liu.seSearch for publications in DiVA
Change search
Refine search result
1234 1 - 50 of 160
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • oxford
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 1.
    Abbasi, Mazhar Ali
    et al.
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Hussain Ibupoto, Zafar
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Hussain, Mushtaque
    Linköping University, Department of Science and Technology, Physics and Electronics. 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.
    Lu, Jun
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Nur, Omer
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Willander, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Decoration of ZnO nanorods with coral reefs like NiO nanostructures by the hydrothermal growth method and their luminescence study2014In: Materials, ISSN 1996-1944, E-ISSN 1996-1944, Vol. 7, no 1, p. 430-440Article in journal (Refereed)
    Abstract [en]

    Composite nanostructures of coral reefs like p-type NiO on n-type ZnO nanorods have been decorate on fluorine-doped tin oxide glass substrates by the hydrothermal growth. Structural characterization was performed by field emission scanning electron microscopy,  high-resolution transmission electron microscopy and X-ray diffraction techniques. This investigation has shown that the adopted synthesis has led to high crystalline quality nanostructures. Morphological study shows that the coral reefs like nanostructures are densely packed on the ZnO nanorods. Cathodoluminescence (CL) spectra for the synthesized composite nanostructures were dominated by a near band gap emission at 380 nm and by a broad interstitial defect related luminescence centered at ~630 nm. Spatially resolved CL images reveal that the luminescence originates mainly from the ZnO nanorods.

  • 2.
    Alnoor, Hatim
    et al.
    Linköping University, Department of Science and Technology. Linköping University, Faculty of Science & Engineering.
    Chey, Chan Oeurn
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Pozina, Galia
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Liu, Xianjie
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Khranovskyy, Volodymyr
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Willander, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Nour, Omer
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Effect of precursor solutions stirring on deep level defects concentration and spatial distribution in low temperature aqueous chemical synthesis of zinc oxide nanorods2015In: AIP Advances, ISSN 2158-3226, E-ISSN 2158-3226, Vol. 5, no 8, article id 087180Article in journal (Refereed)
    Abstract [en]

    Hexagonal c-axis oriented zinc oxide (ZnO) nanorods (NRs) with 120-300 nm diameters are synthesized via the low temperature aqueous chemical route at 80 degrees C on silver-coated glass substrates. The influence of varying the precursor solutions stirring durations on the concentration and spatial distributions of deep level defects in ZnO NRs is investigated. Room temperature micro-photoluminesnce (mu-PL) spectra were collected for all samples. Cathodoluminescence (CL) spectra of the as-synthesized NRs reveal a significant change in the intensity ratio of the near band edge emission (NBE) to the deep-level emission (DLE) peaks with increasing stirring durations. This is attributed to the variation in the concentration of the oxygen-deficiency with increasing stirring durations as suggested from the X-ray photoelectron spectroscopy analysis. Spatially resolved CL spectra taken along individual NRs revealed that stirring the precursor solutions for relatively short duration (1-3 h), which likely induced high super saturation under thermodynamic equilibrium during the synthesis process, is observed to favor the formation of point defects moving towards the tip of the NRs. In contrary, stirring for longer duration (5-15 h) will induce low super saturation favoring the formation of point defects located at the bottom of the NRs. These findings demonstrate that it is possible to control the concentration and spatial distribution of deep level defects in ZnO NRs by varying the stirring durations of the precursor solutions.

  • 3.
    Alnoor, Hatim
    et al.
    Linköping University, Department of Science and Technology. Linköping University, Faculty of Science & Engineering.
    Pozina, Galia
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Khranovskyy, Volodymyr
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Liu, Xianjie
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Iandolo, Donata
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Willander, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Nur, Omer
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Influence of ZnO seed layer precursor molar ratio on the density of interface defects in low temperature aqueous chemically synthesized ZnO nanorods/GaN light-emitting diodes2016In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 119, no 16, p. 165702-Article in journal (Refereed)
    Abstract [en]

    Low temperature aqueous chemical synthesis (LT-ACS) of zinc oxide (ZnO) nanorods (NRs) has been attracting considerable research interest due to its great potential in the development of light-emitting diodes (LEDs). The influence of the molar ratio of the zinc acetate (ZnAc): KOH as a ZnO seed layer precursor on the density of interface defects and hence the presence of non-radiative recombination centers in LT-ACS of ZnO NRs/GaN LEDs has been systematically investigated. The material quality of the as-prepared seed layer as quantitatively deduced by the X-ray photoelectron spectroscopy is found to be influenced by the molar ratio. It is revealed by spatially resolved cathodoluminescence that the seed layer molar ratio plays a significant role in the formation and the density of defects at the n-ZnO NRs/p-GaN heterostructure interface. Consequently, LED devices processed using ZnO NRs synthesized with molar ratio of 1:5M exhibit stronger yellow emission (similar to 575 nm) compared to those based on 1:1 and 1:3M ratios as measured by the electroluminescence. Furthermore, seed layer molar ratio shows a quantitative dependence of the non-radiative defect densities as deduced from light-output current characteristics analysis. These results have implications on the development of high-efficiency ZnO-based LEDs and may also be helpful in understanding the effects of the ZnO seed layer on defect-related non-radiative recombination. Published by AIP Publishing.

  • 4.
    Alnoor, Hatim
    et al.
    Linköping University, Department of Science and Technology. Linköping University, Faculty of Science & Engineering.
    Pozina, Galia
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Willander, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Nur, Omer
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Seed layer synthesis effect on the concentration of interface defects and emission spectra of ZnO nanorods/p-GaN light-emitting diode2017In: Physica Status Solidi (a) applications and materials science, ISSN 1862-6300, E-ISSN 1862-6319, Vol. 214, no 1, article id 1600333Article in journal (Refereed)
    Abstract [en]

    As the low-temperature aqueous chemical synthesis (LT-ACS), holds great promises for the synthesis of one-dimensional (1D) ZnO nanostructure-based light-emitting diodes (LEDs) and hence require parameter tuning for optimal performance. N-ZnO nanorods (NRs)/p-GaN heterojunction LEDs have been synthesized by the LT-ACS using ZnO nanoparticle (NPs) seed layers prepared with different precursor solutions. The effect of these seed layers on the interface defect properties and emission intensity of the as-synthesized n-Zn/p-GaN heterojunction LEDs has been demonstrated by spatially resolved cathodoluminescence (CL) and electroluminescence (EL) measurements, respectively. A significant reduction of the interface defects in the n-ZnO NRs/p-GaN heterostructure synthesized from a seed layer prepared from zinc acetate (ZnAc) with a mixture of potassium hydroxide (KOH) and hexamethylenetetramine (HMTA) (donated as ZKH seed) compared with those prepared from ZnAc and KOH (donated as ZK seed) is observed as revealed by spatially resolved CL. Consequently, the LEDs based on n-ZnO NRs/p-GaN prepared from ZKH seed show an improvement in the yellow emission (approximate to 578nm) compared to that based on the ZK seed as deduced from the electroluminescence measurements. The improvement in the yellow EL emission on the ZKH LED probably attributed to the low presence of the non-radiative defect as deduced by light-output current (L-I) characteristics analysis.

