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Stress Distribution and Critical Thickness of Thin Epitaxial Films

Published online by Cambridge University Press:  26 February 2011

S. Sharan
Affiliation:
Department of Materials Science and Engineering, North Carolina State University, Raleigh, N. C. 27695 – 7916
J. Narayan
Affiliation:
Department of Materials Science and Engineering, North Carolina State University, Raleigh, N. C. 27695 – 7916
K. Jagannadham
Affiliation:
Department of Materials Science and Engineering, North Carolina State University, Raleigh, N. C. 27695 – 7916
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Abstract

We have calculated the stress distribution and critical thickness for the growth of strained epilayers having various values of misfit between the epilayer and the substrate. During formation of epitaxial films, the growth (pseudomorphic) occurs upto a certain thickness with planar spacing normal to the interface being essentially the same both in the substrate and the film. Above a critical thickness it becomes energetically favorable for the film to contain dislocations. This occurs usually by generating glide dislocations near the free surface because there is a lack of dislocation sources in mostly “defect-free” semiconductor materials. We present an analysis of the critical phenomena in semiconductors based upon this experimental fact. In all the previous analyses, the critical step associated with the generation of dislocations was neglected. We also consider finite (island) growth of thin films and its effect on critical phenomena. The experimental results show the presence of glide dislocations in Ge/Si with the extra half planes in silicon substrate.

Type
Research Article
Copyright
Copyright © Materials Research Society 1988

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References

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