Critical strain for Sn incorporation into spontaneously graded Ge/GeSn core/shell nanowires

Marco Albani, Simone Assali, Marcel A. Verheijen, Sebastian Koelling, Roberto Bergamaschini, Fabio Pezzoli, Erik P.A.M. Bakkers, Leo Miglio*

*Corresponding author for this work

    Research output: Contribution to journalArticleScientificpeer-review

    20 Citations (Scopus)

    Abstract

    We address the role of non-uniform composition, as measured by energy-dispersive x-ray spectroscopy, in the elastic properties of core/shell nanowires for the Ge/GeSn system. In particular, by finite element method simulations and transmission electron diffraction measurements, we estimate the residual misfit strain when a radial gradient in Sn and a Ge segregation at the nanowire facet edges are present. An elastic stiffening of the structure with respect to the uniform one is concluded, particularly for the axial strain component. More importantly, refined predictions linking the strain and the Sn percentage at the nanowire facets enable us to quantitatively determine the maximum compressive strain value allowing for additional Sn incorporation into a GeSn alloy. The progressive incorporation with increasing shell thickness, under constant growth conditions, is specifically induced by the nanowire configuration, where a larger elastic relaxation of the misfit strain takes place.

    Original languageEnglish
    Pages (from-to)7250-7256
    JournalNanoscale
    Volume10
    Issue number15
    DOIs
    Publication statusPublished - 2018

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