  • 5.
    Alnoor, Hatim
    et al.
    Linköping University, Department of Science and Technology. Linköping University, Faculty of Science & Engineering.
    Savoyant, Adrien
    Aix Marseille University, France.
    Liu, Xianjie
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Pozina, Galia
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Willander, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Nur, Omer
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    An effective low-temperature solution synthesis of Co-doped [0001]-oriented ZnO nanorods2017In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 121, no 21, article id 215102Article in journal (Refereed)
    Abstract [en]

    We demonstrate an efficient possibility to synthesize vertically aligned pure zinc oxide (ZnO) and Co-doped ZnO nanorods (NRs) using the low-temperature aqueous chemical synthesis (90 degrees C). Two different mixing methods of the synthesis solutions were investigated for the Co-doped samples. The synthesized samples were compared to pure ZnO NRs regarding the Co incorporation and crystal quality. Electron paramagnetic resonance (EPR) measurements confirmed the substitution of Co2+ inside the ZnO NRs, giving a highly anisotropic magnetic Co2+ signal. The substitution of Zn2+ by Co2+ was observed to be combined with a drastic reduction in the core-defect (CD) signal (g similar to 1.956) which is seen in pure ZnO NRs. As revealed by the cathodoluminescence (CL), the incorporation of Co causes a slight red-shift of the UV peak position combined with an enhancement in the intensity of the defect-related yellow-orange emission compared to pure ZnO NRs. Furthermore, the EPR and the CL measurements allow a possible model of the defect configuration in the samples. It is proposed that the as-synthesized pure ZnO NRs likely contain Zn interstitial (Zn-i(+)) as CDs and oxygen vacancy (V-O) or oxygen interstitial (O-i) as surface defects. As a result, Co was found to likely occupy the Zn-i(+), leading to the observed CDs reduction and hence enhancing the crystal quality. These results open the possibility of synthesis of highly crystalline quality ZnO NRs-based diluted magnetic semiconductors using the low-temperature aqueous chemical method. Published by AIP Publishing.

  • 6.
    Bergman, JP
    et al.
    Linkoping Univ, Dept Phys & Measurement Technol, SE-58183 Linkoping, Sweden ABB Corp, SE-72178 Vasteras, Sweden Okmet AB, SE-58183 Linkoping, Sweden.
    Jakobsson, H
    Linkoping Univ, Dept Phys & Measurement Technol, SE-58183 Linkoping, Sweden ABB Corp, SE-72178 Vasteras, Sweden Okmet AB, SE-58183 Linkoping, Sweden.
    Storasta, Liutauras
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Carlsson, Fredrik
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Magnusson, Björn
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Sridhara, S
    Linkoping Univ, Dept Phys & Measurement Technol, SE-58183 Linkoping, Sweden ABB Corp, SE-72178 Vasteras, Sweden Okmet AB, SE-58183 Linkoping, Sweden.
    Pozina, Galia
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Lendenmann, H
    Linkoping Univ, Dept Phys & Measurement Technol, SE-58183 Linkoping, Sweden ABB Corp, SE-72178 Vasteras, Sweden Okmet AB, SE-58183 Linkoping, Sweden.
    Janzén, Erik
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Characterisation and defects in silicon carbide2002In: Materials Science Forum, Vols. 389-393, 2002, Vol. 389-3Conference paper (Refereed)
    Abstract [en]

    In this work we present experimental results of several defects in 4H Sic that are of interest both from a fundamental and physical point of view. And also of great importance for device applications utilizing the Sic material. These defects include the temperature stable so called D1 defect, which is created after irradiation. This optical emission has been identified as an isoelectronic defect bound at a hole attractive pseudodonor, and we have been able to correlate this to the electrically observed hole trap HS1 seen in minority carrier transient spectroscopy (MCTS). It also includes the UD1 defect observed using absorption and FTIR and which is believed to be responsible for the semi-insulating behavior of material grown by the High temperature, HTCVD technique. Finally, we have described the formation and proper-ties of critical, generated defect in high power Sic bipolar devices. This is identified as a stacking fault in the Sic basal plane, using mainly white beam synchrotron Xray topography. The stacking fault is both optically and electrically active, by forming extended local potential reduction of the conduction band.

  • 7.
    Bergman, Peder
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Pozina, Galia
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Monemar, Bo
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Dalfors, J.
    Sernelius, Bo
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics.
    Holtz, Per-Olof
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Amano, H.
    Akasaki, I.
    Radiative recombination in InGaN/GaN multiple quantum well2000In: ICSCRM 99,1999, 2000, p. 1571-Conference paper (Refereed)
  • 8.
    Bergman, Peder
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Pozina, Galia
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Monemar, Bo
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Kamiyama, S
    Linkoping Univ, Dept Phys & Measurement Technol, SE-58183 Linkoping, Sweden Meijo Univ, Dept Elect Engn & Elect, Tempaku Ku, Nagoya, Aichi 468, Japan Meijo Univ, Elect & High Tech Res Ctr, Tempaku Ku, Nagoya, Aichi 468, Japan.
    Iwaya, M
    Linkoping Univ, Dept Phys & Measurement Technol, SE-58183 Linkoping, Sweden Meijo Univ, Dept Elect Engn & Elect, Tempaku Ku, Nagoya, Aichi 468, Japan Meijo Univ, Elect & High Tech Res Ctr, Tempaku Ku, Nagoya, Aichi 468, Japan.
    Amano, H
    Linkoping Univ, Dept Phys & Measurement Technol, SE-58183 Linkoping, Sweden Meijo Univ, Dept Elect Engn & Elect, Tempaku Ku, Nagoya, Aichi 468, Japan Meijo Univ, Elect & High Tech Res Ctr, Tempaku Ku, Nagoya, Aichi 468, Japan.
    Akasaki, I
    Linkoping Univ, Dept Phys & Measurement Technol, SE-58183 Linkoping, Sweden Meijo Univ, Dept Elect Engn & Elect, Tempaku Ku, Nagoya, Aichi 468, Japan Meijo Univ, Elect & High Tech Res Ctr, Tempaku Ku, Nagoya, Aichi 468, Japan.
    Photoluminescence and electroluminescence characterization of InxGa1-x/InyGa1-yN multiple quantum well light emitting diodes2002In: Materials Science Forum, Vols. 389-393, 2002, Vol. 389-3, p. 1493-1496Conference paper (Refereed)
    Abstract [en]

    We report on a study of radiative recombination in In0.11Ga0.89N/In.0.01Ga0.99N multiple quantum wells (MQWs). The QWs were nominally undoped, while the InGaN barriers were Si doped. The MQW part is situated in the depletion field of a pn-junction structure with electrical contacts, so that both photoluminescence (PL) and electroluminescence (EL) can be studied as a function of bias. The PL and EL spectra are distinctly different, in particular at low temperatures. The spectral properties and related differences in PL decay times reflect different recombination conditions in the MQW region for the individual QWs.

  • 9.
    Buyanova, Irina A.
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Chen, Weimin
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    Pozina, Galia
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Hai, P.N.
    Monemar, Bo
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Xin, H.P.
    Department of Electrical and Computer Engineering, University of California, San Diego, CA 92093-0407, United States.
    Tu, C.W.
    Department of Electrical and Computer Engineering, University of California, San Diego, CA 92093-0407, United States.
    Optical properties of GaNAs/GaAs structures2001In: Materials Science & Engineering: B. Solid-state Materials for Advanced Technology, ISSN 0921-5107, E-ISSN 1873-4944, Vol. 82, no 1-3, p. 143-147Article in journal (Refereed)
    Abstract [en]

    We review our recent results on optical characterization of MBE-grown GaNAs/GaAs quantum structures with N content up to 4.5%, by employing photoluminescence (PL), PL excitation, and time-resolved PL spectroscopies. The dominant PL mechanism has been determined as recombination of excitons trapped by potential fluctuations of the band edge, due to composition disorder and strain nonuniformity of the alloy. The estimated value of the localization potential is around 60 meV for the low-temperature grown structures and can be reduced by increasing the growth temperature or using post-growth rapid thermal annealing (RTA). © 2001 Elsevier Science S.A.

