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Title: Atomic scale formation mechanism of edge dislocation relieving lattice strain in a GeSi overlayer on Si(001)
Authors: Maras, E.
Pizzagalli, L.
Ala-Nissila, Tapio
Jonsson, H.
Keywords: Surfaces, interfaces and thin films
Two-dimensional materials
Issue Date: 2017
Publisher: Nature Publishing Group © The Author(s)
Citation: MARAS, E. ... et al, 2017. Atomic scale formation mechanism of edge dislocation relieving lattice strain in a GeSi overlayer on Si(001). Scientific Reports, 7, 11966.
Abstract: Understanding how edge misfit dislocations (MDs) form in a GeSi/Si(001) film has been a long standing issue. The challenge is to find a mechanism accounting for the presence of these dislocations at the interface since they are not mobile and cannot nucleate at the surface and glide towards the interface. Furthermore, experiments can hardly detect the nucleation and early stages of growth because of the short time scale involved. Here we present the first semi-quantitative atomistic calculation of the formation of edge dislocations in such films. We use a global optimization method and density functional theory calculations, combined with computations using potential energy functions to identify the best mechanisms. We show that those previously suggested are relevant only for a low film strain and we propose a new mechanism which accounts for the formation of edge dislocations at high film strain. In this one, a 60° MD nucleates as a "split" half-loop with two branches gliding on different planes. One branch belongs to the glide plane of a complementary 60° MD and therefore strongly favors the formation of the complementary MD which is immediately combined with the first MD to form an edge MD.
Description: This is an Open Access Article. It is published by Nature Publishing Group under the Creative Commons Attribution 4.0 International Licence (CC BY). Full details of this licence are available at: http://creativecommons.org/licenses/by/4.0/
Sponsor: This work has been supported in part by the Academy of Finland through its COMP CoE (T.A.-N., nos 251748 and 284621) and FiDiPro (E.M. and H.J., no. 263294) grants. We acknowledge computational resources provided by the Aalto Science-IT project and CSC IT Center for Science Ltd in Espoo, Finland.
Version: Published
DOI: 10.1038/s41598-017-12009-y
URI: https://dspace.lboro.ac.uk/2134/26995
Publisher Link: https://doi.org/10.1038/s41598-017-12009-y
Appears in Collections:Published Articles (Maths)

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