Numerical Study of Small Accelarations Influence on Composition Uniformity of a Growing Crystal
- Paper number
IAC-05-A2.4.04
- Author
Dr. Alexander Senchenkov, Design Bureau of General Machine-Building (KBOM), Russia
- Year
2005
- Abstract
NUMERICAL STUDY OF SMALL ACCELERATIONS INFLUENCE ON COMPOSITION UNIFORMITY OF A GROWING CRYSTAL. Contact author: A.S.Senchenkov KBOM, Berezhkovskaya emb. 22, 121059 Moscow, Russia Ph.: +70952406103, fax: +70952404196, e-mail: senchenkov@rambler.ru Co-Authors: I.V.Barmin, N.A.Gorev, A.I.Kiryanov KBOM, Berezhkovskaya emb. 22, 121059 Moscow, Russia Ph.: +70952406044, fax: +70952404196, e-mail: barmin@kbom.msk.ru In experiments on semiconductor crystal growth onboard different spacecrafts the numerous proofs of strong influence of small accelerations on growing crystal composition are obtained. Especially strong influence was observed at crystal growth of solid solutions. Hence, by ground preparation of experiments on Space Material Science, it is desirable to carry out a numerical modeling of prospective process with using the mathematical models which are as much as possible taking into account real conditions of the flight. Real dynamic conditions onboard a spacecraft has a complex three-dimensional character. The resulting vector of accelerations changes permanently both on magnitude, and on direction. Therefore three-dimensional models should be applied to numerical modeling of space experiments. In the presentation the results of calculations, in three-dimensional problem definition, for the dynamic conditions measured onboard FOTON spacecraft, for two typical space experiments on semiconductor crystal growth are resulted: growth of the doped crystal (Ge:Ga) and growth of the solid solution (ZnxCd1-xTe). Change in time of a flow pattern in the melt, in particular, near to the growing interface, and influence of this flow on the crystallization interface shape are shown. As the result, the composition distribution of the crystal growing in the considered conditions is calculated. The comparative analysis of small accelerations influence on composition of the growing crystal for two considered cases is given: growth of the doped crystal and growth of the solid solution. Influence of the small accelerations in the second case considerably stronger, because at growth of ternary compounds the temperature at the crystallization interface depends on the component concentration in the melt. As the influence of weak convective flows on concentration field in the case of semiconductor crystal growth essentially stronger, than on temperature field, these flows cause strong deformation of the growing interface and, as a consequence, lead to inhomogeneity of composition in the crystal cross-sections.
- Abstract document
- Manuscript document
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