Electronic Resource
s.l. ; Stafa-Zurich, Switzerland
Solid state phenomena
Vol. 131-133 (Oct. 2007), p. 293-302
ISSN:
1662-9779
Source:
Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
Topics:
Physics
Notes:
The coherent agglomeration of interstitial oxygen into single-plane and double-planeplates can explain the two peaks in the M-shaped nucleation curves in Czochralski silicon. Thedensity of nucleation sites for the double-plane plates corresponds to the VO2 concentration. Abinitio calculations have shown that the agglomeration of oxygen atoms in single-plane and doubleplaneplates is energetically favorable. These plates are under compressive strain. VO2agglomeration plays only a minor role for modeling the M-shaped nucleation curves because ofprior homogenization treatments. It is of much higher impact if as-grown wafers are subjected tonucleation anneals because of the higher vacancy concentration which was frozen in during crystalcooling. This results in higher nucleation rates at higher temperatures.Because the oxygen diffusivity below 700 °C is important for the nucleation rate and manycontroversial results about the diffusivity in this temperature range were published, we haveanalyzed the data from literature. We have demonstrated that the effective diffusivity of oxygen attemperatures below 700 °C which corresponds to the quasi equilibrium dimer concentration is verysimilar to the extrapolation from oxygen diffusivity at high temperature. The high effectivediffusivities from out-diffusion and precipitation experiments, and the somewhat lower effectivediffusivities from dislocation locking experiments are the result of an ongoing formation of fastdiffusing dimers because the equilibrium is disturbed as the result of the strongly increasingdifference in the diffusion length between interstitial oxygen and the fast diffusing dimer withdecreasing temperature
Type of Medium:
Electronic Resource
URL:
http://www.tib-hannover.de/fulltexts/2011/0528/02/24/transtech_doi~10.4028%252Fwww.scientific.net%252FSSP.131-133.293.pdf
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