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  • 1
    Electronic Resource
    Electronic Resource
    Photocapacitance study of bulk deep levels in ZnSe grown by molecular-beam epitaxy (2000)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 87 (2000), S. 730-738 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The influence of initial growth conditions and lattice matching on the deep level spectrum of n-ZnSe grown on GaAs by molecular-beam epitaxy is investigated by means of deep level optical spectroscopy. A detailed study of both the steady-state and transient photocapacitance allows us to measure optical threshold energies, concentrations, and emission rates of electronically active defects in the ZnSe layer. Several deep levels are found in the ZnSe layer at Ec−Et=1.15, 1.46, 1.90, and 2.25 eV with concentrations in the 1012–1014 cm−3 range. When a 2-nm-thick composition controlled interface layer is grown at different beam pressure ratios prior to the ZnSe growth, a distinct decrease in the 1.46 eV level concentration with increasing Se content is found. Deposition of a lattice-matched InxGa1−xAs buffer layer prior to the ZnSe growth reduces the concentration of both the 1.15 and 1.46 eV levels by over an order of magnitude, indicating the role of lattice matching in the ZnSe overlayer. We also perform depth profiling of the defect distributions within the ZnSe overlayer to see the effect of the ZnSe thickness on the concentration of these levels as well as their possible association to the ZnSe/GaAs interface. We find that only the 2.25 eV level concentration shows a dependence on depth, increasing as the II–VI/III–V interface is approached. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.371933
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  • 2
    Electronic Resource
    Electronic Resource
    Intrinsic stress in chemical vapor deposited diamond films: An analytical model for the plastic deformation of the Si substrate (2001)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 90 (2001), S. 1227-1236 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The intrinsic stress in diamond film deposited on a Si substrate is difficult to measure because high-temperature deposition induces plastic deformation in the Si and so renders useless an elastic solution. In this study, an analytical model is proposed to estimate intrinsic stress using a substrate-curvature technique and considering the plastic deformation of substrate. The stress distribution of the as-deposited film is affected not only by the intrinsic stress of the film but also by the bending and plastic deformation of the substrate. In this model, the distribution is formulated, based on elastic/plastic plate-bending theory, in terms of substrate curvatures, intrinsic stress in the film, and yield stress of the substrate. The intrinsic stress of the film together with the yield stress of the substrate can be obtained from experimentally measured substrate curvatures by solving two equilibrium equations and a moment-relaxation equation describing the film removal. Diamond films were deposited by microwave plasma chemical vapor deposition at varying film thicknesses and deposition temperatures. For the application of the model, the curvature of the film-removed substrate was measured as well as that of as-deposited substrate. The results show that overestimated intrinsic stress can be corrected successfully through this new model. The validity of the results was confirmed by stress measurement using a Raman-peak-shift method. In addition, the generation mechanism of intrinsic stress is analyzed as reflecting a competition between a grain-size effect and nondiamond carbon effect. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1383263
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  • 3
    Electronic Resource
    Electronic Resource
    Deep levels in p-type InGaAsN lattice matched to GaAs (1999)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 74 (1999), S. 2830-2832 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Deep-level transient spectroscopy measurements were utilized to investigate deep-level defects in metal–organic chemical vapor deposition-grown, unintentionally doped p-type InGaAsN films lattice matched to GaAs. The as-grown material displayed a high concentration of deep levels distributed within the band gap, with a dominant hole trap at Ev+0.10 eV. Postgrowth annealing simplified the deep-level spectra, enabling the identification of three distinct hole traps at 0.10, 0.23, and 0.48 eV above the valence-band edge, with concentrations of 3.5×1014, 3.8×1014, and 8.2×1014 cm−3, respectively. A direct comparison between the as-grown and annealed spectra revealed the presence of an additional midgap hole trap, with a concentration of 4×1014 cm−3 in the as-grown material. The concentration of this trap is sharply reduced by annealing, which correlates with improved material quality and minority-carrier properties after annealing. Of the four hole traps detected, only the 0.48 eV level is not influenced by annealing, suggesting this level may be important for processed InGaAsN devices in the future. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.124028
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  • 4
    Electronic Resource
    Electronic Resource
    Evidence for a dominant midgap trap in n-ZnSe grown by molecular beam epitaxy (1999)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 75 (1999), S. 832-834 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A midgap deep level in n-type ZnSe grown by molecular beam epitaxy (MBE) on In0.04Ga0.96As/GaAs is detected and investigated by deep level optical spectroscopy and cathodoluminescence spectroscopy. The deep level has an optical threshold energy of 1.46 eV below the conduction band edge, and its concentration strongly depends on the Zn:Se beam pressure ratio during initial nucleation of the ZnSe layer. The concentration of this level decreases by a factor of ∼8 for Se rich vs Zn rich nucleation conditions, correlating with a decrease in the Se vacancy concentration for Se-rich nucleation. The investigation of photocapacitance transients revealed a strong interaction of the 1.46 eV level with both the conduction and the valence bands. Moreover, this level showed the largest optical cross section (emission rate of ∼103 s−1) of all of the levels found in the ZnSe layer. Taken together, these observations suggest this level may be an important recombination-generation center in MBE-grown ZnSe devices on GaAs substrates. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.124528
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  • 5
    Electronic Resource
    Electronic Resource