  • 10.
    Buyanova, Irina
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Bergman, Peder
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Pozina, Galia
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Chen, Weimin
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Rawal, S.
    Norton, D.P.
    Pearton, S.J.
    Osinsky, A.
    Dong, J.W.
    Mechanism for radiative recombination in ZnCdO alloys2007In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 90, no 26Article in journal (Refereed)
    Abstract [en]

    Temperature dependent cw- and time-resolved photoluminescence combined with absorption measurements are employed to evaluate the origin of radiative recombination in ZnCdO alloys grown by molecular-beam epitaxy. The near-band-edge emission is attributed to recombination of excitons localized within band tail states likely caused by nonuniformity in Cd distribution. Energy transfer between the tail states is argued to occur via tunneling of localized excitons. The transfer is shown to be facilitated by increasing Cd content due to a reduction of the exciton binding energy and, therefore, an increase of the exciton Bohr radius in the alloys with a high Cd content. © 2007 American Institute of Physics.

  • 11.
    Buyanova, Irina
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Bergman, Peder
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Pozina, Galia
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Chen, Weimin
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Rawal, S.
    Norton, D.P.
    Pearton, S.J.
    Osinsky, A.
    Dong, J.W.
    Origin of near-band-edge emission in ZnCdO alloys2007In: 2007 MRS Fall Meeting,2007, 2007, p. 319-Conference paper (Other academic)
  • 12.
    Buyanova, Irina
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    Chen, Weimin
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    Pozina, Galia
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Bergman, Peder
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Monemar, Bo
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Xin, H. P.
    Tu, C. W.
    Mechanism for low-temperature photoluminescence in GaNAs/GaAs structures grown by molecular-beam epitaxy1999In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 75, no 4, p. 501-Article in journal (Refereed)
    Abstract [en]

     The mechanism for low-temperature photoluminescence (PL) emissions in GaNAs epilayers and GaAs/GaNxAs1 - x quantum well (QW) structures grown by molecular-beam epitaxy is studied in detail, employing PL, PL excitation, and time-resolved PL spectroscopies. It is shown that even though quantum confinement causes a strong blueshift of the GaNAs PL emission, its major characteristic properties are identical in both QW structures and epilayers. Based on the analysis of the PL line shape, its dependence on the excitation power and measurement temperature, as well as transient data, the PL emission is concluded to be caused by a recombination of excitons trapped by potential fluctuations in GaNAs.

  • 13.
    Buyanova, Irina
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    Chen, Weimin
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    Pozina, Galia
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Hai, P. N.
    Thinh, N. Q.
    Goldys, E. M.
    Xin, H. P.
    Tu, C. W.
    Optical and electronic properties of GaNAs/GaAs structures2000Conference paper (Refereed)
    Abstract [en]

     We review our recent results from studies of electronic properties of GaNAs/GaAs structures with low nitrogen content, by photoluminescence (PL), PL excitation, time-resolved PL spectroscopies as well as optically detected magnetic resonance (ODMR) and cyclotron resonance (ODCR) studies. The issues to be addressed include key material-related properties and fundamental electronic parameters of the GaNAs alloy, relevant to device applications, such as identification of the dominant recombination processes in the alloy, compositional dependence of the electron effective mass and band alignment in the GaNAs/GaAs heterostructures. 

  • 14.
    Buyanova, Irina
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    Chen, Weimin
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    Pozina, Galia
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Hai, P. N.
    Xin, H. P.
    Tu, C. W.
    Recombination processes in GaNAs/GaAs structures2001Conference paper (Refereed)
  • 15.
    Buyanova, Irina
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    Chen, Weimin
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    Pozina, Galia
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Monemar, Bo
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Xin, H. P.
    Tu, C. W.
    Mechanism for Light Emission in GaNAs/GaAs Structures Grown by Molecular Beam Epitaxy1999In: Physica status solidi. B, Basic research, ISSN 0370-1972, E-ISSN 1521-3951, Vol. 216, no 1, p. 125-129Article in journal (Refereed)
    Abstract [en]

     A detailed photoluminescence (PL) study reveals that the low-temperature PL emission in GaNAs epilayers and GaAs/GaNxAs1 - x quantum well structures grown by molecular beam epitaxy is governed by recombination of localized excitons. This conclusion is based on the analysis of the PL lineshape, its dependence on the excitation power and measurement temperature, as well as PL transient data. The depth of the localization potential is estimated as about 60 meV, varying slightly among the different structures.

  • 16.
    Buyanova, Irina
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    Pozina, Galia
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Bergman, Peder
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Chen, Weimin
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    Xin, H. P.
    Tu, C. W.
    Time-resolved studies of photoluminescence in GaNxP1-x alloys: Evidence for indirect-direct band gap crossover2002In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 81, no 1, p. 52-Article in journal (Refereed)
    Abstract [en]

     Time resolved photoluminescence spectroscopy is employed to monitor the effect of N incorporation on the band structure of GaNP alloys. Abrupt shortening in radiative lifetime of near-band gap emissions, arising from excitonic radiative recombination within N-related centers, is found to occur at very low N compositions of around 0.5%, i.e., within the same range as the appearance of the direct-band gap-like transitions in the photomodulated transmission spectra of GaNP reported previously. The effect has been attributed to an enhancement in oscillator strength of optical transitions due to band crossover from indirect to direct-band gap of the alloy.

  • 17.
    Buyanova, Irina
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    Pozina, Galia
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Chen, Weimin
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    Xin, H. P.
    Tu, C. W.
    Time-resolved studies of photoluminescence in GaNP epilayers and multiple quantum well structures2002In: E-MRS 2002 Spring Meeting,2002, 2002Conference paper (Other academic)
  • 18.
    Buyanova, Irina
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    Pozina, Galia
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor 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.
    Band alignment in the GaNAs/GaAs quantum structures2001Conference paper (Refereed)
    Abstract [en]

     The band alignment in the GaN_xAs_1-x/GaAs quantum well (QW) structures with low N composition is studied by employing time-resolved photoluminescence (PL) spectroscopy, PL polarization measurements and optically-detected cyclotron resonance (ODCR) studies. The type I band line-up is concluded based on the following experimental results. Firstly, radiative lifetime of the near band gap PL emission in the GaNAs/GaAs MQW structures is nearly identical to that for the spatially direct PL transitions in the GaNAs epilayers. Secondly, the observed polarization of the PL emission in GaNAs QWs (preferentially along the growth direction) is more consistent with the type I band line-up in the GaNAs/GaAs QWs. Thirdly, since the ODCR peaks arising from the free electrons and free holes in GaAs disappear under resonant excitation of the GaNAs MQWs, the photo-excited holes are spatially confined within the GaNAs layers under the resonant excitation condition.

