Kinetic control of morphology and composition in Ge/GeSn core/shell nanowires

Simone Assali (Corresponding author), Roberto Bergamaschini (Corresponding author), Emilio Scalise (Corresponding author), Marcel A. Verheijen, Marco Albani, Alain Dijkstra, Ang Li, Sebastian Koelling, Erik P.A.M. Bakkers, Francesco Montalenti, Leo Miglio

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The growth of Sn-rich group-IV semiconductors at the nanoscale can enrich the understanding of the fundamental properties of metastable GeSn alloys. Here, we demonstrate the effect of the growth conditions on the morphology and composition of Ge/GeSn core/shell nanowires by correlating the experimental observations with a theoretical interpretation based on a multiscale approach. We show that the cross-sectional morphology of Ge/GeSn core/shell nanowires changes from hexagonal to dodecagonal upon increasing the supply of the Sn precursor. This transformation strongly influences the Sn distribution as a higher Sn content is measured under the {112} growth front. Ab initio DFT calculations provide an atomic-scale explanation by showing that Sn incorporation is favored at the {112} surfaces, where the Ge bonds are tensile-strained. A phase-field continuum model was developed to reproduce the morphological transformation and the Sn distribution within the wire, shedding light on the complex growth mechanism and unveiling the relation between segregation and faceting. The tunability of the photoluminescence emission with the change in composition and morphology of the GeSn shell highlights the potential of the core/shell nanowire system for optoelectronic devices operating at mid-infrared wavelengths.

Original languageEnglish
Pages (from-to)2445-2455
Number of pages11
JournalACS Nano
Issue number2
Publication statusPublished - 25 Feb 2020


  • first-principles calculations
  • germanium tin
  • heterostructure
  • kinetic growth model
  • photoluminescence
  • segregation
  • semiconductor nanowire


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