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Relaxation of Capped Strained Layers Via the Formation of Microtwins

Published online by Cambridge University Press:  25 February 2011

D. M. Hwang ,
S. A. Schwarz ,
T. S. Ravi ,
R. Bhat  and
C. Y. Chen
D. M. Hwang
Affiliation:
Bellcore, Red Bank, New Jersey 07701–7040, USA
S. A. Schwarz
Affiliation:
Bellcore, Red Bank, New Jersey 07701–7040, USA
T. S. Ravi
Affiliation:
Bellcore, Red Bank, New Jersey 07701–7040, USA
R. Bhat
Affiliation:
Bellcore, Red Bank, New Jersey 07701–7040, USA
C. Y. Chen
Affiliation:
Bellcore, Red Bank, New Jersey 07701–7040, USA
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Abstract

A new strain relief mechanism in epitaxial layers of lattice mismatched face-centered cubic materials is identified using transmission electron microscopy. For an embedded strained layer near its critical thickness, we find that the primary strain-relaxation channel is through the formation of microtwins. A monolayer microtwin (a stacking fault) spanning the strained layer can form when a pair of partial dislocations of the <112> /6 type with antiparallel Burgers vectors are generated inside the strained layer and glide to the opposite interfaces. A series of partial dislocations can result in a microtwin several monolayers thick. For embedded strained layers of materials with small stacking fault energy, the formation of partial dislocation pairs is an energetically-favored strain relaxation channel, as compared to the formation of perfect dislocation pairs in the conventional double-kink model. Therefore, the mechanism proposed here poses fundamental limitations for strained layer device structures.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 202: Symposium C – Evolution of Thin Film and Surface Microstructure , 1990 , 531
Copyright
Copyright © Materials Research Society 1991

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References

REFERENCES

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