GLORIA

GEOMAR Library Ocean Research Information Access

feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 77 (1995), S. 1705-1709 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: GaN films were grown on (100) GaAs substrates by metalorganic chemical vapor deposition and were found to be of (200) cubic or (111) cubic/(0002) hexagonal phase. Their photoluminescence characteristics remained invariant with material phase. We report assignment of band-edge photoluminescence near 3.36 eV and 3.15–3.31 eV in apparently cubic GaN to intrinsic/bound excitons and phonon-assisted, donor-acceptor pair recombination respectively, on the basis of observed temperature and intensity dependences. A free exciton energy of 3.375 eV is deduced at 6.5 K. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 2
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Effects of growth interruption on the optical and the structural properties of InGaN/GaN quantum wells were investigated by using photoluminescence, transmission electron microscopy, optical microscopy, and high resolution x-ray diffraction. The InxGa1−xN/GaN (x〉0.2) quantum wells used in this study were grown on c-plane sapphire by using metalorganic chemical vapor deposition. The interruption was carried out by closing the group-III metalorganic sources before and after the growths of the InGaN quantum well layers. The transmission electron microscopy images show that with increasing interruption time, the quantum-dot-like regions and well thickness decreased due to indium reevaporation or the thermal etching effect. As a result the photoluminescence peak position was blueshifted and the intensity was reduced. Temperature- and excitation-power-dependent photoluminescence spectra support the results of transmission electron microscopy measurements. The sizes and the number of V defects did not differ with the interruption time. The interruption time is not directly related to the formation of defects. The V defect originates at threading dislocations and inversion domain boundaries due to higher misfit strain. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 3
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 89 (2001), S. 5454-5459 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Deep-level defect-related optical properties of undoped n-type GaN grown by metalorganic chemical vapor deposition are investigated using photoluminescence (PL), optical absorption (OA), photoconductivity (PC), and persistent photoconductivity (PPC) measurements. From the temperature dependence of the PL and OA, we find that the yellow luminescence (YL) is due to shallow-to-deep donor recombination. PL, PC, and PPC results manifest a strong correlation in properties related to deep levels. Samples which emit YL exhibit a PC peak at 1.9 eV due to the photoionization of deep levels as well as to the persistent photoconductivity effect, whereas samples with no YL have no PC peak in the forbidden gap and no PPC at any photon energy, suggesting a common origin. Furthermore, two types of PPC behavior were observed depending on the sample quality: typical stretched exponential decay in relatively thick samples and photocurrent quenching and a subsequent reduction of the dark current in thin samples. An explanation of the latter phenomenon based on photoinduced metastable electron traps in a highly defective layer near the interface is suggested from the temporal behavior of the PC. These traps seem to disappear slowly after the illuminating light is turned off. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 4
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 71 (1992), S. 5427-5432 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Microstructures of silicon films deposited on SiO2 substrates by low-pressure chemical vapor deposition using Si2H6 gas were investigated and compared to those using conventional SiH4 gas by transmission electron microscopy and x-ray diffraction. The deposition rate of the Si2H6 process was about ten times higher than that of SiH4 process at low temperatures (〈550 °C). The transition deposition temperature from amorphous to polycrystalline film was found to be around 580 °C, which was similar to that of the SiH4 process. The film deposited at 600 °C was partially crystalline and had equi-axed grains with the largest average grain size of 0.3 μm while the films using SiH4 has needle-like columnar grains with smaller sizes (200 A(ring)). The x-ray diffraction analysis showed that the structural disorder to amorphously deposited Si films increases as deposition temperature decreases. The grain size in the film after crystallization at 600 °C strongly depended on the deposition temperature and the deposition rate, producing a larger grain size at a lower deposition temperature and/or at a higher deposition rate (Si2H6 deposition compared to SiH4 deposition). The apparent increase in grain size can be explained as a result of the lowered number of crystal nuclei due to a decrease in the number of pre-existing microcrystallites serving as heterogeneous nucleation seeds. When the deposition rate was lower than the critical value (approximately 2–4 nm/min), the grain size in the crystallized film decreased for both SiH4 and Si2H6 films. The maximum grain sizes were 4.5 and 0.3 μm at the deposition temperatures of 485 and 550 °C for the films using Si2H6 and SiH4 gases, respectively.
