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  • 1
    Electronic Resource
    Electronic Resource
    Impact ionization thresholds in GexSi1−x alloys and strained layers (1992)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 71 (1992), S. 3821-3826 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Impact ionization rates in GexSi1−x alloys and strained layers are expected to be strongly influenced by the threshold energies for ionization. We have calculated the threshold energies along the principal crystal axes from empirical pseudopotential band structures for Ge, Si, and GexSi1−x alloys (x=0.25, 0.5, 0.75). Both relaxed (cubic) and strained [tetragonal, grown on (001) cubic Si] alloys were examined. The ionization process with the lowest threshold energy in Si is different from that in Ge, for both electron- and hole-initiated ionization. For the cubic alloys, the lowest thresholds are "Si-like'' for compositions up to approximately x=0.65. The effect of strain on the GexSi1−x alloys is to increase the ratio of the lowest hole threshold to the lowest electron threshold for all compositions, suggesting the possibility that GexSi1−x strained layer avalanche photodiodes may exhibit superior noise properties.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.350897
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  • 2
    Electronic Resource
    Electronic Resource
    High-speed InP/Ga0.47In0.53As superlattice avalanche photodiodes with very low background doping grown by continuous trichloride vapor-phase epitaxy (1986)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 60 (1986), S. 2609-2612 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Trichloride vapor-phase epitaxy has been employed in a single chamber reactor to achieve the continuous (noninterrupted) growth of n−InP/n−In0.53Ga0.47As/InP superlattice structures for avalanche photodetector applications. Very low background doping has been achieved in both the InP (n≈1×1014 cm−3) and the superlattice layers (n=1×1015 cm−3). We report the details of the epitaxial crystal growth as well as analysis of the structures by secondary ion mass spectrometry and transmission electron microscopy. Avalanche photodiodes have been fabricated by Zn diffusion in the InP layer and mesa etching. The devices exhibit an intrinsic response time (full width at half maximum) of 66 ps at λ=1.5 μm which is the shortest so far achieved in superlattice photodetectors. Dark currents of 50 nA at unity gain, multiplication factors of 6, and breakdown voltages exceeding −120 V have been measured.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.337129
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  • 3
    Electronic Resource
    Electronic Resource
    Ultrafast characterization of an in-plane gate transistor integrated with photoconductive switches (1995)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 66 (1995), S. 1228-1230 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: An in-plane gate field-effect transistor is characterized by ultrafast electro-optic sampling. The transistor is monolithically integrated with photoconductive switches in coplanar waveguide and 〈0.5 ps measurement time resolution is achieved. The gate-drain capacitance of the transistor is obtained as 1.8 fF at zero drain voltage from displacement current transients. The gate-drain capacitance is dominated by parasitic capacitance and the intrinsic gate-drain capacitance is estimated as less than 0.2 fF. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.113245
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  • 4
    Electronic Resource
    Electronic Resource
    Avalanche breakdown in AlxGa1−xAs alloys and Al0.3Ga0.7As/GaAs multilayers (1995)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 66 (1995), S. 2876-2878 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.113459
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  • 5
    Electronic Resource
    Electronic Resource
    Impact ionization in GaAs: Distribution of final electron states determined from hydrostatic pressure measurements (1995)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 67 (1995), S. 3304-3306 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.115228
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  • 6
    Electronic Resource
    Electronic Resource
    A review of recent journal highlights focusing on atopic dermatitis (2003)
    Oxford, UK : Blackwell Science Ltd
    Clinical and experimental dermatology 28 (2003), S. 0 
    Details
    ISSN: 1365-2230
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2230.2003.01361.x
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  • 7
    Electronic Resource
    Electronic Resource
    In search for predictive factors for atopy in human cord blood (2005)
    Oxford, UK : Munksgaard International Publishers
    Allergy 60 (2005), S. 0 
    Details
    ISSN: 1398-9995
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Since early prevention is regarded as an important corner stone in the management of atopic diseases, the identification of reliable markers detecting individuals at risk are of major interest. Therefore, many efforts have been made to unravel reliable predictors for atopy which might identify children at risk and allow the initiation of preventive strategies at an early stage. In the past, much scientific energy has been forced in particular on the development of as noninvasive methods as possible to reach this goal. It is obvious that the identification of markers for atopy at the earliest time of life – namely immediately after birth – represents one of the most attractive attempts. In consequence various studies have been initiated to address this issue investigating markers for atopy in cord blood. Most of them have been geared to our current knowledge about cellular and soluble factors which are dysregulated in adolescent atopic individuals. Although the findings of these studies will improve our knowledge about the initial evolution of atopy, several parameters evaluated did not show any association or have led to almost conflicting results. In order to provide an up-date about the current developments in this field, recent research findings on predictive factors for atopy in cord blood are summarized in the following synopsis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1398-9995.2005.00815.x
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  • 8
    Electronic Resource
    Electronic Resource
    New treatment modalities for granuloma faciale (2003)
    Oxford, UK : Blackwell Science Ltd
    British journal of dermatology 149 (2003), S. 0 
    Details
    ISSN: 1365-2133
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Granuloma faciale (GF) is a rare, chronic skin disorder in which numerous treatment modalities have been used without any consistent long-term effect. We report three cases of GF, two of which were successfully treated with the Laserscope potassium-titanyl-phosphate 532-nm laser within 2 weeks and one with topical tacrolimus ointment 0·1%. Our observations suggest that these new treatment modalities for GF, which we report here for the first time, can provide effective and non-invasive treatment for this disease.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2133.2003.05550.x
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  • 9
    Electronic Resource
    Electronic Resource
    Transport properties of dual quantum dots
    Amsterdam : Elsevier
    Surface Science 305 (1994), S. 659-663 
    Details
    ISSN: 0039-6028
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0039-6028(94)90973-3
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  • 10
    Electronic Resource
    Electronic Resource
    The role of antigen presenting cells at distinct anatomic sites: they accelerate and they slow down allergies (2004)
    Oxford, UK : Munksgaard International Publishers
    Allergy 59 (2004), S. 0 
    Details
    ISSN: 1398-9995
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: It has been repeatedly demonstrated that allergic reactions are driven by the continuous flow of antigen uptake and presentation processes, which are perpetuated mainly by dendritic cells (DC). The ability of allergens to cause allergic inflammation is contingent upon the presence of an immunological milieu and microenvironment that either privileges Th2 responses or prohibits these reactions by the induction of contraregulatory anti-inflammatory activities of the immune system. In the light of recent developments it appears that DC have to manage two opposing tasks: on the one hand they can favor pro-inflammatory reactions and actively induce a T-cell response, yet on the other hand they serve an important function as ‘silencers’ in the immune system by sending out anti-inflammatory, tolerance inducing signals. This unique capacity of DC has opened several exciting possibilities for a role of DC in both – accelerating and slowing down allergic reactions. It is therefore a challenge to understand in which way DC subtypes located at distinct anatomic sites with frequent allergen exposure, such as the skin, the nasal mucosa, the respiratory tree or the mucosa of the intestinal tract can have an impact on mechanisms involved in tolerance induction or effective immunity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1398-9995.2003.00337.x
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