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  • 1
    Electronic Resource
    Electronic Resource
    Low-temperature annealing of shallow arsenic-implanted layers (1987)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 61 (1987), S. 2189-2194 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Silicon layers implanted with 10 keV arsenic have been characterized using the differential Hall effect, secondary-ion-mass spectrometry, and Rutherford backscattering. Arsenic has been implanted to doses up to 2×1015 cm−2 and the layers have been annealed for 15 min at temperatures in the range 600–900 °C. The maximum free-carrier concentration and sheet resistance obtainable are 2.8×1014 cm−2 and 320 Ω/(D'Alembertian), respectively, for a dose of 1×1015 cm−2 annealed at 700 °C. There is evidence for both the loss of arsenic into a thin surface layer and the incomplete electrical activation of the arsenic remaining in the bulk. It is proposed that incomplete electrical activation is due to clustering in the amorphous phase during the solid-phase-epitaxial regrowth of the layer rather than clustering in the crystalline phase after the regrowth has occurred.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.337979
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Defects and leakage currents in BF2-implanted preamorphized silicon (1986)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 60 (1986), S. 3567-3575 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: High-dose silicon implants have been used to preamorphize the surface of single-crystal silicon prior to the implantation of low-energy BF2. The preamorphization results in shallow junction formation with minimal channeling of the boron, but high concentrations of electrically active defects are formed, leading to excessive reverse bias leakage currents. Measurements of leakage current and deep-level defects indicated that two distinct types of electrically active defects were important: those associated with what are probably complexes or clusters of point defects located near the far end of the range of the implanted silicon, and those associated with extended defects (loops) at the edge of the regrown amorphous region. The former defects were deep-level donors present in high concentrations (〉1017 cm−3) after regrowth of the amorphous layer at 600 or 700 °C and resulted in leakage currents 〉10−4 A/cm2. These centers could be annealed out at 800 °C reducing the leakage current to values between 5×10−8 and 2×10−5 A/cm2 depending upon the relative locations of the extended defects and the metallurgical junction. Measurements and modeling have shown that the location of the band of extended defects is critical in controlling the leakage current and that it will need to be a few hundred angstroms shallower than the junction itself for the associated generation current to be fully suppressed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.337613
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Mobile ion effects in low-temperature silicon oxides (1989)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 66 (1989), S. 187-190 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Mobile ions in oxides formed on silicon by low-temperature processes have been studied using a combination of bias-temperature stress and triangular voltage sweep experiments. It is found that these oxides contain intrinsically low concentrations of mobile ions (〈1010 cm−2) and that the ionic instabilities which are seen are due to alkali metal ions rather than other contaminants or the inherent water and hydrogen. Mobile sodium behaves slightly differently in low-temperature oxides compared with conventional thermal oxides, and can be gettered and passivated using a low-temperature process. It is shown that sodium ions are trapped by polycrystalline silicon during plasma hydrogenation, and that atomic hydrogen is involved in this process. The trapped ions are released back into the oxide during subsequent bias-temperature stressing.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.343902
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    A comparison between Sb and As implantation for the formation of highly conducting shallow silicon layers (1987)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 62 (1987), S. 3441-3443 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Highly conducting silicon layers of less than 500 A(ring) in thickness have been formed following the implantation of 12-keV antimony or 10-keV arsenic and subsequent annealing at 700 °C for 15 min. Minimum resistivities of 2.2×10−4 Ω cm for antimony and 6.5×10−4 Ω cm for arsenic at a dose of 1×1015 cm−2 are obtained, with corresponding peak electrical activities of ∼4.8×1020 cm−3 and ∼1.6×1020 cm−3, respectively. Both correspond to metastable states well above the equilibrium solid solubilities. Whereas the arsenic activity remains almost unchanged for anneals of up to ∼300 min, the higher antimony activity decreases, but remains above that of the arsenic.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.339310
