International Journal of Microgravity Science and Application
Online ISSN : 2188-9783
The Critical Growth Rate for Particle Incorporation during the Directional Solidification of Solar Silicon under Microgravity
Tina SORGENFREI Thomas JAUSSArne CRÖLLChristian REIMANNJochen FRIEDRICHMartin VOLZ
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JOURNAL OPEN ACCESS

2017 Volume 34 Issue 1 Pages 340115-

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Abstract

Foreign phase particles, which are engulfed by a growth front and then incorporated into a growing crystal, can cause a variety of problems. These problems can influence the crystal growth process and the preparation of the crystal or reduce the performance of resulting devices. In photovoltaics, the incorporation of SiC particles in VGF silicon leads to a relatively high material loss due to wire saw damages and shunts in the resulting solar cells. Due to the setup of the directional solidification the formation of SiC particles can hardly be avoided. Therefore, it is important to control the incorporation of the particles. It is known that the incorporation is dependent on the size of the particles and on the velocity of the moving solid-liquid interface. Existing theoretical models describe the transition between pushing and engulfment, but growth experiments show that the experimental values for the transition between these two states deviate significantly from the theoretical ones. In this work, several experiments under 1 G conditions and an experiment under µg conditions were done to investigate this question. The µg setup is necessary to get as close as possible to diffusive conditions which are the basic parameters for the theoretical calculations.

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© 2017 The Japan Society of Microgravity Application
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