  • 19.
    Buyanova, Irina
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    Pozina, Galia
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor 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.
    Evidence for type I band alignment in GaNAs/GaAs quantum structures by optical spectroscopies2002Conference paper (Refereed)
    Abstract [en]

     Type I band line-up in GaNxAs1−x/GaAs multiple quantum wells (MQW) with xless-than-or-equals, slant3% is concluded based on the following experimental results: (i) a comparable radiative decay time of the GaNAs-related photoluminescence (PL) measured from single GaNAs epilayers and the GaNAs/GaAs MQW structures, (ii) the observed PL polarization, and (iii) the spatial confinement of photoexcited holes within the GaNAs layers under resonant excitation of the GaNAs MQW.

  • 20.
    Buyanova, Irina
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    Pozina, Galia
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor 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.
    Type I band alignment in the GaNxAs1-x/GaAs quantum wells2001In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 63, no 3, p. 333031-333034Article in journal (Refereed)
    Abstract [en]

    Three independent experimental techniques, namely, time-resolved photoluminescence (PL) spectroscopy, PL polarization, and optically detected cyclotron resonance, are employed to determine the band alignment of GaNxAS1-x/GaAs quantum structures with a low-N composition. It is concluded that band lineup is type I based on the following experimental results: (i) comparable radiative decay time of the GaNAs-related emission measured from single GaNAs epilayers and from GaNAs/GaAs quantum well (QW) structures, (ii) polarization of the GaNAs-related emission, and (iii) spatial confinement of the photoexcited holes within the GaNAs layers under resonant excitation of the GaNAs QW's.

  • 21.
    Buyanova, Irina
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    Pozina, Galia
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Hai, P. N.
    Thinh, N. Q.
    Bergman, Peder
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Chen, Weimin
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    Xin, H. P.
    Tu, C. W.
    Mechanism for rapid thermal annealing improvements in undoped GaNxAs1-x/GaAs structures grown by molecular beam epitaxy2000In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 77, no 15, p. 2325-Article in journal (Refereed)
    Abstract [en]

     A systematic investigation of the effect of rapid thermal annealing (RTA) on optical properties of undoped GaNAs/GaAs structures is reported. Two effects are suggested to account for the observed dramatic improvement in the quality of the GaNxAs1-x/GaAs quantum structures after RTA: (i) improved composition uniformity of the GaNxAs1-x alloy, deduced from the photoluminescence (PL), PL excitation and time-resolved measurements; and (ii) significant reduction in the concentration of competing nonradiative defects, revealed by the optically detected magnetic resonance studies.

  • 22.
    Choubina, Tatiana
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Glazov, M.M.
    Toropov, A.A.
    Gippius, N.A.
    Vasson, A.
    Leymarie, J.
    Kavokin, A.
    Usui, A.
    Bergman, Peder
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Pozina, Galia
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Monemar, Bo
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    The slow light in GaN2008In: ICPS2008,2008, 2008, p. 647-Conference paper (Refereed)
  • 23.
    Choubina, Tatiana
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Glazov, M.M.
    Toropov, A.A.
    Ivanov, Ivan Gueorguiev
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Gippius, N.A.
    Vasson, A.
    Leymaire, J.
    Kavokin, A.
    Usui, A.
    Bergman, Peder
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Pozina, Galia
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Monemar, Bo
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Realization of slow light in GaN crystals2008In: IWN 2008,2008, 2008Conference paper (Refereed)
  • 24.
    Duc Tran, Thien
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor 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.
    Amano, Hiroshi
    Department of Electrical Engineering and Computer Science, Nagoya University, Chikusa-ku, Nagoya, Japan.
    Monemar, Bo
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Janzén, Erik
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Hemmingsson, Carl
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Deep level study of Mg-doped GaN using deep level transient spectroscopy and minority carrier transient spectroscopy2016In: Physical Review B, ISSN 2469-9950, Vol. 94, no 4, article id 045206Article in journal (Refereed)
    Abstract [en]

    Deep levels in Mg doped GaN have been studied using deep level transient spectroscopyand minority charge carrier transient spectroscopy. Two traps are revealed in the investigatedtemperature range. In the substrate, one electron trap labelled ET1 (EC – 0.158 eV) is observedand in the Mg-doped layer, one hole trap labelled HT1 has been revealed. By varying theelectric field, it is found that the hole trap HT1 exhibits an electric field enhanced hole emissionrate. Using four theoretical models based on 3-dimensional Coulombic Poole-Frenkel effect, 3-dimensional square well Poole-Frenkel effect, phonon assisted tunneling, and 1-dimensionalCoulombic Poole-Frenkel effect including phonon assisted tunneling, the experimental data arefitted in order to justify the field enhanced emission process. It is found that the 1-dimensionalCoulombic Poole-Frenkel model including phonon assisted tunneling is consistent with theexperimental data. Since the trap exhibits Poole-Frenkel effect, we suggest it is acceptor like.From the theoretical model, the zero field activation energy of HT1 and an estimate of the holecapture cross section have been determined as Ev+0.57 eV and 1.9x10-15 cm2, respectively.Since the level is only observed in Mg-doped material, it is suggested that the trap can beassociated with a Mg related defect.

  • 25.
    Duc Tran, Thien
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor 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.
    Janzén, Erik
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Hemmingsson, Carl
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Investigation of deep levels in bulk GaN material grown by halide vapor phase epitaxy2013In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 114, no 15Article in journal (Refereed)
    Abstract [en]

    Electron traps in thick free standing GaN grown by halide vapor phase epitaxy were characterized by deep level transient spectroscopy. The measurements revealed six electron traps with activation energy of 0.252 (E1), 0.53 (E2), 0.65 (E4), 0.69 (E3), 1.40 (E5), and 1.55 eV (E6), respectively. Among the observed levels, trap E6 has not been previously reported. The filling pulse method was employed to determine the temperature dependence of the capture cross section and to distinguish between point defects and extended defects. From these measurements, we have determined the capture cross section for level E1, E2, and E4 to 3.2 × 10−16 cm2, 2.2 × 10−17 cm2, and 1.9 × 10−17 cm2, respectively. All of the measured capture cross sections were temperature independent in the measured temperature range. From the electron capturing kinetic, we conclude that trap E1, E2, and E3 are associated with point defects. From the defect concentration profile obtained by double correlated deep level transient spectroscopy, we suggest that trap E4 and E6 are introduced by the polishing process.

  • 26.
    Duc Tran, Thien
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor 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.
    Nguyen, Tien Son
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Janzén, Erik
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Kordina, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Ohshima, Takeshi
    Japan Atomic Energy Agency, Takasaki, Japan.
    Hemmingsson, Carl
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Thermal behavior of irradiation-induced-deep levels in bulk GaN2015Manuscript (preprint) (Other academic)
    Abstract [en]

    Bulk GaN grown by halide vapor phase epitaxy and irradiated by 2 MeV electrons at a fluence of 5×1016 cm-2 were studied by deep level transient spectroscopy. After irradiation, two new peaks labelled D0 (EC – 0.18 eV) and D1 (EC – 0.13 eV) are observed. From isochronal annealing studies in the temperature range of 350 - 600 K, it is observed that peak D0 is completely annealed out already at 550 K while the broad peak D1 has a more complex annealing behavior. The concentration of D1 is decreasing during annealing and its peak position is shifted to higher temperatures, until a relatively stable peak labelled D2 (EC – 0.24 eV) is formed. From an isothermal annealing study of D2, it is concluded that the annealing process can be described by a first order annealing process with an activation energy and prefactor of 1.2 eV and 6.6 × 105 s-1, respectively. From the large pre-factor it is concluded that the annihilation of D2 is governed by a long-range migration process. From its annealing behavior, it is suggested that trap D2 may be related to the VGa.

