Misfit dislocation and threading dislocation distributions in InGaAs and GeSi/Si partially relaxed heterostructures (Articolo in rivista)

Type
Label
  • Misfit dislocation and threading dislocation distributions in InGaAs and GeSi/Si partially relaxed heterostructures (Articolo in rivista) (literal)
Anno
  • 2002-01-01T00:00:00+01:00 (literal)
Alternative label
  • Ferrari C. 1, Rossetto G. 2, Fitzgerald E.A. 3 (2002)
    Misfit dislocation and threading dislocation distributions in InGaAs and GeSi/Si partially relaxed heterostructures
    (literal)
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  • Ferrari C. 1, Rossetto G. 2, Fitzgerald E.A. 3 (literal)
Pagina inizio
  • 437 (literal)
Pagina fine
  • 440 (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#numeroVolume
  • 91 (literal)
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  • X-ray topography technique is normally used to investigate sample with a low density of structural defects due to the relatively large size of defect image given by X-ray diffraction. Nevertheless in partially relaxed structures with misfit dislocation (MD) density up to 10000 cm-1, the rather large fluctuation of local MD density produces a contrast in X-ray topographs which can be used to study the MD distribution. Thanks to that particular features, X-ray topography has been used to study InGaAs and GeSi/Si samples with lattice mismatch. The analysis of the X-ray topographs evidenced that the increase of the strain release leads to the formation of much shorter MD segments, the main responsible for such mechanism being the blocking mechanism of MDs. The shorter average MD length for comparable MD linear dislocation densities in GeSi/Si heterostructures with respect to InGaAs/GaAs ones are due to the lower glide mobility of dislocations, as confirmed by the topograph of a metastable GeSi/Si heterostructure beyond the critica] thickness. As a result the threading dislocation densities evaluated by the strain release and the average length of the MD segments increase more rapidly with the strain release in GeSi/Si heterostructures with respect to equivalent InGaAs/GaAs ones. In comparison InGaAs/GaAs composition graded heterostructures show much longer MD segments thus confirming the reduction of dislocation interaction in such systems. (literal)
Note
  • ISI Web of Science (WOS) (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#affiliazioni
  • 2 ICIS-CNR; 1 CNR; 3 MIT USA (literal)
Titolo
  • Misfit dislocation and threading dislocation distributions in InGaAs and GeSi/Si partially relaxed heterostructures (literal)
Abstract
  • Single and compositionally graded InGaAs/GaAs and SiGe/Ge partially relaxed heterostructures of equivalent lattice mismatch and thickness have been characterized by high resolution X-ray diffraction and by X-ray double crystal topography. X-ray topography evidences a rapid decrease of the average length of misfit dislocation segments with the increase of the density of misfit dislocations both in InGaAs and GeSi/Si structures. For an equivalent amount of strain release, SiGe/Si heterostructures exhibit shorter misfit dislocation lengths with respect to InGaAs/GaAs heterostructures. Compositionally graded InGaAs/GaAs heterostructures show much longer misfit dislocation segments with respect to equivalent single heterostructures, thus confirming the effectiveness of composition grading to reduce the dislocation interaction. The threading dislocation density evaluated from the lattice mismatch and the average length of the misfit dislocations on the basis of a simple formula increases more rapidly as a function of strain release in GeSi/Si heterostructures with respect to InGaAs/GaAs ones. (literal)
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