    Type of Medium: Electronic Resource
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 5
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 76 (2000), S. 1021-1023 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Photoconductivity and optical absorption measurements were employed to analyze deep levels in undoped n-type GaN films grown on sapphire substrate by metalorganic chemical vapor deposition. At room temperature, the photoconductivity measurement exhibits a broad level at around 1.90 eV. Similarly, the optical absorption spectrum shows a deep level located at 1.87 eV within the band gap, which is best described by a transition from a donor charge-transfer level to the conduction band, according to Lucovsky theory. A persistent photoconductivity whose behavior is distinctive from that of previously reported work for n- or p-type GaN epitaxial films was observed. The photocurrent quenching and decreased dark current in the persistent photoconductivity effect suggest that metastable electron states are formed in the band gap to trap electrons which tunnel out the potential barrier with long recovery time. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 6
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 76 (2000), S. 1149-1151 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A two-band model involving the heavy- and light-hole bands was adopted to analyze the temperature-dependent Hall effect measured on Mg-doped p-type GaN epilayers. At 300 K, the hole concentration was determined to be nearly twice the Hall concentration estimated from the measured Hall coefficient, meanwhile the Hall mobility of heavy hole turned out to be only half of the measured one. It is shown that the scattering by space charge and acoustic deformation potential is anomalously enhanced in Mg-doped GaN, and that the light hole affects conspicuously the observed transport parameters. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 7
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Temperature-dependent Hall effect measurements on unintentionally doped n-type GaN epilayers show that, above room temperature, the Hall-mobility values of different samples vary parallel with each other with temperature. We demonstrate that this anomaly is mainly due to a conductive layer near the GaN/sapphire interface for thin samples with low carrier density. Through trapping electrons, threading edge dislocations (TEDs) debilitate the epilayer contribution in a two-layer mixed conduction model involving the epilayer and the near-interface layer. The trapping may, in part, explain low mobility and anomalous transport in pure GaN layers. Scattering by TEDs is important only at low temperatures. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 8
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 9
    Electronic Resource
    Electronic Resource
    Copenhagen : Munksgaard International Publishers
    Allergy 56 (2001), S. 0 
    ISSN: 1398-9995
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Background: Buckwheat flour (BF) is known as a potent food allergen. Sensitization to it usually occurs by ingestion but also by inhalation in occupational or domestic exposure. Buckwheat chaff-stuffed pillows (BCP) can be contaminated with BF during the process of pilling, and many Korean children and adults use BCP for health reasons. Methods and Results: We here present three cases of BF allergy in children using BCP, who had been treated as nonatopic asthmatics after undergoing the routine allergy skin tests and serologic tests. We took careful clinical histories, and performed skin prick tests (SPT), the radioimmunoassay (RIA) for specific IgE, the BCP-elimination test, the BF bronchial provocation test, and IgE Western blot. All three children showed positive skin reactions to BF, but none of them had positive reactions to house-dust mites. Nocturnal asthmatic symptoms were improved during 7 days of BCP elimination, and asthmatic responses were observed by bronchial provocation tests with homemade BF extract. Serum BF-specific IgE antibodies and several IgE-binding proteins were detected by RIA and Western blot analysis, respectively. Conclusions: Thus, a small amount of BF attached to BCP can induce BF sensitization, and BCP should be considered a main cause of childhood nocturnal asthma in those asthmatics exposed to these pillows.
    Type of Medium: Electronic Resource
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 10
    Publication Date: 2012-08-09
    Description: Author(s): M. Matsuda, R. S. Fishman, T. Hong, C. H. Lee, T. Ushiyama, Y. Yanagisawa, Y. Tomioka, and T. Ito We have determined the full magnetic dispersion relations of multiferroic BiFeO 3 . In particular, two excitation gaps originating from magnetic anisotropies have been clearly observed. The direct observation of the gaps enables us to accurately determine the Dzyaloshinskii-Moriya (DM) interaction and... [Phys. Rev. Lett. 109, 067205] Published Wed Aug 08, 2012
    Keywords: Condensed Matter: Electronic Properties, etc.
    Print ISSN: 0031-9007
    Electronic ISSN: 1079-7114
    Topics: Physics
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...