  • 27.
    Duc Tran, Thien
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor 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.
    Nguyen, Tien Son
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Kordina, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Janzén, Erik
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Ohshima, Takeshi
    Japan Atomic Energy Agency, Takasaki, Japan.
    Hemmingsson, Carl
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Deep levels in as-grown and electron-irradiated n-type GaN studied by deep level transient spectroscopy and minority carrier transient spectroscopy2016In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 119, no 9Article in journal (Refereed)
    Abstract [en]

    By minority carrier transient spectroscopy on as-grown n-type bulk GaN produced by halide vapor phase epitaxy (HVPE) one hole trap labelled H1 (EV + 0.34 eV) has been detected. After 2 MeV-energy electron irradiation, the concentration of H1 increases and at fluences higher than 5×1014 cm-2, a second hole trap labelled H2 is observed. Simultaneously, the concentration of two electron traps, labelled T1 (EC - 0.12 eV) and T2 (EC - 0.23 eV) increases. By studying the increase of the concentration versus electron irradiation fluences, the introduction rate of T1 and T2 using 2 MeV-energy electrons was determined to 7X10-3 cm-1 and 0.9 cm-1, respectively. Due to the low introduction rate of T1 and the low threading dislocation density in the HVPE bulk GaN material, it is suggested that the defect is associated with a primary defect decorating extended structural defects. The high introduction rate of the trap H1 suggests that the H1 defect is associated with a primary intrinsic defect or a complex.

  • 28.
    Duc Tran, Thien
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor 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.
    Nguyen, Tien Son
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Ohshima, Takeshi
    Japan Atomic Energy Agency, Takasaki, Japan.
    Janzén, Erik
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Hemmingsson, Carl
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Electronic properties of defects in high-fluence electron irradiated bulk GaN2016In: Physica status solidi. B, Basic research, ISSN 0370-1972, E-ISSN 1521-3951, Vol. 253, no 3, p. 521-526Article in journal (Refereed)
    Abstract [en]

    Using deep level transient spectroscopy, deep levels and capture cross sections of defects introduced by high-fluence electron irradiation of thick halide vapour phase epitaxy grown GaN has been studied. After irradiation with 2 MeV electrons to a high-fluence of 5×1016 cm-2, four deep trap levels, labelled T1 (EC – 0.13 eV), T2 (EC – 0.18 eV), T3 (EC – 0.26 eV) T4 and a broad band of peaks consisting of at least two levels could be observed. These defects, except T1 and T3, were annealed out after annealing at 650 K for 2 hours. The capture cross section is found to be temperature independent for T2 and T3, while T1 shows an decresing capture cross section with increasing temperature, suggesting that electron capturing to this deep level is governed by a cascade capturing process.

  • 29.
    Duc, Tran Thien
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor 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.
    Son, Nguyen Tien
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Janzén, Erik
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Ohshima, Takeshi
    Japan Atomic Energy Agency (JAEA), Takasaki, Japan.
    Hemmingsson, Carl
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Capture cross section of electron-irradiation-induced defects in bulk GaN grown by halide vapor phase epitaxy2014Manuscript (preprint) (Other academic)
    Abstract [en]

    Electron-irradiation-induced defects in GaN grown by halide vapor phase epitaxy is studied by deep level transient spectroscopy in which the capture cross section and its temperature dependence of the deep levels was determined by the filling pulse method. Before irradiation, one trap level, labelled ET4 (EC – 0.244 eV), was observed. After performing electron irradiation with an energy of 2 MeV at a fluence of 5 × 1016 cm-2, four deep trap levels, labelled ET1 (EC – 0.178 eV), ET2 (EC – 0.181 eV), ET3 (EC – 0.256 eV) and ET5 appeared. After annealing at 650K for 2 hours, only two irradiation induced deep levels, ET1 and ET3, were observed. By varying the rate windows, the temperature dependence of the capture cross section of the two deep levels ET1 and ET2 and ET3 was studied. The temperature behavior of ET2 and ET3 capture cross section is independent on temperature whereas the capture cross section of the deep level ET1 depends strongly on the temperature. It is suggested that electron capturing is govern by a multiphonon process to the level ET1.

  • 30.
    Duc, Tran Thien
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor 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.
    Son, Nguyen Tien
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Janzén, Erik
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Ohshima, Takeshi
    Japan Atomic Energy Agency (JAEA), Takasaki, Japan.
    Hemmingsson, Carl
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Radiation-induced defects in GaN bulk grown by halide vapor phase epitaxy2014In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 105, no 10, p. 102103-Article in journal (Refereed)
    Abstract [en]

    Defects induced by electron irradiation in thick free-standing GaN layers grown by halide vapor phase epitaxy were studied by deep level transient spectroscopy. In as-grown materials, six electron traps, labeled D2 (E-C-0.24 eV), D3 (E-C-0.60 eV), D4 (E-C-0.69 eV), D5 (E-C-0.96 eV), D7 (E-C-1.19 eV), and D8, were observed. After 2MeV electron irradiation at a fluence of 1 x 10(14) cm(-2), three deep electron traps, labeled D1 (E-C-0.12 eV), D5I (E-C-0.89 eV), and D6 (E-C-1.14 eV), were detected. The trap D1 has previously been reported and considered as being related to the nitrogen vacancy. From the annealing behavior and a high introduction rate, the D5I and D6 centers are suggested to be related to primary intrinsic defects.

  • 31. Duteil, F.
    et al.
    Du, Chun-Xia
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Joelsson, K.B.
    Persson, Per
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics.
    Hultman, Lars
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics.
    Pozina, Galia
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Ni, Wei-Xin
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface and Semiconductor Physics .
    Hansson, Göran
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface and Semiconductor Physics .
    Luminescence and microstructure of Er/O co-doped Si structures grown by MBE using Er and SiO evaporation2000In: Materials Science in Semiconductor Processing, ISSN 1369-8001, E-ISSN 1873-4081, Vol. 3, no 5-6, p. 523-528Article in journal (Refereed)
    Abstract [en]

    Er and O co-doped Si structures have been prepared using molecular-beam epitaxy (MBE) with fluxes of Er and O obtained from Er and silicon monoxide (SiO) evaporation in high-temperature cells. The incorporation of Er and O has been studied for concentrations of up to 2×1020 and 1×1021 cm-3, respectively. Surface segregation of Er can take place, but with O co-doping the segregation is suppressed and Er-doped layers without any indication of surface segregation can be prepared. Si1-xGex and Si1-yCy layers doped with Er/O during growth at different substrate temperatures show more defects than corresponding Si layers. Strong emission at 1.54µm associated with the intra-4f transition of Er3+ ions is observed in electroluminescence (EL) at room temperature in reverse-biased p-i-n-junctions. To optimize the EL intensity we have varied the Er/O ratio and the temperature during growth of the Er/O-doped layer. Using an Er-concentration of around 1×1020 cm-3 we find that Er/O ratios of 1:2 or 1:4 give higher intensity than 1:1 while the stability with respect to breakdown is reduced for the highest used O concentrations. For increasing growth temperatures in the range 400-575 °C there is an increase in the EL intensity. A positive effect of post-annealing on the photoluminescence intensity has also been observed.

