maximal detected degree of the spin polarization is about 25%.

  • 347. Thinh, N. Q.
    et al.
    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.
    Xin, H. P.
    Tu, C. W.
    Formation of nonradiative defects in molecular beam epitaxial GaNxAs1-x studied by optically detected magnetic resonance2001In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 79, no 19, p. 3089-Article in journal (Refereed)
    Abstract [en]

    The formation of two nonradiative defects (i.e., an AsGa-related complex and an unknown deep-level defect with g = 2.03) in GaNxAs1-x epilayers and GaAs/GaNxAs1-x multiple-quantum-well structures, grown by molecular beam epitaxy, is studied by the optically detected magnetic resonance technique. It is shown that contributions by these defects in competing carrier recombination strongly vary with the nitrogen composition. An increase in the growth temperature or postgrowth rapid thermal annealing significantly reduces the influence of the nonradiative defects studied, and is accompanied by a remarkable improvement in the optical properties of the structures.

  • 348. Thinh, N. Q.
    et al.
    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.
    Xin, H. P.
    Tu, C. W.
    Grown-in intrinsic defect in GaNAs2001In: Proceedings of the 21st International Conference on Defects in Semiconductors, 2001Conference paper (Other academic)
  • 349. Thinh, N. Q.
    et al.
    Buyanova, Irina
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    Hai, P. N.
    Chen, Weimin
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    Xin, H. P.
    Tu, C. W.
    Properties of a grown-in intrinsic defect in GaNAs2001In: APS 2001 March Meeting,2001, Bull. Amer. Phys. Soc.: APS , 2001, Vol. 46, p. 1185-Conference paper (Refereed)
    Abstract [en]

    Properties of a grown-in intrinsic defect in GaNAs alloys and GaNAs/GaAs quantum well structures with low N composition have been investigated by optically detected magnetic resonance (ODMR). The characteristic hyperfine (HF) structure, arising from S=1/2 and I=3/2, suggests a complex involving the As_Ga antisite as being the most likely candidate for the responsible defect. The strong HF interaction evidences a high localization of the wavefunction of the unpaired electron near the As_Ga antisite, which is found to be rather insensitive to either N composition or quantum confinement. The formation mechanism for the defect has been studied by varying growth temperature or by performing post-growth rapid thermal annealing. It is shown that the defect can be preferably introduced during molecular beam epitaxy (MBE) growth at low temperature under non-equilibrium conditions, similar to the case of its parental compound GaAs grown under similar conditions.

  • 350.
    Thinh, N. Q.
    et al.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Buyanova, Irina
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Hai, P. N.
    Linköping University, Department of Physics, Chemistry and Biology. 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.
    Xin, H. P.
    Department of Electrical and Computer Engineering, University of California, La Jolla, California, USA.
    Tu, C. W.
    Department of Electrical and Computer Engineering, University of California, La Jolla, California, USA.
    Signature of an intrinsic point defect in GaNxAs1-x2001In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 63, no 3, p. 332031-332034Article in journal (Refereed)
    Abstract [en]

    The first experimental signature of an intrinsic defect in GaNAs is provided from an optically detected magnetic resonance study. The resolved central hyperfine structure identifies the defect with a nuclear spin I = 3/2, containing either an AsGa antisite or a Ga interstitial. From the strength of the hyperfine interaction and the growth conditions, a complex involving the AsGa antisite seems to be a more likely candidate.

456789 301 - 350 of 403
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • 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