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Plastic Flow in Si/Ge Quantum Well Structures

Published online by Cambridge University Press:  28 February 2011

M. E. Twigg  and
D. J. Godbey
M. E. Twigg
Affiliation:
GEO-Centers, Inc., 10903 Indian Head Highway, Fort Washington, MD 20742
D. J. Godbey
Affiliation:
Naval Research Laboratory, Code 6816, Washington, D. C. 20375
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Abstract

Plastic flow is driven by excess stress, which can be calculated from lattice strain and dislocation line tension. In order to better understand and model plastic flow, we have derived an expression for the dislocation line tension in thin film structures for double kink (dislocation dipole) extension of a threading dislocation. From these calculations, we conclude that the presence of a free surface (i.e. the vacuum/solid interface) significantly reduces the line tension for an extended double kink. For the specific case of a 50nm thick Si0.7 Ge0.3 layer capped with lum of silicon, we find that the line tension is approximately 30% less than the estimate of an analogous model that neglects the influence of a free surface. Therefore, in order to obtain an accurate estimate of the excess stress for a double kink, one must allow for the influence of a free surface.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 160 , 1989 , 83
Copyright
Copyright © Materials Research Society 1990

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References

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