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  • 1
    Digitale Medien
    Digitale Medien
    Alignment system for crossed parabolic x-ray mirrors (2000)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 71 (2000), S. 2292-2295 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: We describe the implementation of a crossed graded parabolic x-ray mirror system that is suitable for incorporation into both conventional and high resolution x-ray diffraction systems. A novel optical alignment system has been devised that permits independent adjustment of the positions and the angular settings of the mirrors. This alignment system is simple and inexpensive to construct, yet is mechanically stable and easy to use. The crossed mirror system has been successfully introduced into both protein crystallography and high resolution x-ray diffraction systems. © 2000 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1150444
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  • 2
    Digitale Medien
    Digitale Medien
    Chemical investigations of GaAs wafer bonded interfaces (2001)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 90 (2001), S. 5991-5999 
    Details
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: The bonding chemistry of various GaAs-to-oxide/GaAs bonded samples was investigated using multiple internal transmission Fourier transform infrared spectroscopy for thermally annealed and thermocompression annealed samples. The oxides used in these investigations included a native GaAs oxide as well as two compositions of borosilicate glass (BSG) deposited by low-pressure chemical vapor deposition (LPCVD). For the thermally annealed samples, the hydrogen-bonded H2O/OH groups on the hydrophilic surface form a room temperature bond without the application of pressure. Chemical changes at the wafer-bonded interface occur in two temperature regions. For anneals between 200 and 400 °C for 1 h in N2, the H2O/OH groups react and evolve H that becomes absorbed within the oxide. The LPCVD BSG oxide was chemically unaltered during anneals in this temperature range, however, the GaAs native oxide underwent chemical modification. Initially, the GaAs oxide consisted of As(III)–O and Ga–O related oxides. The As(III)–O oxides react to form free As and Ga–O during annealing between 200 and 400 °C. For anneals between 500 and 600 °C, the reaction of H2O/OH groups continue and the H becomes infrared inactive, most likely forming H2 voids at the bonded interface. In addition, As(V)–O related oxides were observed during thermal annealing in this temperature range. No detectable chemical changes in the BSG were observed over the temperature range investigated. Samples that were annealed under an estimated 1–10 MPa of pressure had similar chemical changes to thermally annealed samples.© 2001 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1416139
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  • 3
    Digitale Medien
    Digitale Medien
    Microstamping of freestanding bipolymer features (2001)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 78 (2001), S. 3741-3743 
    Details
    ISSN: 1077-3118
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Microscale bipolymer features have been fabricated by microstamping. Rigid silicon stamps with microwells as small as 40 fl in volume were used. Bipolymer columns, 2 μm by 2 μm in cross section and 10 μm tall, were stamped from these small microwells. The top 1.5 μm of each column was made of polyetherimide with the remaining 8.5 μm being made from an ethyl cyanoacrylate. The ability to accurately fabricate microscale features consisting of more than one polymer has many potential uses. As an example, the potential use of bipolymer features in nerve guides is discussed. © 2001 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1371784
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  • 4
    Digitale Medien
    Digitale Medien
    Oriented crystallization of GaSb on a patterned, amorphous Si substrate (2001)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 78 (2001), S. 1358-1360 
    Details
    ISSN: 1077-3118
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Oriented crystallization of GaSb on patterned, oxidized Si substrates was achieved by metalorganic chemical vapor deposition. The Si substrate was formed by patterning an array of inverted square pyramids having {111} sidewall facets, using lithography and anisotropic etching in KOH. The orientation and structure of GaSb crystals, at various stages of the growth, were examined by scanning electron microscopy and x-ray diffraction. X-ray diffraction pole figure analysis shows that {111} planes of GaSb are predominantly parallel to the {111} planes of the inverted pyramids. Extra (111) spots observed in the x-ray diffraction pole figure are interpreted in terms of multiple twinning of GaSb. © 2001 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1352657
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  • 5
    Digitale Medien
    Digitale Medien
    Fabrication of InAs/AlSb/GaSb heterojunction bipolar transistors on Al2O3 substrates by wafer bonding (2001)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 78 (2001), S. 2232-2234 
    Details
    ISSN: 1077-3118
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: High-frequency integrated circuit applications of GaSb-based materials are hampered by the lack of a suitable lattice-matched insulating substrate. Wafer bonding was used to fabricate InAs/AlSb/GaSb-based heterojunction bipolar transistors (HBTs) on an insulating sapphire substrate through a low temperature bonding process that results in a high bond strength and permitted the mechanical and chemomechanical removal of the initial GaSb substrate. The use of selective etches allows for the retention of the epitaxial device layers over virtually the entire wafer area. Minimal degradation of the transferred layers occurred in the bonding and substrate removal process. The resulting transferred structures were fabricated into functional HBTs exhibiting a dc current gain of ∼5. © 2001 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1359140
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  • 6
    Digitale Medien
    Digitale Medien
    Growth of oriented lithium niobate on silicon by alternating gas flow chemical beam epitaxy with metalorganic precursors (2000)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 76 (2000), S. 2125-2127 
    Details
    ISSN: 1077-3118
