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  • Electronic Resource  (4)
  • 1985-1989  (4)
  • 1955-1959
  • 81.40E  (2)
  • Phenolics  (2)
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Applied physics 42 (1987), S. 227-232 
    ISSN: 1432-0630
    Keywords: 81.40E ; 61.80B ; 61.70T ; 71.55
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract We have investigated the annealing behaviour of electrically-active defects induced in virgin n-type and residual in As+ implanted p-type silicon after laser irradiation, using the rapid thermal annealing technique (RTA). Spectra from deep level transient spectroscopy (DLTS) show that three majority carrier traps at E (0.32 eV), E (0.45 eV) and E (0.53 eV) were induced in the n-type Si after Nd-Yag laser treatment at 1.6 J cm−2. Annealing in a rapid thermal furnace at 600 °C for times between 5 and 60 s resulted in a linear decrease of the concentration of these defects and for times ≧ 60 s, they are no longer detectable. A similar result was obtained in the case of the multiple energy As+ implanted samples in which two majority carrier traps at H (0.30 eV), H (0.58 eV) and a minority carrier trap E (0.53 eV) completely disappeared after annealing for 45 s at 600 °C, in spite of the very high concentration of the H (0.58 eV) defect (〉1015 cm−3 up to a depth of about 1.5 μm). A comparison of the annealing rates of the E (0.32 eV) trap using the RTA and the conventional thermal annealing (CTA) techniques at 600 °C showed that the former is at least 30 times faster than the latter. Sheet resistance measurements show that the level of dopant deactivation, due to post-laser thermal treatment at 500 °C (in order to obtain the same reduction in residual defect concentration), is less in the RTA processed samples than in those annealed using conventional methods. These results lend strong support to the hypothesis of ionization-induced enhancement of defect annealing, and to our knowledge, represent the first report of the observation of the phenomenon using the RTA technique.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Applied physics 49 (1989), S. 233-237 
    ISSN: 1432-0630
    Keywords: 61.16D ; 61.70N ; 81.40E ; 61.50
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract We have studied the influence of conventional and rapid thermal treatments at 850°C for 30 min and 10 s, respectively, on the recombination activity of theε9,ε13 (P-type) andε25 (N-type) grain boundaries in silicon. The analyses were made by scanning electron microscopy (SEM) working in the electron beam induced current mode (EBIC) and completed by minority carrier diffusion length measurements. The main result obtained from this study shows the importance of the rapid thermal process as a suitable thermal treatment for polycrystalline materials.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Oecologia 79 (1989), S. 563-565 
    ISSN: 1432-1939
    Keywords: Phenolics ; Fine roots ; Stress gradient ; Vegetation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Chemical quality of fine roots (〈1 mm diameter) was determined over a gradient of species composition in the Mixed Mesophytic Forest Region. Ash-free nitrogen, calcium, and phosphorus concentrations of roots declined by 49, 41, and 72%, respectively, over a gradient of increasing soil acidity (pH 5.3 to 4.7). Lignin concentration was unrelated to either the vegetation gradient or any of the soil changes it encompassed; however, astringent phenolics increased by 275% over the same gradient. Trends in the chemical constituency of fine roots suggest that the production of phenolics in below-ground plant parts is increased on nutrient-poor sites. This response is best related to changes in species composition, especially increasing importancy of Quercus spp.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-1939
    Keywords: Phenolics ; Stress gradient ; Vegetation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The chemical constituency of flowering dogwood (Cornus florida L.) and red maple (Acer rubrum L.) foliage was analyzed over a species compositional gradient to test the hypothesis that over subtle gradients of moisture and nutrient availability production of phenolic compounds will be increased on sites of greatest stress. Calcium and nitrogen concentrations declined along the gradient in both species, while phosphorus showed a significant decline only in red maple. Lignin concentrations in both species were unrelated to the vegetation gradient, but astringent phenolics increased by 156% and 159% in dogwood and red maple, respectively. The correlation between production of polyphenolds and site quality supports previous observations that under conditions of environmental stress production of many secondary compounds is increased, and suggests that this relationship is significant over subtle environmental gradients.
    Type of Medium: Electronic Resource
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