  • 32. Ellison, A
    et al.
    Magnusson, Björn
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Sundqvist, B
    Pozina, Galia
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Bergman, Peder
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Janzén, Erik
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Vehanen, A
    SiC crystal growth by HTCVD2004In: Materials Science Forum, Vols. 457-460, 2004, Vol. 457-460, p. 9-Conference paper (Refereed)
    Abstract [en]

    Advances in the development of the HTCVD technique for growth of bulk 2-inch diameter 4H SiC crystals are reviewed with demonstration of micropipe density down to 0.3 cm(-2), low crystal bending and X-ray rocking curve widths of 12". High Al doping in p-type substrates enables resistivities down to 0.5 Omega cm without increased micropipe density, while too high N doping causes spontaneous stacking faults formation in annealed n-type substrates. High purity semi-insulating wafers, grown under conditions reducing the incorporation of Si-vacancies, exhibit lower density of vacancy clusters and better properties for microwave device applications.

  • 33.
    Evropeytsev, E. A.
    et al.
    Ioffe Inst, Russia.
    Jmerik, V. N.
    Ioffe Inst, Russia.
    Nechaev, D. V.
    Ioffe Inst, Russia.
    Rouvimov, S.
    Univ Notre Dame, IN 46556 USA.
    Shubina, T. V.
    Ioffe Inst, Russia.
    Kaibyshev, V. Kh
    Ioffe Inst, Russia.
    Pozina, Galia
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Ivanov, S. V.
    Ioffe Inst, Russia.
    Toropov, A. A.
    Ioffe Inst, Russia.
    Coexistence of type-I and type-II band line-ups in 1-2 monolayer thick GaN/AlN single quantum wells2017In: 4TH INTERNATIONAL SCHOOL AND CONFERENCE ON OPTOELECTRONICS, PHOTONICS, ENGINEERING AND NANOSTRUCTURES (SAINT PETERSBURG OPEN 2017), IOP PUBLISHING LTD , 2017, Vol. 917, article id 062050Conference paper (Refereed)
    Abstract [en]

    GaN/AlN quantum wells (QWs) with varied nominal thickness of 0.5-4 monolayers have been studied by time-resolved photoluminescence (PL) spectroscopy. The structures demonstrate an emission peak with the thickness-dependent wavelength in the range 225-320 nm. The observed temporal behavior of PL between 225 and 280 nm can be described as a superposition of fast and slow decaying components with characteristic decay time constants of the order of 0.1-0.7 ns and 7-30 ns, respectively. The fast PL component with the decay time smaller than 1 ns dominates in the thicker GaN insertions and tends to vanish in the thinnest ones, where the slow PL component becomes progressively longer. These observations imply formation in the GaN/AlN monolayer-thick layers of an inhomogeneous excitonic system involving both direct and indirect in space excitons.

  • 34.
    Evropeytsev, E. A.
    et al.
    Ioffe Institute, Russia.
    Sorokin, S. V.
    Ioffe Institute, Russia.
    Klimko, G. V.
    Ioffe Institute, Russia.
    Gronin, S. V.
    Ioffe Institute, Russia.
    Sedova, I. V.
    Ioffe Institute, Russia.
    Belyaev, K. G.
    Ioffe Institute, Russia.
    Ivanov, S. V.
    Ioffe Institute, Russia.
    Pozina, Galia
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Toropov, A. A.
    Ioffe Institute, Russia.
    Structural properties and vertical transport in ZnSe/CdSe superlattices grown on an In0.3Ga0.7As metamorphic buffer layer2016In: PHYSICA STATUS SOLIDI C: CURRENT TOPICS IN SOLID STATE PHYSICS, VOL 13 NO 7-9, WILEY-V C H VERLAG GMBH , 2016, Vol. 13, no 7-9, p. 503-506Conference paper (Refereed)
    Abstract [en]

    We report on the growth by molecular-beam epitaxy of short-period ZnSe/ CdSe superlattices (SLs) on an In0.3Ga0.7As metamorphic buffer layer. Such SLs are considered as a promising material for a wide band-gap photoactive p-n junction in a hybrid monolithic Ge/InxGa1-xAs/In-y(Al,Ga)(1-y)As/II-VI solar cell. Lattice-matching of the SLs to the In0.3Ga0.7As layer is confirmed by X-ray diffractometry. Vertical transport of photoexcited carriers is investigated by means of both steady state and time-resolved photoluminescence techniques in heterostructures containing the ZnSe/CdSe SL with an enlarged quantum well (EQW). Characteristic times of the carrier transport across the SL towards EQW are evaluated in the temperature range 120-300 K. (C) 2016 WILEY-VCH Verlag GmbH amp; Co.

  • 35.
    Forsberg, Mathias
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Hemmingsson, Carl
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Amano, Hiroshi
    Department of Electrical Engineering and Computer Science, Nagoya University, Japan.
    Pozina, Galia
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Dynamic properties of excitons in ZnO/AlGaN/GaN hybrid nanostructures2015In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 5, no 7889, p. 1-5Article in journal (Refereed)
    Abstract [en]

    Hybrid samples based on ZnO colloidal nanocrystals (NCs) deposited on AlGaN/GaN quantum well (QW) structures with different top barrier thickness d = 3, 6 and 9 nm are studied by time-resolved photoluminescence. Thermal behavior of the QW exciton lifetime in the hybrids and in the bare QW structures has been compared and it has been found that the QW exciton recombination rate increases in the hybrid having d = 3 nm and decreases in the hybrid with d = 6 nm, while no change has been observed for the structure with d = 9 nm. It is suggested that non-radiative resonance energy transfer from the QW excitons to the ZnO NCs and a variation of the surface potential can both influence the QW exciton lifetime in the hybrids.

  • 36.
    Forsberg, Mathias
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Hemmingsson, Carl
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Amano, Hiroshi
    Nagoya University, Japan.
    Pozina, Galia
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Time-resolved photoluminescence properties of hybrids based on inorganic AlGaN/GaN quantum wells and colloidal ZnO nanocrystals2015In: Superlattices and Microstructures, ISSN 0749-6036, E-ISSN 1096-3677, Vol. 87, p. 38-41Article in journal (Refereed)
    Abstract [en]

    Dynamic properties are studied for the AlGaN/GaN quantum well (QW) structures with and without the coating of colloidal ZnO nanocrystals (NCs). The QW exciton recombination rate was reduced in such hybrids compared to the bare QW structure only in the sample with the thinnest cap layer of 3 nm. Assuming that one of the recombination mechanisms in this hybrid is non-radiative resonant energy transfer (NRET) between the QW and the energy acceptor material i.e. ZnO NCs, the maximum pumping efficiency was estimated to be similar to 42% at 60 K. The NRET effect is, however, vanished after several months despite that the hybrid structures are composed of chemically stable components. (C) 2015 Published by Elsevier Ltd.

  • 37.
    Forsberg, Mathias
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Serban, Alexandra
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Hsiao, Ching-Lien
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Junaid, Muhammad
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Birch, Jens
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Pozina, Galia
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Near band gap luminescence in hybrid organic-inorganic structures based on sputtered GaN nanorods2017In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 7, article id 1170Article in journal (Refereed)
    Abstract [en]

    Novel hybrid organic-inorganic nanostructures fabricated to utilize non-radiative resonant energy transfer mechanism are considered to be extremely attractive for a variety of light emitters for down converting of ultaviolet light and for photovoltaic applications since they can be much more efficient compared to devices grown with common design. Organic-inorganic hybrid structures based on green polyfluorene (F8BT) and GaN (0001) nanorods grown by magnetron sputtering on Si (111) substrates are studied. In such nanorods, stacking faults can form periodic polymorphic quantum wells characterized by bright luminescence. In difference to GaN exciton emission, the recombination rate for the stacking fault related emission increases in the presence of polyfluorene film, which can be understood in terms of Forster interaction mechanism. From comparison of dynamic properties of the stacking fault related luminescence in the hybrid structures and in the bare GaN nanorods, the pumping efficiency of non-radiative resonant energy transfer in hybrids was estimated to be as high as 35% at low temperatures.