    Optically and thermally detected deep levels in n-type Schottky and p+-n GaN diodes (2000)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 76 (2000), S. 3064-3066 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: N-Schottky and p+–n GaN junctions are currently used for different technologies. A comparison of the deep levels found throughout the entire band gap of n-GaN grown by metal-organic chemical vapor deposition under both configurations is presented. Both deep level optical spectroscopy and deep level transient spectroscopy measurements are used allowing the observation of both majority and minority carrier traps. Deep levels at Ec−Et=0.58–0.62, 1.35, 2.57–2.64, and 3.22 eV are observed for both diode configurations, with concentrations in the ∼1014–1016 cm−3 range. The 0.58–0.62 eV level appears correlated with residual Mg impurities in the n side of the p+–n diode measured by secondary-ion-mass spectroscopy, while the 1.35 eV level concentration increases by a factor of ∼4 for the Schottky junction possibly correlating with the carbon profile. The 2.57–2.64 eV level is a minority carrier hole trap in n-GaN, likely related to the yellow photoluminescence band, and is detected both optically from the conduction band (2.64 eV) and thermally from the valence band (0.87 eV). © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.126580
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  • 6
    Electronic Resource
    Electronic Resource
    Growth of Sesbania rostrata (Brem) with stem nodules under controlled conditions (1992)
    Oxford, UK : Blackwell Publishing Ltd
    Plant, cell & environment 15 (1992), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: A series of experiments was carried out in an attempt to produce nodulated plants of Sesbania rostrata with qualities more closely resembling those in the wild than has been achieved to date. When groups of five plants were grown in a controlled climate chamber in pipes containing ∼12dm3 modified Jensen's medium with 6mol m−3 nitrate, the daily growth in height reached 5 cm and at 30 d the plants were ∼40cm high. At this time, the stems were inoculated with Azorhizobium caulinodans ORS 571 and the medium replaced with Jensen's medium without nitrate. In the subsequent 19-d period ∼300 nodules (representing 〉50% of the potential infection sites) developed on each stem. The nodules increased linearly in size over this time to ∼15mg. Specific acetylene reduction activity, ARA ((μmol C2H4 mg−1 h−1) rose to 45 between days 5 and 10 after inoculation and plateaued; total ARA rose to ∼200 μmol C2H4 plant−1 h−1. Under the conditions described the plants grew vigorously, and reproducibly uniform yields of nodules with high ARA activities were obtained. As outlined, the procedure offers a standard system in which, within a 2-week period after inoculation, individual strains of bacteria can be quantitatively compared in their ability to induce nodulation and N2-fixation. Physiological and biochemical aspects of the nodulated system can be much more readily approached than with plants producing only root nodules. The inhibitory effects of stem nodules induced by wild type and two mutant strains of Azorhizobium on the development and activity of root nodules are described.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-3040.1992.tb01026.x
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  • 7
    Electronic Resource
    Electronic Resource
    Nitrofurantoin quadruple therapy for Helicobacter pylori infection: effect of metronidazole resistance (2001)
    Oxford UK : Blackwell Science Ltd
    Alimentary pharmacology & therapeutics 15 (2001), S. 0 
    Details
    ISSN: 1365-2036
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Antibiotic resistance has increasingly been recognized as the major cause of treatment failure for Helicobacter pylori infection. New therapies for patients with metronidazole- or clarithromycin-resistant H. pylori are needed.〈section xml:id="abs1-2"〉〈title type="main"〉Aim:To investigate the role of nitrofurantoin quadruple therapy for the treatment of H. pylori.〈section xml:id="abs1-3"〉〈title type="main"〉Methods:Patients with confirmed H. pylori infection received nitrofurantoin (100 mg t.d.s.), omeprazole (20 mg b.d.), Pepto-Bismol (two tablets t.d.s.), and tetracycline (500 mg t.d.s.) for 14 days. Four or more weeks after the end of therapy, outcome was assessed by repeat endoscopy with histology and culture or urea breath testing.〈section xml:id="abs1-4"〉〈title type="main"〉Results:Thirty patients were entered, including 25 men and five women; the mean age was 54.9 years. The most common diagnoses were duodenal ulcer (23%) and GERD (18%). The intention-to-treat cure rate was 70% (95% CI: 50.6–85%). Nitrofurantoin quadruple therapy was more effective with metronidazole-sensitive strains (88%; 15 out of 17) than with metronidazole-resistant strains (33%; three out of nine; P=0.008). Two of the treatment failures had pre-treatment isolates susceptible to metronidazole, which were resistant after therapy.〈section xml:id="abs1-5"〉〈title type="main"〉Conclusions:Because nitrofurantoin quadruple therapy performed inadequately in the presence of metronidazole resistance, we conclude that nitrofurantoin is unlikely to find clinical utility for the eradication of H. pylori.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2036.2001.00945.x
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  • 8
    Electronic Resource
    Electronic Resource
    Influence of the Tendon Membrane on Swelling and Thermal Stability (1964)
    [s.l.] : Nature Publishing Group
    Nature 201 (1964), S. 159-160 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] EXPERIMENTAL investigations of swelling in collagen are frequently carried out on the fiber bundles from tendon, which is probably the purest and most highly ordered form of collagen in the body. However, Jordan-Lloyd and Marriott1 directed attention to the restriction on swelling imposed by the ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/201159a0
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  • 9
    Electronic Resource
    Electronic Resource
    Solvent effect on rate for anionic nucleophilic substitution reaction of 4-nitrophenyl acetate in aqueous acetonitrile
    Amsterdam : Elsevier
    Tetrahedron Letters 33 (1992), S. 2023-2026 
    Details
    ISSN: 0040-4039
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0040-4039(92)88130-W
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  • 10
    Electronic Resource
    Electronic Resource
    Analysis of Microfracture Behavior of P/M 2009 Al-SiC Composites (1995)
    s.l. ; Stafa-Zurich, Switzerland
    Key engineering materials Vol. 104-107 (July 1995), p. 655-664 
    Details
    ISSN: 1013-9826
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/01/44/transtech_doi~10.4028%252Fwww.scientific.net%252FKEM.104-107.655.pdf
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