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  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 86 (1999), S. 3616-3623 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The microstructure of ZnSe/ZnTe multiple quantum well-based pseudo-ohmic contacts to p-ZnSe was investigated using transmission electron microscopy and high-resolution transmission electron microscopy. In the case of samples consisting of five ZnSe/ZnTe multiple quantum wells, both pure edge Lomer dislocations and 60° dislocations were identified at the interface between the ZnSe/ZnTe multiple quantum wells and the ZnTe overlayer, along with partial dislocations bounding stacking faults. The dominant dislocations at the interface are Lomer dislocations. In the case of samples grown under group II-rich conditions, the interface exhibits corrugations. At the top and bottom of the corrugations, the Lomer dislocations are dominant and in the slope of the corrugations, 60° dislocations are dominant. In the case of samples grown using migration-enhanced epitaxy, V-shaped defects consisting of three dislocations associated with two stacking faults are formed. The total Burgers vector of the V-shaped defects is a〈100〉. The increasing total thickness and the number of ZnSe/ZnTe multiple quantum wells leads tend to make the dominant defects dissociated 60° dislocations. © 1999 American Institute of Physics.
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  • 2
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 80 (1996), S. 6651-6654 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Ag ions were implanted in LiNbO3 at energies of 25 keV and 3 MeV. Optical absorption spectra were measured in the visible range. A large absorption peak due to small colloidal Ag metal was observed at 460 and 510 nm for the as-implanted sample at 3 MeV and 25 keV, respectively. Subsequently, the samples were heated in air up to 600 °C. The absorption peak moved toward longer wavelengths up to 560 nm when the sample was heated at high temperature. Small droplets of metallic Ag expelled from the implanted layer formed on the surface of the sample even when the samples were held at room temperature. The number and size of the droplets grew with time and their growth was accelerated when the samples were heated at high temperature. © 1996 American Institute of Physics.
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  • 3
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 74 (1999), S. 1824-1826 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The defect structure of optically degraded ZnCdSe quantum wells was investigated using transmission electron microscopy. The defects were composed of the dislocation dipoles with a Burgers vector of b=−(a/2)[101] inclined at 45° to the (001) plane. The dislocation dipoles consist of two segments aligned along the [11¯0] direction and the [120] direction. The [11¯0] dipole segments lying in the (111¯) plane were developed by the recombination-enhanced dislocation glide process, while the [1¯2¯0] dipole segments lying in the (2¯11) plane were developed by the recombination-enhanced dislocation climb process. Both processes operate simultaneously. © 1999 American Institute of Physics.
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  • 4
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 69 (1996), S. 1588-1590 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We propose a transient recombination-enhanced defect-generation model to analyze the degradation of optical output powers of blue-green II–VI light-emitting diodes (LEDs). We find an analytical solution and discover a set of universal curves for the time dependence of optical output power, which agree very well with the experimental data for strained CdZnSe quantum-well structures. Our model shows that the optical power can be non-exponential in character and its long-time behavior has a 1/t dependence. This 1/t dependence is also related to the growth of the defect density, which should behave as a t1/2 dependence. The generation of new defects due to electron-hole recombination at the defect sites is found to be the dominant degradation mechanism for II–VI LEDs. © 1996 American Institute of Physics.
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  • 5
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 69 (1996), S. 3893-3895 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have studied the gain characteristics of gain-guided quantum well II–VI laser diodes by measuring the amplified spontaneous emission spectra under several pulsed conditions. The temperature rise during one current pulse affects the gain characteristics and the L-I characteristics. The net modal gain at constant peak current increases with the pulse width. The peak gain for long pulses shows a superlinear dependence on injection current. In this case, the L-I curve is very steep above threshold and sometimes shows an internal quantum efficiency of more than unity. This leads to an underestimation of the internal cavity loss giving a value inconsistent with the one obtained from the gain spectra. With short pulse currents (〈200 ns), the peak gain shows a weak sublinear dependence on injection current. The cavity losses obtained from the gain spectra and the L-I characteristics at short pulses are consistent. As a result, we obtain the intrinsic gain characteristics of gain-guided quantum well II–VI laser diodes. © 1996 American Institute of Physics.