  • 38.
    Forsberg, Mathias
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Serban, Alexandra
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Poenaru, Iuliana
    Fraunhofer ISC, Project Group Materials Recycling and Resource Strategy IWKS, Hanau, Germany.
    Hsiao, Ching-Lien
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Junaid, Mohammad
    RWTH Aachen University, Aachen, Germany.
    Birch, Jens
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. 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.
    Stacking fault related luminescence in GaN nanorods2015In: Nanotechnology, ISSN 0957-4484, E-ISSN 1361-6528Article in journal (Refereed)
    Abstract [en]

    Optical and structural properties are presented for GaN nanorods grown in the [0001]direction on Si(111) substrates by direct-current reactive magnetron sputter epitaxy.Transmission electron microscopy reveals clusters of dense stacking faults (SFs) regularlydistributed along the c-axis. A strong emission at ~3.42 eV associated with basal plane SFsdemonstrates thermal stability up to room temperatures together with a relatively shortrecombination time suggesting carrier localization in the system similar to multiple quantumwells.

  • 39.
    Goldys, EM
    et al.
    Macquarie Univ, Div Informat & Commun Sci, N Ryde, NSW, Australia Linkoping Univ, Dept Phys & Measurement Technol, S-58183 Linkoping, Sweden.
    Godlewski, M
    Macquarie Univ, Div Informat & Commun Sci, N Ryde, NSW, Australia Linkoping Univ, Dept Phys & Measurement Technol, S-58183 Linkoping, Sweden.
    Paskova, Tanja
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Pozina, Galia
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Monemar, Bo
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Characterization of red emission in nominally undoped hydride vapor phase epitaxy GaN2001In: MRS Internet journal of nitride semiconductor research, ISSN 1092-5783, E-ISSN 1092-5783, Vol. 6, no 1, p. art. no.-1Article in journal (Refereed)
    Abstract [en]

    We report characterization of the red emission band in hydride vapor phase epitaxial GaN using cathodoluminescence spectroscopy and imaging and time-resolved photoluminescence. The observed properties of the emission are consistent with recombination of excitons bound at close donor-acceptor pairs. The time evolution of the emission signal during electron beam irradiation supports the association of the red emission with charged centres.

  • 40.
    Gubaydullin, A. R.
    et al.
    St Petersburg Academic University, Russia; University of Claude Bernard Lyon 1, France.
    Symonds, C.
    University of Claude Bernard Lyon 1, France.
    Bellessa, J.
    University of Claude Bernard Lyon 1, France.
    Ivanov, K. A.
    St Petersburg Academic University, Russia; ITMO University, Russia.
    Kolykhalova, E. D.
    St Petersburg Academic University, Russia; Ioffe Institute, Russia.
    Sasin, M. E.
    Ioffe Institute, Russia.
    Lemaitre, A.
    University of Paris Saclay, France.
    Senellart, P.
    University of Paris Saclay, France.
    Pozina, Galia
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Kaliteevski, M. A.
    St Petersburg Academic University, Russia; ITMO University, Russia; Ioffe Institute, Russia.
    Enhancement of spontaneous emission in Tamm plasmon structures2017In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 7, article id 9014Article in journal (Refereed)
    Abstract [en]

    It was theoretically and experimentally demonstrated that in metal/semiconductor Tamm plasmon structures the probability of spontaneous emission can be increased despite losses in metal, and theoretical analysis of experimental results suggested that the enhancement could be as high as one order of magnitude. Tamm plasmon structure with quantum dots has been fabricated and the emission pattern has been measured. Electromagnetic modes of the structure have been analyzed and modification of spontaneous emission rates has been calculated showing a good agreement with experimentally observed emission pattern.

  • 41.
    Gubaydullin, A. R.
    et al.
    St Petersburg Acad Univ, Russia; Univ Claude Bernard Lyon 1, France.
    Symonds, C.
    Univ Claude Bernard Lyon 1, France.
    Bellessa, J.
    Univ Claude Bernard Lyon 1, France.
    Ivanov, K. A.
    St Petersburg Acad Univ, Russia; ITMO Univ, Russia.
    Kolykhalova, E. D.
    St Petersburg Acad Univ, Russia; Ioffe Inst, Russia; St Petersburg Sci Ctr, Russia.
    Sasin, M. E.
    Ioffe Inst, Russia.
    Pozina, Galia
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Kaliteevski, M. A.
    St Petersburg Acad Univ, Russia; ITMO Univ, Russia; Ioffe Inst, Russia.
    Purcell Effect in Tamm Plasmon Structures with QD Emitter2018In: Semiconductors (Woodbury, N.Y.), ISSN 1063-7826, E-ISSN 1090-6479, Vol. 52, no 4, p. 452-457Article in journal (Refereed)
    Abstract [en]

    We study Tamm plasmon structure based on GaAs/Al0.95GaAs distributed Bragg reflector covered by thin silver layer, with active area formed by InAs quantum dots. We have measured the spectral and angular characteristics of photoluminescence and performed theoretical calculation of the spontaneous emission rate (modal Purcell factor) in the structure by using S-quantization formalism. We show that for Tamm plasmon mode the spontaneous emission can be enhanced by more than an order of magnitude, despite absorption in metallic layer.

  • 42.
    Harati Zadeh, Hamid
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Paskov, Plamen
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Pozina, Galia
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Holtz, Per-Olof
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Monemar, Bo
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Kamiyama, S.
    Iwaya, M.
    Amano, H.
    Akasaki, I.
    Effect of n-type modulation doping on the photoluminescence of GaN/Al0.07Ga0.93N multiple quantum wells2002In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 80, no 8, p. 1373-Article in journal (Refereed)
    Abstract [en]

    [No abstract available]

  • 43.
    Harati Zadeh, Hamid
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Paskov, Plamen
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Pozina, Galia
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Holtz, Per-Olof
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Monemar, Bo
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Kamiyama, S.
    Iwaya, M.
    Amano, H.
    Akasaki, I.
    Photoluminescence study of Si doped GaN/AlGaN multi quantum wells2003In: ICPS 2002,2002, 2003, p. D-109-Conference paper (Refereed)
  • 44.
    Harati Zadeh, Hamid
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Paskov, Plamen
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Pozina, Galia
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Holtz, Per-Olof
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Monemar, Bo
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Kamiyama, S.
    Iwaya, M.
    Amano, H.
    Akasaki, I.
    Photoluminescence study of Si doped GaN/GaN/Al0.07Ga0.93N multi quantum wells2002In: NANO-7/ECOSS-21,2002, 2002, p. 13-Conference paper (Other academic)
  • 45.
    Harati Zadeh, Hamid
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Paskov, Plamen
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Pozina, Galia
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Holtz, Per-Olof
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Monemar, Bo
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Kamiyama, S.
    Iwaya, M.
    Amano, H.
    Akasaki, I.
    The influence of Si-donor doping on the exciton localization in modulation- doped GaN/AlGaN multi quantum wells2002In: 14th Indium Phosphide and Related Materials Conference IPRM 2002,2002, 2002, p. 495-Conference paper (Refereed)
  • 46. Haratizadeh, H.
    et al.
    Monemar, Bo
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Paskov, Plamen
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Holtz, Per-Olof
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Pozina, Galia
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Kamiyama, S.
    Department of Electrical Engineering, Meijo University, 1-501 Shiogamaguchi, Tempaku-ku, Nagoya 468, Japan.
    Iwaya, M.
    Department of Electrical Engineering, Meijo University, 1-501 Shiogamaguchi, Tempaku-ku, Nagoya 468, Japan.
    Amano, H.
    Department of Electrical Engineering, Meijo University, 1-501 Shiogamaguchi, Tempaku-ku, Nagoya 468, Japan.
    Akasaki, I.
    Department of Electrical Engineering, Meijo University, 1-501 Shiogamaguchi, Tempaku-ku, Nagoya 468, Japan.
    Time resolved photoluminescence study of Si modulation doped GaN/Al 0.07Ga0.93N multiple quantum wells2004In: Physica status solidi. B, Basic research, ISSN 0370-1972, E-ISSN 1521-3951, Vol. 241, no 5, p. 1124-1133Article in journal (Refereed)
    Abstract [en]

