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Minimum energy path for the nucleation of misfit dislocations in Ge/Si(0 0 1) heteroepitaxy

Trushin, O. and Maras, E. and Stukowski, A. and Granato, E. and Ying, S. C. and Jónsson, H. and Ala-Nissila, T. (2016):
Minimum energy path for the nucleation of misfit dislocations in Ge/Si(0 0 1) heteroepitaxy.
In: Modelling and Simulation in Materials Science and Engineering, IOP Publishing, pp. 035007, 24, (3), ISSN 0965-0393,
[Online-Edition: http://dx.doi.org/10.1088/0965-0393/24/3/035007],
[Article]

Abstract

A possible mechanism for the formation of a 90° misfit dislocation at the Ge/Si(0 0 1) interface through homogeneous nucleation is identified from atomic scale calculations where a minimum energy path connecting the coherent epitaxial state and a final state with a 90° misfit dislocation is found using the nudged elastic band method. The initial path is generated using a repulsive bias activation procedure in a model system including 75 000 atoms. The energy along the path exhibits two maxima in the energy. The first maximum occurs as a 60° dislocation nucleates. The intermediate minimum corresponds to an extended 60° dislocation. The subsequent energy maximum occurs as a second 60° dislocation nucleates in a complementary, mirror glide plane, simultaneously starting from the surface and from the first 60° dislocation. The activation energy of the nucleation of the second dislocation is 30% lower than that of the first one showing that the formation of the second 60° dislocation is aided by the presence of the first one. The simulations represent a step towards unraveling the formation mechanism of 90° dislocations, an important issue in the design of growth procedures for strain released Ge overlayers on Si(1 0 0) surfaces, and more generally illustrate an approach that can be used to gain insight into the mechanism of complex nucleation paths of extended defects in solids.

Item Type: Article
Erschienen: 2016
Creators: Trushin, O. and Maras, E. and Stukowski, A. and Granato, E. and Ying, S. C. and Jónsson, H. and Ala-Nissila, T.
Title: Minimum energy path for the nucleation of misfit dislocations in Ge/Si(0 0 1) heteroepitaxy
Language: English
Abstract:

A possible mechanism for the formation of a 90° misfit dislocation at the Ge/Si(0 0 1) interface through homogeneous nucleation is identified from atomic scale calculations where a minimum energy path connecting the coherent epitaxial state and a final state with a 90° misfit dislocation is found using the nudged elastic band method. The initial path is generated using a repulsive bias activation procedure in a model system including 75 000 atoms. The energy along the path exhibits two maxima in the energy. The first maximum occurs as a 60° dislocation nucleates. The intermediate minimum corresponds to an extended 60° dislocation. The subsequent energy maximum occurs as a second 60° dislocation nucleates in a complementary, mirror glide plane, simultaneously starting from the surface and from the first 60° dislocation. The activation energy of the nucleation of the second dislocation is 30% lower than that of the first one showing that the formation of the second 60° dislocation is aided by the presence of the first one. The simulations represent a step towards unraveling the formation mechanism of 90° dislocations, an important issue in the design of growth procedures for strain released Ge overlayers on Si(1 0 0) surfaces, and more generally illustrate an approach that can be used to gain insight into the mechanism of complex nucleation paths of extended defects in solids.

Journal or Publication Title: Modelling and Simulation in Materials Science and Engineering
Volume: 24
Number: 3
Publisher: IOP Publishing
Uncontrolled Keywords: dislocation, nucleation, nudged elastic band method, Ge, Si
Divisions: 11 Department of Materials and Earth Sciences
11 Department of Materials and Earth Sciences > Material Science
11 Department of Materials and Earth Sciences > Material Science > Materials Modelling
Date Deposited: 28 Apr 2016 11:48
Official URL: http://dx.doi.org/10.1088/0965-0393/24/3/035007
Identification Number: doi:10.1088/0965-0393/24/3/035007
Funders: Academy of Finland through FiDiPro program : Grant Nr. 263294, COMP CoE : Grant Nr. 251748, Fundacao de Amparo a Pesquisa do Estado de Sao Paulo-FAPESP : Grant Nr. 2014/15372-3, Russian Foundation for Basic Reserch : Grant Nr. 14-00139a, Brazilian Initiative Collaboration Grant - Watson Institute at Brown University
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