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: We present the results of investigations of LiNbO3 film growth on Si by conventional chemical beam epitaxy (CBE) and by alternating gas flow deposition with alkoxide precursors. Both growth methods produced films with an intervening interface amorphous layer, whose thickness depends strongly on growth and annealing temperatures. While films grown by chemical beam epitaxy were always polycrystalline, the LiNbO3 films grown by alternating gas flow deposition were oriented materials. Based on our studies, we hypothesize that the alternating layer deposition technique enhances bulk interdiffusion efficiency of metal ions leading to a more controlled epitaxy of LiNbO3 on Si relative to conventional CBE growth. © 2000 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.126274
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  • 7
    Digitale Medien
    Digitale Medien
    Chemical role of oxygen plasma in wafer bonding using borosilicate glasses (2001)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 79 (2001), S. 3413-3415 
    Details
    ISSN: 1077-3118
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Plasma-treated oxide layers are commonly used in wafer bonding applications. Borosilicate glass (BSG) layers deposited by low-pressure chemical vapor deposition treated with an O2 plasma in reactive ion etching mode for 5 min at 0.6 W/cm2 and rinsed with DI H2O readily bond to GaAs and Si. The chemical role of this prebonding treatment was investigated using attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy. The peak intensities for both the Si–O and B–O absorbance bands decreased in intensity as a result of the plasma treatment is consistent with the uniform sputtering of 9.8 nm±0.8 nm of BSG. Polarization dependent ATR-FTIR revealed that the H2O/OH absorbance bands decreased in peak intensity with the OH groups being preferentially oriented perpendicular to the sample surface after the plasma treatment. The subsequent DI H2O rinse restores the water to the surface while removing B2O3 from the BSG layer. This prebonding treatment, therefore, results in a hydrophilic bond, but alters the composition of the BSG film at the bonded interface. © 2001 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1418454
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  • 8
    Digitale Medien
    Digitale Medien
    Experimental test for elastic compliance during growth on glass-bonded compliant substrates (2000)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 76 (2000), S. 2541-2543 
    Details
    ISSN: 1077-3118
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Highly mismatched films (In0.44Ga0.56As, 3% mismatch) grown well beyond their critical thickness (to 3 μm) on GaAs glass-bonded compliant substrates exhibit surfaces four times smoother and strain distributions twice as narrow as films grown simultaneously on conventional GaAs substrates. The compliant substrates consist of a thin (∼10 nm) GaAs template layer bonded via a borosilicate glass to a mechanical handle wafer. The improvement of highly mismatched films grown well beyond their critical thickness on compliant substrate structures is commonly modeled in terms of an elastic partitioning of strain from the film to the thin (∼10 nm) single-crystal template layer. The present study is a direct test for this mechanism of elastic compliance. A comparison is reported of the strain in 92 nm In0.09Ga0.91As films and 76 nm In0.03Ga0.97As films grown simultaneously on conventional GaAs substrates and the compliant substrates responsible for the improved structural quality of In0.44Ga0.56As films. Elastic partitioning of strain from the mismatched film to the 10 nm template layer prior to the onset of misfit dislocations is not observed for films grown on these glass-bonded compliant substrates. © 2000 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.126402
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  • 9
    Digitale Medien
    Digitale Medien
    Anti-E in pregnancy (2000)
    Oxford, UK : Blackwell Publishing Ltd
    BJOG 107 (2000), S. 0 
    Details
    ISSN: 1471-0528
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: Since the introduction of anti-Rhesus (Rh) D prophylaxis for RhD-negative women, other Rh and non-Rh red cell alloantibodies have become relatively more important and are now responsible for the greater proportion of haemolytic disease of the newborn. Anti-C and anti-E are the most commonly implicated non-D Rh antibodies in the pathogenesis of haemolytic disease of the newborn1. In 1977 Pepperell et al.2 reported the outcome of 44 women with anti-E. This is the only published series that investigates the implications of anti-E during pregnancy. The present report presents a retrospective study of the outcome of 122 pregnancies in which anti-E was the sole alloantibody detected.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1471-0528.2000.tb11662.x
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  • 10
    Digitale Medien
    Digitale Medien
    Current conservation genetics: building an ecological approach to the synthesis of molecular and quantitative genetic methods (2002)
    Oxford, UK : Blackwell Science, Ltd
    Ecology of freshwater fish 11 (2002), S. 0 
    Details
    ISSN: 1600-0633
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract Although neutral molecular markers have long been important tools for describing genetic variation in threatened fish species, many of the most critical questions in conservation relate more to quantitative genetic variation than to neutral markers. Quantitative genetic studies are typically expensive and time-consuming to conduct, especially in some of the long-lived vertebrates of conservation concern. The present review of recent literature in fish conservation genetics examines the traditional role of molecular studies in describing conservation units and providing indirect inference about local adaptation and adaptive potential. Of special interest are approaches that use a combination of molecular and quantitative genetic methods. Such studies are likely to provide important new insights into many conservation-related problems. The review also explores how increasing interest in non-neutral molecular markers is contributing to our understanding of the geographic scale and evolutionary importance of local adaptation in threatened populations. It is increasingly clear that advanced genetic technologies for the exploration of neutral and non-neutral molecular variation are leading to a fundamental shift in the way complex phenotypic traits are studied. This new synthesis of methods will have dramatic implications for fish conservation genetics and biology in general.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1034/j.1600-0633.2002.110105.x
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