The symmetry and existence ranges of GaSb and AlSb (111) A and B surface reconstructions are investigated using azimuthal-scan reflection high-energy electron diffraction (ARHEED) in a molecular-beam-epitaxy (MBE) environment. ARHEED patterns of all reconstructions within the accessible MBE group V flux-substrate temperature parameter field are presented and analyzed. The transition borders are mapped out as a reference for future growth experiments. The experimental results are interpreted on the basis of general construction principles for (111) surfaces of III-V semiconductors. ARHEED allows the complete determination of the two-dimensional in-plane reciprocal lattice in a single, continuous measurement. This allows the unambiguous identification of the reconstructions on (111) surfaces where the intrinsic symmetry is masked by the 120 • domain structure and possible disorder.
LaLuO 3 layers are epitaxially grown on Si(111) by molecular beam epitaxy using high temperature effusion sources. Samples are prepared by simultaneous as well as alternating growth of La2O3 and Lu2O3. Grazing incidence x-ray diffraction indicates that the resulting crystal structure of the alloys is cubic. Simultaneous and alternating growth with a monolayer period lead to the same distribution of La and Lu with no preferential ordering. In all cases the lattice mismatch to Si is less than 0.6%. The experimental results are analyzed by studying the energetics of hexagonal, bixbyite, and perovskite (La1−xLux)2O3 crystal structures employing density functional theory.
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