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Emission of a Half-Rectangular Dislocation Loop from the Surface of a Compositionally Graded Epilayer

Published online by Cambridge University Press:  21 February 2011

Tong-Yi Zhang
Tong-Yi Zhang*
Affiliation:
Department of Mechanical Engineering Hong Kong University of Science and Technology Clear Water Bay, Kowloon, Hong Kong
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Abstract

When a half-rectangular perfect or partial dislocation loop is emitted from the surface of a strained epilayer, the optimum dislocation shape occurs at a saddle point of the total energy profile as a function of the dislocation width and length. The activation energy and the optimum shape are calculated for either a compositionally graded or uniform epilayer. The results indicate that 1) dislocation emission is more difficult in a compositionally graded layer than in a compositionally uniform layer; and 2) the ratio of threading dislocation density to mismatch dislocation density is lower in a compositionally graded layer than in a compositionally uniform layer. Theoretical results agree with experimental observations [1,2].

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References

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