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  • 1
    Electronic Resource
    Electronic Resource
    Defects in Carbon Allotropes Studied by Positron Annihilation (2008)
    s.l. ; Stafa-Zurich, Switzerland
    Materials science forum Vol. 607 (Nov. 2008), p. 149-151 
    Details
    ISSN: 1662-9752
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Slow positron beam technique has been employed to study the defects of graphite, nanophase C, as well as the structural changes in un-doped, B-doped and S-doped diamond films with annealing temperatures. The results show that the concentration of defects in nanophase C is higher than that in graphite. The vacancy concentration in the S-doped diamond film is higher than that in un-doped one. The addition of small amount of B atoms leads to the decrease of the vacancy concentration in the film. The vacancy concentration in un-doped diamond film would decrease after annealing at temperature below 600ºC, while vacancy concentration will increase after annealing at temperatures above 900ºC. The vacancy concentration in the 40 Ω cm B-doped diamond film decreases at annealing temperatures higher than 200ºC
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/02/20/transtech_doi~10.4028%252Fwww.scientific.net%252FMSF.607.149.pdf
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Influence of Sintering Temperature on Defects in Porous Silica Monoliths Studied by Positron Annihilation Techniques (2008)
    s.l. ; Stafa-Zurich, Switzerland
    Materials science forum Vol. 607 (Nov. 2008), p. 204-206 
    Details
    ISSN: 1662-9752
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Positron lifetime and coincidence Doppler broadening spectra for porous silica calcined at temperatures from 900 to 1500 oC have been measured. As the sintering temperatures increasing from 900 to 1000 oC, the height of the peaks of the ratio curves decrease, and the τ3 increases, which is due to the exclusion of the gas and the organic substance out of the cavities. As the sintering temperatures increasing from 1000 to 1250 oC, some of the defects were recovered, the grains of low quarts appearing and growing. This gives rise to the increase of the height of the peak of the ratio curve, and the decrease of lifetime (τ1,τ2 and τ3). As the sintering temperatures increasing from 1250 to 1500oC, the height of the peak of the ratio curve decreases, and the lifetime increases due to the phase transition of low quartz to cristobalite
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/02/20/transtech_doi~10.4028%252Fwww.scientific.net%252FMSF.607.204.pdf
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    The Behavior of Oxygen and Defects in Si-Based Semiconductor Studied by Positron Annihilation Techniques (2008)
    s.l. ; Stafa-Zurich, Switzerland
    Materials science forum Vol. 607 (Nov. 2008), p. 131-133 
    Details
    ISSN: 1662-9752
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Slow positron beam and coincidence Doppler broadening techniques have been used to follow temperature-induced defects and structural changes in Cz-Si with an initial oxygen content of 1.1×1018 cm-3. Oxygen is recognized as a peak at about 11.85×10-3m0c on the ratio curves. For Cz-Si annealed at 480 oC/15h or 600 oC/15h, the ratio curves show the presence of vacancy-like defects, but they are not associated with oxygen. For Cz-Si annealed at 480 oC/15h, then followed by a 600 oC/15h heat treatment, the ratio curves show the signal of O atom. The ratio curves of Cz-Si, thermally treated by a two-step (480oC/15h + 600oC/15h) pre-annealing, followed by a one-step annealing under different hydrostatic argon pressures and annealed temperatures, also show a peak at 11.85×10-3m0c. The height of the peak varies with different samples. Experimental results indicate that the SiO2 film will form on the surface of Cz-Si after the heat treatment
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/02/20/transtech_doi~10.4028%252Fwww.scientific.net%252FMSF.607.131.pdf
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Positron Annihilation on the Surfaces of Single Crystals of Si, SiO〈sub〉2〈/sub〉, Graphite and Cu (2008)
    s.l. ; Stafa-Zurich, Switzerland
    Materials science forum Vol. 607 (Nov. 2008), p. 152-154 
    Details
    ISSN: 1662-9752
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Slow positron beam technique has been applied to measure the Doppler broadening spectra for single crystals of Cu, SiO2, graphite, virgin Si, and Si without oxide film. The results show that the Cu ratio curve shows a high peak due to Cu having 10 electrons in the 3d shells. The ratio curve of SiO2 is higher than that of graphite. For the single crystal of Cu, SiO2, graphite, and Si without oxide film, the S (W) parameters decrease (increase) as positron implantation energy increasing. Defects on the surface lead to higher S (lower W) value. For the virgin Si and the thermally grown SiO2-Si samples, the S (W) parameters increase (decrease) as positron implantation energy increasing. It can be due to Si atom at surface, with two dangling bonds, tend to form silicon oxide with O. The W parameter for the single crystal of Cu is relatively high as compared with that of the single crystals of SiO2 and graphite
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/02/20/transtech_doi~10.4028%252Fwww.scientific.net%252FMSF.607.152.pdf
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    Paper (German National Licenses)
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