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  • 1
    Electronic Resource
    Electronic Resource
    Effect of Hydrostatic Pressure on Self-Interstitial Diffusion in Si, Ge, Si〈Ge〉 Crystals: Quantum-Chemical Simulations Ge (2007)
    s.l. ; Stafa-Zurich, Switzerland
    Solid state phenomena Vol. 131-133 (Oct. 2007), p. 271-276 
    Details
    ISSN: 1662-9779
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Physics
    Notes: A theoretical modeling of the diffusion of self-interstitials in silicon and germaniumcrystals both at normal and high hydrostatic pressure has been carried out using molecularmechanics, semiempirical (PM3, PM5) and ab-initio (SIESTA) methods. According to thesimulation for the Si and Ge neutral interstitials (I0) both in silicon and germanium crystals morestable configuration is 〈110〉 split interstitial. T is the stable configuration for the double positiveinterstitial I++, but the interstitial is displaced from the high-symmetry site. Stability of 〈110〉 splitinterstitialis not changed under hydrostatic pressure. The activation barriers for the diffusion ofinterstitials were determined and equal to ΔEa(Si)(〈110〉 -〉 T1)=0.69 eV; ΔEa (Ge)(〈110〉 -〉T1)=1.1 eV. For mixed interstitials the calculated activation barriers equal Si[removed info]Emix = 1.06 eV,Ge[removed info]Emix = 0.86 eV. Hydrostatic pressure decreases the activation barriers ΔEa(Si), ΔEa (Ge)
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/02/24/transtech_doi~10.4028%252Fwww.scientific.net%252FSSP.131-133.271.pdf
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  • 2
    Electronic Resource
    Electronic Resource
    Radiation-Induced Defect Reactions in Cz-Si Crystals Contaminated with Cu (2007)
    s.l. ; Stafa-Zurich, Switzerland
    Solid state phenomena Vol. 131-133 (Oct. 2007), p. 363-368 
    Details
    ISSN: 1662-9779
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Physics
    Notes: The influence of Cu contamination on radiation-induced defect reactions in n-typeCzochralski-grown silicon (Cz-Si) crystals has been studied by means of the Hall effect technique,deep level transient spectroscopy (DLTS) and high-resolution Laplace DLTS with supportingtheoretical modeling of defects.It is found that the contamination of Cz-Si samples with Cu does not influence significantly theenergy spectrum and introduction rates of the principal electrically active defects induced byelectron irradiation. The vacancy-oxygen (VO) centre, divacancy (V2) and a complex consisting ofa silicon self-interstitial with the oxygen dimer (IO2) are found to be the dominant radiation-induceddefects in Cu-contaminated samples as well as in uncontaminated ones. An isochronal annealingstudy has shown that the presence of Cu affects the annealing behaviour of the vacancy-relateddefects. In Cu-doped samples the VO centre disappears upon annealing at significantly lowertemperatures (175-250°C) compared to those of the VO disappearance in the uncontaminatedsamples (300-375°C). The disappearance of the VO centres in the Cu-doped samples occurssimultaneously with an anti-correlated introduction of a defect with an energy level at about Ec-0.60 eV. It is suggested that this defect is formed by the interaction of a mobile Cu atom with theVO complex. According to results of quantum-chemical modelling, in the most stableconfiguration of the Cu-VO defect a Cu atom occupies a tetrahedral interstitial position nearest tothe elongated Si-Si bond of the VO centre. The presence of the Cu atom is found to result in thefurther elongation of the Si-Si bond and a shift of the VO acceptor level to the middle of the gap.The annealing behaviour of V2 has also been found to be different in the irradiated Cu-dopedsamples compared to that in the uncontaminated ones. The most probable reason for this differenceis an interaction of mobile Cu atoms with di-vacancies. An energy level at about Ec-0.17 eV hasbeen tentatively assigned to a complex consisting of a Cu atom and a di-vacancy
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/02/24/transtech_doi~10.4028%252Fwww.scientific.net%252FSSP.131-133.363.pdf
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  • 3
    Electronic Resource
    Electronic Resource
    General Model of Diffusion of Interstitial Oxygen in Silicon, Germanium and Silicon - Germanium Crystals (2005)
    s.l. ; Stafa-Zurich, Switzerland
    Solid state phenomena Vol. 108-109 (Dec. 2005), p. 413-418 
    Details
    ISSN: 1662-9779
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Physics
    Notes: A theoretical modelling of the oxygen diffusivity in silicon, germanium and Si1-xGex (O) crystals both at normal and high hydrostatic pressure has been carried out using molecular mechanics, semiempirical and ab initio methods. It was established that the diffusion process of an interstitial oxygen atom (Oi) is controlled by the optimum configuration of three silicon (germanium) atoms nearest to Oi. The calculated values of the activation energy [removed info]Ea (Si) = 2.59 eV, [removed info]Ea(Ge) = 2.05 eV and pre-exponential factor D0(Si) = 0.28 cm2 s−1, D0(Ge) = 0.39 cm2 s−1 are in good agreement with experimental ones and for the first time describe perfectly the experimental temperature dependence of the Oi diffusion constant in Si crystals (T = 350–1200 ◦C). Hydrostatic pressure (P ≤ 80 kbar) results in a linear decrease of the diffusion barrier (∂P [removed info]Ea (P) = −4.38 × 10−3 eV kbar−1 for Si crystals). The calculated pressure dependence of Oi diffusivity in silicon crystals agrees well with the pressure-enhanced initial growth of oxygen-related thermal donors. The simulation (PM5) has revealed that in Si1-xGex crystals there are two mechanisms of variation of Oi diffusion barrier. The increase of lattice constant leads to the linear increase of the diffusion barrier. Strains around Ge atoms decrease the diffusion barrier. Formation of gradient of diffusion barrier in the volume of Si1-xGex may be responsible for the experimentally observed suppression of generation of TD in Si1-xGex (O) crystals
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/02/21/transtech_doi~10.4028%252Fwww.scientific.net%252FSSP.108-109.413.pdf
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