The Characteristics of Interface Misfit Dislocations for Epitaxial alpha-Fe2O3 on alpha-Al2O3(0001)
Alpha-Fe2O3(0001) films of thickness equal to {approx}7 nm and {approx}70 nm were epitaxially grown on alpha-Al2O3(0001) by oxygen plasma assisted molecular beam epitaxy (OPA-MBE). The interfaces were characterized using high resolution transmission electron microscopy (HRTEM), electron energy-loss spectroscopy (EELS), and x-ray diffraction (XRD). The interface exhibited coherent regions separated by equally-spaced misfit dislocations. When imaged from the[2110] 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[0110] 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 alpha-Al2O3 and alpha-Fe2O3, implying that the lattice mismatch is accommodated mainly be interface misfit dislocations above the critical thickness, which is less than 7 nm. This conclusion is also corroborated by the measured residual strain of {approx}0.5% determined from x-ray diffraction for the 70 nm film . EELS analysis reveals that the Fe L2,3-edge shows no measurable chemical shift relative to the L2,3-edge of structural Fe3?, indicating complete oxidation of Fe in the as-grown film.
- Research Organization:
- Pacific Northwest National Lab., Richland, WA (US)
- Sponsoring Organization:
- US Department of Energy (US)
- DOE Contract Number:
- AC06-76RL01830
- OSTI ID:
- 15001089
- Report Number(s):
- PNNL-SA-35865; THSFAP; KC0201020; TRN: US200412%%469
- Journal Information:
- Thin Solid Films, Vol. 414; Other Information: PBD: 1 Jul 2002; ISSN 0040-6090
- Country of Publication:
- United States
- Language:
- English
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