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  • 1985-1989  (13)
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Material
Years
Year
  • 1
    Electronic Resource
    Electronic Resource
    In situ observation of molecular beam epitaxy of GaAs and AlGaAs under deficient As4 flux by scanning reflection electron microscopy (1989)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 55 (1989), S. 622-624 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The initial stages of molecular beam epitaxial (MBE) growth of GaAs and AlGaAs are directly observed by scanning reflection electron microscopy. Under deficient As4 flux, it is shown that dark areas appear within several layers of growth, but disappear within several seconds of growth interruption, indicating that they are droplets of Ga and Al. The distance between the droplets is approximately 1 μm, which is identical in GaAs and AlGaAs growth. Thus, the diffusion length of Ga and Al on a group III-rich surface at around 600 °C is estimated to be about 5000 A(ring), which is the largest among previous reports. The role of droplet disappearance in interface flattening in alternating supply MBE is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.101829
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Carbon reduction in GaAs films grown by laser-assisted metalorganic molecular beam epitaxy (1989)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 55 (1989), S. 451-453 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Secondary-ion mass spectroscopy and cathodoluminescence (CL) studies were carried out on GaAs films grown by Ar+ laser-assisted metalorganic molecular beam epitaxy. The Ar+ laser irradiation leads to the formation of a 400-μm-diam spot. In the growth temperature range 425–500 °C, the carbon concentration within the spot is maintained at 1017 cm−3, while that in the area not irradiated by the laser increases from 1017 to 1019 cm−3. The process of decomposition of the triethylgallium molecules and the mechanism by which the carbon concentration is maintained by the laser irradiation are discussed in detail. Low-temperature CL spectra revealed that the CL signal intensity in the selectively grown spot was some ten times greater than that in the area not irradiated by the laser.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.101872
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Cathodoluminescence study of substrate offset effects on interface step structures of quantum wells (1989)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 54 (1989), S. 436-438 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The interface structures of single quantum wells grown on vicinal (100) substrates with a controlled offset 0.2° are studied by cathodoluminescence microscopy. Bright and dark stripe patterns are periodically observed in monochromatic images of the single quantum wells and the stripes replicate stair-like stepped interfaces. It is further shown that the observed terrace width is several times larger than the average interstep distance of monolayer steps calculated from the offset angle and that the step height is not one monolayer. Based on the results, a new interface structure model has been proposed that takes the offset angle into account. Finally, it is shown that employing growth interruption during epitaxial growth as an interface smoothing technique has limitations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.100944
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Analysis of scanning deep level transient spectroscopy (1987)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 51 (1987), S. 1617-1619 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Fundamental processes such as charge generation, trapping and emission, and collection in scanning deep level transient spectroscopy (SDLTS) are analyzed. It is concluded that SDLTS is more sensitive to minority-carrier traps than to majority-carrier traps and that a two-dimensional map of SDLTS peak signal magnitude, i.e., SDLTS image, of minority-carrier traps does not necessarily show the trap concentration distribution. A practical equation for trap concentration is derived by utilizing an electron beam induced current. Concentration of a hole trap with an activation energy 0.45 eV in an n-type as-grown liquid encapsulated Czochralski GaAs is calculated to be 1×1016 cm−3.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.98573
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    Paper (German National Licenses)
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  • 5
    Electronic Resource
    Electronic Resource
    Neighbor burrow-plugging in Ilyoplax pusillus (Crustacea: Brachyura: Ocypodidae) (1987)
    Springer
    Marine biology 95 (1987), S. 299-303 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The burrow living ocypodid crab Ilyoplax pusillus (De Haan, 1835) sometimes plugs the burrow of neighbors situated from 1.0 to 8.3 cm away with surface mud, while the neighbor, termed the pluggee, is in the burrow. Most pluggers were large males, whereas pluggees were smaller than pluggers and had a sex ratio close to 1:1. After being plugged, most pluggees usually reemerged on the surface within 5 min, but occasionally took up to 77 min to do so. The plugger always foraged or performed waving displays around the burrow of the pluggee while the pluggee stayed inside the burrow. Although the activity site of the pluggee was originally directed toward the burrow of the plugger or the adjacent area, after reemergence its activity site was oriented toward another direction. From these observations, it is suggested that neighbor burrow-plugging is a behavior adopted mainly by large males as a means of maintaining the area of their surface activities against smaller neighbors. My observations were made from June 1984 to June 1985 at Fukuro River Estuary, central Japan.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00409017
