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The Nucleation and Propagation of Misfit Dislocations aear the Critical Thickness in Ge-Si Strained Epilayers

Published online by Cambridge University Press:  26 February 2011

E. P. Kvam ,
D. J. Eaglesham ,
D. M. Maher ,
C. J. Humphreys ,
J. C. Bean ,
G. S. Green  and
B. K. Tanner
E. P. Kvam
Affiliation:
Department of Materials Science and Engineering, University of Liverpool, Liverpool L693BX, UK
D. J. Eaglesham
Affiliation:
Department of Materials Science and Engineering, University of Liverpool, Liverpool L693BX, UK
D. M. Maher
Affiliation:
Department of Materials Science and Engineering, University of Liverpool, Liverpool L693BX, UK AT&T Bell Laboratories, Murray Hill, NJ 07974, USA
C. J. Humphreys
Affiliation:
Department of Materials Science and Engineering, University of Liverpool, Liverpool L693BX, UK
J. C. Bean
Affiliation:
Department of Materials Science and Engineering, University of Liverpool, Liverpool L693BX, UK
G. S. Green
Affiliation:
Department of Physics, University of Durham, Durham DH1 3HP, UK
B. K. Tanner
Affiliation:
Department of Physics, University of Durham, Durham DH1 3HP, UK
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Abstract

The nucleation and propagation of misfit dislocations in Ge-Si strained epilayers on (100) Si have been investigated using transmission electron microscopy and X-ray diffraction topography at low lattice parameter mismatch (˜ 0.8%). Misfit dislocations nucleate as half loops which are predominantly unfaulted (> 90%) at the advancing growth interface. Under the driving force of the epilayer strain, unfaulted half loops glide and expand on inclined { 111 }planes toward the heterointerface (i.e. substrate/epilayer interface). These unfaulted half loops consist of a 60°-dislocation segment which lies along < 011> in a plane parallel to the heterointerface (i.e. (100)) and this segment is connected to the growth interface by two screw dislocation segments which both lie on the same inclined {111} glide plane. As 60° dislocations reach the heterointerface on each of the four inclined {111} variants, they form an orthogonal array of misfit dislocations which lie along [011] and [011]. At higher lattice parameter mismatch (˜ 2%), there appear to be some important changes in the dislocation behavior and these changes result in orthogonal arrays of heterointerface dislocations which are predominantly edge type (i.e. 90°dislocations).

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 104 , 1987 , 623
Copyright
Copyright © Materials Research Society 1988

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References

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