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  • 6
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Materials science forum Vol. 251-254 (Oct. 1997), p. 227-234 
    ISSN: 1662-9752
    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
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  • 7
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Materials science forum Vol. 251-254 (Oct. 1997), p. 785-792 
    ISSN: 1662-9752
    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
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Probability theory and related fields 114 (1999), S. 291-308 
    ISSN: 1432-2064
    Keywords: Mathematics Subject Classification (1991): 60H07, 60H05, 60G30
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract. An evaluation of a stochastic oscillatory integral with quadratic phase function and analytic amplitude function is given by using solutions of Jacobi equations. The evaluation will be obtained as an application of real change of variable formulas and holomorphic prolongations of analytic functions on a real Wiener space. On the way we shall see how a Jacobi equation appears in the evaluation by using the Malliavin calculus.
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Journal of materials science 34 (1999), S. 5885-5891 
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Joints between Y-TZP (Yttria containing Tetragonal Zirconia Polycrystal) and metallic materials (type SUS304 stainless steel and Mo) were fabricated, using brazing alloy (Ag-Cu-Ti) sheet. Y-TZP disks having different Y2O3 contents, grain size were prepared for changing their transformability from tetragonal to monoclinic phase. Y-TZP disks with various thickness were joined with metal disks with constant thickness in order to change the thermal stress states. Transformation in Y-TZP was investigated by changing cooling rates from the joining temperature. Transformed fraction was larger under presence of tensile thermal stress (σrr). The transformed fraction decreased when cooled at a faster rate, which was related with time-dependent characteristics of the transformation in Y-TZP. A large fraction of transformation was detected in the coarse grained Y-TZP joined with Mo, although no transformation was detected in the unjoined state when cooled at the same rate. Transformation of Y-TZP joined with metallic materials was discussed, considering the effects of residual stress and the time dependent features of the transformation.
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  • 10
    Electronic Resource
    Electronic Resource
    Weinheim [u.a.] : Wiley-Blackwell
    Materials and Corrosion/Werkstoffe und Korrosion 48 (1997), S. 1-9 
    ISSN: 0947-5117
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Oxidation von intermetallischen Verbindungen - Japanische AktivitätenDie in den letzten Jahren in Japan durchgeführten Oxidationsuntersuchungen an intermetallischen Verbindungen werden zusammengefaßt und kritisch bewertet. Die Hauptanstrengungen richteten sich auf die Verbesserung des Oxidationswiderstandes von Werkstoffen auf TiAl-Basis. Die versuchten Methoden beinhalten Legierungszugaben, Oberflächenbehandlungen und eine Kombination von beiden. Die Legierungszugaben zu TiAl werden hier näher betrachtet. Durch die Zugabe von 0.2Zr, 0.2Hf oder 500 ppm Cl und beim Nb-Ionen-Implantieren wird durch die Bildung von Al2O3-Zunder ein ausgezeichneter Oxidationswiderstand erreicht. Die Voroxidation unter reduziertem Sauerstoffdruck führte ebenfalls zur Bildung eines schützenden Al2O3-Zunders. Keramische Beschichtungen and Beschichtungen vom Typ MCrAlY zeigten einige Verbesserungen im Oxidationswiderstand. Untersuchungen an anderen Aluminiden mit aktuellem Interesse gibt es nur relativ wenig. Andererseits werden zunehmend Studien an Siliciden durchgeführt, wenn auch deren Anzahl noch gering ist verglichen mit Werkstoffen auf TiAl-Basis. In den Schlußfolgerungen werden Zielrichtungen für zukünftige Untersuchungen aufgezeigt.
    Notes: Oxidation studies on intermetallic compounds carried out in Japan in the last ten years have been summarized and critically reviewed. The major effort was expended to improve the oxidation resistance of TiAl-base materials. The methods tried include alloying additions, surface treatments and combinations of the both. Alloying additions to TiAl were more closely reviewed here. An excellent oxidation resistance was obtained owing to the formation of Al2O3 scales by alloying additions of 0.2Zr, 0.2Hf or 500 ppm Cl, and by Nb-ion implantation. Preoxidation under reduced oxygen pressures also resulted in the formation of protective Al2O3 scales. Ceramic coatings and MCrAlY type coatings showed some improvement in the oxidation resistance. Studies on other aluminides of current interest arc relatively few. On the other hand, studies on suicides arc becoming more active than before, though still few in comparison with TiAl-base materials. In the concluding remarks directions for future studies are shown.
    Additional Material: 14 Ill.
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