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    Paper (German National Licenses)
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  • 6
    Electronic Resource
    Electronic Resource
    Radioactive heating and layered structure of cometary nuclei (1988)
    Springer
    Earth, moon and planets 40 (1988), S. 303-313 
    Details
    ISSN: 1573-0794
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Following the work of Whipple and Stefanik, radioactive heating by uranium, thorium and pottasium of a cometary nucleus is discussed. The assumed composition is that of interstellar medium. If thermal diffusivity is 10−4 cm2s−1, the central temperature of a nucleus with radius 10 km can be above 50 K, while if the thermal diffusivity is 5 × 10−3, the central temperature can be only 25 K or so. Volatile gases such as N2 and CO will flow toward the outer part of the nucleus and are lost in their first several approaches to the sun. This mechanism appears capable of explaining the depletion of N2 and CO relative to the interstellar abundance. It is argued that unfamiliar activity of comet Bowell could be explained by sublimation mainly of N2 and CO.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00192648
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  • 7
    Electronic Resource
    Electronic Resource
    Photometric and photo accoustic measurement of the absorbance of micro-organisms and its relation to the micro-organism-grain hypothesis (1985)
    Springer
    Astrophysics and space science 117 (1985), S. 401-406 
    Details
    ISSN: 1572-946X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Absorption ofE. Coli and other micro-organisms are measured by the standard optical spectroscopy and by the photo-accoustic method. The former method does not yield an extinction peak at λ=220 nm but yields a weak one at λ=270 nm, while by the latter method absorption peaks at λ=220 nm and a weaker one at λ=270 nm have been found for the spore of Bacillus subtilis. The well-known amino-acid, triptophan shows absorption peaks at λ=220 and 280 nm. It is tentatively concluded that for the micro-organism model of interstellar grains to be viable, they may have to be spores rather than ordinary cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00650165
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    Paper (German National Licenses)
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  • 8
    Electronic Resource
    Electronic Resource
    A spectroscopic study of the microorganism model of interstellar grains (1986)
    Springer
    Astrophysics and space science 124 (1986), S. 377-388 
    Details
    ISSN: 1572-946X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The microorganism model of interstellar grains is investigated by spectroscopy from the infrared (IR), visible to the ultraviolet (UV) wave regions.E. coli, yeast and spores ofBacillus subtilis exhibit absorption bands at λ=3.1 and 9.7 μm; they also exhibit several absorptions at 6∼8 μm which are in agreement with the observed IS extinction curves. To obtain the extinction curves in the visible and UV regions, dry films of microorganism are prepared on a MgF2 plate or synthesized quartz plate and their spectra measured. In the wavelength region 190∼400 nm, conventional spectrophotometers are adopted for the measurement. The extinction curve of the film ofE. coli is similar to the observed IS curve. For the wave-range 100〈λ〈400 nm, a vacuum UV spectrometer is adopted to avoid absorptions due to O2 in the atmosphere. The extinction spectra by this method are in agreement with the result obtained by the conventional method where comparison is possible. The extinction curves ofE. coli and yeast are such that they incrase towards the short wavelength and exhibit a peak at λ-190 nm, which is different from the well-known IS peak at λ=220 nm. It remains to be seen whether interstellar low temperatures (10∼40 K) can shift the peak position in the extinction curve of biochemical materials.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00656048
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  • 9
    Electronic Resource
    Electronic Resource
    Organic model of interstellar grains (1987)
    Springer
    Astrophysics and space science 132 (1987), S. 409-414 
    Details
    ISSN: 1572-946X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Extinction efficiency of grains is calculated from the Mie formula on the premise that the grains are of organic composition. The optical constants adopted for the calculations are those ofE. coli, polystyrene and bovine albumin. The grain radiusa is assumed to obey a distribution of the formN(a) ∝a −α and the value of α is chosen so as to make the calculated extinction curve match the observed interstellar extinction curve. Although the calculated curve gives a reasonably good fit to the observed extinction curve for wavelength less than 2100 Å, at longer wavelength region agreement is poor. It is concluded that another component is required for the organic model to be viable.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00641771
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    Paper (German National Licenses)
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  • 10
    Electronic Resource
    Electronic Resource
    A neutron activation analysis of iridium concentration in Yamato carbonaceous chondrite (1988)
    Springer
    Earth, moon and planets 42 (1988), S. 301-302 
    Details
    ISSN: 1573-0794
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Iridium concentration in extra-terrestrial bodies is an important quantity in relation to Ir-rich geological layers. Ir concentration of a Yamato carbonaceous chondrite (Y-793321) has been measured by a neutron activation method. The measurement yields a value (0.57 ± 0.06) Μg per gramme for the chondrite.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00058494
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