    The effects of the Si doping level on the recombination dynamics and carrier (exciton) localization in modulation doped GaN/Al0.07Ga 0.93N 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 10 20 cm-3) show almost exponential decay curves at 2 K, suggesting the recombination of free electrons and localized holes. This localization effect appears even at high electron concentrations to cancel the expected lowering of the radiative lifetime with doping at 2 K, such a lowering is clearly observed at elevated temperatures for the highly doped samples, however. 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. Only the PL peak of the undoped and low-doped samples shows a redshift with time delay, related to the photogenerated carriers. © 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  • 47.
    Hemmingsson, Carl
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Materials Science . Linköping University, The Institute of Technology.
    Boota, M
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Rahmatalla, R O
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Junaid, M
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Pozina, Galia
    Linköping University, Department of Physics, Chemistry and Biology, Materials Science . Linköping University, The Institute of Technology.
    Birch, Jens
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Health Sciences.
    Monemar , Bo
    Linköping University, Department of Physics, Chemistry and Biology, Materials Science . Linköping University, The Institute of Technology.
    Growth and characterization of thick GaN layers grown by halide vapour phase epitaxy on lattice-matched AlInN templates2009In: JOURNAL OF CRYSTAL GROWTH, ISSN 0022-0248 , Vol. 311, no 2, p. 292-297Article in journal (Refereed)
    Abstract [en]

    We have investigated the feasibility to use GaN lattice-matched Al0.82In0.18N as a starting layer for growth of thick GaN using halide vapor phase epitaxy (HVPE). The buffer, which consisted of Al0.82In0.18N(0 0 0 1) on a 50-nm-thick TiN(1 1 1) seed layer, was grown by magnetron sputter epitaxy (MSE) on a 2 Al2O3(0 0 0 1) substrate. It was found that the surface morphology of the GaN strongly depends on the choice of carrier gases. Using a mixture of hydrogen and nitrogen results in a rough morphology, while growth in pure nitrogen gives layers of good morphology and high transparency. For a 30-pm-thick GaN film, the threading dislocation (TD) density, as determined by cathodoluminescence, is about similar to 3 x 10(8) cm(-2). By transmission electron microscopy (TEM), it was revealed that the threading dislocations originate from the buffer layer and the GaN/Al0.82In0.18N interface. The GaN/Al0.82In0.18N interface is roughened during growth due to a chemical incompatibility between the HVPE process and the Al0.82In0.18N layer. Additionally, the GaN layers are cracked due to tensile strain indicating initial growth of crystallites which eventually coalesce and hence build up a tensile stress in the film.

  • 48.
    Hemmingsson, Carl
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Paskov, Plamen
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Pozina, Galia
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Heuken, M.
    Schineller, B.
    Monemar, Bo
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Growth of bulk GaN in a vertical hydride vapour phase epitaxy reactor2006In: Superlattices and Microstructures, ISSN 0749-6036, E-ISSN 1096-3677, Vol. 40, no 4-6 SPEC. ISS., p. 205-213Article in journal (Refereed)
    Abstract [en]

    Using the hydride vapour phase epitaxy technique, we have grown 2-inch diameter bulk GaN material with a thickness up to 2 mm. The growth was performed in a vertical hot-walled reactor at atmospheric pressure. In this geometry, the process gases are distributed from the bottom upwards through the reactor. We present recent results on growth and characterization of the bulk GaN material. The structural and optical properties of the layers have been studied using decorative etching, optical microscopy, scanning electron microscopy, X-ray diffraction, cathodoluminescence, and low temperature photoluminescence. © 2006 Elsevier Ltd. All rights reserved.

  • 49.
    Hemmingsson, Carl
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Paskov, Plamen
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Pozina, Galia
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Heuken, M.
    Aixtron AG, D-52072 Aachen, Germany.
    Schineller, B.
    Aixtron AG, D-52072 Aachen, Germany.
    Monemar, Bo
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Hydride vapour phase epitaxy growth and characterization of thick GaN using a vertical HVPE reactor2007In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 300, no 1, p. 32-36Article in journal (Refereed)
    Abstract [en]

    Growth of 2-inch diameter bulk GaN layers with a thickness up to 2 mm is demonstrated in a vertical hydride vapour phase growth reactor. Morphology, dislocations, optical and electrical properties of the material have been investigated using atomic force microscopy, optical microscopy, decorative etching in hot H3PO4, Hall measurements and low-temperature photoluminescence. Atomic force microscopy reveals a two-dimensional step flow growth mode with step bunching for layers with a thickness of 250 µm. As the growth proceeds, the morphology is changed to a hill and valley structure. The EPD was determined to 5×105 cm-2 for a 2 mm thick layer. The Hall mobility and the carrier concentration were determined. For a 1.7 mm thick layer at 300 K the mobility and the carrier concentration is 520 cm2/V s and about 4×1017 cm-3, respectively. Low-temperature photoluminescence spectra measured on a 350 µm thick freestanding layer show the DBE line at 3.4707 eV with a full-width half-maximum of 1 meV, confirming a stress free GaN layer. © 2006 Elsevier B.V. All rights reserved.

  • 50.
    Hemmingsson, Carl
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor 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.
    Optimization of low temperature GaN buffer layers for halide vapor phase epitaxy growth of bulk GaN2013In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 366, p. 61-66Article in journal (Refereed)
    Abstract [en]

    We have studied growth and self-separation of bulk GaN on c-oriented Al2O3 using low temperature (LT) GaN buffer layers. By studying the X-ray diffraction (XRD) signature for the asymmetric and symmetric reflections versus the LT-GaN thickness and V/III precursor ratio, we observe that the peak width of the reflections is minimized using a LT buffer thickness of ∼100–300 nm. It was observed that the V/III precursor ratio has a strong influence on the morphology. In order to obtain a smooth morphology, the V/III precursor ratio has to be more than 17 during the growth of the buffer layer. By using an optimized LT buffer layer for growth of a 20 μm thick GaN layer, we obtain a XRD peak with a full width at half maximum of ∼400 and ∼250 arcs for (002) and (105) reflection planes, respectively, and with a dark pit density of ∼2.2×108 cm−2. For layers thicker than 1 mm, the GaN was spontaneously separated and by utilizing this process, thick free freestanding 2″ GaN substrates were manufactured.

1234 1 - 50 of 160
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • oxford
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf