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  • Springer  (13)
  • Wiley  (7)
  • International Union of Crystallography (IUCr)  (4)
  • American Institute of Physics (AIP)  (2)
  • 1985-1989  (16)
  • 1970-1974  (10)
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  • 1
    Electronic Resource
    Electronic Resource
    Wavelength selective infrared microscopy: A nondestructive and quick method for the investigation of buried structures in optoelectronic devices (1986)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 60 (1986), S. 3401-3406 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: In this paper we present an optical method to control the geometry of buried layers in optoelectronic heterostructures. The technique uses an optical microscope equipped for infrared applications and relies on the fact that the different layers of the multilayer structure have different band gaps. Accordingly transmission/absorption, reflectance, and photoluminescence of the inidividual layers exhibit their characteristic near-band-gap spectral variations at different wavelengths. By appropriate selection of the wavelength range used for image formation, any layer of interest can be made visible. As an example we investigated a mushroom-type InGaAsP/InP 1500-nm laser structure with subsequent mass transport. Both technological steps, the formation of the mushroom by underetching, and the regrowth by mass transport represent critical processes in the fabrication of these index-guided lasers. Our results show clearly that the successful accomplishment of the process can be controlled by images of the selected buried layer. Contrast and resolution of the pictures are sufficient to show any irregularity in etching or regrowth. The main advantage of the method is that it offers the possibility of investigating whole wafers without sample preparation and in a nondestructive way, which is in marked contrast to observation with a scanning electron microscope, where only profiles along cleaved facets can be inspected.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.337637
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  • 2
    Electronic Resource
    Electronic Resource
    Thermal degradation effects in InP (1988)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 63 (1988), S. 4677-4682 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Thermal degradation in InP has been regarded to be equivalent to surface deformation. By means of luminescence microscopy we discovered a much larger scale of degradation effects. Crystallographic defects of several geometrical characteristics have been observed although the surfaces seemed to be perfectly smooth. The standard methods of protection against degradation used in liquid phase epitaxy turned out to be unreliable concerning the invisible degradation effects. We propose a model which describes the evolution of degradation starting with invisible crystallographic defects. An extreme loss of phosphorus concentrated around dislocations causes local melting representing the final and visible stage of degradation. We suppose that P vacancies which have never been noticed before are responsible for inhomogeneities affecting processing and the reliability of optoelectronic devices.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.340122
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  • 3
    Electronic Resource
    Electronic Resource
    The crystal structure of (NH4)4UF8 (1970)
    Copenhagen : International Union of Crystallography (IUCr)
    Acta crystallographica 26 (1970), S. 38-44 
    Details
    ISSN: 1600-5740
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0567740870001899
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  • 4
    Electronic Resource
    Electronic Resource
    The crystal structure of cesium nonafluorodiuranate(IV), CsU2F9 (1973)
    Copenhagen : International Union of Crystallography (IUCr)
    Acta crystallographica 29 (1973), S. 460-462 
    Details
    ISSN: 1600-5740
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S056774087300275X
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  • 5
    Electronic Resource
    Electronic Resource
    Preparation and single-crystal structure of β-NH4UF5, ammonium pentafluoruranate(IV) (1974)
    Copenhagen : International Union of Crystallography (IUCr)
    Acta crystallographica 30 (1974), S. 1966-1970 
    Details
    ISSN: 1600-5740
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0567740874006194
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  • 6
    Electronic Resource
    Electronic Resource
    Single-crystal structure of lead uranate(VI) (1986)
    Oxford [u.a.] : International Union of Crystallography (IUCr)
    Acta crystallographica 42 (1986), S. 1684-1685 
    Details
    ISSN: 1600-5759
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0108270186090947
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  • 7
    Electronic Resource
    Electronic Resource
    A finite element scheme for domains with corners (1972)
    Springer
    Numerische Mathematik 20 (1972), S. 1-21 
    Details
    ISSN: 0945-3245
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract This paper is concerned with the rate of convergence of the finite element method on polygonal domains in weighted Sobolev spaces. It is shown that the use of different spaces of trial and test functions will restrict the usual low rate of convergence to a neighborhood of each vertex of the polygonal domain.L 2-convergence and lower bounds on the error are also studied.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01436639
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  • 8
    Electronic Resource
    Electronic Resource
    Can interaction coefficients be determined from cencus data? (1985)
    Springer
    Oecologia 66 (1985), S. 194-198 
    Details
    ISSN: 1432-1939
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The method of estimating interactions proposed independently by Pimm and Schoener is studied using field data from the community of rodents which lives in the arid, rocky habitats of Israel. One important problem the method addresses is how to remove the effects of habitat heterogeneity on the estimate. We tried six different variations of the analysis scheme outlined by Crowell and Pimm, and found their results qualitatively inconsistent. This was especially true when we compared the results produced from separate habitat variables with those produced from the principal components of the habitat variation. Another problem, this one not previously addressed, is great variation in the average abundance of the different species. We discovered that the ratio of the average abundances of two species is the best predictor of the value of their coefficients of interaction. Common species appear to have weak influence on rare ones; rare ones appear to have strong influence on common ones. The statistical mechanism which produces this relationship is clear, indicating that the relationship is an artifact.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00379854
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  • 9
    Electronic Resource
    Electronic Resource
    Potential CO2-induced climate effects on North American wheat-producing regions (1985)
    Springer
    Climatic change 7 (1985), S. 367-389 
    Details
    ISSN: 1573-1480
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The environmental requirements for growth of winter, spring, and fallsown spring wheats in North America are specified and compared to temperature results from the control run of the Goddard Institute for Space Studies general circulation model (GISS GCM) and observed precipitation in order to generate a simulated map of current wheat production regions. The simulation agrees substantially with the actual map of wheat-growing regions in North America. Results from a doubled CO2 run of the climate model are then used to generate wheat regions under the new climatic conditions. In the simulation, areas of production increase in North America, particularly in Canada, due to increased growing degree units (GDU). Although wheat classifications may change, major wheat regions in the United States remain the same under simulated doubled CO2 conditions. The wheat-growing region of Mexico is identified as vulnerable due to high temperature stress. Higher mean temperatures during wheat growth, particularly during the reproductive stages, may increase the need for earlier-maturing, more heat-tolerant cultivars throughout North, America. The soil moisture diagnostic of the climate model is used to analyze potential water availability in the major wheat region of the Southern Great Plains.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00139053
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  • 10
    Electronic Resource
    Electronic Resource
    Hummingbird isolegs in an experimental system (1986)
    Springer
    Behavioral ecology and sociobiology 19 (1986), S. 313-322 
    Details
    ISSN: 1432-0762
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Optimal foraging theory was first looked upon as a tool to study the evolution of niches in community ecology. Isoleg theory is being developed to reestablish it as such a tool. Isoleg theories are maps of isolegs in a graph whose axes are population densities. There are two kinds of isolegs: some are lines of equal optimal behavior in the graph; others mark threshold combinations of densities past which sudden shifts in behavior should occur. A technique for determining whether isolegs exist is described and applied to hummingbird data. These data were collected experimentally in the field expressly to test one isoleg model. All three species of hummingbird exhibited at least one of the sudden-shift type of isoleg. Their behaviors map onto the density graph in the predicted portions of the graph with only one exception. The data also support the prediction that behavior in the field is disjunct, i.e. subject to substantial, abrupt, discontinuous changes produced by very small continuous changes in a control variable. Some evidence for continuous control was also found, but it is ambiguous. Theory predicts that the two forms of control should be found together in some optimal systems.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00295704
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