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Stress Distribution and Critical Thicknesses of Thin Epitaxial Films

Published online by Cambridge University Press:  28 February 2011

S. Sharan
Affiliation:
Dept. of Materials Science and Engineering, North Carolina State University Raleigh, N. C. 27695
K. Jagannadham
Affiliation:
Dept. of Materials Science and Engineering, North Carolina State University Raleigh, N. C. 27695
J. Narayan
Affiliation:
Dept. of Materials Science and Engineering, North Carolina State University Raleigh, N. C. 27695
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Abstract

We have calculated stress distribution and critical thickness for the growth of strained epilayers having various values of mismatch between the epilayer and the substrate. The present analysis has been carried out assuming that the nucleation of a misift dislocation is controlled by the activation energy. Further, a misfit dislocation is nucleated when the areal strain energy density of the coherent film exceeds the activation energy associated with the misfit dislocation configuration. The latter term has been deternmined using the discrete dislocation method in conjunction with a surface dislocation analysis. The surface dislocation configuration is obtained by minimizing the total energy associated with the two-phase medium. It is verified that the free surface boundary conditions and the continuity of stresses acrosss the interface are satisfied by the surface dislocation array. These energy calculations are expected to be more accurate than those performed by previous workers.

Type
Research Article
Copyright
Copyright © Materials Research Society 1987

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References

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