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Critical Thickness for Strained Quantum Wires

Published online by Cambridge University Press:  15 February 2011

T. J. Gosling
Affiliation:
Department of Applied Mathematics and Theoretical Physics, Cambridge, CB3 9EW, United Kingdom
L. B. Freund
Affiliation:
Division of Engineering, Brown University, Providence, RI 02912, U.S.A.
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Abstract

The stability of strained quantum wires against the propagation of threading dislocations is considered, using a critical thickness criterion due to Matthews and Blakeslee that is extensively used for strained layers. Given first are results for the critical mismatch at which a buried wire of a given thickness becomes susceptible to degradation. It is found that a wire, once buried, is extremely stable, being able to support, without loss of coherency, around five times the lattice mismatch that can be supported by a buried strained layer of the same thickness. It is concluded that if a strained wire contains dislocations then those dislocations must have been introduced during its growth, when the top surface of the wire is exposed. To investigate this, the results of finite element calculations are presented that give the critical relationship between mismatch and thickness during the growth of a triangular quantum wire being deposited in a [110]-oriented V-groove in a patterned (001) substrate. The results may be approximately expressed through an expression of the same form as that derived by Matthews and Blakeslee for a strained layer, but with modified coefficients obtained via the finite element analysis. Contact is made with the limited experimental evidence available.

Type
Research Article
Copyright
Copyright © Materials Research Society 1995

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