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1

Digitale Medien

Avalanche breakdown in AlxGa1−xAs alloys and Al0.3Ga0.7As/GaAs multilayers (1995)

David, J. P. R. ; Allam, J. ; Adams, A. R. ; [weitere]

Woodbury, NY : American Institute of Physics (AIP)

Applied Physics Letters 66 (1995), S. 2876-2878

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ISSN: 1077-3118

Quelle: AIP Digital Archive

Thema: Physik

Notizen: The avalanche breakdown voltage (Vb) has been measured in a range of bulk AlxGa1−xAs alloys and Al0.3Ga0.7As/GaAs multilayer structures. The bulk alloys show a linear dependence of Vb on x up to at least x=0.6. Multilayers with thin (≤100 A(ring)) dimensions follow this trend, with Vb being determined by the average Al fraction of the multilayer "pseudoalloy''. For thicker (≥500 A(ring)) layers Vb tends to a mean of the bulk values of the layers. The transition from pseudoalloy to bulklike behavior is interpreted in terms of the momentum and energy relaxation lengths, estimated for bulk GaAs using a Monte Carlo solution of the semiclassical transport equation. © 1995 American Institute of Physics.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1063/1.113459

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2

Digitale Medien

Tailoring the heavy-hole and light-hole quantum-confined Stark effect using multistrain-stepped quantum wells (1995)

Silver, M. ; Greene, P. D. ; Adams, A. R.

Woodbury, NY : American Institute of Physics (AIP)

Applied Physics Letters 67 (1995), S. 2904-2906

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ISSN: 1077-3118

Quelle: AIP Digital Archive

Thema: Physik

Notizen: We show theoretically how the quantum-confined Stark effect (QCSE) shifts of the E1–HH1 and E1–LH1 energy transitions can be engineered to be closely matched over the entire range of applied fields up to ±100 kV/cm using structures containing more than one strained-layer composition within each well. In contrast, conventional quantum wells that contain a single uniform composition within each well can at best have the energy levels for the HH1 and LH1 states matched at only one field value. Furthermore, we show how the TE and TM absorption spectra are modified using multistrain-stepped structures leading to improved polarization-insensitive QCSE modulators. © 1995 American Institute of Physics.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1063/1.114837

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3

Digitale Medien

Role of radiative and nonradiative processes on the temperature sensitivity of strained and unstrained 1.5 μm InGaAs(P) quantum well lasers (1995)

Braithwaite, J. ; Silver, M. ; Wilkinson, V. A. ; [weitere]

Woodbury, NY : American Institute of Physics (AIP)

Applied Physics Letters 67 (1995), S. 3546-3548

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ISSN: 1077-3118

Quelle: AIP Digital Archive

Thema: Physik

Notizen: By measuring the spontaneous emission from strained and unstrained 1.5 μm InGaAs quantum well lasers as a function of temperature we deduce the temperature dependence of the radiative current density at threshold corresponds to a characteristic temperature T0≈300 K, close to that expected from theory, whereas T0 of the threshold current is around 60 K. We conclude from our analysis that the large temperature dependence of long wavelength lasers is due to Auger recombination. © 1995 American Institute of Physics.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1063/1.114916

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4

Digitale Medien

Impact ionization in GaAs: Distribution of final electron states determined from hydrostatic pressure measurements (1995)

Allam, J. ; Adams, A. R. ; Pate, M. A. ; [weitere]

Woodbury, NY : American Institute of Physics (AIP)

Applied Physics Letters 67 (1995), S. 3304-3306

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ISSN: 1077-3118

Quelle: AIP Digital Archive

Thema: Physik

Notizen: We have measured the avalanche breakdown voltage (Vb) in GaAs p-i-n diodes as a function of hydrostatic pressure up to 14 kbar. The pressure coefficient of Vb was small and opposite in sign compared to that of the band gap. A lucky-drift calculation of Vb including the effects of pressure on both the phonon scattering and ionization rates showed that the ionization threshold energy does not scale with the band gap. Instead, the effective threshold scales with an average of the energies of the Γ, X, and L conduction-band minima. This is direct evidence that pair production yields final electron states distributed between conduction-band valleys. © 1995 American Institute of Physics.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1063/1.115228

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5

Digitale Medien

Some biochemical properties and antibiotic sensitivities of Pasteurella piscidda isolated in Greece and comparison with strains from Japan, France and Italy (1995)

BAKOPOULOS, V. ; ADAMS, A. ; RICHARDS, R. H.

Oxford, UK : Blackwell Publishing Ltd

Journal of fish diseases 18 (1995), S. 0

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ISSN: 1365-2761

Quelle: Blackwell Publishing Journal Backfiles 1879-2005

Thema: Biologie , Medizin

Notizen: Abstract The biochemical properties and antibiotic sensitivity patterns of 13 Pasteurella piscicida isolates from Greece are described and compared with 10 Japanese and five European (Italian and French) isolates. Morphologically and biochemically, all isolates of P. piscidda tested were nearly identical and only minor differences could be detected with reference to the level of acid production from sugars (especially from glucose). Greek, Italian and French isolates showed similar antibiotic sensitivity patterns, being resistant to erythromycin, kanamycin and streptomycin, and sensitive to most of the other antibiotics tested. Resistance was also demonstrated for some isolates towards the potentiated sulphonamides. The Japanese isolates appeared to be resistant to a larger range of antibiotics including erythromycin, kanamycin, streptomycin, oxolinic acid, oxytetracycline and chloramphenicol. Multiple resistance of Japanese strains was also noted. These results are discussed in the light of future measures for the control of pasteurellosis.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1111/j.1365-2761.1995.tb01260.x

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6

Digitale Medien

Ultrastructural changes in cultured human periodontal ligament cells exposed to dental materials (1995)

Adams, A. M. ; Soames, J. V. ; Searle, R. F.

Hoboken, NJ : Wiley-Blackwell

Journal of Biomedical Materials Research 29 (1995), S. 999-1004

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ISSN: 0021-9304

Schlagwort(e): Chemistry ; Polymer and Materials Science

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Medizin , Technik allgemein

Notizen: The cytopathic effects of a range of dental restorative cements were examined by electron microscopy using an in vitro model with cultured test cells derived from human periodontal ligament. Monolayers were fixed and processed in situ after 2, 24, and 48 h exposure. Many cells showed lysis after two hours exposure consistent with immediate acute injury. Cultures subsequently recovered, reflecting different susceptibilities of cells to injury, and at later stages showed distinct patterns of cell damage in response to different restorative materials. These were related primarily to either cytoplasmic or nuclear damage and to changes resembling apoptosis. © 1995 John Wiley & Sons, Inc.

Zusätzliches Material: 10 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/jbm.820290812

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