Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The characteristics of an ion implantation-induced defect in a silicon substrate are investigated. This defect is considered to be a complex of a point defect and a substrate dopant atom. The experiments are conducted by focusing on the dependence of the substrate dopant species (phosphorus and boron) on defect formation. The characteristics of the defect are investigated by measuring the bulk generation lifetime (τg) of metal–oxide–semiconductor capacitors, in which Si+ has been implanted to form the dopant-related defects in the substrate (damaging implantation) after gate oxide formation. As a result, it is found that the τg of the boron-doped substrate is one to two orders of magnitude smaller than that of the phosphorus-doped substrate for the same Nsub under the same implantation conditions. The temperature dependence of τg shows that the energy level of the defect is located at the intrinsic Fermi level, independent of the substrate dopant species and the concentration. By measuring the dependence of τg on the temperature of postdamaging implantation annealing, it is shown that the defects vanish at about 800 °C for both types of substrate. Also, it is found that the amount of dopant-related defects depends on the implantation ion species. BF2+ implantation forms more defects than As+ implantation. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 2
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Dependence of the leakage currents in BF2+ implanted junctions on the dopant concentration of the n-type substrate was investigated. It was clarified that the leakage currents of low-temperature-annealed junctions increase as the substrate dopant concentration increases, while high-temperature-annealed junctions have the opposite dependence. We demonstrate that low-leakage currents can be achieved in low-temperature-annealed junctions by using lightly doped silicon substrate. It was confirmed that the higher leakage currents in low-temperature-annealed junctions originate from the implantation-induced defects existing deeply in the substrate. Considering the results of both BF2+ implanted p+n junction and As+ implanted n+p junction, we discuss an implantation-induced defect generation mechanism. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 3
    ISSN: 0749-503X
    Keywords: Saccharomyces carlsbergensis ; acetate ester ; alcohol ; acetyltransferase ; Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The nucleotide sequences of alcohol acetyltransferase genes isolated from lager brewing yeast, Saccharomyces carlsbergensis have been determined. S. carlsbergensis has one ATF1 gene and another homologous gene, the Lg-ATF1 gene. There was a high degree of homology between the amino acid sequences deduced for the ATF1 protein and the Lg-ATF1 protein (75·7%), but the N-terminal region has a relatively low degree of homology.Southern analysis and contour-clamped homogeneous electric field analysis of Saccharomyces strains suggest that the ATF1 gene is located on chromosome XV in S. cerevisiae and that the Lg-ATF1 gene might originate from the ‘non-S. cerevisiae’ genome of S. carlsbergensis, which is similar to that of S. bayanus and S. pastorianus. The nucleotide sequence data reported in this paper will appear in the DDBJ, EMBL and GenBank data banks with the Accession Numbers D63449 (ATF1) and D63450 (Lg-ATF1).
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 4
    ISSN: 0749-503X
    Keywords: S. pastorianus ; S. cerevisiae ; S. bayanus ; chromosome co-existence ; chromosomal rearrangement ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The bottom fermenting yeasts in our collection were classified as Saccharomyces pastorianus on the basis of their DNA relatedness. The genomic organization of bottom fermenting yeast was analysed by Southern hybridization using eleven genes on chromosome IV, six genes on chromosome II and five genes on chromosome XV of S. cerevisiae as probes. Gene probes constructed from S. cerevisiae chromosomes II and IV hybridized strongly to the 820-kb chromosome and the 1500-kb chromosome of the bottom fermenting yeast, respectively. Five gene probes constructed from segments of chromosome XV hybridized strongly to the 1050-kb and the 1000-kb chromosomes. These chromosomes are thought to be S. cerevisiae-type chromosomes. In addition, these probes also hybridized weakly to the 1100-kb, 1350-kb, 850-kb and 700-kb chromosome. Gene probes constructed from segments including the left arm to TRP1 of chromosome IV and the right arm of chromosome II hybridized to the 1100-kb chromosome of S. pastorianus. Gene probes constructed using the right arm of chromosome IV and the left arm of chromosome II hybridized to the 1350-kb chromosome of S. pastorianus. These results suggested that the 1100-kb and 1350-kb chromosomes were generated by reciprocal translocation between chromosome II and IV in S. pastorianus. Three gene probes constructed using the right arm of chromosome XV hybridized weakly to the 850-kb chromosome, and two gene probes from the left arm hybridized weakly to the 700-kb chromosome. These results suggested that chromosome XV of S. cerevisiae was rearranged into the 850-kb and 700-kb chromosomes in S. pastorianus. These weak hybridization patterns were identical to those obtained with S. bayanus. Therefore, two types of chromosome co-exist independently in bottom fermenting yeast: one set which originated from S. bayanus and another set from S. cerevisiae. This result supports the hypothesis that S. pastorianus is a hybrid of S. cerevisiae and S. bayanus. © 1998 John Wiley & Sons, Ltd.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 5
    ISSN: 0749-503X
    Keywords: alcohol acetyltransferase ; ATF1 gene ; OLE1 gene ; unsaturated fatty acid ; oxygen ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The ATF1 gene encodes an alcohol acetyl transferase which catalyzes the synthesis of acetate esters from acetyl CoA and several kinds of alcohols. ATF1 expression is repressed by unsaturated fatty acids or oxygen. Analysis using ATF1-lacZ fusion plasmid revealed that ATF1 gene expression is widely repressed by a variety of unsaturated fatty acids, and the degree of ATF1 transcriptional repression varies according to the structure of the unsaturated fatty acids. Interestingly, it was noted that the degree of ATF1 transcriptional repression was related to the melting point of unsaturated fatty acids added to the medium. The OLE1 gene, which encodes Δ-9 fatty acid desaturase, has been reported to be repressed by unsaturated fatty acids. Transcription of OLE1 was also repressed by a wide variety of unsaturated fatty acids under anaerobic conditions. The degree of transcriptional repression of OLE1 was also related to the melting point of the added unsaturated fatty acids. Therefore, it is considered that ATF1 and OLE1 transcription are regulated in response to cell membrane fluidity. As has been reported for OLE1, the repression of ATF1 by unsaturated fatty acids was relieved in a disruptant carrying a faa1 and faa4 double mutation, two fatty acid activation genes. However, the ATF1 transcript in this double gene disruptant was repressed by oxygen. These results suggested that ATF1 transcription was co-regulated by the same mechanism as the OLE1 gene and that unsaturated fatty acids and oxygen repressed the ATF1 transcript by a different regulation pathway. © 1998 John Wiley & Sons, Ltd.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 6
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: In order to clarify the origin of enhanced leakage currents observed in As+-implanted junctions annealed at a temperature as low as 450 °C [M. M. Oka, A. Nakada, K. Tomita, T. Shibata, T. Ohmi, and T. Nitta, Jpn. J. Appl. Phys. 34, 796 (1995)], two-step implantation/anneal experiments have been conducted and the spatial distribution of end-of-range defects has been investigated. As a result, it has been demonstrated that the residual damage in 450 °C annealed junctions is strongly influenced by the doping level of p-type silicon substrate. The defects were found deeply distributing in the substrate, i.e., about 350 nm below the silicon surface when the doping level was 2.5×1015 cm−3. The defect distribution further extends for higher boron doping levels. Taking these experimental results into account, As +-implanted n+p junctions were formed on substrates having varying doping levels. About two orders of magnitude reduction in the leakage current was observed with decrease in the substrate boron concentration from 1016 to 1014 cm −3. For low boron concentration of 1.6×1014 cm−3, the leakage current level as low as 1.7×10−9 A/cm2 has been achieved by a 450 °C postimplantation annealing. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...