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Global transition path search for dislocation formation in Ge on Si(001)

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posted on 19.01.2018, 13:44 by E. Maras, O. Trushin, A. Stukowski, Tapio Ala-Nissila, Hannes Jonsson
© 2016 Elsevier B.V.Global optimization of transition paths in complex atomic scale systems is addressed in the context of misfit dislocation formation in a strained Ge film on Si(001). Such paths contain multiple intermediate minima connected by minimum energy paths on the energy surface emerging from the atomic interactions in the system. The challenge is to find which intermediate states to include and to construct a path going through these intermediates in such a way that the overall activation energy for the transition is minimal. In the numerical approach presented here, intermediate minima are constructed by heredity transformations of known minimum energy structures and by identifying local minima in minimum energy paths calculated using a modified version of the nudged elastic band method. Several mechanisms for the formation of a 90° misfit dislocation at the Ge–Si interface are identified when this method is used to construct transition paths connecting a homogeneously strained Ge film and a film containing a misfit dislocation. One of these mechanisms which has not been reported in the literature is detailed. The activation energy for this path is calculated to be 26% smaller than the activation energy for half loop formation of a full, isolated 60° dislocation. An extension of the common neighbor analysis method involving characterization of the geometrical arrangement of second nearest neighbors is used to identify and visualize the dislocations and stacking faults.

History

School

  • Science

Department

  • Mathematical Sciences

Published in

Computer Physics Communications

Volume

205

Pages

13 - 21

Citation

MARAS, E. ...et al., 2016. Global transition path search for dislocation formation in Ge on Si(001). Computer Physics Communications, 205, pp. 13-21.

Publisher

© Elsevier

Version

AM (Accepted Manuscript)

Publisher statement

This work is made available according to the conditions of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0) licence. Full details of this licence are available at: https://creativecommons.org/licenses/by-nc-nd/4.0/

Acceptance date

01/04/2016

Publication date

2016

Notes

This paper was accepted for publication in the journal Computer Physics Communications and the definitive published version is available at https://doi.org/10.1016/j.cpc.2016.04.001

ISSN

0010-4655

Language

en

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