The characteristics of interface misfit dislocations for epitaxial α-Fe2O3 on α-Al2O3(0001)

Chong Min Wang, S. Thevuthasan, F. Gao, D. E. McCready, Scott A. Chambers

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    24 Citations (Scopus)

    Abstract

    α-Fe2O3(0001) films of thickness equal to ∼7 nm and ∼70 nm were epitaxially grown on α-Al2O3(0001) by oxygen plasma-assisted molecular beam epitaxy. The interfaces were characterized using high resolution transmission electron microscopy, electron energy-loss spectroscopy, and X-ray diffraction. The interface exhibited coherent regions separated by equally-spaced misfit dislocations. When imaged from the [2̄110] direction, the dislocation spacing is 7.0 ± 1.1 nm for the 70-nm-thick specimen, and 7.2 ± 0.1 nm for the 7-nm-thick specimen. When imaged from the [011̄0] direction, the dislocation spacing is 4.5 ± 0.1 nm for the 7-nm-thick specimen. The experimentally observed dislocation spacings are approximately consistent with those calculated from the lattice mismatch between α-Al2O3 and α-Fe2O3, implying that the lattice mismatch is accommodated mainly by interface misfit dislocations above the critical thickness, which is less than 7 nm. This conclusion is also corroborated by the measured residual strain of ∼0.5% determined from X-ray diffraction for the 70 nm film. Electron-energy-loss-spectroscopy analysis reveals that the Fe L2,3-edge shows no measurable chemical shift relative to the L2,3-edge of structural Fe+3, indicating complete oxidation of Fe in the as-grown film.

    Original languageEnglish
    Pages (from-to)31-38
    Number of pages8
    JournalThin Solid Films
    Volume414
    Issue number1
    DOIs
    Publication statusPublished - 1 Jul 2002

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    Keywords

    • Aluminium oxide
    • Interfaces
    • Iron oxide
    • Transmission electron microscopy

    ASJC Scopus subject areas

    • Electronic, Optical and Magnetic Materials
    • Surfaces and Interfaces
    • Surfaces, Coatings and Films
    • Metals and Alloys
    • Materials Chemistry

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