Structural analysis of Si(111) surfaces during homoepitaxial growth

A. Ichimiya, H. Nakahara, T. Hashizume, T. Sakurai

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    13 Citations (Scopus)

    Abstract

    Atomic structures of Si(111) surfaces during silicon growth are investigated by reflection high-energy electron diffraction (RHEED) and scanning tunneling microscopy (STM). For silicon deposition on the substrate at room temperature, it is concluded that backbonds of adatoms of Takayanagi's dimer-adatom-stacking-fault (DAS) structure are broken at an initial stage of the deposition. The adsorbed atoms are nucleated randomly on the surface, and coalescence of the growth nuclei occurs with few nuclei crossing the dimer rows of the DAS structure. For further deposition, the dimers and the stacking faults remain at the interface between the substrate and the growth amorphous layer. At the substrate temperature of about 300°C, rocking curves of RHEED intensities from the surface during growth are very different from the curve before growth. The structure of the growing surface layer is determined as a pyramidal cluster-type structure by analysis with RHEED dynamical calculations. At this temperature, characteristic features of a cluster structure are found on the surface at an initial stage of the growth. Since crystal nuclei smaller than half the cluster segment are scarcely observed in the STM images, it is concluded that the cluster is the smallest unit of nucleation of homoepitaxial growth. At substrate temperatures from 400 to 600°C a mixed phase of 5 × 5 and 7 × 7 structures, which is the DAS structure, is observed by RHEED and STM. It is discussed that the formation of metastable structures, such as the pyramidal cluster-type structure and the 5 × 5 one, promotes successive epitaxial growth accompanied with stacking-fault dissolution at the dimer-stacking-fault framework.

    Original languageEnglish
    Pages (from-to)284-292
    Number of pages9
    JournalSurface Science
    Volume298
    Issue number2-3
    DOIs
    Publication statusPublished - 1993 Dec 20

    ASJC Scopus subject areas

    • Condensed Matter Physics
    • Surfaces and Interfaces
    • Surfaces, Coatings and Films
    • Materials Chemistry

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