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Modeling of Undercooling, Nucleation, and Multiple Phase Front Formation in Pulsed-Laser-Melted Amorphous Silicon*

Published online by Cambridge University Press:  25 February 2011

R. F. Wood
Affiliation:
Solid State Division, Oak Ridge National Laboratory, P. O. Box X, Oak Ridge, TN 37831
G. A. Geist
Affiliation:
Engineering Physics and Mathematics Division, Oak Ridge National Laboratory, P. O. Box X, Oak Ridge, TN 37831
A. D. Solomon
Affiliation:
Engineering Physics and Mathematics Division, Oak Ridge National Laboratory, P. O. Box X, Oak Ridge, TN 37831
D. H. Lowndes
Affiliation:
Solid State Division, Oak Ridge National Laboratory, P. O. Box X, Oak Ridge, TN 37831
G. E. Jellison Jr.
Affiliation:
Solid State Division, Oak Ridge National Laboratory, P. O. Box X, Oak Ridge, TN 37831
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Abstract

Recently available experimental data indicate that the solidification of undercooled molten silicon prepared by pulsed laser melting of amorphous silicon is a complex process. Time-resolved reflectivity and electrical conductivity measurements provide information about near-surface melting and suggest the presence of buried molten layers. Transmission electron micrographs show the formation of both fine- and large-grained polycrystalline regions if the melt front does not penetrate through the amorphous layer. We have carried out extensive calculations using a newly developed computer program based on an enthalpy formulation of the heat conduction problem. The program provides the framework for a consistent treatment of the simultaneous formation of multiple states and phase-front propagation by allowing material in each finite-difference cell to melt, undercool, nucleate, and solidify under prescribed conditions. Calculations indicate possibilities for a wide variety of solidification behavior. The new model and selected results of calculations are discussed here and comparisons with recent experimental data are made.

Type
Research Article
Copyright
Copyright © Materials Research Society 1985

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Footnotes

*

Research sponsored by the Division of Materials Sciences, U.S. Department of Energy under contract DE-AC05-840R21400 with Martin Marietta Energy Systems, Inc.

References

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