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  • 5
    Electronic Resource
    Electronic Resource
    RFLP Mapping in Plant Breeding: New Tools for an Old Science (1989)
    [s.l.] : Nature Publishing Company
    Nature biotechnology 7 (1989), S. 257-264 
    Details
    ISSN: 1546-1696
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: [Auszug] Breeders have traditionally improved plant varieties by selecting on the basis of phenotype. Now restriction fragment length polymorphism (RFLP) linkage maps are being constructed for most major crop plants and these maps provide a more direct method for selecting desirable genes via their linkage ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/nbt0389-257
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  • 6
    Electronic Resource
    Electronic Resource
    RFLP analysis of the size of chromosomal segments retained around the Tm-2 locus of tomato during backcross breeding (1989)
    Springer
    Theoretical and applied genetics 77 (1989), S. 353-359 
    Details
    ISSN: 1432-2242
    Keywords: Introgression ; Linkage drag ; Lycopersicon ; Restriction fragment length polymorphisms ; Tobacco mosaic virus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Genes introduced into cultivated plants by backcross breeding programs are flanked by introgressed segments of DNA derived from the donor parent. This phenomenon is known as linkage drag and is frequently thought to affect traits other than the one originally targeted. The Tm-2 gene of Lycopersicon peruvianum, which confers resistance to tobacco mosaic virus, was introduced into several different tomato cultivars (L. esculentum) by repeated backcrossing. We have measured the sizes of the introgressed segments flanking the Tm-2 locus in several of these cultivars using a high density map of restriction fragment length polymorphic (RFLP) markers. The smallest introgressed segment is estimated to be 4 cM in length, while the longest is over 51 cM in length and contains the entire short arm of chromosome 9. Additionally, RFLP analysis was performed on remnant seed from different intermediate generations corresponding to two different backcross breeding programs for TMV resistance. The results reveal that plants containing desirable recombination near the resistance gene were rarely selected during backcrossing and, as a result, the backcross breeding method was largely ineffective in reducing the size of linked DNA around the resistance gene. We propose that, by monitoring recombination around genes of interest with linked RFLP markers, one can quickly and efficiently reduce the amount of linkage drag associated with introgression. Using such a procedure, it is estimated that an introgressed segment can be obtained in two generations that is as small as that which would otherwise require 100 backcross generations without RFLP selection.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00305828
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  • 7
    Electronic Resource
    Electronic Resource
    Restriction fragment length polymorphism maps and the concept of graphical genotypes (1989)
    Springer
    Theoretical and applied genetics 77 (1989), S. 95-101 
    Details
    ISSN: 1432-2242
    Keywords: RFLPs ; Haplotypes ; Selection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary With the advent of high density restriction fragment length polymorphism (RFLP) maps, it has become possible to determine the genotype of an individual at many genetic loci simultaneously. Often, such RFLP data are expressed as long strings of numbers or letters indicating the genotype for each locus analyzed. In this form, RFLP data can be difficult to interpret or utilize without complex statistical analysis. By contrast, numerical genotype data can also be expressed in a more useful, graphical form, known as a “graphical genotype”, which is described in detail in this paper. Ideally, a graphical genotype portrays the parental origin and allelic composition throughout the entire genome, yet is simple to comprehend and utilize. In order to demonstrate the usefulness of this concept, graphical genotypes for individuals from backcross and F2 populations in tomato are described. The concept can also be utilized in more complex mating schemes involving two or more parents. A model that predicts the accuracy of graphical genotypes is presented for hypothetical RFLP maps of varying marker spacing. This model indicates that graphical genotypes can be more than 99% correct in describing a genome of total size, 1000 cM, with RFLP markers located every 10 cM. In order to facilitate the application of graphical genotypes to genetics and breeding, we have developed computer software that generates and manipulates graphical genotypes. The concept of graphical genotypes should be useful in whole genome selection for polygenic traits in plant and animal breeding programs and in the diagnosis of heterogenously based genetic diseases in humans.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00292322
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